Organic spin clusters: Macrocyclic-macrocyclic polyarylmethyl polyradicals with very high spin S = 5-13

Published on Web 05/08/2004

Organic Spin Clusters: Macrocyclic-Macrocyclic

Polyarylmethyl Polyradicals with Very High Spin S ) 5-13

Andrzej Rajca,* Jirawat Wongsriratanakul, and Suchada Rajca

Contribution from the Department of Chemistry, UniVersity of Nebraska,

Lincoln, Nebraska 68588-0304

Received December 5, 2003; E-mail: arajca1@unl.edu

Abstract: Synthesis and magnetic studies of a new class of organic spin clusters, possessing alternating

connectivity of unequal spins, are described. Polyarylmethyl polyether precursors to the spin clusters, with

linear and branched connectivity between calix[4]arene-based macrocycles, are prepared via modular,

multistep syntheses. Their molecular connectivity and stereoisomerism are analyzed using NMR

spectroscopy. The absolute masses (4-10 kDa) are determined by FABMS and GPC/MALS. Small angle

neutron scattering (SANS) provides the radii of gyration of 1.2-1.8 nm. The corresponding polyradicals

with 15, 22, and 36 triarylmethyls, which are prepared and studied as solutions in tetrahydrofuran-d₈, may

be described as S′ ) 7/2, 1/2, 7/2 spin trimer (average S ) 5-6), S′ ) 7/2, 1/2, 6/2, 1/2, 7/2 spin pentamer

(average S ) 7-9), and spin nonamer (average S ) 11-13), respectively, as determined by SQUID

magnetometry and numerical fits to linear combinations of the Brillouin functions. For spin trimer and

pentamer, the quantitative magnetization data are fit to new percolation models, based upon random

distributions of chemical defects and ferromagnetic vs antiferromagnetic couplings. The value of S ) 13 is

the highest for an organic molecule.

1. Introduction

In 1, one chemical defect at any of the four 4-biphenyl-

substituted triarylmethyl sites in the dendritic branches would

disrupt the exchange coupling and drastically lower the overall

value of S. Furthermore, the component spins (S′) for the branch

(S′ ) 5/2) and the core (S′ ) 4/2) have similar values (Figure

1); thus, if their exchange coupling is reversed from ferromag-

netic-to-antiferromagnetic, as a result of the out-of plane twisting

at one of the biphenyl moieties, both average value of S and

average number of unpaired electrons are drastically lowered.^1,3

One approach to counter this problem is to replace the

dendritic branches with macrocyclic branches, to minimize the

impact of chemical defects.^13,15However, sterically large macro-

cyclic branches may introduce problems with both synthesis

and exchange coupling (through severe out-of-plane twisting).

The use of a relatively long linker, such as bis(biphenylene)-

methyl, for connecting the branch to the core may alleviate these

problem. Implementation of this design leads to a new class of

“organic spin clusters”,^22-24possessing alternating connectivity

of unequal spins, as illustrated by polyradicals 2 (spin trimer),

3 (spin pentamer), and 4 (spin nonamer) (Figure 2).³

Dendritic-macrocyclic polyradical 1 is designed as an “or-

ganic spin cluster” (Figure 1).^1,2Its average value of spin

quantum number, S ≈ 10, in the ground state, is the highest

among organic molecules.^2-12However, both the average value

of S and average number of unpaired electrons in 1 are below

the expected values for a polyradical with 24 ferromagnetically

coupled electron spins.¹There are two key problems to

consider: chemical defects (incomplete generation of unpaired

electrons) and antiferromagnetic couplings (caused by out-of-

plane twisting of the π system).^3,13-21

(1) Rajca, S.; Rajca, A.; Wongsriratanakul, J.; Butler, P.; Choi, S. J. Am. Chem.

Soc. 2004, 126, in press.

(2) Rajca, A.; Wongsriratanakul, J.; Rajca, S.; Cerny, R. Angew. Chem. Int.

Ed. 1998, 37, 1229-1232.

(3) Rajca, A. Chem. Eur. J. 2002, 8, 4834-4841.

(4) Itoh, K., Kinoshita, M., Eds.; Molecular Magnetism; Gordon and Breach:

Kodansha, 2000; pp 1-337.

(5) Lahti, P. M., Ed. Magnetic Properties of Organic Materials; Marcel

Dekker: New York, 1999; pp 1-713.

(6) Crayston, J. A.; Devine, J. N.; Walton, J. C. Tetrahedron 2000, 56, 7829-

7857.

(7) Rajca, A.; Wongsriratanakul, J.; Rajca, S. Science 2001, 294, 1503-1505.

(8) Rajca, A.; Rajca, S.; Wongsriratanakul, J. J. Am. Chem. Soc. 1999, 121,

6308-6309.

(17) Silverman, S. K.; Dougherty, D. A. J. Phys. Chem. 1993, 97, 13273-

13283.

(9) Iwamura, H.; Koga, N. Acc. Chem. Res. 1993, 26, 346-351.

(10) Matsuda, K.; Nakamura, N.; Inoue, K.; Koga, N.; Iwamura, H. Bull. Chem.

Soc. Jpn. 1996, 69, 1483-1494.

(18) Kanno, F.; Inoue, K.; Koga, N.; Iwamura, H. J. Am. Chem. Soc. 1993,

115, 847-850.

(19) Fang, S.; Lee, M.-S.; Hrovat, D. A.; Borden, W. A. J. Am. Chem. Soc.

1995, 117, 6727-6731.

(11) Nishide, H.; Ozawa, T.; Miyasaka, M.; Tsuchida, E. J. Am. Chem. Soc.

2001, 123, 5942-5946.

(20) Rajca, A.; Rajca, S. J. Chem. Soc., Perkin 2 1998, 1077-1082.

(21) Shultz, D. A.; Fico, R. M., Jr.; Bodnar, S. H.; Kumar, K.; Vostrikova, K.

E.; Kampf, J. W.; Boyle, P. D. J. Am. Chem. Soc. 2003, 125, 11761-

11771.

(12) Michinobu, T.; Inui, J.; Nishide, H. Org. Lett. 2003, 5, 2165-2168.

(13) Rajca, A. Chem. ReV. 1994, 94, 871-893.

(14) Rajca, A.; Utamapanya, S. J. Am. Chem. Soc. 1993, 115, 10688-10694.

(15) Rajca, A.; Rajca, S.; Padmakumar, R. Angew. Chem., Int. Ed. Engl. 1994,

33, 2091-2093.

(22) Rajca, A.; Rajca, S. J. Am. Chem. Soc. 1996, 118, 8121-8126.

(23) Rajca, A.; Wongsriratanakul, J.; Rajca, S. J. Am. Chem. Soc. 1997, 119,

11674-11686.

(16) Dvolaitzky, M.; Chiarelli, R.; Rassat, A. Angew. Chem., Int. Ed. Engl. 1992,

31, 180-181.

(24) Rajca, A. Mol. Cryst. Liq. Cryst. 1997, 305, 567-577.

9

6608

J. AM. CHEM. SOC. 2004, 126, 6608-6626

Organic Spin Clusters

A R T I C L E S

Figure 1. Dendritic-macrocyclic polyradical 1 (S ≈ 10) as spin pentamer.

Overall design of polyradicals 2, 3, and 4 is based upon S .

1/2 macrocyclic modules connected with S ) 1/2 bis(biphen-

ylene)methyl linkers. Such alternating connectivity of unequal

spins is expected to address out-of-plane twistings, which may

reverse the sign of exchange coupling from ferromagnetic to

antiferromagnetic. For example, pentadecaradical 2 may be

viewed as a quasilinear trimer of unequal spins, S₁- 1/2 - S₁,

where S₁) 7/2 (Figures 2 and 3). The reversal of both

ferromagnetic couplings to antiferromagnetic ones would lower

the overall value of S from 2S₁+ 1/2 to 2S₁- 1/2, i.e., only by

one unit. The limited cancellation of spins is expected to exist

for random distribution of ferromagnetic and antiferromagnetic

couplings as well. This is in contrast to 1, in which directly

connected spins are approximately equal, e.g., S′ ) 5/2 and S′

) 4/2 in 1 (Figure 1).

The design, based upon partial cancellation of unequal spins

through antiferromagnetic coupling, corresponds to a “ferri-

magnetic coupling scheme”, which is widely applied to organo-

metallic ferrimagnets.^25,26Examples are coordination polymers

and networks of nitroxides, e.g., antiferromagnetic couplings

of S ) 5/2 Mn^IIwith S ) 1/2 nitronyl nitroxides or S ) 1

dinitroxides (or S ) 3/2 trinitroxides).^27,28Examples of organic

radicals (carbenes), which are intended for such partial cancel-

lation of spins, give relatively values of S ) 1 only.²⁹

Polyradicals 2-4 may also be viewed as linear and branched

fragments of the first conjugated polymer with magnetic

ordering.^7,8Analysis of magnetic data for such model molecules

(25) (a) Manriquez, J. M.; Yee, G. T.; McLean, R. S.; Epstein, A. J.; Miller, J.

S. Science 1991, 252, 1415-1417. (b) Holmes, S. M.; Girolami, G. S. J.

Am. Chem. Soc. 1999, 121, 5593-5594.

(26) For progress in organic ferrimagnets, see: (a) Buchanenko, A. L. Russ.

Chem. ReV. 1990, 59, 307-319. (b) Hosokoshi, Y.; Katoh, K.; Nakazawa,

Y.; Nakano, H.; Inoue, K. J. Am. Chem. Soc. 2001, 123, 7921-7922. (c)

Shiomi, D.; Kanaya, T.; Sato, K.; Mito, M.; Takeda, K.; Takui, T. J. Am.

Chem. Soc. 2001, 123, 11823-11824.

(27) Caneshi, A.; Gatteschi, D.; Rey, P. Prog. Inorg. Chem. 1991, 39, 331-

429.

(28) Iwamura, H.; Inoue, K.; Koga, N. New J. Chem. 1998, 201-210.

(29) Tricarbene with triplet ground state: Itoh, K.; Takui, T.; Teki, Y.; Kinoshita,

T. Mol. Cryst. Liq. Cryst. 1989, 176, 49-66.

Figure 2. Macrocyclic-macrocyclic polyradicals 2, 3, and 4 as organic

spin clusters.

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J. AM. CHEM. SOC. VOL. 126, NO. 21, 2004 6609

A R T I C L E S

Rajca et al.

these are two C_s-, two C₂-, and two C₁-symmetric isomers

(Figure 4).

Only three major isomers are isolated for each macrocycle:

C_s-symmetric 10A (and 11A) and two C₁-symmetric 10B and

10C (11B and 11C). Also, a small amount of C₂-symmetric

heptaether 11D is obtained. For each isomer, FABMS gives

the expected (M - OCH₃)⁺isotopic cluster ions; the pentaether-

diols 10 show additional, intense (M - OH)⁺isotopic cluster

ions. Measured and calculated isotopic distributions for both

cluster ions show satisfactory agreement. The presence of the

OH groups in pentaether-diols (10A-10C) is corroborated by

the IR absorptions in the 3400-3600 cm^-1range and the D₂O

exchange experiments using ¹H NMR spectroscopy. The ¹H and

¹³C NMR spectra (Tables 1s-4s, Supporting Information) show

reasonable agreement (less a few spectral overlaps) between

the expected and observed number of resonances. Although the

point groups of symmetry are determined, the two possible

structures within the same point group of symmetry are

indistinguishable by standard NMR spectroscopy.³⁴For the C_s-

symmetric isomer, NMR spectra are best interpreted in terms

of five nonequivalent sets of two 4-tert-butylphenyl groups; the

four 1,3,5-trisubstituted benzene rings appear as a pair of

equivalent rings and a pair of nonequivalent rings. The NMR

spectra for the C₂-symmetric 11D are similar to the C_s-

symmetric 11A, except for one diastereotopic pair of 4-tert-

butylphenyl groups in 11D, as expected for this chiral isomer.³⁵

¹H chemical shifts for the diastereotopic 4-tert-butylphenyl

groups are significantly different (∆δ ) 0.012-0.064 ppm) in

both aromatic (7.478 and 7.182 vs 7.414 and 7.194 ppm) and

tert-butyl (1.196 vs 1.146 ppm) regions. For each C₁-symmetric

isomer (11B and 11C), 10 nonequivalent 4-tert-butylphenyl

groups and four nonequivalent 1,3,5-trisubstituted benzene rings

are found, as expected.

Figure 3. Alternating connectivity of unequal spins in pentadecaradical 2.

may provide a rational for extraordinary extent of net ferro-

magnetic exchange couplings leading to high values of magnetic

moment (or S) in such polymers.³⁰

This article describes the synthesis and characterization of a

novel series of high-spin polyradicals 2, 3, and 4 with 15, 22,

and 36 triarylmethyls, respectively (Figure 2). Their correspond-

ing average values of S are 5-6, 7-9, and 11-13. The S ) 13

is a new record for an organic molecule.

2. Results and Discussion

2.1. Synthesis of Polyethers. Modular and convergent

synthesis is used to prepare polyethers 2-(OMe)₁₅, 3-(OMe)₂₂,

and 4-(OMe)₃₆. The synthesis is carried out in three stages: (1)

preparation of 1,3-phenylene-connected macrocyclic monofunc-

tionalized modules, (2) attachment of linkers to the monofunc-

tionalized modules (“modules-with-linkers”), and (3) attachment

of monofunctionalized modules-with-linkers to macrocyclic

cores, forming bis(biphenylene)methyl moieties (Schemes 1 and

2).

2.1.1. Macrocyclic Monofunctionalized Modules 11. 5-

Bromo-1,3-dilithiobenzene,³¹prepared by double Br/Li ex-

changes from 1,3,5-tribromobenzene, is treated with 1-(4-tert-

butylbenzoyl)-pyrrolidine to give diketone 5 (Scheme 1).

Analogously, ketone 7 is obtained from 1,3-dibromoaryl com-

pound 6,¹⁵via mono Br/Li exchange. Double Br/Li exchange

on 6, using t-BuLi (4.2 equiv) in ether, is followed with addition

of ketone 7 (2.4 equiv); the resultant diol 8 is obtained as a

mixture (1:0.4-1:0.9) of two diastereomers in 46-51% yields.

Diol 8 is converted to dibromopentaether 9 in 67-90% yield

using NaH in THF. The macrocyclic ring of calix[4]arene is

constructed through the addition of the bis(aryllithiums) to

diketones.^1,32,33In the present synthesis, the bis(aryllithiums)

are generated in situ from a mixture of diastereomers dibromo-

pentaether 9 and then condensed with diketone 5; final

concentrations of 5 and 9 are 0.006 M. Three cis/trans isomers

of pentaether-diols 10A-10C are isolated in 5-12% yields

(19-24% overall yields). Etherification gives the corresponding

heptaethers (modules) 11A-11C in moderate yields. Also, a

small amount of heptaether 11D is isolated from the reaction

mixture containing 11A.

2.1.2. Modules-with-Linkers 15. Linker 14 is prepared from

1,4-dibromobenzene and 1,4-diiodobenzene in 76% overall yield

(Scheme 1). Negishi coupling is employed to connect racemic

linker 14 to the macrocyclic modules (achiral 11A and racemic

11B) providing modules-with-linkers 15A and 15B in about 50%

isolated yields (Scheme 1).³⁶15A and 15B are isolated as

racemate and a ∼1:1 mixture of diastereomers, respectively. In

FABMS, the expected (M - OCH₃)⁺isotopic cluster ions have

dominant intensity in the m/z ) 480-3000 range. The assign-

ments of NMR spectra for 15A and 15B (Figures 1s and 2s

and Table 5s, Supporting Information, and Figures 5 and 6)

are discussed in the following paragraphs.

For 15A, six singlets (1:1:1:1:2:2) are found in the methoxy

1

group region of the H NMR (500 MHz, 293 K) spectrum,

(34) Crystals of adequate quality for single-crystal X-ray diffraction could not

be obtained for 11A-11D. Structures of the C_s- and C₂-symmetric isomers

(11A and 11D) could in principle be determined via laborious chemical

transformation to more symmetric compounds, such as octaethers.¹⁵Point

groups of symmetry for such octaethers are analogous to the isomers of

tetrabromo-calix[4]arene core 18 in ref 1. The C_s-symmetric isomers are

expected to give octaethers with C_4Vand C_2hpoint groups; similarly, the

C₂-symmetric isomers are expected to give octaethers with D_2dand C_2h

point groups. In both cases, the octaethers are distinguishable by NMR

spectroscopy. This procedure would fail for the C₁-symmetric isomers

because both isomers of the corresponding octaethers possess a C_spoint

group.

(35) The experiments with the mixed chiral shift agent, such as Ag(fod)

and ytterbium tris[3-heptafluoropropylhydroxymethylene)-(+)-camphorate

(Yb(hpfc)), and 11D in chloroform-d (with 11A as reference) were not

successful, that is, there was no detectable change in the ¹H NMR spectral

patterns (no additional splittings) for the C₂-symmetric 11D.

(36) Negishi, E.; King, A. O.; Okukado, N. J. Org. Chem. 1977, 42, 1821-

1823.

Assuming fast conformational exchange, six cis/trans isomers

are possible for both pentaether-diols 10 and heptaethers 11;

(30) (a) The design annelated macrocyclic organic spin clusters, addressing the

dimensionality of the conjugated polymer with magnetic ordering, is

described in Rajca, A.; Wongsriratanakul, J.; Rajca, S.; Cerny, R. L. Chem.

Eur. J. 2004, 10, in press. (b) The possible role of magnetic shape anisotropy

in the conjugated polymer with magnetic ordering is addressed in ref 1.

(31) Bromo-1,3-dilithiobenzene: Rot, N.; Bickelhaupt, F. Organometallics 1997,

16, 5027-5031.

(32) Rajca, A.; Padmakumar, R.; Smithhisler, D. J.; Desai, S. R.; Ross, C. R.;

Stezowski, J. J. J. Org. Chem. 1994, 59, 7701-7703.

(33) Rajca, A.; Rajca, S.; Desai, S. R. J. Am. Chem. Soc. 1995, 117, 806-816.

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A R T I C L E S

Scheme 1. Synthesis of Modules 11, Linker 14, and Modules-with-Linkers 15^a

^aConditions: (i) t-BuLi (4 equiv), ether, -78 °C for 1.5 h; (ii) 1-(4-tert-butylbenzoyl)pyrrolidine as solid, -78 °C to room temperature for 1 d; (iii)

t-BuLi (2 equiv), THF, -78 °C for 3.5 h; (iv) 1-(4-tert-butylbenzoyl)pyrrolidine as 0.5 M solution in THF, -78 °C to room temperature for 12 h; (v) t-BuLi

(4.2 equiv), ether, -78 °C for 2 h, then -20 °C for 30 min, then 7 (2.2 equiv), -78 °C to room temperature for 2.5 d; (vi) NaH (3-11 equiv), THF, then

indicated diols 8, 10A-10C, or alcohol 13, 0 °C to room temperature for 3 h, then MeI (8-18 equiv), 0 °C to room temperature for 1 d; (vii) 9 (0.009 M

in THF), then t-BuLi (4.0 equiv), -78 °C for 2.5 h, then -20 °C for 15 min, then 5 (1.0 equiv, 0.02 M in THF), -78 °C to room temperature for 1 d; (viii)

t-BuLi (2.1-2.2 equiv), THF, -78 °C for 3 h, then -20 °C for 10 min, then ZnCl₂(1.1-1.2 equiv), -78 °C to room temperature for 3-5 h; (ix) 14 (2.0

equiv), then Pd(PPh₃)₄(3 mol %), 100 °C, 1.5 d; (x) n-BuLi (1.0 equiv), ether, -78 °C for 2 h; (xi) 12, -78 °C to room temperature for 1 d, then I₂(0.10

equiv). Stereoisomers 11C and 11D are not analytically pure.

suggesting that at least one pair of methoxy groups is dia-

stereotopic. In the aromatic region, four types of benzene rings

(color-coded in Figure 5) are assigned, on the basis of the ¹H-

¹H COSY spectrum, spectral patterns, and relative integrations.

The pair of 1,3,5-trisubstituted benzene rings (rings A and A′,

Figure 5), which is equivalent in the C_s-symmetric 11A, is now

diastereotopic, showing as two pairs of nearly coincident (∆δ

≈ 0.003 ppm) 1-proton triplets (J ) 2 Hz) and one 2-proton

triplet (J ) 2 Hz). The other nonequivalent pair of 1,3,5-

trisubstituted benzene rings (rings B and C, Figure 5) still

appears as two sets of three 1-proton triplets with J ) 2 Hz

(Figure 1s, Supporting Information). Ten 4-proton doublets (J

) 8-9 Hz), with pairwise correlations in the COSY spectrum,

may correspond to two sets of five 1,4-disubstituted benzene

rings (rings 1-5 and 1′-5′, Figure 5); although the two sets

should be diastereotopic, the chemical shift differences may not

be detectable. Four 2-proton doublets (J ) 8-9 Hz) and the

4-proton singlet at 7.247 ppm may be assigned to the remaining

1,4-disubstituted benzene rings (rings 6-8, Figure 5). Overall,

the ¹H NMR spectra for 15A largely reflect the 2-fold symmetry

of the macrocyclic module 11A, except for the very few

resolvable, small diastereotopic splittings.

For 15B, eight resonances (three protons each) are found in

1

the methoxy group region of the H NMR (500 MHz, 293 K)

spectrum; however, five of those resonances are further split

(∆δ ≈ 0.001-0.003 ppm) into two singlets each (with ap-

proximately equal peak height). In the aromatic region, two types

of benzene rings (color-coded in Figure 6) are assigned, on the

basis of ¹H-¹H COSY spectrum, spectral patterns, and relative

integrations. For the 1,3,5-trisubstituted benzene rings (rings

A-D, Figure 6), majority of the 12 1-proton resonances are

either appearing as two triplets (∆δ ≈ 0.003 ppm) or are

broadened, unlike well-defined triplets for 11B (Figure 2s,

Supporting Information). These additional splittings are less

noticeable in the more spectrally overlapped region of 1,4-

disubstituted benzene rings (rings 1-13, Figure 6). In this

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Rajca et al.

a

Scheme 2. Synthesis of Polyethers 2-(OMe)₁₅, 3-(OMe)₂₂, and 4-(OMe)₃₆

^a(i) t-BuLi (2.1-2.2 equiv), THF, -78 °C for 3-4 h, then -20 °C for 10 min, then ZnCl₂(1.1-1.2 equiv), -78 °C to room temperature for 3 h; (ii)

16 (0.5 equiv), then Pd(PPh₃)₄(3 mol %), 100 °C, 1.5 d; (iii) t-BuLi (5 equiv), THF, -78 °C for 2 h, then -20 °C for 10 min, then ZnCl₂(4.5 equiv), -78

°C to room temperature for 3-5 h; (iv) 15B (∼3 equiv), then Pd(PPh₃)₄(4 mol %), 100 °C, 3 d; (v) t-BuLi (10 equiv), THF, -78 °C for 2 h, then -20 °C

for 10 min, then ZnCl₂(∼5 equiv), -78 °C to room temperature for ∼5 h; (vi) 15A (∼6 equiv), then Pd(PPh₃)₄(10 mol %), 100 °C, 2-3 d; (vii) 15B (1

equiv), then Pd(PPh₃)₄(2 mol %), 100 °C, 1 d.

Figure 4. Possible cis/trans isomers of diols 10 and modules 11. Open and closed circles correspond to the relative orientation of the OMe (and OH) groups.

region, 24 2-proton doublets (J ) 8-9 Hz), which are correlated

pairwise in the COSY spectrum, account for 12 1,4-disubstituted

benzene rings. However, the 13th ring appears as two 1-proton

singlets and one 2-proton singlet (all within 0.007 ppm), i.e.,

two overlapped AB systems. In the aromatic region of the ¹³C

NMR spectra, 46 resonances are resolved vs the expected 38

for quaternary carbons; in particular, two resonances at 121.62

and 121.60 ppm for C-Br group are found. These observations

suggest that 15B is isolated as nearly equimolar mixture of two

diastereomers, which possess nearly identical chemical shifts.

2.1.3. Polyethers 2-(OMe)₁₅, 3-(OMe)₂₂, and 4-(OMe)₃₆.

Negishi coupling is employed to form the target polyethers,

forming bis(biphenylene)methyl moieties (Scheme 2).³⁶

Pentadecaether 2-(OMe)₁₅is obtained via condensation of

module 11B and symmetrical linker 16; the target pentadecaether

is isolated as two fractions, both mixtures of diastereomers, in

57% overall yield. Because C₁-symmetric 11B is used as a

racemic mixture and a pseudoasymmetric center is formed, three

diastereomers are possible for 2-(OMe)₁₅, i.e., one pair of

enantiomers and two meso compounds.

Condensation of the module-with-linker 15B (3 equiv, two

diastereomers) with C₁-symmetric dibromo-calix[4]arene core

17 (1 equiv) gives docosaether (22-ether) 3-(OMe)₂₂as a

mixture of diastereomers in 34% and 56% yields.^37,38As 15B

(37) Rajca, A.; Lu, K.; Rajca, S. J. Am. Chem. Soc. 1997, 119, 10335-10345.

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Organic Spin Clusters

A R T I C L E S

Figure 5. Module-with-linker 15A with numbering scheme for the

1

assignment of H NMR spectra.

Figure 7. FABMS (ONPOE) for pentadecaether 2-(OMe)₁₅(plot A) and

22-ether 3-(OMe)₂₂(plot B). Main plots: low-resolution spectra. Inset

plots: high-resolution spectra (red lines) and simulations of the isotopic

intensities at natural isotopic abundance (green lines) for the (M - OCH₃)⁺

and (M - 2OCH₃)²⁺ion clusters.

coupling of 15B gives the product (49% yield) with FABMS

and ¹H NMR data identical to that for 20B-(OMe)₁₆(Scheme

2).⁴¹

Figure 6. Module-with-linker 15B with numbering scheme for the

assignment of NMR spectra.

In the synthesis of 36-ether 4-(OMe)₃₆, the side products 19-

(OMe)₂₈and 20A-(OMe)₁₆are isolated in 8% and 8.5% yields,

respectively (Scheme 2). The target 36-ether 4-(OMe)₃₆and

side product 19-(OMe)₂₈are difficult to separate by chroma-

tography on silica, as a result of not only the overlapping R_f-

values but also low recovery of the polyethers. Presumably, the

polyethers are slowly demethylated upon contact with silica,

especially with activated silica.⁴²For example, small amounts

of monodemethylation products of 20A-(OMe)₁₆(labeled as

20A-(OMe)₁₅OH), which are identified in selected samples of

both 4-(OMe)₃₆and 19-(OMe)₂₈by FABMS (Figure 8).

2.1.3.A. FABMS of Target Polyethers and Their Side

Products. FABMS for the target polyethers 2-(OMe)₁₅,

3-(OMe)₂₂, and 4-(OMe)₃₆show intense (M - OCH₃)⁺ions.

The isotopic intensities are resolved for both singly and doubly

charged ions in 2-(OMe)₁₅and 3-(OMe)₂₂; only broadened, av-

erage mass peaks are found for 4-(OMe)₃₆(Figures 7 and 8).

Both fractions of pentadecaether 2-(OMe)₁₅give indistin-

guishable low-resolution FABMS in the m/z 1000-5000 range,

is an approximately equimolar mixture of C₁-symmetric dia-

stereomers and C₁-symmetric 17 is racemic, the product

3-(OMe)₂₂possesses five distinct chiral elements; therefore, a

complex mixture of diastereomers is possible.

Similarly, hexatricontaether (36-ether) 4-(OMe)₃₆is obtained

in 7-32% yields from racemic module-with-linker 15A (5-6

equiv) and C_4V-symmetric tetrabromo-calix[4]arene core 18.³⁹

Because racemic 15A and achiral C_4V-symmetric 18 are used

in the synthesis of 36-ether 4-(OMe)₃₆, the four constitutionally

identical and circularly disposed chiral centers in 4-(OMe)₃₆

should lead to a mixture of diastereomers (two pairs of

enantiomers and two meso compounds).⁴⁰

In the synthesis of 22-ether 3-(OMe)₂₂, the side product 20B-

(OMe)₁₆, corresponding to the homocoupling product of the

modules-with-linker 15B, is isolated in 3% yield. Direct Negishi

(38) The C₁-symmetric 17 corresponds to the least polar cis/trans isomer 7A in

ref 37.

(39) Synthesis and characterization of the C_4V-symmetric tetrabromo-calix[4]-

arene core 18 is described in refs 1 and 2.

(41) The ¹H chemical shifts for both products are within 0.01 ppm at room

temperature.

(40) For other examples of cyclostereoisomerism, see: Eliel, E. L.; Wilen, S.

H. Stereochemistry of Organic Compounds; Wiley: New York, 1994,

1176-1177.

(42) Our previous attempts to separate polyarylmethyl polyethers using either

normal or reverse phase HPLC have not been successful. For selected

chromatographic separations, silica is activated at 200 °C.

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Rajca et al.

however, the m/z spacings between the fragmentation ions for

the m/z 4995 region (m/z 7-8) are approximately half of those

for the m/z 10022 region. Also, the widths of the isotopic

envelopes appear narrower for the m/z 4995 region compared

to the m/z 10022 region. This suggests that the peaks at m/z

10022 and 4995 correspond to singly and doubly charged ions

(M - OCH₃)⁺and (M - 2OCH₃)²⁺, respectively. The positions

of the remaining peaks at m/z 7761, 3865, and 4479 are matched

well by the low-resolution spectrum of a mixture, containing

the side products such as 19-(OMe)₂₈and 20A-(OMe)₁₅(OH)

(Figure 8B).^43,44The minor peaks at m/z 7761 and 3865 are

assigned to the side product 19-(OMe)₂₈; these two peaks

correspond to the singly and doubly charged ions (M - OCH₃)⁺

and (M - 2OCH₃)²⁺, respectively. The small peak at m/z 4479

may be the (M - OCH₃)⁺ion for the “demethylation product”

side product 20A-(OMe)₁₅(OH). Because the ionization ef-

ficiency for polyarylmethyl polyethers decreases dramatically

in relation to mass, the relative intensities of the ions observed

in the mass spectra are severely distorted, overestimating relative

content of the side products with lower molecular weights.^30a,43,44

For the (M - OCH₃)⁺ion of 4-(OMe)₃₆, the high-resolution

spectra for two different samples give the peak maxima at m/z

10021.5 and 10021.9; these values are 1-2 amu below the

calculated average mass (10023.45) and peak maximum mass

(10023.04) for the formula C₇₁₉H₈₂₁O₃₅for the (M - OCH₃)⁺

ion cluster. Considering the instrumental limitations and the

observed shifts to the lower m/z for the isotopic clusters from

homologous polyethers, this 1-2 amu mass difference may not

be unusual in this high m/z range. Also, the isotopic envelope

for the (M - OCH₃)⁺ion of 19-(OMe)₂₈is somewhat shifted

to the lower m/z values, compared to the simulated envelope

for the formula C₅₅₇H₆₃₅O₂₇at the natural isotopic abundance

(Figure 8B).

Figure 8. FABMS (ONPOE) for 36-ether 3-(OMe)₃₆(plot A) and side

product 19-(OMe)₂₈(plot B). Main plots: low-resolution spectra. Inset

plots: fragmentation patterns for the m/z 10022 and m/z 4995 peaks of

3-(OMe)₃₆(black lines), and high-resolution spectra (red lines) and

simulations of the isotopic intensities at natural isotopic abundance (green

lines) for the (M - OCH₃)⁺ion clusters.

showing the dominant peak at m/z 4165. The high-resolution

spectrum reveals an isotopic cluster ion, which matches well

with the calculated spectrum for the singly charged (M -

OCH₃)⁺ion, except for the small extra intensity on the side of

the lower m/z (Figure 7A). Additional small peaks (<10%

relative amplitude) are found in the m/z 2060-2190 region. The

high-resolution spectrum show a doubly charged isotopic cluster

ion at m/z 2066 (spacing of m/z 0.5 for isotopic peaks) for the

(M - 2OCH₃)²⁺ion. Also, singly charged cluster at m/z 2185

for the (M - C₁₄₄H₁₆₇O₇)⁺ion is found; this ion corresponds

to the loss of “macrocyclic module with benzene ring”, with

the possible formation of a relatively stable R-methoxybenz-

hydryl cation.

For 22-ether 3-(OMe)₂₂, the low-resolution FABMS shows

the dominant peak at m/z 6117; the high-resolution spectrum

gives an isotopic cluster in satisfactory agreement with the

calculated spectrum for the singly charged (M - OCH₃)⁺ion,

i.e., C₄₃₉H₅₀₅O₂₁formula, at natural abundance (Figure 7B). Now

the “excess” of the experimental intensity on the low m/z side

of the (M - OCH₃)⁺ion appears to be increased, compared to

that in 2-(OMe)₁₅. All other peaks in the m/z 2000-8000 range

have relatively small amplitude (<3%). The doubly charged

(M - 2OCH₃)²⁺ion possesses an isotopic cluster near m/z 3043;

the experimental and calculated isotopic intensities are in a good

agreement. The peak corresponding to the loss of the outer

“module with benzene ring” appears at m/z 4137 (less m/z 1980)

in the low-resolution spectrum.

2.1.3.B. Gel Permeation Chromatography with Multiangle

Light Scattering (GPC/MALS) and Small Angle Neutron

Scattering (SANS) of Target Polyethers. Polyethers 2-(OMe)₁₅,

3-(OMe)₂₂, and 4-(OMe)₃₆elute in the expected order of

increased hydrodynamic radii for greater molecular weights

(Figure 3s, Supporting Information). The weight-average mo-

lecular masses (M_w) for 2-(OMe)₁₅, 3-(OMe)₂₂, and 4-(OMe)₃₆

are ∼5, ∼7.5, and ∼12 kDa, respectively; the polydispersities

(PD ) M_w/M_n) are in the 1.00-1.02 range, as expected for

monodisperse oligomers (Table 6s, Supporting Information).

Assuming that only about ∼80% of the injected mass of

polyether is eluted, good agreement with the formula masses is

obtained. Similar discrepancies between the M_wand the formula

mass were also observed for other polyarylmethyl polyethers.^1,30a,45

Radii of gyration (R_g) for polyethers 2-(OMe)₁₅, 3-(OMe)₂₂,

and 4-(OMe)₃₆in tetrahydrofuran-d₈(THF-d₈) are 1.2, 1.3, and

1.8 nm, respectively, as determined by small angle neutron

scattering (SANS).⁴⁶

(43) GPC/MALS for the identical sample of 19-(OMe)₂₈, which was used for

the FABMS in Figure 8B, shows two peaks with the relative peak

amplitudes of about 10:1. For the more intense peak, which is found at the

shorter elution time, the corrected M_w(assuming ∼80% elution fraction)

approximately matches the formula mass for 19-(OMe)₂₈. The minor peak

observed in GPC/MALS is tentatively assigned to 20A-(OMe)₁₅(OH).

1

(44) The H NMR spectra for the sample of 4-(OMe)₃₆, for which FABMS is

shown in Figure 8A, indicate that relative integration for 19-(OMe)₂₈is

For 36-ether 4-(OMe)₃₆, the low-resolution FABMS shows

the two most intense peaks at m/z 10022 (100%) and 4995 (85%)

(Figure 8A). Both peaks have similar fragmentation patterns;

about 10%.

(45) For 4-(OMe)₃₆, contribution from about 10% content of 19-(OMe)₂₈(ref

44) to the measured M_wwould be negligible, considering other sources of

error.

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2.1.3.C. NMR Spectroscopy of Target Polyethers. ¹H NMR

(500 MHz) spectra for polyethers 2-(OMe)₁₅, 3-(OMe)₂₂, and

4-(OMe)₃₆are recorded in benzene-d₆at 293, 328, and 348 K.

The best resolved spectra are typically obtained at the highest

available temperature (348 K).

For pentadecaether 2-(OMe)₁₅, ¹H NMR spectra are slightly

different for the two isolated fractions and each fraction shows

a mixture of at least two diastereomers. Only the fraction of

higher R_f, which is used for further studies (including generation

of polyradicals), is analyzed. Both the tert-butyl group and the

methoxy group regions contain 10-13 resonances; few of them

are broadened and only partially resolved at 293 and 348 K.

When integrations of the tert-butyl group region and the

methoxy group region are normalized to a single diastereomer,

few resonances with fractional integrations (e.g., 3 H in the tert-

butyl group region) are found, as expected for a mixture of

diastereomers.

For a 2-fold-symmetric stereoisomer of 2-(OMe)₁₅, four 1,3,5-

trisubstituted and 12 1,4-disubstituted benzene rings are expected

Figure 9. 36-Ether 3-(OMe)₃₆with numbering scheme for the assignment

of NMR spectra.

in the aromatic region of H NMR spectrum. H-¹H COSY

spectra at and 293 and 348 K may be assigned for 1,3,5-

trisubstituted benzene rings; all 24 cross-peaks for the expected

four sets of three 2-proton J ) 2 triplets are found (Figure 4s,

Supporting Information). However, selected 2-proton “triplets”

are broadened or split into two nearly overlapping triplets, and

their cross-peaks are distorted from the usual shape. The spec-

trally congested 1,4-disubstituted benzene rings are not assigned.

1

the 1-proton resonances is consistent with the presence of

diastereomers.

¹H NMR spectra of 36-ether 4-(OMe)₃₆at 348 K show one

predominant isomer, in which the outer and the inner calix[4]-

arene rings are approximately 2-fold and tetra-fold symmetric,

respectively (Figure 9).

In the tert-butyl group region, six singlets (36, 72, 72, 72,

72, 72 protons) in the 1.18-1.26 ppm range and an upfield-

shifted 36-proton set of five singlets in the 1.07-1.09 ppm range

(resembling a pentuplet) are found (Figure 10). Because this

upfield group of resonances becomes increasingly complex at

lower temperatures (328 and 293 K), conformational equilibria

or diastereomers may be involved. The possibility of a

conformation with lower than tetrafold symmetry (on the NMR

time scale) or the presence of more than one diastereomer may

be illustrated by the splitting of the 36-proton singlet at 348 K

into a pair of 18-proton singlets (∆δ ≈ 0.003 ppm) at 293 K

(Figure 10).

1

For 22-ether 3-(OMe)₂₂, H NMR spectra at 293, 328, or

348 K show a mixture of at least two diastereomers (Figures

5s-8s, Supporting Information). The tert-butyl group region is

too congested for a meaningful analysis. Only about half of the

expected 30 resonances (for one diastereomer) are resolved in

the 1.27-1.13 ppm region.

1

In the methoxy group region of the H NMR spectra, 22

distinct 3-proton singlets are expected for each diastereomer.

At 348 K, 21 distinct resonances are resolved; however, five

singlets integrate only to about 0.9-1.0 protons each and two

other singlets (with similar chemical shifts) integrate together

to 1.6 protons. An analogous spectrum, with 26 distinct reso-

nances, is obtained at 293 K; in particular, the most downfield

3-proton singlet at 348 K (at 3.106 ppm) splits into two singlets

(3.104 and 3.100 ppm) (Figure 6s, Supporting Information).

Six singlets (1:1:1:1:2:3) are found in the methoxy group

region of the ¹H NMR (500 MHz, 348 K) spectrum (Figure 9s,

Supporting Information), suggesting that at least one pair of

the methoxy groups is diastereotopic, analogously to that found

in module-with-linker 15A. Except for the most downfield 12-

proton broad singlet at 3.176 ppm, the remaining singlets are

within the 3.01-2.89 ppm range, which is similar to that for

11A and 15A.

1

In the aromatic region of the H NMR spectrum (and H-

¹H COSY) for 3-(OMe)₂₂, 12 1,3,5-trisubstituted and 34 1,4-

disubstituted benzene rings are expected for each diastereomer.

The best resolved ¹H-¹H COSY spectrum at 348 K could only

be assigned in part for 1,3,5-trisubstituted benzene rings; the

cross-peaks for 1,4-disubstituted benzene rings are very con-

gested (Figure 8s, Supporting Information). Twelve sets of three

1-proton J ) 2 triplets are expected for 12 1,3,5-trisubstituted

benzene rings. In the actual spectrum, many resonances are

broadened, resulting in the absence of several cross-peaks. Three

sets of three 1-proton resonances and four sets of three 2-proton

resonances are found; one set of three 1-proton resonances could

not be identified. Most of the 1- and 2-proton resonances with

the resolved coupling appear as pairs of nearly coincident J )

2 triplets (∆δ ≈ 0.003-0.004 ppm); this additional splitting of

1

The aromatic region of the H NMR spectrum (and H-¹H

COSY) for 4-(OMe)₃₆at 348 K shows 10 and eight cross-peaks

between the J ) 2 and J ) 8-9 multiplets, respectively (Figure

11). The J ) 2 multiplets appear as three correlated sets: the

first set has one pair of nearly coincident (∆δ ≈ 0.004 ppm)

4-proton triplets and two 8-proton triplets (rings A and A′,

Figures 9 and 11), and each of the other two sets consists of a

4-proton triplet and 8-proton doublet (rings B and C, Figures 9

and 11). Two broad singlets at 8.015 (4 H) and 7.936 (8 H)

ppm, which do not show a COSY cross-peak, account for the

four 1,3,5-trisubstituted benzene rings of the macrocyclic core

(ring D, Figures 9 and 11). The remaining resonances in the

aromatic region account for all 1,4-disubstituted benzene rings

(rings 1-9, Figures 9 and 11): 10 16-proton and six 8-proton

doublets (J ) 8-9) are correlated pairwise in the ¹H-¹H COSY

(46) The values of R_gare obtained from the Guinier fits in the q-ranges, for

which R_gq < 1.10. The small angle neutron scattering (SANS) experiments

and the data handling are described in Supporting Information.

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Figure 11. ¹H-¹H DQF COSY NMR (500 MHz, benzene-d₆) spectrum

for 4-(OMe)₃₆at 348 K.

Figure 10. ¹H NMR (500 MHz, benzene-d₆) spectra for the tert-butyl group

region of 4-(OMe)₃₆.

spectrum, and two 8-proton singlets at 7.443 and 7.438 ppm

are interpreted as a nearly isochronous AB system. In the one

bond ¹³C-¹H coupling HMQC experiment at 348 K (Figure

1

10s, Supporting Information), H resonances in the aromatic

region show the expected cross-peaks (with a few spectral over-

laps), except for the four broadened peaks at 8.015 (bs), 7.936

(bs), 7.661 (bt, J ≈ 2 Hz), and 7.594 (bd, J ≈ 9 Hz) ppm.

Overall, NMR spectra for 4-(OMe)₃₆at 348 K may be viewed

as superposition of the spectra for the macrocyclic core 18 and

four module-with-linkers 15A, less differences in chemical shifts

and dynamic behavior.

Figure 12. Polyether 20A-(OMe)₁₆with numbering scheme for the

assignment of H NMR spectra.

Direct comparison of the ¹H NMR spectra for 4-(OMe)₃₆and

20A-(OMe)₁₆provides additional evidence for the spectral

assignments for 4-(OMe)₃₆(Figures 12-14). For a homo-

coupling product of racemic module-with-linker 15A, two

diastereomers are expected, i.e., the pair of enantiomers and

1

singlets in the 1.07-1.09 ppm range (Figure 13), (2) in the

methoxy group region, the most downfield, broad 12-proton

singlet at 3.176 ppm (Figure 13), and (3) in the aromatic region,

two broad singlets at 8.015 (4 H), 7.936 (8 H) ppm and two

COSY-correlated doublets at 7.457 (J ) 8, 8 H), 7.410 (J ) 8,

1

the meso compound. The H NMR spectra for 20A-(OMe)₁₆

show the expected 2-fold symmetry at 293, 328, and 348 K.

However, the 18-proton resonance in the tert-butyl group region

is split into two overlapping singlets of equal peak height (the

most downfield peaks at 1.237 and 1.236 ppm at 348 K) (Figure

13). Analogous splitting of the most downfield 36-proton

resonance in the tert-butyl group region is observed for

4-(OMe)₃₆at 293 K. The spectral differences between the two

compounds allow for identification of the resonances for the

macrocyclic core of 4-(OMe)₃₆at 348 K (ring 9 with the tert-

butyl group, methoxy group, and ring D, Figure 9): (1) in the

tert-butyl group region, the upfield-shifted 36-proton set of five

1

8 H) (Figure 14). This accounts for all H resonances of the

macrocyclic core. The degree of broadening and chemical shifts

may suggest that two 8-proton COSY-correlated doublets at

7.594 (broad) and 7.223 ppm (at 348 K) correspond to the 1,4-

connected benzene ring (ring 6, Figure 9) adjacent to the

macrocyclic core (Figure 14).

2.2. Generation of Polyradicals 2, 3, and 4. Polyethers

2-(OMe)₁₅, 3-(OMe)₂₂, and 4-(OMe)₃₆(0.8-2.1 mg per sample)

are converted to the corresponding polyradicals 2, 3, and 4,

respectively. The relevant chemistry and technical procedures

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Figure 13. ¹H NMR (500 MHz, C₆D₆, 348 K) spectra of the methoxy

group regions (left side) and tert-butyl group regions (right side) for

4-(OMe)₃₆(top plots) and for side product 20A-(OMe)₁₆(bottom plots).

In the upper left plot, two resonances (3.130 and 3.110 ppm) labeled with

asterisks correspond to 19-(OMe)₂₈.

Figure 14. ¹H NMR (500 MHz, benzene-d₆, 348 K) spectra for the aromatic

regions of 4-(OMe)₃₆and 20A-(OMe)₁₆.

are described elsewhere.¹Samples of polyradicals in tetrahydro-

furan-d₈(THF-d₈, 0.06-0.08 mL) are used for magnetic studies.

2.3. Models for Analysis of Magnetic Data for Polyradicals

2, 3, and 4. Two types of linear combinations of Brillouin

functions are used for numerical fitting of the M vs H data

magnetic data at low temperatures (T ) 1.8-5 K).

The first type of linear combination consists of two or three

Brillouin functions, B(S_n), n ) 1 and 2, corresponding to the

values of spin S₁and S₂:

The second type of linear combination consists of relatively

large number of Brillouin functions generated by the following

percolation model:

M ) 11180N ΣA_iB(S_i)

(2)

In eq 2, N corresponds to number of moles of polyradical

(based on the weight of polyether). Coefficients A_iand spin

values S_iare optimized through two variable parameters,

probabilities q and p. Only two variable parameters are used to

avoid overparametrization. The q and p are defined as follows:

(1) probability for ferromagnetic (J > 0) and antiferromagnetic

(J < 0) coupling through each biphenylene coupling unit are q

and 1 - q, respectively, (2) probabilities for an unpaired electron

and a chemical defect at a triarylmethyl site are p and 1 - p,

respectively. In our previously reported percolation models for

polyarylmethyls, only ferromagnetic interactions were consid-

ered; both p and the number of moles of polyradical (or M_sat)

were viariable parameters, i.e., the model only fit the curvature

of M vs H data.^2,14,23The present percolation model is

quantitative, i.e., both curvature and value of magnetization are

numerically fit, using the number of moles of polyradical as an

input parameter. The chemical defects are treated according to

the identical procedure, as described previously for other

percolation models of polyarylmethyl polyradicals. Only spin

systems at the 4-biphenyl-substituted sites are explicitly enumer-

ated; chemical defects at the other triarylmethyl sites are

accounted for approximately, by scaling their contribution to

the value of spin with a factor of p.²³

M_sat[B(S₁) + w₂B(S₂)]

M )

(1)

1 + w₂

Magnetization at saturation (M_sat) corresponds to M at saturation

(H/T . 1).⁴⁷The coefficient w₂depends on S₁, S₂, and molar

fractions of the two spin systems. Four variable parameters, M_sat,

S₁, S₂, and w₂, are used for polyradicals with relatively large

values of S. For lower values of S, only three parameters are

employed by setting the parameter S₂to 1/2. The values of spin-

average spin quantum number, S_s) (S₁+ w₂S₂)/(1 + w₂), are

calculated from the optimized parameters. The values of M_sat

are reported per triarylmethyl site (more precisely, per triaryl-

methyl ether); value of 1 µ_Bwould correspond to one unpaired

electron per site. Value of M_sat< 1 µ_Bcorresponds to a fraction

of an unpaired electron per triarylmethyl site. Because M_satis

measured at low temperatures (T ) 1.8-5 K), both antiferro-

magnetic interactions and chemical defects may contribute to

its low values. Furthermore, incomplete mass transfer of

polyethers (electrostatic fine powders) and intermediate poly-

carbanions into the quartz sample tube may lower the measured

value of M_sat.

Enumeration of spin systems with respect to parameters q

and p is illustrated using organic spin pentamer, corresponding

to docosaradical (22-radical) 3 (Figure 15). In this spin pentamer,

(47) Carlin, R. L. Magnetochemistry; Springer: Berlin, 1986.

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Figure 16. Plots of average spin (S_s, full lines) and magnetization at

saturation (M_sat, dotted lines) for percolation model (eq 2) for penta-

decaradical 2 (plot A) and 22-radical 3 (plot B). The black, red, and green

lines correspond to parameter p set to 1.0, 0.9, and 0.8, respectively.

ways to distribute one chemical defect between the two

4-biphenyl-substituted sites, the actual number of spin systems

is doubled from eight to 16.

Overall, 128 spin systems are enumerated from 15 configura-

tions for the organic spin pentamer, corresponding to 22-radical

3. Each spin system, derived from the configuration with r

ferromagnetic (J > 0) biphenylene coupling units and s unpaired

electrons, enters into the linear combination of Brillouin

functions (eq 2) with a factor of b_r,s) [q^r(1 - q)^4-r][ p^s(1 -

p)^2-s]. (Detailed equations are provided in the Supporting

Information: eqs 1s-7s and Table 7s.)

Analogous procedure for enumeration of spin systems with

respect to parameters q and p is applied to the organic spin

trimer, corresponding to pentadecaradical 2. Overall, six con-

figurations, with 0-2 antiferromagnetic (J < 0) couplings

through biphenylene coupling units and 0-1 chemical defects

at the 4-biphenyl-substituted sites are considered. Each spin

system, derived from the configuration with r ferromagnetic (J

> 0) biphenylene coupling units and s unpaired electrons, enters

into the linear combination of Brillouin functions (eq 2) with a

factor of b_r,s) [q^r(1 - q)^2-r][ p^s(1 - p)^1-s].

Figure 15. Organic spin pentamer of component spins, 7/2, 1/2, 6/2, 1/2,

7/2, corresponding to 22-radical 3. (A) Spin systems for the configuration

with two antiferromagnetic (J < 0) couplings through the biphenylene

coupling units and zero chemical defects at the 4-biphenyl-substituted sites.

(B) Spin systems for the configuration with one antiferromagnetic (J < 0)

coupling through the biphenylene coupling units and one chemical defect

at the 4-biphenyl-substituted sites.

component spins, 7/2, 1/2, 6/2, 1/2, 7/2, are connected via four

biphenylene coupling units.

Overall, 15 configurations, with 0-4 antiferromagnetic (J <

0) couplings through biphenylene coupling units and 0-2

chemical defects at the 4-biphenyl-substituted sites, are con-

sidered. Two representative configurations are analyzed.

The first configuration involves two antiferromagnetic (J <

0) couplings through biphenylene coupling units and zero

chemical defects at the 4-biphenyl-substituted sites (Figure 15A).

For this configuration, there are six ways to distribute two

antiferromagnetic (J < 0) and two ferromagnetic (J > 0)

biphenylene coupling units, leading to the following spin

systems: S ) 10p, S ) 10p, S ) 4p, S ) 4p, S ) 4p - 1, and

S ) 4p + 1.

Values for S_s, M_sat, and øT_maxare calculated from the variable

parameters q and p. The behavior of S_sand M_satwithin this

percolation model (eq 2) is shown in Figure 16.

The second configuration involves one antiferromagnetic (J

< 0) coupling through biphenylene coupling units and one

chemical defect at the 4-biphenyl-substituted sites (Figure 15B).

In the presence of one chemical defect at the 4-biphenyl-

substituted site, there are four ways to distribute one antiferro-

magnetic (J < 0) and three ferromagnetic (J > 0) biphenylene

coupling units, leading to the following eight spin systems: S

) 3.5p, S ) 3.5p, S ) 3.5p, S ) 3.5p, S ) 0.5 + 6.5p, S ) 0.5

+ 6.5p, S ) 0.5 + 0.5p, S ) 0.5 - 0.5p. Because there are two

For pentadecaradical 2 with p ) 1.0 (no chemical defects),

S_sas a function of q has a shallow minimum S_s≈ 6.35 at q ≈

0.25; as expected, the limiting values are S_s) 6.5 for q ) 0

(all-antiferromagnetic couplings) and S_s) 7.5 for q ) 1.0 (all-

ferromagnetic couplings). For M_sat, the minimum value M_sat(min)

≈ 0.50 is found at q(min) ≈ 0.4; at this value of q, S_sis

approximately equal to 6.4 (S_s≈ 6.4). For 22-radical 3 with p

) 1.0, relatively deep minima S_s≈ 6.71 and M_sat≈ 0.447 both

at q ≈ 0.4 are found; the limiting values are S_s) 9 for q ) 0

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A R T I C L E S

Table 1. Summary of Magnetic Data and Numerical Fits to the

Percolation Model and Eq 1 (S₂) 1/2) for Pentadecaradical 2 at T

) 1.8 K^a

c

parameter

dependence

eq 2

øT_max

M

sat

^b(µ_B)

(emuKmol^-1

eq 2 eq 1

)

sample mass^a

label (mg)

S

eq 2

S ^d

s

q

p

eq 2

1552 0.98 0.88 0.79

1561 1.30 0.80 0.86

1590 1.00 0.75 0.79

1652 0.91 0.74 0.89

0.961

0.932

0.940

0.896

5.2 0.67 0.67 15.7 15.4 5.1

5.7 0.64^e0.64 16.2^e16.0 5.6^e

4.9 0.57 0.57 12.6 12.5 4.8

5.8 0.60 0.60 15.2 15.2 5.7

b

^aMass of pentadecaether 2-(OMe)₁₅. M_satper mole of triarylmethyl

ether. ^cøT_maxper mole of 2-(OMe)₁₅measured at 500 Oe. ^dNumerical fit

using eq 1 with three variable parameters and parameter dependence within

the 0.64-0.90 range for all samples. ^eAfter annealing at 293 K for about

30 min, M_sat) 0.41 µ_B, øT_max≈ 8 emuKmol^-1, and S_s≈ 3.7 (eq 1 with

three variable parameters).

and S_s) 11 for q ) 1.0. For both 2 and 3, when p ) 0.9 and

p ) 0.8, the S_sis significatntly shifted to lower values. M_sathas

relatively small dependence with respect to p. This suggests

that in the presence of random antiferromagnetic couplings,

relatively large values of S_sare still possible, even with relatively

small fraction of unpaired electrons remaining at low temper-

ature.

Figure 17. SQUID magnetometry for pentadecaradical 2 in THF-d₈(sample

label 1652, Table 1). Main plot: M/M_satvs H/T. Solid lines, labeled S )

7.5 and S_s) 5.8, correspond to plots of Brillouin function with S ) 7.5

and numerical fit of the experimental data at 1.8 K using the percolation

model, respectively. Inset plot: øT vs T.

2.4. Magnetic Studies of Polyradicals 2, 3, and 4. For a

typical sample of polyradical in THF-d₈, magnetization (M) is

measured as a function of magnetic field (H ) 0-5 × 10⁴Oe

at five or four temperatures in the T ) 1.8-10 K range) and

temperature (T ) 1.8-150 K at H ) 5000 Oe and, for selected

samples, 500 and/or 50 Oe). For selected samples, the following

sequences of measurements are carried out: first, without

annealing (with sample chamber degassed at 90 K); second,

with prior annealing at 170 K (slightly above the melting point

of the matrix); and third, after exposure of the sample to room

temperature for a short period (30-70 min). After completion

of these measurements, point-by-point background corrections

for diamagnetism are carried out (Experimental Section).

The results and discussion of magnetic studies are sum-

marized and illustrated in Tables 1-3 and Figures 17-19.

2.4.1. Magnetic Data for Polyradicals 2, 3, and 4, Which

Are Strictly Handled at Low Temperatures (T e 170 K).

Numerical fits to the M vs H/T data for 2, using the percolation

model (eq 2), give q ) 0.74-0.88 and p ) 0.79-0.89 (Table

1). The optimized values of q and p correspond to spin-average

spin, S_s) 4.9-5.8. Similar values of S_sare obtained from the

numerical fits of the M vs H/T data, using eq 1 (Table 1, last

column).⁴⁸As expected for q, p < 1, S_sis less than 15/2, the

theoretical value of S for defect-free, ferromagnetically coupled

pentadecaradical. Most interestingly, the values of M_sat) 0.57-

0.67 µ_Bare in quantitative agreement with the experiment (Table

1). The quality of the numerical fits is illustrated in Figure 17

for a sample of 2 with S_s≈ 5.8.

Figure 18. SQUID magnetometry for 22-radical 3 in THF-d₈(sample label

1594, Table 2). Main plot: M/M_satvs H/T. Solid lines, labeled S ) 11 and

S_s) 9.1, correspond to plots of Brillouin function with S ) 11 and numerical

fit of the experimental data at 1.8 K using the percolation model,

respectively. Inset plot: øT vs T.

dependence is in the 0.92-0.95 range. Similar values of S_scould

be obtained from fits to eq 1; however, the use of four variable

parameters, which are necessary to reproduce the curvature of

magnetization for 3, leads to overparametrization. The values

of M_sat) 0.57-0.65 µ_Bare nearly identical to those in 2. The

agreement between the percolation model and the experiment

is excellent for values of M_sat(Table 2).⁵⁰

Excellent numerical fits to the M vs H/T data for 3 are

obtained as illustrated in Figure 18. A relatively narrow range

of q ) 0.75-0.81 and large values of p ) 0.90-1.00 are

obtained, compared to 2 (Table 2). The three samples of 3 with

the largest values of parameter p ) 0.98-1.00 have the largest

values of S_s) 8-9, near the theoretical value of S ) 11 for

defect-free, ferromagnetically coupled 22-radical.⁴⁹Parameter

The percolation model (eq 2) is not developed for hexa-

tricontaradical (36-radical) 4. Explicit enumeration of very

(50) As mentioned earlier in the text and discussed in a greater detail in ref 1,

an incomplete mass transfer may lead to an underestimate of values of

M

_sat(and øT), which are calculated on the basis of the weighed masses of

(48) For numerical fits of the M vs H/T data for pentadecaradical 2 at 1.8 K,

using eq 1, moderate parameter dependence in the 0.67-0.89 range is found.

(49) This near perfect generation of 22-radical 3 may be the result of a more

extensive effort in its generation; only a subset of samples is reported.

polyethers. For 2 and 3, numerical fits to the percolation model, which

include the mass of the polyether as a third variable parameter, are

overparametrized; the fitted masses are typically greater (by 10-20%),

compared to the weighed masses.

9

J. AM. CHEM. SOC. VOL. 126, NO. 21, 2004 6619

A R T I C L E S

Rajca et al.

Table 3. Summary of Magnetic Data and Numerical Fits to the

Table 2. Summary of Magnetic Data and Numerical Fits to the

Percolation Model (T ) 1.8 K) for 22-Radical 3^a

Linear Combination of Brillouin Functions (Eq 1, Four Variable

Parameters, T ) 1.8 K) for 36-Radical 4^a

c

parameter

dependence

eq 2

øT_max

(emuKmol^-1

M

sat

^b(µ_B)

)

c

d

sample polyether mass^banneal

M

sat

parameter

øT_max

sample mass^a

S

s

label

synth no.^a(mg)

(K)

170 12

170

170 11

293^e

170 13

293^edia

S

s

(µ_B)

dependence (emuKmol^-1

)

label

(mg)

q

p

eq 2

1111

1339

1595

I

II

1.65

0.78

0.91

0.62 0.45-0.99 58 (5000)

0.41 0.57-0.98 29 (5000)

0.63 0.55-0.99 71 (50)

0.45 0.59-0.99 34 (50)

0.70 0.62-0.97 88 (500)

dia

0.56 0.61-0.98 70 (50)

dia dia

1010

1168

2.09 0.79 0.91

1.21 0.77 0.99

0.947

0.924

0.938

0.949

0.932

0.919

7.4 0.59 0.59 24.9 27.2

8.5 0.60 0.60 30.3 31.2

7.9 0.59 0.59 27.9 28.6

7.1 0.57 0.57 25.5 25.5

9.1 0.65 0.65 35.9 35.9

8.2 0.58 0.58 28.9 29.1

8

1231^d1.50 0.77 0.95

7

1327

1594^e0.89 0.81 1.00

1636 0.89 0.75 0.98

0.97 0.78 0.90

1620

1670

1686

III

0.84

dia

1.11 e170 12

293^edia

^aMass of 22-ether 3-(OMe)₂₂(sample labels 0997 and 1555). M_satper

mole of triarylmethyl ether. ^cøT_maxper mole of 3-(OMe)₂₂measured at

500 Oe. ^dNumerical fit at 3 K and øT_maxat 200 Oe. ^eAfter annealing at

293 K for about 50 min, S_s≈ 3.7 (eq 1), M_sat) 0.33 µ_B, and øT_max) 9.2

b

1.10 e170 12.5 0.72 0.64-0.98 86 (500)

293^f

5

0.38 0.68-0.99 21 (500)

emuKmol^-1

.

^a36-ether 4-(OMe)₃₆from three different syntheses was used (Experi-

c

mental Section). ^bMass of 36-ether 4-(OMe)₃₆. M_satper mole of triaryl-

methyl ether. ^døT_maxper mole of 4-(OMe)₃₆measured at indicated magnetic

field (Oe). ^eAnnealing for about 30 min. ^fAnnealing for about 70 min.

rise in øT with decreasing temperature down to 1.8 K are

obtained for 2 and its higher homologues, respectively.⁵¹

The approximate ideal paramagnetic behavior for 2 at low

temperatures found in the øT vs T plots is consistent with the

use of the Brillouin functions for the M vs H data. Because the

net ferromagnetic couplings in 3 and 4 span the whole

temperature range down to 1.8 K, the numerical fits to the

Brillouin functions (eqs 1 and 2) may not be adequate. However,

such numerical fits still provide useful approximation, i.e.,

excellent agreement between the experiment and the percolation

models is obtained in 2 and 3 for the maximum values of øT at

low temperature (øT_max). Also, this agreement illustrates ac-

curacy of the percolation models at both high H (M_sat) and low

H (øT_max) regimes.

The maximum values of øT for the plateau at low temperature

(øT_max) are below those for the defect-free ferromagnetically

coupled polyradicals (Figures 17-19); this is consistent with

the less than expected values of S and M_sat. For the four best

samples of 2, 3, and 4, øT_maxvalues are 13-16, 28-36, and

70-88 emuKmol^-1, respectively; the monodisperse S ) 15/2,

S ) 11, and S ) 18 polyradicals should give S(S + 1)/2 )

31.875, 66, and 171 emuKmol^-1, respectively.

Figure 19. SQUID magnetometry for 36-radical 4 in THF-d₈(sample label

1620, Table 3). Main plot: M/M_satvs H/T. Solid lines, labeled S ) 18 and

S_s) 13.3, correspond to plots of Brillouin function with S ) 18 and

numerical fit of the experimental data at 1.8 K, respectively. The numerical

fit is based upon linear combination of two Brillouin functions (eq 1) with

four variable parameters. Inset plot: øT vs T.

2.4.2. Thermal Stability (Persistence) of Polyradicals.

Selected samples of polyradicals are studied after exposure to

room temperature for about 0.5-1 h. In each case, only eq 1 is

employed for numerical fits to the M vs H/T data; the percolation

models do not give adequate fits, as expected. For a sample of

2 (S_s) 5.7, M_sat) 0.64 µ_B, and øT_max≈ 16 emuKmol^-1), the

corresponding values are 3.7, 0.41 µ_B, and 8 emuKmol^-1, after

annealing at room temperature for about 30 min (Table 1).

Similar behavior is found for one sample of 3 after annealing

at room temperature for about 50 min, i.e., the value of S_s

decreases from 9.1 to 3.8 and the value of M_satdecreases by

about factor of 2 (Table 2). Four samples of 4 are annealed at

room temperature for 30-70 min (Table 3). For two of the

samples with S_s) 11 and S_s) 12.5, after 30 and 70 min at

room temperature, S_s) 7 and S_s) 5 are obtained, respectively.

However, the other two samples of 4 become diamagnetic after

30 min at room temperature. One possibility is that excess of

iodine is present in those samples and it reacts with radicals at

higher temperature. Overall, polyradicals 2-4 are relatively

large number of possible r,s-configurations would not be

practical. Furthermore, side products found in 36-ether 4-(OMe)₃₆

would further complicate the percolation model. Numerical fits

using eq 1 with four variable parameters give values of S_s)

8-13 for 36-radical 4; for the four best samples of 4, S_s)

12-13, still significantly below S ) 18 for defect-free,

ferromagnetically coupled 36-radical. The values of M_satare in

the 0.41-0.72 µ_Brange; however, M_satis in the 0.63-0.72 µ_B

range for the best four samples (Figure 19, Table 3). There is

no obvious correlation between the experimental values of S_s

and M_sat.

The M vs T data at H ) 5000, 500, and/or 50 Oe are plotted

as the product of magnetic susceptibility per mole of starting

polyether (ø ) M/H) and temperature vs temperature, i.e., øT

vs T for polyradicals 2, 3, and 4 (inset plots in Figures 17-19).

For all polyradicals, the values of øT are increasing with

decreasing temperature from 150 to about 5 K, indicating the

thermal depopulation of the low spin excited states. This

behavior is consistent with the presence of a weak ferromagnetic

coupling. In the T ) 5-1.8 K range and low magnetic fields

(e.g., 500 or 50 Oe), a nearly flat curve (plateau) and a slower

(51) The downward turn in øT at H ) 5000 Oe is caused by the paramagnetic

saturation, as illustrated in Figure 11s, Supporting Information.

9

6620 J. AM. CHEM. SOC. VOL. 126, NO. 21, 2004

Organic Spin Clusters

A R T I C L E S

7.821, 7.297), 7.821 (t, J ) 2, 2 H, 8.202, 7.297), 7.297 (t, J ) 2, 2 H,

8.202, 7.821). Rings B and C: 7.775 (t, J ) 2, 1 H, 7.650), 7.650 (d,

J ) 2, 2 H, 7.775), 7.770 (d, J ) 1.5, 2 H, 7.734), 7.734 (br, 1 H,

7.770). 1,4-Disubstituted benzene rings 1,1′-5,5′: 7.565 (d, J ) 9, 4

H, 7.271), 7.271 (d, J ) 9, 4 H, 7.565); 7.542 (d, J ) 9, 4 H, 7.211),

7.211 (d, J ) 9, 4 H, 7.542); 7.443 (d, J ) 8, 4 H, 7.261), 7.261 (d,

J ) 9, 4 H, 7.443); 7.389 (d, J ) 8, 4 H, 7.189), 7.189 (d, J ) 8, 4 H,

7.389); 7.335 (d, J ) 8, 4 H, 7.201), 7.201 (d, J ) 9, 4 H, 7.335).

Aliphatic region: 3.016 (s, 6 H), 2.914 (s, 3 H), 2.883 (s, 6 H), 2.776

(s, 6 H), 1.264 (s, 18 H), 1.242 (s, 18 H), 1.223 (s, 18 H), 1.221 (s, 18

persistent at room temperature; S_s) 7 for 4 is the highest value

of S in a polyradical exposed to room temperature for an

extended period.

3. Conclusion

Polyarylmethyl polyethers, in which calix[4]arene-based

macrocyclic modules are connected with bis(biphenylene)methyl

linkers, are prepared. Although the presence of slow intercon-

version (on the NMR time scale) between significantly populated

conformers may not be strictly excluded, most likely the

polyethers are mixtures of diastereomers (with nearly coincident

NMR chemical shifts). Radii of gyration for polyethers in

tetrahydrofuran-d₈are in the 1.2-1.8 nm range. The corre-

sponding polyradicals are likely to possess sizes similar to those

of polyethers.¹

Polyradicals possess relatively large values of average S; the

value S ≈ 13 for the branched 36-radical 4 is the highest among

organic molecules. Notably, the values of S increase with the

increasing number of the S ) 1/2 radicals (triarylmethyls).

Pentadecaradical 2 and 22-radical 3, in which macrocyclic

modules are connected with bis(biphenylene)methyl linkers in

a quasilinear fashion, provide excellent model compounds for

unequal-spin clusters with random distribution of ferromagnetic

and antiferromagnetic couplings. Because polyradicals 2-4 may

be viewed as linear and branched fragments of the first

conjugated polymer with magnetic ordering, our analyses of

magnetic data for 2 and 3 may provide a rational for extra-

ordinary extent of net ferromagnetic exchange couplings leading

to high values of magnetic moment (or S) in such polymers.

1

H), 1.187 (s, 18 H). H NMR (500 MHz, C₆D₆, 328 K): 8.20-7.10

(m, 52 H), 3.015 (s, 6 H), 2.919 (s, 3 H), 2.901 (s, 6 H), 2.812 (s, 6

H), 1.228 (s, 18 H), 1.222 (s, 18 H), 1.213 (s, 36 H), 1.192 (s, 18 H).

¹H NMR (500 MHz, C₆D₆, 348 K): 8.20-7.10 (m, 52 H), 3.017 (s, 6

H), 2.921 (s, 3 H), 2.909 (s, 6 H), 2.830 (s, 6 H), 1.232 (s, 18 H),

1.225 (s, 18 H), 1.219 (s, 36 H), 1.198 (s, 18 H). ¹³C{¹H}DEPT(135°)-

NMR (125 MHz, EM ) -1.30, GB ) 0.90, C₆D₆, 293 K): aromatic

quaternary region, expected, 17 resonances; found, 17 resonances at

150.3 (q), 150.0 (q), 149.9 (q), 149.81 (q), 149.74 (q), 148.7 (q), 145.1

(q), 144.5 (q), 143.6 (q), 142.92 (q), 142.86 (q), 142.56 (q), 142.51

(q), 142.4 (q), 141.2 (q), 140.6 (q), 122.3 (q); aromatic nonquaternary

region, expected, 17 resonances; found 13 resonances at 130.2, 129.89,

129.88, 129.6, 129.5, 129.37, 129.32, 128.0, 127.3, 125.31, 125.26,

125.24, 125.1; aliphatic region, 88.0 (q), 87.8 (q), 87.61 (q), 87.57 (q),

52.59, 52.51, 52.47, 52.3, 34.79 (q), 34.75 (q), 31.85, 31.81.

Module 11B. Clear solid (softened at 177 °C and melted at 183-

185 °C). Anal. Calcd for C₁₃₈H₁₆₃O₇Br: C, 82.31; H, 8.16. Found:

82.41; H, 8.33. IR (cm^-1): 1594 (Ar), 1082 (C-O-C). FABMS (3-

NBA) cluster: m/z (% RA for m/z ) 400-2440) at (M - OCH₃)⁺

1980.0 (63), 1981.0 (81), 1982.0 (100), 1983.0 (90), 1984.0 (58), 1985.0

(28); calcd for C₁₃₇H₁₆₀O₆Br at (M - OCH₃)⁺1980.1 (46), 1981.1 (71),

1

1982.1 (100), 1983.1 (98), 1984.1 (65), 1985.1 (32), 1986.1 (12). H

1

NMR (500 MHz, EM ) -1.80, GB ) 0.80, C₆D₆, 293 K, H-¹H

Experimental Section

COSY cross-peaks in aromatic region): 1,3,5-Trisubstituted benzene

rings (rings A - D): Ring A: 8.177 (t, J ) 2, 1 H, 7.791, 7.448),

7.791 (t, J ) 2, 1 H, 8.177, 7.448), 7.448 (t, J ) 2, 1 H, 8.177, 7.791).

Ring B: 8.120 (t, J ) 2, 1 H, 7.642, 7.504), 7.642 (t, J ) 2, 1 H,

8.120, 7.504), 7.504 (t, J ) 2, 1 H, 8.120, 7.642). Ring C: 7.859 (t, J

) 2, 1 H, 7.822, 7.752), 7.822 (t, J ) 2, 1 H, 7.859, 7.752), 7.752 (t,

J ) 2, 1 H, 7.859, 7.822). Ring D: 7.781 (t, J ) 2, 1 H, 7.759, 7.672),

7.759 (t, J ) 2, 1 H, 7.781, 7.672), 7.672 (t, J ) 2, 1 H, 7.781, 7.759).

1,4-Disubstituted benzene rings 1-10: 7.548 (d, J ) 9, 2 H, 7.232),

7.232 (d, J ) 9, 2 H, 7.548); 7.547 (d, J ) 9, 2 H, 7.269), 7.269 (d,

J ) 9, 2 H, 7.547); 7.501 (d, J ) 9, 2 H, 7.366), 7.366 (d, J ) 9, 2 H,

7.501); 7.458 (d, J ) 9, 2 H, 7.180), 7.180 (d, J ) 9, 2 H, 7.458);

7.452 (d, J ) 9, 2 H, 7.226), 7.226 (d, J ) 9, 2 H, 7.452); 7.452 (d,

J ) 9, 2 H, 7.206), 7.206 (d, J ) 9, 2 H, 7.452); 7.426 (d, J ) 9, 2 H,

7.206), 7.206 (d, J ) 9, 2 H, 7.426); 7.405 (d, J ) 9, 2 H, 7.134),

7.134 (d, J ) 9, 2 H, 7.405); 7.402 (d, J ) 9, 2 H, 7.179), 7.179 (d,

J ) 9, 2 H, 7.402); 7.371 (d, J ) 9, 2 H, 7.142), 7.142 (d, J ) 9, 2 H,

7.371). Aliphatic region: 3.028 (s, 3 H), 2.982 (s, 3 H), 2.925 (s, 3 H),

2.914 (s, 3 H), 2.858 (s, 3 H), 2.812 (s, 3 H), 2.775 (s, 3 H), 1.239 (s,

9 H), 1.217 (s, 9 H), 1.215 (s, 9 H), 1.212 (s, 9 H), 1.201 (s, 9 H),

1.199 (s, 9 H), 1.197 (s, 9 H), 1.190 (s, 9 H), 1.161 (s, 9 H), 1.153 (s,

Macrocyclic Modules: 11A, 11B, 11C, and 11D. A round-bottom

flask with sidearm was charged with NaH (0.12 g of 60% dispersion

in mineral oil, 3.0 mmol). After removal of the mineral oil with pentane

under nitrogen flow, THF (2.0 mL) was added, and then, during cooling

with an ice bath, macrocyclic diol 10A (0.541 g, 0.272 mmol) in THF

(4.0 mL) was added. The resultant suspension was stirred for 2 h, during

which time the temperature of cooling bath was allowed to reach

ambient temperature. After the bath was recooled to 0 °C, MeI (0.30

mL, 4.817 mmol) was added. Following 20 h of stirring at ambient

temperature, aqueous workup was carried out. After extraction with

ether, the organic layer was dried over MgSO₄and concentrated in

vacuo to give a light yellow solid. Column chromatography (flash silica

gel, 3-5% ether in hexane) gave 249 mg (45%) of clear solid, which

was used for the next step (softened at 139 °C and melted at 164-166

°C). From four other reactions on the 0.9, 0.56, 0.25, and 0.1 g scales,

0.836 g (44-57%) of macrocyclic module 11A was isolated from 1.841

g of macrocyclic diol 10A. Starting from macrocyclic diol 10B (0.365

g), module 11B (0.218 g, 59%) was obtained. Overall, from five

reactions on the 1.5, 0.7 (2), 0.4 (2) g scales, 1.505 g (40%) of module

10B was isolated from 3.687 g of 10B. From two reactions on the 0.5

and 0.1 g scales, 0.198 g (33%) of module 10B was isolated. From

two reactions, starting from 0.8148 g of impure 10A, 0.0268 g (3%)

of module 11D was also isolated.

1

9 H). H NMR (500 MHz, EM ) -1.70, GB ) 0.80, C₆D₆, 328 K):

8.20-7.10 (m, 52 H), 3.024 (s, 3 H), 2.980 (s, 3 H), 2.928 (s, 3 H),

2.910 (s, 3 H), 2.868 (s, 3 H), 2.819 (s, 3 H), 2.785 (s, 3 H), 1.239 (s,

9 H), 1.219 (s, 9 H), 1.213 (s, 18 H), 1.202 (s, 9 H), 1.199 (s, 9 H),

1.197 (s, 9 H), 1.191 (s, 9 H), 1.161 (s, 9 H), 1.154 (s, 9 H). ¹H NMR

Module 11A. Anal. Calcd for C₁₃₈H₁₆₃O₇Br: C, 82.31; H, 8.16.

Found: 82.59; H, 7.96. IR (cm^-1): 1595 (Ar), 1085 (C-O-C).

FABMS (3-NBA) cluster: m/z (% RA for m/z ) 400-2140) at (M -

OCH₃)⁺1980.0 (62), 1981.0 (81), 1982.0 (100), 1983.0 (83), 1984.0

(55), 1985.0 (27); calcd for C₁₃₇H₁₆₀O₆Br at (M - OCH₃)⁺1980.1 (46),

1981.1 (71), 1982.1 (100), 1983.1 (98), 1984.1 (65), 1985.1 (32), 1986.1

1

(500 MHz, EM ) -1.80, GB ) 0.80, C₆D₆, 348 K, H-¹H COSY

cross-peaks in aromatic region): 1,3,5-Trisubstituted benzene rings

(rings A - D): Ring A: 8.045 (t, J ) 2, 1 H, 7.712, 7.378), 7.712 (t,

J ) 2, 1 H, 8.045, 7.378), 7.378 (t, J ) 2, 1 H, 8.045, 7.712). Ring B:

7.998 (t, J ) 2, 1 H, 7.618, 7.435), 7.618 (t, J ) 2, 1 H, 7.998, 7.435),

7.435 (t, J ) 2, 1 H, 7.998, 7.618). Ring C: 7.791 (t, J ) 2, 1 H,

7.756, 7.666), 7.666 (t, J ) 2, 1 H, 7.791, 7.756), 7.756 (t, J ) 2, 1 H,

1

(12). H NMR (500 MHz, EM ) -1.50, GB ) 0.80, C₆D₆, 293 K,

¹H-¹H COSY cross-peaks in aromatic region): 1,3,5-Trisubstituted

benzene rings (rings A, A′, B, C): Rings A, A′: 8.202 (t, J ) 2, 2 H,

9

J. AM. CHEM. SOC. VOL. 126, NO. 21, 2004 6621

A R T I C L E S

Rajca et al.

7.791, 7.666). Ring D: 7.720 (t, J ) 2, 1 H, 7.645, 7.615), 7.645 (t, J

) 2, 1 H, 7.720, 7.615), 7.615 (t, J ) 2, 1 H, 7.720, 7.645).

1,4-Disubstituted benzene rings 1-10: 7.492 (d, J ) 9, 2 H, 7.221),

7.221 (d, J ) 9, 2 H, 7.492); 7.490 (d, J ) 9, 2 H, 7.252), 7.252 (d,

J ) 9, 2 H, 7.490); 7.429 (d, J ) 9, 2 H, 7.317), 7.317 (d, J ) 9, 2 H,

7.429); 7.429 (d, J ) 9, 2 H, 7.205), 7.205 (d, J ) 9, 2 H, 7.429);

7.403 (d, J ) 9, 2 H, 7.226), 7.226 (d, J ) 9, 2 H, 7.403); 7.380 (d,

J ) 9, 2 H, 7.198), 7.198 (d, J ) 9, 2 H, 7.380); 7.386-7.353 (m, 8

H, 7.196-7.133), 7.196-7.133 (m, 8 H, 7.386-7.353). Aliphatic

region: 3.012 (s, 3 H), 2.974 (s, 3 H), 2.932 (s, 3 H), 2.901 (s, 3 H),

2.892 (s, 3 H), 2.844 (s, 3 H), 2.810 (s, 3 H), 1.239 (s, 9 H), 1.224 (s,

9 H), 1.212 (s, 9 H), 1.206 (s, 9 H), 1.205 (s, 9 H), 1.199 (s, 9 H),

1.197 (s, 9 H), 1.192 (s, 9 H), 1.160 (s, 9 H), 1.157 (s, 9 H). ¹³C{¹H}-

DEPT(135°)NMR (125 MHz, EM ) -1.20, GB ) 0.80, C₆D₆, 293

K): aromatic quaternary region, expected, 32 resonances; found, 29

resonances at 150.5 (q), 150.2 (q), 150.00 (q), 149.97 (q), 149.92 (q),

149.80 (q), 149.75 (q), 149.66 (q), 149.0 (q), 148.6 (q), 145.8 (q), 144.7

(q), 144.3 (q), 143.81 (q), 143.79 (q), 143.67 (q), 143.2 (q), 143.1 (q),

143.0 (q), 142.7 (q), 142.4 (q), 142.17 (q), 142.16 (q), 142.0 (q), 141.9

(q), 141.6 (q), 141.1 (q), 140.4 (q), 122.5 (q); aromatic nonquaternary

region, expected, 32 resonances; found 21 resonances at 130.16, 130.07,

130.05, 129.98, 129.82, 129.79, 129.67, 129.60, 129.57, 129.53, 129.46,

129.41, 129.13, 129.04, 126.6, 125.43, 125.32, 125.26, 125.17, 125.13,

125.07; aliphatic region, 88.2 (q), 87.81 (q), 87.70 (q), 87.65 (q), 82.63

(q), 52.8, 52.54, 52.52, 52.51, 52.49, 52.47, 34.83 (q), 34.79 (q), 34.76

(q), 34.74 (q), 31.88, 31.86, 31.82, 31.78, 31.74.

7.601 (t, J ) 2, 1 H, 7.866, 7.737). Ring C: 7.840 (t, J ) 2, 1 H,

7.691, 7.682), 7.691 (t, J ) 2, 1 H, 7.840, 7.682), 7.682 (t, J ) 2, 1 H,

7.840, 7.691). Ring D: 7.791 (t, J ) 2, 1 H, 7.770, 7.516), 7.770 (t, J

) 2, 1 H, 7.791, 7.516), 7.516 (t, J ) 2, 1 H, 7.770, 7.645).

1,4-Disubstituted benzene rings 1-10: 7.506 (d, J ) 8, 2 H, 7.233),

7.233 (d, J ) 9, 2 H, 7.506); 7.489 (d, J ) 9, 2 H, 7.215), 7.215 (d,

J ) 9, 2 H, 7.489); 7.488 (d, J ) 9, 2 H, 7.252), 7.252 (d, J ) 9, 2 H,

7.488); 7.469 (d, J ) 9, 2 H, 7.240), 7.240 (d, J ) 9, 2 H, 7.469);

7.458 (d, J ) 9, 2 H, 7.250), 7.250 (d, J ) 8, 2 H, 7.458); 7.442 (d,

J ) 9, 2 H, 7.209), 7.209 (d, J ) 9, 2 H, 7.442); 7.426 (d, J ) 9, 2 H,

7.208), 7.208 (d, J ) 9, 2 H, 7.426); 7.397 (d, J ) 9, 2 H, 7.220),

7.220 (d, J ) 9, 2 H, 7.397); 7.369 (d, J ) 9, 2 H, 7.248), 7.248 (d,

J ) 8, 2 H, 7.369); 7.355 (d, J ) 9, 2 H, 7.167), 7.167 (d, J ) 9, 2 H,

7.355). Aliphatic region: 3.008 (s, 3 H), 2.978 (s, 3 H), 2.959 (s, 3 H),

2.900 (s, 3 H), 2.895 (s, 3 H), 2.850 (s, 3 H), 2.785 (s, 3 H), 1.240 (s,

9 H), 1.225 (s, 9 H), 1.221 (s, 9 H), 1.218 (s, 9 H), 1.212 (s, 9 H),

1.205 (s, 27 H), 1.200 (s, 9 H), 1.189 (s, 9 H). ¹³C{¹H}DEPT(135°)-

NMR (125 MHz, C₆D₆, 293 K): aromatic quaternary region, expected,

32 resonances; found, 28 resonances at 150.5 (q), 150.4 (q), 150.2 (q),

149.94 (q), 149.87 (q), 149.81 (q), 149.7 (q), 149.6 (q), 147.9 (q), 145.0

(q), 144.55 (q), 144.45 (q), 144.41 (q), 143.8 (q), 143.7 (q), 143.51

(q), 143.47 (q), 143.38 (q), 143.0 (q), 142.9 (q), 142.79 (q), 142.69

(q), 142.4 (q), 142.0 (q), 140.9 (q), 140.5 (q), 140.3 (q), 122.2 (q);

aromatic nonquaternary region, expected, 32 resonances; found 23

resonances at 131.1, 130.9, 130.3, 130.0, 129.8, 129.6, 129.52, 129.48,

129.41, 129.36, 129.18, 129.16, 129.11, 128.85, 128.76 (C₆D₅H),

128.68, 128.23, 128.18, 127.5, 125.4, 125.23, 125.20, 125.17, 125.0;

aliphatic region, 88.23 (q), 88.15 (q), 87.84 (q), 87.75 (q), 87.71 (q),

87.62 (q), 52.68, 52.64, 52.59, 52.55, 52.49, 52.39, 34.84 (q), 34.80

(q), 34.77 (q), 31.85, 31.82, 31.78.

Module 11C. This C₁-symmetric isomer is not pure; extra peaks in

1

the H and ¹³C NMR spectra are found. Clear solid (softened at 184

°C and melted at 189-191 °C). Anal. Calcd for C₁₃₈H₁₆₃O₇Br: C, 82.31;

H, 8.16. Found: 82.41; H, 8.33. IR (cm^-1): 1594 (Ar), 1083 (C-O-

C). FABMS (3-NBA) cluster: m/z (% RA for m/z ) 320-2440) at (M

- OCH₃)⁺1980.0 (61), 1981.0 (86), 1982.0 (100), 1983.0 (84), 1984.0

(57), 1985.0 (27); calcd for C₁₃₇H₁₆₀O₆Br at (M - OCH₃)⁺1980.1 (46),

Module 11D. This C₂-symmetric isomer is not pure; additional peaks

1

in the H and ¹³C NMR spectra are found. Yellow solid (softened at

100 °C and melted at 113-115 °C). IR (cm^-1): 1594 (Ar), 1082 (C-

O-C). FABMS (3-NBA) cluster: m/z (% RA for m/z ) 400-2140)

at (M - OCH₃)⁺1980.0 (65), 1981.0 (79), 1982.0 (100), 1983.0 (87),

1984.0 (61), 1985.0 (28); calcd for C₁₃₇H₁₆₀O₆Br at (M - OCH₃)⁺:

1980.1 (46), 1981.1 (71), 1982.1 (100), 1983.1 (98), 1984.1 (65), 1985.1

1

1981.1 (71), 1982.1 (100), 1983.1 (98), 1984.1 (65), 1985.1 (32). H

NMR (500 MHz, EM ) -1.00, GB ) 0.44, C₆D₆, 298 K): 8.20-

7.10 (m, 52 H), 3.017 (s, 3 H), 2.990 (s, 3 H), 2.953 (s, 3 H), 2.882 (s,

3 H), 2.872 (s, 3 H), 2.782 (s, 3 H), 2.735 (s, 3 H), 1.224 (s, 9 H),

1.208 (s, 9 H), 1.205 (s, 9 H), 1.201 (s, 9 H), 1.196 (s, 9 H), 1.189 (s,

9 H), 1.186 (s, 9 H), 1.181 (s, 9 H), 1.178 (s, 9 H), 1.157 (s, 9 H). ¹H

1

(32), 1986.1 (12). H NMR (500 MHz, EM ) -1.80, GB ) 0.80,

1

C₆D₆, 293 K, H-¹H COSY cross-peaks in aromatic region): 1,3,5-

1

NMR (500 MHz, EM ) -0.84, GB ) 0.44, C₆D₆, 328 K, H-¹H

Trisubstituted benzene rings (rings A,A′,B,C): Rings A, A′: 8.008 (t,

J ) 2, 2 H, 7.767, 7.581), 7.767 (t, J ) 2, 2 H, 8.008, 7.581), 7.581

(t, J ) 2, 2 H, 8.008, 7.767). Rings B and C: 7.878 (t, J ) 1.5, 1 H,

7.736), 7.736 (d, J ) 1.5, 2 H, 7.878), 7.871 (t, J ) 2, 1 H, 7.794),

7.794 (d, J ) 2, 2 H, 7.871). 1,4-Disubstituted benzene rings 1,1′-5,5′:

7.530 (d, J ) 9, 4 H, 7.222), 7.222 (d, J ) 8, 4 H, 7.530); 7.491 (d,

J ) 8, 4 H, 7.212), 7.212 (d, J ) 9, 4 H, 7.491); 7.478 (d, J ) 8, 2 H,

7.182), 7.182 (d, J ) 9, 2 H, 7.478) (diastereotopic); 7.467 (d, J ) 8,

4 H, 7.236), 7.236 (d, J ) 8, 4 H, 7.467); 7.446 (d, J ) 8, 4 H, 7.180),

7.180 (d, J ) 8, 4 H, 7.446); 7.414 (d, J ) 9, 2 H, 7.194), 7.194 (d,

J ) 9, 2 H, 7.414) (diastereotopic). Aliphatic region: 2.950 (s, 6 H),

2.942 (s, 6 H), 2.840 (s, 3 H), 2.807 (s, 6 H), 1.208 (s, 18 H), 1.196 (s,

27 H), 1.180 (s, 18 H), 1.156 (s, 18 H), 1.146 (s, 9 H). ¹³C{¹H}DEPT-

(135°)NMR (125 MHz, EM ) -0.30, GB ) 0.50, C₆D₆, 293 K):

aromatic quaternary region, expected, 19 resonances; found, 19

resonances at 150.5 (q), 150.0 (q), 149.9 (q), 149.8 (q), 149.57 (q),

149.54 (q), 148.6 (q), 144.40 (q), 144.35 (q), 143.8(q), 143.3(q), 143.09

(q), 142.96 (q), 142.64 (q), 142.59 (q), 142.3 (q), 142.0 (q), 140.6 (q),

122.5 (q); aromatic nonquaternary region, expected, 19 resonances;

found 18 resonances at 129.92, 129.89, 129.84, 129.7, 129.34, 129.31,

129.24, 129.16, 128.5, 129.0, 128.8, 128.7, 127.4, 126.4, 125.4, 125.24,

125.21, 125.1; aliphatic region, 88.2 (q), 87.70 (q), 87.64 (q), 87.56

(q), 52.8, 52.48, 52.46, 52.41, 34.79 (q), 34.77 (q), 34.75 (q), 34.70

(q), 31.85, 31.83, 31.81, 31.72.

COSY cross-peaks in aromatic region): 1,3,5-Trisubstituted benzene

rings (rings A - D): Ring A: 7.938 (t, J ) 2, 1 H, 7.891, 7.488),

7.891 (t, J ) 2, 1 H, 7.938, 7.488), 7.488 (t, J ) 2, 1 H, 7.938, 7.891).

Ring B: 7.904 (t, J ) 2, 1 H, 7.776, 7.628), 7.776 (t, J ) 2, 1 H,

7.904, 7.628), 7.628 (t, J ) 2, 1 H, 7.904, 7.776). Ring C: 7.891 (t, J

) 2, 1 H, 7.695, 7.688), 7.695 (t, J ) 2, 1 H, 7.891, 7.688), 7.688 (t,

J ) 2, 1 H, 7.891, 7.695). Ring D: 7.815 (t, J ) 2, 1 H, 7.797, 7.536),

7.797 (t, J ) 2, 1 H, 7.815, 7.536), 7.536 (t, J ) 2, 1 H, 7.815, 7.797).

1,4-Disubstituted benzene rings 1-10: 7.526 (d, J ) 9, 2 H, 7.233),

7.233 (d, J ) 9, 2 H, 7.526); 7.515 (d, J ) 9, 2 H, 7.215), 7.215 (d,

J ) 9, 2 H, 7.515); 7.511 (d, J ) 9, 2 H, 7.252), 7.252 (d, J ) 9, 2 H,

7.511); 7.496 (d, J ) 9, 2 H, 7.240), 7.240 (d, J ) 9, 2 H, 7.496);

7.482 (d, J ) 9, 2 H, 7.250), 7.250 (d, J ) 9, 2 H, 7.482); 7.453 (d,

J ) 9, 2 H, 7.209), 7.209 (d, J ) 9, 2 H, 7.453); 7.437 (d, J ) 9, 2 H,

7.208), 7.208 (d, J ) 9, 2 H, 7.437); 7.411 (d, J ) 9, 2 H, 7.220),

7.220 (d, J ) 9, 2 H, 7.411); 7.385 (d, J ) 9, 2 H, 7.248), 7.248 (d,

J ) 9, 2 H, 7.385); 7.362 (d, J ) 9, 2 H, 7.167), 7.167 (d, J ) 9, 2 H,

7.362). Aliphatic region: 3.010 (s, 3 H), 2.982 (s, 3 H), 2.955 (s, 3 H),

2.893 (s, 3 H), 2.886 (s, 3 H), 2.824 (s, 3 H), 2.769 (s, 3 H), 1.231 (s,

9 H), 1.217 (s, 9 H), 1.216 (s, 9 H), 1.210 (s, 9 H), 1.207 (s, 9 H),

1.198 (s, 18 H), 1.194 (s, 9 H), 1.192 (s, 9 H), 1.177 (s, 9 H). ¹H NMR

1

(500 MHz, EM ) -0.51, GB ) 0.47, C₆D₆, 348 K, H-¹H COSY

cross-peaks in aromatic region): 1,3,5-Trisubstituted benzene rings

(rings A - D): Ring A: 7.892 (t, J ) 2, 1 H, 7.857, 7.454), 7.857 (t,

J ) 2, 1 H, 8.045, 7.454), 7.454 (t, J ) 2, 1 H, 7.892, 7.857). Ring B:

7.866 (t, J ) 2, 1 H, 7.737, 7.601), 7.737 (t, J ) 2, 1 H, 7.866, 7.601),

Module-with-Linker: 15A and 15B. t-BuLi (0.172 mL of a ∼1.5

M solution in pentane, 0.26 mmol, Acros) was added to a solution of

module 11A (0.238 g, 0.118 mmol) in THF (1.40 mL) in a heavy-wall

9

6622 J. AM. CHEM. SOC. VOL. 126, NO. 21, 2004

Organic Spin Clusters

A R T I C L E S

Schlenk vessel at -78 °C. After 3 h, the reaction mixture was warmed

to -20 °C for 10 min and then recooled to -78 °C. Following addition

of ZnCl₂(0.166 mL of 0.81 M solution in ether, 0.134 mmol), the

reaction mixture was allowed to attain ambient temperature for 2 h.

The resultant clear light orange solution was transferred to a glovebox.

Pd(PPh₃)₄(4.0 mg, 0.0035 mmol) and racemic linker 14 (0.127 mg,

0.236 mmol) were added to the reaction mixture. Subsequently, the

reaction mixture was heated in an oil bath at 100 °C for 1.5 days. After

extraction with ether, the organic layer was dried over MgSO₄and

concentrated in vacuo to give a yellow solid. Column chromatography

(TLC grade silica gel, 3-5% ether in hexane), followed by the treatment

with ether/MeOH, gave 0.145 mg (52%) of module-with-linker 15A

as a white powder (softening to clear solid at 209-211 °C). From two

other reactions on the 0.3 and 0.3 g scales, 0.338 g (39-59%) of

module-with-linker 15A was obtained from 0.597 g of module 11A.

Module-with-linker 15B (0.386 mg, 58%) was obtained as white powder

(softening to clear solid at 203-205 °C), starting from 0.572 g of

module 11B. From another reaction, 0.323 g (56%) of 15B was obtained

from 0.493 g of module 11B.

7.977 (t, t, J ) 2, J ) 2, 1 H, 7.094, [7.869, 7.866]), 7.094 (br, 1 H,

[7.979, 7.977], [7.869, 7.866]), 7.869, 7.866 (t, t, J ) 2, J ) 2, 1 H,

[7.979, 7.977], 7.094). Ring D: 7.794, 7.790 (t, t, J ) 2, J ) 2, 1 H,

[7.767, 7.763]), [7.686, 7.683]), 7.767, 7.763 (t, t, J ) 2, J ) 2, 1 H,

[7.794, 7.790]), [7.686, 7.683]), 7.686, 7.683 (t, t, J ) 2, J ) 2, 1 H,

[7.794, 7.790]), [7.767, 7.763]). Rings 1-13: 7.591 (d, J ) 9, 2 H,

7.207), 7.207 (d, J ) 9, 2 H, 7.591); 7.556 (d, J ) 9, 2 H, 7.225),

7.225 (d, J ) 9, 2 H, 7.556); 7.556 (d, J ) 9, 2 H, 7.198), 7.198 (d,

J ) 9, 2 H, 7.556); 7.519 (d, J ) 9, 2 H, 7.165), 7.165 (d, J ) 8, 2 H,

7.519); 7.490 (d, J ) 9, 2 H, 7.273), 7.273 (d, J ) 9, 2 H, 7.490);

7.474 (d, J ) 9, 2 H, 7.199), 7.199 (d, J ) 9, 2 H, 7.474); 7.465 (d,

J ) 8, 2 H, 7.213), 7.213 (d, J ) 8, 2 H, 7.465); 7.463 (d, J ) 9, 2 H,

7.155), 7.155 (d, J ) 9, 2 H, 7.463); 7.402 (d, J ) 9, 2 H, 7.145),

7.145 (d, J ) 9, 2 H, 7.402); 7.404 (d, J ) 9, 2 H, 7.291), 7.291 (d,

J ) 9, 2 H, 7.404); 7.404 (d, J ) 9, 2 H, 7.142), 7.142 (d, J ) 9, 2 H,

7.404); 7.386 (d, J ) 9, 2 H, 7.159), 7.159 (d, J ) 9, 2 H, 7.386);

7.381 (d, J ) 9, 2 H, 7.273), 7.273 (d, J ) 9, 2 H, 7.381); 7.254,

7.252 (s, s, 2 H), 7.247 (s, 2 H); two overlapped AB systems. Aliphatic

region: 3.000 (s, 3 H), 2.966, 2.964 (s, 3 H), 2.921 (s, 3 H), 2.913,

2.912 (s, 3 H), 2.900 (s, 3 H), 2.877, 2.876 (s, 3 H), 2.862, 2.859 (s,

3 H), 2.852, 2.850 (s, 3 H), 1.228 (s, 9 H), 1.217 (s, 9 H), 1.201 (s, 9

H), 1.194 (s, 9 H), 1.190 (s, 9 H), 1.187 (s, 9 H), 1.179 (s, 9 H), 1.168

Module-with-Linker 15A. Anal. Calcd for C₁₆₂H₁₈₇O₈Br: C, 83.08;

H, 8.05. Found: 83.56; H, 8.47. IR (cm ^-1): 1593 (Ar), 1083 (C-

O-C). FABMS (3-NBA) cluster: m/z (% RA for m/z ) 480-3000)

at (M - OCH₃)⁺2308.2 (52), 2309.2 (81), 2310.2 (99), 2311.2 (100),

2312.2 (78), 2313.4 (39), 2314.4 (21); calcd for C₁₆₁H₁₈₄O₇Br at (M -

OCH₃)⁺: 2308.3 (36), 2309.3 (65), 2310.3 (95), 2311.3 (100), 2312.3

(75), 2313.3 (42), 2314.3 (18), 2315.3 (6). ¹H NMR (500 MHz, EM )

1

(s, 9 H), 1.163 (s, 18 H), 1.159 (s, 9 H). H NMR (500 MHz, EM )

-1.50, GB ) 0.80, C₆D₆, 328 K, ¹H-¹H COSY cross-peaks in aromatic

region): Ring A: 8.030 (t, J ) 2, 1 H, 7.837, 7.572), 7.837 (t, J ) 2,

1 H, 8.030, 7.572), 7.572 (t, J ) 2, 1 H, 8.030, 7.837). Ring B: 7.964,

7.960 (t, J ) 2, J ) 2, 1 H, 7.748, 7.636), 7.748 (t, J ) 2, 1 H, [7.964,

7.960], 7.636), 7.636 (t, J ) 2, 1 H, [7.964, 7.960], 7.748). Ring C:

7.944 (t, J ) 2, 1 H, [7.864, 7.861], 7.837), 7.864, 7.861 (t, J ) 2, J

) 2, 1 H, 7.944, 7.837), 7.837 (t, J ) 2, 1 H, 7.944, [7.864, 7.861]).

Ring D: 7.765, 7.762 (t, J ) 2, J ) 2, 1 H, 7.678, 7.643), 7.678 (bt,

J ) 2, 1 H, [7.765, 7.762], 7.643), 7.643 (t, J ) 2, 1 H, [7.765, 7.762],

7.678). Rings 1-13: 7.554 (d, J ) 9, 2 H, 7.205), 7.205 (d, J ) 9, 2

H, 7.554); 7.522 (d, J ) 9, 2 H, 7.224), 7.224 (d, J ) 9, 2 H, 7.522);

7.519 (d, J ) 9, 2 H, 7.200), 7.200 (d, J ) 9, 2 H, 7.519); 7.504 (d,

J ) 9, 2 H, 7.178), 7.178 (d, J ) 9, 2 H, 7.504); 7.459 (d, J ) 9, 2 H,

7.188), 7.188 (d, J ) 9, 2 H, 7.459); 7.448 (d, J ) 9, 2 H, 7.167),

7.167 (d, J ) 9, 2 H, 7.448); 7.446 (d, J ) 9, 2 H, 7.249), 7.249 (d,

J ) 9, 2 H, 7.446); 7.436 (d, J ) 9, 2 H, 7.213), 7.213 (d, J ) 9, 2 H,

7.436); 7.408 (d, J ) 9, 2 H, 7.314), 7.314 (d, J ) 9, 2 H, 7.408);

7.376 (d, J ) 9, 2 H, 7.146), 7.146 (d, J ) 9, 2 H, 7.376); 7.368 (d,

J ) 9, 2 H, 7.270), 7.270 (d, J ) 9, 2 H, 7.368); 7.364 (d, J ) 9, 2 H,

7.163), 7.163 (d, J ) 9, 2 H, 7.163); 7.258, 7.254 (s, s, 1 H, 1 H),

7.251 (s, 2 H); two overlapped AB systems. Aliphatic region: 2.994

(s, 3 H), 2.964 (s, 3 H), 2.939 (s, 3 H), 2.929, 2.926 (s, 3 H), 2.914 (s,

3 H), 2.893 (s, 3 H), 2.885 (s, 3 H), 2.853, 2.850 (s, 3 H), 1.230 (s, 9

H), 1.219 (s, 9 H), 1.207 (s, 9 H), 1.198 (s, 18 H), 1.192 (s, 9 H),

1.188 (s, 9 H), 1.177 (s, 9 H), 1.174 (s, 9 H), 1.166 (s, 9 H), 1.164 (s,

9 H). ¹³C{¹H}DEPT(135°)NMR (125 MHz, EM ) -1.20, GB ) 0.80,

C₆D₆, 293 K): aromatic quaternary region, expected, 38 resonances;

found, 46 resonances at 150.4 (q), 150.2 (q), 150.00 (q), 149.92 (q),

149.86 (q), 149.83 (q), 149.79 (q), 149.70 (q), 149.5 (q), 146.5 (q),

146.3 (q), 145.09 (q), 144.98 (q), 144.86 (q), 144.57 (q), 144.54 (q),

144.3 (q), 144.2 (q), 143.5 (q), 143.39 (q), 143.35 (q), 143.27 (q), 143.25

(q), 143.08 (q), 143.07 (q), 143.03 (q), 143.01 (q), 142.81 (q), 142.77

(q), 142.67 (q), 142.2 (q), 142.10 (q), 142.08 (q), 142.05 (q), 141.93

(q), 141.56 (q), 141.55 (q), 141.28 (q), 141.22 (q), 141.15 (q), 140.97

(q), 140.93 (q), 140.34 (q), 140.31 (q), 121.62 (q), 121.60 (q); aromatic

nonquaternary region, expected, 38 resonances; found 29 resonances

at 131.5, 131.12, 131.08, 131.00, 130.2, 130.00, 129.97, 129.73, 129.71,

129.68, 129.64, 129.52, 129.49, 129.43, 129.37, 129.2, 128.9, 127.3,

126.17, 126.14, 125.9, 125.39, 125.35, 125.24, 125.20, 125.16, 125.13,

125.07, 125.03; aliphatic region, 88.16 (q), 88.14 (q), 88.11 (q), 87.85

(q), 87.81 (q), 87.65 (q), 87.07 (q), 52.8, 52.59, 52.56, 52.53, 52.49,

52.3, 34.81 (q), 34.80 (q), 34.76 (q), 34.74 (q), 34.71 (q), 31.91, 31.88,

31.86, 31.81, 31.78.

1

-1.40/-2.20, GB ) 0.80/0.90, C₆D₆, 293 K, H-¹H COSY cross-

peaks in aromatic region): Rings A, A′: 8.097, 8.094 (t, t, J ) 2, J )

2, 2 H, [7.974, 7.971], 7.490), 7.974, 7.971 (t, t, J ) 2, J ) 2, 2 H,

[8.097, 8.094], 7.490), 7.490 (t, J ) 2, 2 H, [8.097, 8.094], 7.974).

Rings B and C: 7.924 (d, J ) 2, 2 H, 7.836), 7.836 (br, 1 H, 7.924);

7.877 (t, J ) 2, 1 H, 7.631), 7.631 (d, J ) 2, 2 H, 7.877). Rings 1,1′-

5,5′: 7.579 (d, J ) 9, 4 H, 7.250), 7.250 (d, J ) 9, 4 H, 7.579); 7.555

(d, J ) 8, 4 H, 7.190), 7.190 (d, J ) 9, 4 H, 7.555); 7.488 (d, J ) 9,

4 H, 7.215), 7.215 (d, J ) 9, 4 H, 7.488); 7.442 (d, J ) 9, 4 H, 7.211),

7.211 (d, J ) 9, 4 H, 7.442); 7.375 (d, J ) 8, 4 H, 7.151), 7.151 (d,

J ) 9, 4 H, 7.375). Rings 6-8: 7.399 (d, J ) 8, 2 H, 7.280), 7.280 (d,

J ) 8, 2 H, 7.399); 7.375 (d, J ) 9, 2 H, 7.272), 7.272 (d, J ) 9, 2 H,

7.375); 7.247 (s, 4 H); overlapped AB system. Aliphatic region: 2.982,

2.980 (s, s, 3 H), 2.980 (s, 3 H), 2.917 (s, 6 H), 2.906 (s, 3 H), 2.886

(s, 3 H), 2.850 (s, 6 H), 1.223 (s, 9 H), 1.205 (s, 18 H), 1.192 (s, 9 H),

1.191 (s, 9 H), 1.189 (s, 18 H), 1.179 (s, 18 H), 1.160 (s, 18

H).¹³C{¹H}DEPT(135°)NMR (125 MHz, EM ) -1.00, GB ) 0.80,

C₆D₆, 293 K): aromatic quaternary region, expected, 23 resonances;

found, 22 resonances at 150.4 (q), 150.1 (q), 150.0 (q), 149.88 (q),

149.77 (q), 149.71 (q), 146.4 (q), 145.0 (q), 144.7, 143.6 (q), 143.4

(q), 143.1 (q), 142.77 (q), 142.68 (q), 142.66 (q), 142.5 (q), 141.6 (q),

141.27 (q), 141.22 (q), 140.9 (q), 140.2 (q), 121.6 (q); aromatic

nonquaternary region, expected, 23 resonances; found 18 resonances

at 131.5, 131.0, 130.04, 129.96, 129.6, 129.5, 129.38, 129.34, 129.30,

128.8 (C₆D₅H), 128.0, 127.2, 126.3, 125.4, 125.26, 125.21, 125.18,

125.16, 125.0; aliphatic region, 88.2 (q), 88.1 (q), 87.9 (q), 87.6 (q),

87.1 (q), 52.6, 52.53, 52.51, 52.3, 34.81 (q), 34.79 (q), 34.77 (q), 34.74

(q), 31.87, 31.85, 31.83, 31.81, 31.79.

Module-with-Linker 15B. Calcd for C₁₆₂H₁₈₇O₈Br: C, 83.08; H,

8.05. Found: 83.61; H, 7.72. Found: 81.88; H, 7.72. IR (cm^-1): 1594

(Ar), 1081 (C-O-C). FABMS (3-NBA) cluster: m/z (% RA for m/z

) 480-3000) at (M - OCH₃)⁺: 2308.2 (58), 2309.2 (82), 2310.3 (100),

2311.3 (97), 2312.5 (76), 2313.4 (39), 2314.4 (21); calcd for C₁₆₁

-

H

₁₈₄O₇Br at (M - OCH₃)⁺: 2308.3 (36), 2309.3 (65), 2310.3 (95),

1

2311.3 (100), 2312.3 (75), 2313.3 (42), 2314.3 (18), 2315.3 (6). H

1

NMR (500 MHz, EM ) -1.80, GB ) 0.80, C₆D₆, 293 K, H-¹H

COSY cross-peaks in aromatic region): Rings A: 8.110 (t, J ) 2, 1

H, 7.887, 7.616), 7.887 (t, J ) 2, 1 H, 8.110, 7.616), 7.616 (t, J ) 2,

1 H, 8.110, 7.887). Rings B: 8.022 (br, 1 H, 7.768, 7.692), 7.768 (br,

1 H, 8.022, 7.692), 7.692 (br, 1 H, 8.022, 7.768). Rings C: 7.979,

9

J. AM. CHEM. SOC. VOL. 126, NO. 21, 2004 6623

A R T I C L E S

Rajca et al.

2-(OMe)₁₅. t-BuLi (0.255 mL of a ∼1.50 M solution in pentane,

0.383 mmol, Acros) was added to a solution of module 11B (0.353 g,

0.175 mmol) in THF (2.0 mL) in a heavy-wall Schlenk vessel at -78

°C. After 3 h, the reaction mixture was warmed to -20 °C for 10 min

and then recooled to -78 °C. Following addition of ZnCl₂(0.172 mL

of 1.16 M solution in ether, 0.200 mmol), the reaction mixture was

allowed to attain ambient temperature for 2 h. The resultant clear orange

solution was transferred to a glovebox. Pd(PPh₃)₄(6.8 mg, 0.006 mmol)

and linker 16 (42.8 mg, 0.088 mmol) were added to the reaction

mixture. Subsequently, the reaction mixture was heated in an oil bath

at 100 °C for 1.5 days. After extraction with ether, the organic layer

was dried over MgSO₄and concentrated in vacuo to give 351 mg of

clear yellow solid. Column chromatography (TLC grade silica gel,

5-10% ether in hexane) gave two fractions with similar R_fon TLC:

fraction 1 (higher R_f, 75.5 mg) and fraction 2 (lower R_f, 133.3 mg).

Treatment with ether/MeOH of fraction 1 and fraction 2 gave 63.6 mg

(17%, white powder, softening to clear solid at 221-223 °C) and 113.9

mg (40%, white powder) of 2-(OMe)₁₅as mixtures of diastereomers.

All data are reported below are for fraction 1, following treatment with

MeOH/ether. Anal. Calcd for C₃₀₀H₃₅₀O₁₅: C, 85.87; H, 8.41. Found:

86.02; H, 8.01. IR (cm^-1): 1594 (Ar), 1083 (C-O-C). FABMS

(ONPOE) wide range scan m/z (% RA for m/z ) 1000-5000): 2066.4

(7.5), 2139.5 (6.5), 2185.8 (8), 4132.2 (57), 4164.7 (100); narrow range

scan m/z (% RA for m/z ) 2063-2069) at (M - 2OCH₃)²⁺2065.0

(63), 2065.5 (77), 2066.0 (100), 2066.5 (85), 2067.0 (76), 2067.5 (45),

2068.0 (40); calcd for C₂₉₈H₃₄₄O₁₃at (M - 2OCH₃)²⁺2065.3 (16),

2065.8 (53), 2066.3 (89), 2066.8 (100), 2067.3 (85), 2067.8 (57), 2068.3

(32); narrow range scan m/z (% RA for m/z ) 2180-2193) at (M -

2.860 (bs, 11.30 H), 2.848 (s, 3.54 H), 2.842 (s, 2.27); normalized to

21 resonances for tert-butyl groups (189 H), found 13 resonances at

1.216 (s, 7.06 H), 1.213 (s, 3.08 H), 1.196 (s, 8.52 H), 1.192, 1.191 (s,

s, 13.31 H), 1.177 (bs, 20.76 H), 1.168 (bs, 33.46 H), 1.163, 1.162 (bs,

s, 34.49 H), 1.153 (s, 7.25 H), 1.148 (bs, 43.69 H), 1.141, 1.138 (s, s,

17.37 H).

3-(OMe)₂₂. t-BuLi (0.053 mL of a 1.63 M solution in pentane, 0.086

mmol, Acros, twice titrated with N-pivaloyl-o-toluidine) was added to

a solution of module 17 (30.0 mg, 0.0168 mmol) in THF (0.40 mL) in

a heavy-wall Schlenk vessel at -78 °C. After 2 h at -78 °C, the

reaction mixture was warmed to -20 °C for 10 min and then recooled

to -78 °C. Following addition of ZnCl₂(0.071 mL of 1.06 M solution

in ether, 0.076 mmol), the reaction mixture was allowed to attain

ambient temperature for 2.5 h. The clear yellow solution was transferred

to a glovebox. A solution of Pd(PPh₃)₄(0.025 mL of 0.027 M solution

in THF, 0.68 µmol) and a solution of 15B (118 mg, 0.050 mmol) were

added to the reaction mixture. Subsequently, the reaction mixture was

heated in an oil bath at 100 °C for 3 days. After extraction with ether,

the organic layer was dried over MgSO₄and concentrated in vacuo to

give a clear solid. Column chromatography (TLC grade silica gel,

5-10% ether in hexane) gave fractions 1 and 2 (F1 and F2 in the order

of increasing polarity on silica gel), which were treated with ether/

MeOH: F1, 20B-(OMe)₁₆side product, 3.5 mg (3%) of white solid

softening at 214 °C, melting at 228-229 °C (clear yellow solid) and

becoming clear yellow liquid at 239 °C; F2, 3-(OMe)₂₂, 57.4 mg (56%)

of white solid (softening to clear solid at 239-240 °C). From another

reaction on the same scale, 34.9 mg (34%) of 3-(OMe)₂₂was obtained

from 30.0 mg of 17.

C

₁₄₄H₁₆₇O₇)⁺2184.1 (74), 2185.1 (100), 2186.1 (78), 2187.1 (57),

3-(OMe)₂₂. Anal. Calcd for C₄₄₀H₅₀₈O₂₂: C, 85.95; H, 8.33. Found:

86.31; H, 7.95. IR (cm^-1): 1594 (Ar), 1082 (C-O-C). FABMS

(ONPOE) wide range scan m/z (% RA for m/z ) 2000-8000): 3043

(2.5), 4137 (2.5), 6116.5 (100); narrow range scan m/z (% RA for m/z

) 3039-3048) at (M - 2OCH₃)²⁺3041.4 (57), 3041.9 (76), 3042.4

(92), 3042.9 (100), 3043.4 (87), 3043.9 (72), 3044.4 (51), 3044.9 (35);

calcd for C₄₃₈H₅₀₂O₂₀at (M - 2OCH₃)²⁺3041.4 (20), 3041.9 (48),

3042.4 (80), 3042.9 (100), 3043.4 (100), 3043.9 (82), 3044.4 (59),

3044.9 (36); narrow range scan m/z (% RA for m/z ) 6110-6125) at

(M - OCH₃)⁺6113.9 (42), 6114.9 (70), 6115.9 (100), 6116.9 (100),

6117.9 (96), 6118.9 (74), 6119.9 (54), 6120.9 (34), 6122.0 (21); calcd

for C₄₃₉H₅₀₅O₂₁at (M - OCH₃)⁺6113.8 (20), 6114.9 (48), 6115.9 (80),

6116.9 (100), 6117.9 (100), 6118.9 (83), 6119.9 (59), 6120.9 (37),

2188.1 (30); calcd for C₁₅₆H₁₈₃O₈at (M - C₁₄₄H₁₆₇O₇)⁺2184.4 (56),

2185.4 (100), 2186.4 (89), 2187.4 (52), 2188.4 (23); narrow range scan

m/z (% RA for m/z ) 4156-4176) at (M - OCH₃)⁺4161.6 (42), 4162.6

(73), 4163.7 (100), 4164.7 (100), 4165.7 (81), 4166.7 (52), 4167.7 (32),

4168.7 (16); calcd for C₂₉₉H₃₄₇O₁₄at (M - OCH₃)⁺4161.6 (16), 4162.7

(52), 4163.7 (88), 4164.7 (100), 4165.7 (84), 4166.7 (58), 4167.7 (32),

1

4168.7 (16). H NMR (500 MHz, EM ) -1.95, GB ) 0.85, C₆D₆,

293 K, ¹H-¹H DQF COSY (600 MHz) cross-peaks in aromatic

region): Ring A: 8.093 (bs, 2 H, 7.875, 7.640), 7.875 (bs, 2 H, 8.093,

7.640), 7.640 (bs, 2 H, 8.093, 7.875). Ring B: 7.988 (bs, 2 H, 7.936,

7.819), 7.936 (bs, 2 H, 7.988, 7.819), 7.819 (bs, 2 H, 7.988, 7.936).

Ring C: 7.969 (bs, 2 H, 7.761, 7.732), 7.761 (bs, 2 H, 7.969, 7.732),

7.732 (bs, 2 H, 7.969, 7.761). Ring D: 7.792, 7.782 (bs, bs, 2 H, 7.761,

7.701), 7.761 (bs, 2 H, [7.792, 7.782], 7.701), 7.701 (bs, 2 H, [7.792,

7.782], 7.761). Rings 1-23: 7.134-7.603 (m, 92 H). Aliphatic

region: normalized to 15 resonances for methoxy groups (45 H), found

11 resonances at 3.002 (bs, 6.11 H), 2.986 (s, 1.31 H), 2.974 (s, 2.04

H), 2.951 (bs, 6.17 H), 2.924 (bs, 6.29 H), 2.896, 2.892, 2.887, 2.882

(s, s, s, s, 12.24 H), 2.866 (bs, 5.54 H), 2.842 (bs, 5.29 H); normalized

to 21 resonances for tert-butyl groups (189 H), found 11 resonances at

1.246 (bs, 9.87 H), 1.228 (bs, 9.04 H), 1.223 (bs, 12.66 H), 1.200 (bs,

20.30 H), 1.194, 1.187 (bs, bs, 52.00 H), 1.182, 1.177, 1.173 (bs, bs,

bs, 38.26 H), 1.167, 1.162 (bs, bs, 46.87 H). ¹H NMR (500 MHz, EM

) -1.70, GB ) 0.85, C₆D₆, 328 K): δ 7.10-8.05 (m, 116 H), 2.83-

1

6121.9 (21). H NMR (500 MHz, EM ) -1.90, GB ) 0.90, C₆D₆,

293 K, GE): 7.05-8.20 (m, 172 H). Aliphatic region: expected 22

resonances for the methoxy groups, found 26 resonances (66 H) at

3.104, 3.100 (s, s, 2.78 H), 3.010, 3.008 (s, s, 6.28 H), 2.999 (s, 1.46

H), 2.992, 2.990, 2.988 (s, s, s, 2.49 H), 2.980, 2.977, 2.973, 2.968,

2.966 (s, s, s, s, s, 12.29 H), 2.961 (s, 0.97 H), 2.933, 2.928, 2.924,

2.920, 2.915, 2.910, 2.906, 2.902 (bs, s, s, s, bs, s, s, s, 23.64 H), 2.893,

2.889 (s, s, 5.71 H), 2.874 (bs, 5.35 H), 2.852 (bs, 5.03 H); expected

30 resonances for the tert-butyl groups, found 14+ resonances at 1.256,

1.252, 1.232, 1.229, 1.225, 1.204, 1.197, 1.191, 1.186, 1.179, 1.168,

1.146-1.164, 1.138, 1.135, 1.132 (14 singlets and 1 multiplet, 270 H).

¹H NMR (500 MHz, EM ) -1.40, GB ) 0.90, C₆D₆, 328 K, GE):

7.05-8.15 (m, 172 H), 2.80-3.15 (19 singlets, 66 H), 1.10-1.35 (18

1

3.03 (m, 45 H), 1.15-1.25 (m, 189 H). H NMR (500 MHz, EM )

-1.95, GB ) 0.85, C₆D₆, 348 K, ¹H -¹H DQF COSY (600 MHz) cross-

peaks in aromatic region): Ring A: 7.942 (bs, 2 H, [7.766, 7.762],

7.540), 7.766, 7.762 (t, t, J ) 2, J ) 2, 2 H, 7.942, 7.540), 7.540 (bs,

2 H, 7.942, [7.766, 7.762]). Ring B: 7.901 (t, J ) 2, 2 H, 7.846, 7.737),

7.846 (bt, J ) 2, 2 H, 7.901, 7.737), 7.737 (bs, 2 H, 7.901, 7.846).

Ring C: 7.846 (bt, J ) 2, 2 H, 7.695, 7.613), 7.695 (t, J ) 2, 2 H,

7.846, 7.613), 7.613 (t, J ) 2, 2 H, 7.846, 7.695). Ring D: 7.688 (bs,

2 H, 7.637, 7.610), 7.637 (bs, 2 H, 7.688, 7.610), 7.610 (bs, 2 H, 7.688,

7.637). Rings 1-23: 7.109-7.514 (m, 92 H). Aliphatic region:

normalized to 15 resonances for methoxy groups (45 H), found 10

resonances at 2.973 (s, 1.37 H), 2.961 (bs, 7.59 H), 2.949 (s, 0.64 H),

2.929 (bs, 6.13 H), 2.918 (bs, 5.93 H), 2.883, 2.880 (s, s, 6.23 H),

1

singlets and 1 multiplet, 270 H). H NMR (500 MHz, EM ) -1.20,

GB ) 0.90, C₆D₆, 348 K, ¹H-¹H COSY cross-peaks in aromatic

region): Ring A: 8.061 (br, 1 H, 7.984 (weak)), 8.009 (br, 1 H), 7.984

(br, 1 H, 8.061 (weak)); cross-peaks are missing. Ring B: 7.980 (br,

1 H, [7.840, 7.837], 7.403), 7.840, 7.837 (t, t, J ) 2, J ) 2, 1 H, 7.980,

7.403), 7.403 (br, 1 H, 7.980, [7.840, 7.837]). Rings C/D (tentative

assignment): 7.772 (br), 7.706 (br), 7.699 (br), 7.606 (br); peaks and

cross-peaks are missing. Ring E, E′: 7.989 (br, 2 H, [7.811, 7.808],

7.585), 7.811, 7.808 (t, t, J ) 2, J ) 2, 2 H, 7.989, 7.585), 7.585 (t, J

) 2, 2 H, 7.989, [7.811, 7.808]). Ring F, F′: 7.946 (bs, 2 H, [7.890,

7.886], [7.786, 7.782]), 7.890, 7.886 (t, t, J ) 2, J ) 2, 2 H, 7.946,

[7.786, 7.782]), 7.786, 7.782 (t, t, J ) 2, J ) 2, 2 H, 7.946, [7.890,

9

6624 J. AM. CHEM. SOC. VOL. 126, NO. 21, 2004

Organic Spin Clusters

A R T I C L E S

7.886]). Ring G, G′: 7.899, 7.895 (t, t, J ) 2, J ) 2, 2 H, 7.741,

7.662), 7.741 (t, J ) 2, 2 H, [7.899, 7.895], 7.662), 7.662 (t, J ) 2, 2

H, [7.899, 7.895], 7.741). Ring H, H′: 7.732 (br, 2 H, 7.683, [7.658,

7.654]), 7.683 (br, 2 H, 7.732, [7.658, 7.654]), 7.658, 7.654 ((t, t, J )

2, J ) 2, 2 H, 7.732, 7.683). Rings 1-34: 7.16-7.60 (m, 136 H).

Aliphatic region: expected 22 resonances for the methoxy groups, found

21 resolved resonances (66 H) at 3.106 (s, 2.71 H), 3.026 (s, 0.87 H),

3.020 (s, 0.92 H), 3.015 (s, 0.85 H), 3.010 (s, 0.96 H), 3.004 (s, 6.75

H), 2.996, 2.994 (s, s, 1.63 H), 2.986 (s, 0.93 H), 2.978, 2.972, 2.967,

2.961 (s, s, s, s, 18.07 H), 2.946, 2.943 (s, bs, 5.94 H), 2.926, 2.924,

2.920 (s, s, s, 9.03 H), 2.903 (bs, 11.54 H), 2.890, 2.885 (s, s, 5.80 H);

expected 30 resonances for the tert-butyl groups, found 17 resonances

at 1.263, 1.261, 1.258, 1.254, 1.236, 1.232, 1.216, 1.209, 1.207, 1.203,

1.201, 1.191, 1.187, 1.179, 1.175, 1.156, 1.154 (17 singlets, 270 H).

4-(OMe)₃₆. t-BuLi (0.041 mL of a 1.70 M solution in pentane, 0.070

mmol, Acros, twice titrated with N-pivaloyl-o-toluidine) was added to

a solution of 18 (9.4 mg, 0.0071 mmol) in THF (0.30 mL) in a heavy-

wall Schlenk vessel at -78 °C. After 2 h at -78 °C, the reaction mixture

was warmed to -20 °C for 10 min and then recooled to -78 °C.

Following addition of ZnCl₂(0.030 mL of 1.13 M solution in ether,

0.034 mmol), the reaction mixture was allowed to attain ambient

temperature for 3.5 h. The resultant turbid gel was transferred to a

glovebox. A solution of Pd(PPh₃)₄(0.050 mL of 0.014 M solution in

THF, 0.00070 mmol) and a solution of racemic 15A (102.0 mg, 0.044

mmol) were added to the reaction mixture. Subsequently, the reaction

mixture was heated in an oil bath at 100 °C for 2.5 days. After extraction

with ether, the organic layer was dried over MgSO₄and concentrated

in vacuo to give a clear solid. Analogous procedure was implemented

for the other two reactions. The isolated yields from the reactions I, II,

and III were 7%, 22%, 32%, respectively. For mixtures of compounds,

the relative amounts were determined with ¹H NMR (500 MHz, C₆D₆)

spectroscopy. The purification protocols for each reaction were as

follows.

gel) as clear glasses. Fraction 1 was side product 20A-(OMe)₁₆(white

solid, 8.0 mg, 8%). Fraction 2 (9.0 mg) was 4-(OMe)₃₆and 19-(OMe)₂₈

(10:1). Fraction 3 (13.7 mg) was 4-(OMe)₃₆and 19-(OMe)₂₈(10:1).

FABMS (% RA for m/z ) 2500-12000): 10022 (100), 7762 (45),

4995 (85), 3865 (25). Overall yield 4-(OMe)₃₆was 22.7 mg, 32%, based

on Fractions 2 and 3.

(OMe)₃₆. White solid (softening to clear solid at 272-274 °C). IR

(cm^-1): 1594 (Ar), 1082 (C-O-C). FABMS (ONPOE) wide range

scan m/z (% RA for m/z ) 3000-12000) at (M - OCH₃)⁺: 10021.6

(100), at (M - 2OCH₃)²⁺4995.3 (85). Narrow range scans m/z (% RA

for m/z ) 10005-10040, 9880-11000) at (M - OCH₃)⁺for two

different samples: 10021.5 (100) and 10021.9 (100); calcd for

C

₇₁₉H₈₂₁O₃₅at (M - OCH₃)⁺av mass ) 10023.45, peak maximum

1

mass ) 10023.04. H NMR (500 MHz, EM ) -1.90, GB ) 0.50,

C₆D₆, 293 K, H-¹H DQF-COSY cross-peaks in aromatic region).

1

Rings A, A′: 8.079 (bs, 8 H, 7.983, 7.513), 7.983 (bs, 8 H, 8.079,

7.513), 7.513 (bs, 8 H, 8.079, 7.983). Rings B and C: 7.943 (bs, 8 H,

7.796), 7.796 (bs, 4 H, 7.943); 7.883 (bs, 4 H, 7.637), 7.637 (bs, 8 H,

7.883). Rings 1,1′-5,5′: 7.575 (d, J ) 9, 16 H, 7.253), 7.253 (d, J )

9, 16 H, 7.575); 7.557, 7.561 (d, J ) 9, 16 H, 7.197, 7.200), 7.197,

7.200 (d, J ) 9, 16 H, 7.557, 7.561); 7.487 (d, J ) 9, 16 H, 7.213),

7.213 (d, J ) 9, 16 H, 7.487); 7.439 (d, J ) 8, 16 H, 7.213), 7.213 (d,

J ) 9, 16 H, 7.439); 7.378 (d, J ) 9, 16 H, 7.149), 7.149 (d, J ) 9, 16

H, 7.378). Rings 6-9: 7.637 (bs, 8 H, 7.231), 7.231 (bs, 8 H, 7.637);

7.477 (d, J ) 8, 8 H, 7.295), 7.295 (d, J ) 9, 8 H, 7.477); 7.415 (d,

J ) 9, 8 H, 7.356), 7.356 (d, J ) 9, 8 H, 7.415); 7.378 (d, J ) 9, 8 H,

7.149), 7.149 (d, J ) 9, 8 H, 7.378) (tentative assignment). Aliphatic

region: 3.161 (s, 12 H), 2.986 (s, 12 H), 2.982 (s, 12 H), 2.973 (s, 12

H), 2.912 (s, 24 H), 2.893 (s, 12 H), 2.851(s, 12 H), 2.848 (s, 12 H),

1.253, 1.250 (s, s, 36 H), 1.210 (s, 72 H), 1.196 (s, 144 H), 1.181 (s,

1

72 H), 1.165 (s, 72 H), 1.053 (m, 36 H). H NMR (500 MHz, EM )

-1.30, GB ) 0.90, C₆D₆, 328 K, ¹H-¹H COSY cross-peaks in aromatic

region): Rings A, A′: 8.019, 8.016 (bs, bs, 8 H, 7.912, 7.480), 7.912

(bs, 8 H, [8.019, 8.016], 7.480), 7.480 (bs, 8 H, [8.019, 8.016], 7.912).

Rings B and C: 7.944 (d, J ) 2, 8 H, 7.704), 7.704 (bs, 4 H, 7.944);

7.835 (t, J ) 2, 4 H, 7.597), 7.597 (d, J ) 2, 8 H, 7.835). Ring D:

8.07 (bs, 4 H), 7.95 (bs, 8 H). Rings 1-9: 7.15-7.55 (m, 224 H).

Aliphatic region: 3.172 (bs, 12 H), 2.991, 2.988 (s,s, 36 H), 2.937 (s,

24 H), 2.889 (s, 12 H), 2.876, 2.873 (s, s, 24 H), 1.254 (s, 36 H),

1.216 (s, 72 H), 1.208 (s, 72 H), 1.200 (s, 72 H), 1.190 (s, 72 H),

Reaction I. Column chromatography (TLC grade silica gel, 5-10%

ether in hexane) gave 21.9 mg of clear glass; FABMS (% RA form/z

) 3000-12000) 10021 (8), 7761 (15), 4979 (8), 4492 (100), 3865 (10)

and ¹H NMR spectroscopy showed a mixture of 4-(OMe)₃₆, 19-

(OMe)₂₈, and 20A-(OMe)₁₆, (1:2:2.5). PTLC (activated silica, 8% ether

in hexane, developed 3-4 times) gave two fractions (in order of

increasing polarity). Fraction 1 (less polar, 4.7 mg) was primarily 19-

(OMe)₂₈with a contamination of 20A-(OMe)₁₅(OH). Additional PTLC

(activated silica, 10% ether in hexane), using 3.9 mg of fraction 1,

gave <0.5 mg of 19-(OMe)₂₈. Fraction 2 (7.6 mg) was treated with

MeOH/ether to give 5.2 mg (7%) of clear glass. FABMS (% RA for

m/z ) 2500-12600): 10019 (20), 7761 (<5), 4994 (30), 4478 (100).

A portion of Fraction 2 was filtered through cotton plug. FABMS (%

RA for m/z ) 3500-11000): 10021 (20), 7762 (<5), 4995 (20), 4479

(100). Overall yield 4-(OMe)₃₆is 5.2 mg, 7%, based on Fraction 2.

Reaction II. Column chromatography (TLC grade silica gel, 5-10%

ether in hexane) was carried out twice to produce four fractions.

Treatment with MeOH/ether gave fractions 1-4 (in order of increasing

polarity). Fraction 1 (2.9 mg) was a mixture of 4-(OMe)₃₆, 20A-

(OMe)₁₆, 19-(OMe)₂₈, and unknown impurity. FABMS (% RA for m/z

) 2500-12000): 9992 (10), 7763 (15), 5499 (15), 4995 (<3), 4493

(15). Fraction 2 (10.6 mg) was a mixture of 4-(OMe)₃₆, 19-(OMe)₂₈,

and unknown impurity. FABMS (% RA for m/z ) 2500-12000):

10024 (60), 7762 (50), 5500 (15), 4996 (40), 3866 (25). Fraction 3

(12.1 mg) was a mixture of 4-(OMe)₃₆and 19-(OMe)₂₈(10:1). FABMS

(% RA for m/z ) 2500-12000): 10022 (100), 7762 (60), 4996 (65),

3865 (20). Fraction 4 (14.6 mg) was a mixture of 4-(OMe)₃₆and 19-

(OMe)₂₈(10:1). FABMS (% RA for m/z ) 2500-12000): 10022 (100),

7762 (35), 4996 (55), 3865 (15). Overall yield 4-(OMe)₃₆was 26.7

mg, 22%, based on Fractions 3 and 4.

1

1.179 (s, 72 H), 1.068 (m, 36 H). H NMR (500 MHz, EM ) -1.19,

GB ) 0.48, C₆D₆, 348 K, ¹H -¹H DQF-COSY cross-peaks in aromatic

region): Rings A, A′: 7.983, 7.979 (t, t, J ) 2, J ) 2, 8 H, 7.873,

7.462), 7.873 (t, J ) 2, 8 H, [7.983, 7.979], 7.462), 7.462 (t, J ) 2, 8

H, [7.983, 7.979], 7.873). Rings B and C: 7.935 (d, J ) 2, 8 H, 7.661),

7.661 (bt, J ) 2, 4 H, 7.935); 7.810 (t, J ) 2, 4 H, 7.572), 7.572 (d,

J ) 2, 8 H, 7.810). Rings D: 8.015 (bs, 4 H), 7.936 (bs, 8 H). Rings

1,1′-5, 5′: 7.516 (d, J ) 9, 16 H, 7.207), 7.207 (d, J ) 8, 16 H, 7.516);

7.516 (d, J ) 9, 16 H, 7.240), 7.240 (d, J ) 9, 16 H, 7.516); 7.447 (d,

J ) 9, 16 H, 7.223), 7.223 (d, J ) 8, 16 H, 7.447); 7.399 (d, J ) 9, 16

H, 7.207), 7.207 (d, J ) 8, 16 H, 7.399); 7.348 (d, J ) 8, 16 H, 7.163),

7.163 (d, J ) 9, 16 H, 7.348). Rings 6-9: 7.594 (bd, J ≈ 9, 8 H,

7.223), 7.223 (d, J ) 8, 8 H, 7.594); 7.467 (d, J ) 8, 8 H, 7.294),

7.294 (d, J ) 9, 8 H, 7.467); 7.457 (d, J ) 8, 8 H, 7.410), 7.410 (d,

J ) 8, 8 H, 7.457); 7.443 (s, 8 H), 7.438 (s, 8 H) as AB system.

Aliphatic region: 3.176 (bs, 12 H), 3.005 (s, 12 H), 2.995 (s, 12 H),

2.992 (s, 12 H), 2.949 (s, 24 H), 2.888 (s, 36 H), 1.258 (s, 36 H),

1.220 (s, 72 H), 1.215 (bs, 72 H), 1.206 (bs, 72 H), 1.196 (s, 72 H),

1.188 (s, 72 H), 1.082 (m, 36 H). ¹³C NMR (125 MHz, C₆D₆, 348 K):

aromatic quaternary region, expected, 27 resonances; found, 11

resonances at 150.22 (q), 150.14 (q), 150.11 (q), 150.04 (q), 149.93

1

(q), 149.89, 143.8 (q), 143.5 (q), 143.2 (q), 142.8 (q), 142.7 (q); H-

¹³C NMR (500 MHz, C₆D₆, ¹H-¹³C HMQC-GS cross-peaks in aromatic

nonquaternary region, 348 K), expected, 27 resonances; found 26

resonances at 130.3 (7.465, not assigned), 130.2 (7.416, 7.410, rings

6-9), 130.0 (7.434, 7.443 or 7.438, rings 6-9), 129.92 (7.381, not

Reaction III. Column chromatography (TLC grade silica gel,

5-10% ether in hexane), followed by treatment with ether/MeOH, gave

three isolated fractions (in the order of increasing polarity on silica

9

J. AM. CHEM. SOC. VOL. 126, NO. 21, 2004 6625

A R T I C L E S

Rajca et al.

assigned), 129.88 (7.451, 7.447, rings 1,1′-5,5′), 129.81 (7.399, 7.399,

rings 1,1′-5,5′), 129.66 (7.572, 7.572, rings B or C), 129.63 (7.863,

7.873, rings A,A′), 129.56 (7.522, 7.516, rings 1,1′-5,5′), 129.45 (7.468,

7.467, rings 6-9), 129.45 (7.468, 7.462, rings A,A′), 129.37 (7.348,

7.348, rings 1,1′-5,5′), 129.15 (7.516, 7.516, rings 1,1′-5,5′), 129.11

(7.973, 7.983 and 7.979, rings A,A′), 128.4 (7.809, 7.810, rings B or

C), 127.3 (7.452, 7.457, rings 6-9), 127.2 (7.434, 7.443 or 7.438, rings

6-9), 126.4 (7.933, 7.935, rings B or C), 125.26 (7.282, 7.294, rings

6-9), 125.19 (7.205, 7.207, rings 1,1′-5,5′), 125.19 (7.205, 7.207, rings

1,1′-5,5′), 125.13 (7.227, 7.223, rings 1,1′-5,5′), 125.13 (7.227, 7.223,

rings 6-9), 125.06 (7.292, not assigned), 125.045 (7.25 (sh), 7.240,

rings 1,1′-5,5′), 125.04 (7.148, 7.163, rings 1,1′-5,5′); aliphatic region,

88.4 (q), 88.3 (q), 88.0 (q), 52.75, 52.67, 52.62, 52.53, 34.88 (q), 34.84

(q), 34.82 (q), 34.81 (q), 31.93, 31.90. ¹³C NMR (125 MHz, C₆D₆,

298 K): aromatic quaternary region, expected, 27 resonances; found,

23 resonances at 150.06 (q), 149.97 (q), 149.8 (q), 149.72 (q), 149.67

(q), 146.2 (q), 144.8 (q), 144.6 (q), 143.9 (q), 143.8 (q), 143.5 (q),

143.4 (q), 143.17 (q), 143.15 (q), 142.8 (q), 142.7 (q), 142.5 (q), 142.4

(q), 141.6 (q), 141.2 (q), 140.5 (q), 140.4 (q), 140.3 (q); aromatic

nonquaternary region, expected, 27 resonances; found 16 resonances

at 130.21, 130.12, 130.0, 129.6, 129.4, 129.3, 129.1, 128.9, 127.9, 127.4,

127.1, 126.4, 125.9, 125.3, 125.2, 125.0; aliphatic region, 90.1 (q), 88.2

(q), 88.1 (q), 87.8 (q), 87.6 (q), 87.2 (q), 52.60, 52.51, 52.47, 52.42,

34.80 (q), 34.78 (q), 34.74 (q), 31.88, 31.85.

7.159), 7.159 (d, J ) 9, 8 H, 7.342). Rings 6-8: 7.596 (d, J ) 7, 4 H,

7.496), 7.496 (d, J ) 7, 4 H, 7.596); 7.512 (d, J ) 9, 4 H, [7.294,

7.292]), 7.294, 7.292 (d, d, J ) 9, J ) 9, 4 H, 7.512); 7.476, 7.467 (s,

s, 8 H) AB system; a small singlet at 7.494 is consistent with J ) 9 Hz

coupling constant. Aliphatic region: 3.059 (s, 6 H), 2.993, 2.992 (s, s,

12 H), 2.949 (bs,12 H), 2.889, 2.887 (s, s, 12 H), 2.881 (s, 6 H), 1.237,

1.236 (s, s, 18 H), 1.216 (s, 36 H), 1.209 (s, 36 H), 1.206 (s, 36 H),

1.194 (s, 36 H), 1.184 (s, 36 H).

SQUID Magnetometry. Quantum Design (San Diego, CA) MPMS5S

(with continuous temperature control) was used. The sample tubes were

inserted to the magnetometer at low temperature under helium

atmosphere and then evacuated and purged with helium, as described

elsewhere.¹Following the measurements, sample tubes were stored at

ambient temperature for several weeks, until they were diamagnetic in

the 1.8-150 K range. Such samples were carefully reinserted to the

magnetometer, with the sample chamber at 200 or 290 K. Then, the

temperature was slowly lowered to 10 K to condense the solvent and

to freeze the sample. The identical sequence of measurements, as the

original sample, was carried out. The resultant data were used for the

point-by-point correction for diamagnetism.

Numerical Curve Fitting for Magnetic Data. The SigmaPlot for

Windows software package was used for numerical curve fitting. The

reliability of a fit was measured by the parameter dependence, which

was defined as follows: dependence ) 1 - ((Variance of the parameter,

other parameters constant)/(Variance of the parameter, other param-

eters changing)). Values close to 1 indicated overparametrized fit.

20A-(OMe)₁₆. Softening at 130 °C and melting at 154-156 °C. IR

(cm^-1): 1594 (Ar), 1082 (C-O-C). FABMS (3-NBA) wide range scan

m/z (% RA for m/z ) 2000-8000): for (M - 2OCH₃)²⁺2231.5 (16),

4493.1 (100). Narrow range scan m/z (% RA for m/z ) 4486-4500) at

(M - OCH₃)⁺4490.0 (34), 4491.0 (64), 4492.0 (91), 4493.0 (100),

4494.0 (85), 4495.0 (58), 4496.0 (36), 4497.0 (18); calcd for C₃₂₃H₃₇₁O₁₅

at (M - OCH₃)⁺4489.8 (12), 4490.8 (44), 4491.8 (82), 4492.8 (100),

4493.8 (92), 4494.8 (68), 4495.9 (41), 4496.9 (22). ¹H NMR (600 MHz,

M vs H data at low temperatures (T ) 1.8, 2.5, 3.5, 5, 10 K) were

numerically fit as M vs H/T, using eqs 1 and 2, as described in the

text. (More detailed version of eq 2 is described in the Supporting

Information, i.e., eqs 1s-7s, and Table 7s.) Except for the results for

pentadecaradical 2 (Table 1), the numerical fits were weighed with

magnetization (M); such weighing was especially useful for the most

spin-polydisperse samples (and relatively high values of S_s), improving

the agreement between the fit and the experimental data in the H/T

range near the paramagnetic saturation.

1

EM ) -1.50, GB ) 0.50, C₆D₆, 293 K, H-¹H DQF COSY cross-

peaks in aromatic region): Rings A, A′: 8.098 (br, 4 H, 7.989, 7.508),

7.989 (br, 4 H, 8.098, 7.508), 7.508 (br, 4 H, 8.098, 7.989). Rings B

and C: 7.935 (br, 4 H, 7.819), 7.819 (br, 2 H, 7.935); 7.890 (br, 2 H,

7.641), 7.641 (br, 4 H, 7.890). Rings 1,1′-5,5′: 7.587 (d, J ) 8, 8 H,

7.253), 7.253 (d, J ) 9, 8 H, 7.587); 7.561 (d, J ) 8, 8 H, 7.190),

7.190 (d, J ) 8, 8 H, 7.561); 7.496 (d, J ) 9, 8 H, 7.217), 7.217 (d,

J ) 8, 8 H, 7.496); 7.448 (d, J ) 8, 8 H, 7.213), 7.213 (d, J ) 8, 8 H,

7.448); 7.382 (d, J ) 8, 8 H, 7.149), 7.149 (d, J ) 8, 8 H, 7.382).

Rings 6-8: 7.608 (d, J ) 8, 4 H, 7.504), 7.504 (d, J ) 8, 4 H, 7.608);

7.533 (d, J ) 8, 4 H, 7.289), 7.289 (d, J ) 8, 4 H, 7.533); 7.426,

7.420 (s, s, 8 H) AB system; a small singlet at 7.405 is consistent with

J ) 9 Hz coupling constant. Aliphatic region: 3.028 (s, 6 H), 2.982

(bs, 12 H), 2.911 (bs, 12 H), 2.889 (bs, 6 H), 2.850, 2.846, 2.845 (bs,

s, s 12 H), 1.221 (bs, 18 H), 1.207 (bs, 36 H), 1.194 (bs, 72 H), 1.178,

Acknowledgment. This research was supported by the

National Science Foundation (Chemistry Division) and the

National Center for Neutron Research (beam time on NG3,

grants no. 1781 and no. 2471). We thank Drs. Maren Pink and

Victor G. Young, Jr. of the X-ray Crystallographic Laboratory

at the University of Minnesota for the structure determination

of compound 7E. We thank Drs. Ronald Cerny and Richard

Schoemaker for their help with mass spectral analyses and NMR

spectral determinations. We thank Dr. S. R. Desai for preparation

of selected synthetic intermediates. We thank Drs. Paul Butler

and Sung-Min Choi for technical assistance with the small angle

neutron scattering experiments.

1

1.177 (bs, s, 36 H), 1.159 (bs, 36 H). H NMR (500 MHz, EM )

-0.80, GB ) 0.50, C₆D₆, 328 K): 8.029, 8.025 (t, t, J ) 2, J ) 2, 4

H), 7.936 (d, J ) 2, 4 H), 7.911 (t, J ) 2, 4 H), 7.840 (t, J ) 2, 2 H),

7.719 (bt, J ) 2, 2 H), 7.605 (d, J ) 9, 4 H), 7.592 (d, J ) 2, 4 H),

7.44-7.55 (m, 54 H), 7.420 (d, J ) 9, 8 H), 7.359 (d, J ) 9, 8 H),

7.296, 7.294 (d, d, J ) 9, J ) 9, 4 H), 7.19-7.25 (m, 24 H), 7.158 (d,

J ) 9, 8 H), 3.050 (s, 6 H), 3.992, 3.990 (s, s, 12 H), 2.939 (bs, 12 H),

2.886 (s, 6 H), 2.879, 2.876 (s, s, 12 H), 1.234, 1.232 (s, s, 18 H),

1.214 (s, 36 H), 1.204, 1.203 (s, s, 72 H), 1.190 (s, 36 H), 1.177 (s, 36

H). ¹H NMR (500 MHz, EM ) -0.7, GB ) 0.50, C₆D₆, 348 K, ¹H-

¹H DQF COSY cross-peaks in aromatic region): Rings A, A′: 7.982,

7.979 (t, t, J ) 2, J ) 2, 4 H, 7.989, 7.448), 7.865 (t, J ) 2, 4 H,

[7.982, 7.979], 7.448), 7.448 (t, J ) 2, 4 H, [7.982, 7.979], 7.865).

Rings B and C: 7.922 (d, J ) 2, 4 H, 7.674), 7.674 (t, J ) 2, 2 H,

7.922); 7.812 (t, J ) 2, 2 H, 7.563), 7.563 (d, J ) 2, 4 H, 7.812).

Rings 1,1′-5,5′: 7.512 (d, J ) 9, 8 H, 7.203), 7.203 (d, J ) 9, 8 H,

7.512); 7.512 (d, J ) 9, 8 H, 7.236), 7.236 (d, J ) 8, 8 H, 7.512);

7.444 (d, J ) 9, 8 H, 7.220), 7.220 (d, J ) 9, 8 H, 7.444); 7.398 (d,

J ) 9, 8 H, 7.205), 7.205 (d, J ) 9, 8 H, 7.398); 7.342 (d, J ) 9, 8 H,

Supporting Information Available: Experimental section

(materials and special procedures); NMR spectroscopy and other

analyses; small angle neutron scattering; numerical curve fitting

of magnetic data to the percolation model (eqs 1s-7s, Table

7s, Figure 11s); synthesis and/or characterization of compounds

5, 7, 8, 9, 10A-10C, 12, 13, 14, 19-(OMe)₂₈, and 20B-

(OMe)₁₆; Tables 1s-5s (summary of NMR data for 10A-10C,

modules 11A-11D, and modules-with-linkers 15A and 15B;

Table 6s (summary of GPC/MALS data); Figures 1s-10s

(selected NMR spectra and summary plot of GPC/MALS data).

This material is available free of charge via the Internet at

http://pubs.acs.org.

JA031549B

9

6626 J. AM. CHEM. SOC. VOL. 126, NO. 21, 2004

Article Doi

Organic spin clusters: Macrocyclic-macrocyclic polyarylmethyl polyradicals with very high spin S = 5-13

DOI: 10.1021/ja031549b

Source and publish data:

Authors:

Article abstract of DOI:10.1021/ja031549b

Full text of DOI:10.1021/ja031549b

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