Biaryl-based macrocyclic and polymeric chiral (salophen)Ni(II) complexes: Synthesis and spectroscopic study

Article abstract of DOI:10.1021/jo001276s

Polymeric/oligomeric and macrocyclic (salophen)Ni(II) complexes have been synthesized starting from both an achiral biphenol dialdehyde and an optically active BINOL dialdehyde. It was found that these polysalophens contain nonplanar coordination of Ni(II

Full text of DOI:10.1021/jo001276s

J . Org. Chem. 2001, 66, 481-487
481
Bia r yl-Ba sed Ma cr ocyclic a n d P olym er ic Ch ir a l (Sa lop h en )Ni(II)
Com p lexes: Syn th esis a n d Sp ectr oscop ic Stu d y
Hui-Chang Zhang, Wei-Sheng Huang, and Lin Pu*
Department of Chemistry, University of Virginia, Charlottesville, Virginia 22901
lp6n@virginia.edu
Received August 23, 2000
Polymeric/oligomeric and macrocyclic (salophen)Ni(II) complexes have been synthesized starting
from both an achiral biphenol dialdehyde and an optically active BINOL dialdehyde. It was found
that these polysalophens contain nonplanar coordination of Ni(II) units that are paramagnetic.
This is different from the previously reported (salophen)Ni(II) complexes which are square planar
and diamagnetic. The nonplanar (salophen)Ni(II) units make the new polymeric Ni(II) complexes
different from the helical structure proposed for chiral biaryl-based polymers containing square-
planar (salophen)Ni(II) units. The copolymerization of the chiral binaphthyl monomer with the
achiral biphenyl monomer demonstrates that the chirality of the binaphthyl unit is not propagated
along the biphenyl polymer chain.
Sch em e 1. Syn th esis of a Helica l P olym er ic
(Sa lop h en )Ni(II) Com p lex
In tr od u ction
Transition-metal complexes based on bis(salicylaldi-
minato) ligands such as N,N′-ethylenebis(salicylaldimi-
nato) (salen) and N,N′-disalicylidene-1,2-phenylenedi-
aminato (salophen) have recently been found to exhibit
significant nonlinear optical responses.1-3 The high ther-
mal stability of these coordination compounds makes
them attractive and potentially useful. Polymeric salen
and salophen complexes have also been synthesized for
materials applications.4,5 For example, (salophen)Ni(II)
ladder polymer 2 was prepared by Katz and co-workers
from the condensation of optically active helicene 1 with
1,2-phenylenediamine (Scheme 1).6 In this polymer, the
(salophen)Ni(II) unit is planar, which generates a diama-
genetic conjugated helical structure.
The interesting chemical and physical properties of
both monomeric and polymeric transition metal salophen
complexes have spurred us to construct new polymer
structures for these materials. We are particularly
interested in studying whether helical polymeric salo-
phen-metal complexes can be generated from chiral
biaryl molecules and how the chirality of biaryl molecules
(1) Di Bella, S.; Fragala`, I.; Ledoux, I.; Diaz-Garcia, M. A.; Lacrois,
P. G.; Marks, T. J . Chem. Mater. 1994, 6, 881.
influences the structure and property of the salophen
polymers. Herein, our work on the use of salicylaldehydes
derived from biphenyl as well as optically active binaph-
thyl compounds for the synthesis of novel poly[(salophen)-
Ni(II)] complexes is reported.
(2) (a) Averseng, F.; Lacroix, P. G.; Malfant, I.; Lenoble, G.; Cassoux,
P.; Nakatani, K. Maltey-Fanton, I.; Delaire, J . A.; Aukauloo, A. Chem.
Mater. 1999, 11, 995. (b) Averseng, F.; Lacroix, P. G.; Malfant, I.;
Dahan, F.; Nakatani, K. J . Mater. Chem. 2000, 10, 1013. (c) Lenoble,
G.; Lacroix, P. G.; Daran, J . C.; Di Bella, S.; Nakatani, K. Inorg. Chem.
1998, 37, 2158. (d) Di Bella, S.; Fragala`, I.; Ledoux, I.; Diaz-Garcia,
M. A.; Marks, T. J . J . Am. Chem. Soc. 1997, 119, 9550. (e) Lacroix, P.
G.; Di Bella, S.; Ledoux, I. Chem. Mater. 1996, 8, 541. (f) Di Bella, S.;
Fragala`, I.; Marks, T. J .; Ratner, M. A. J . Am. Chem. Soc. 1996, 118,
12747. (g) Di Bella, S.; Fragala`, I.; Ledoux, I.; Marks, T. J . J . Am. Chem.
Soc. 1995, 117, 9481.
(3) For an early review on metal salen complexes, see: Hobday, M.
D.; Smith, T. D. Coord. Chem. Rev. 1972-1973, 9, 311.
(4) (a) Vitalini, D.; Mineo, P.; Di Bella, S.; Fragala`, Maravigna, P.;
Scamporrino, E. Macromolecules 1996, 29, 4478.
(5) (a) Archer, R. D. Coord. Chem. Rev. 1993, 128, 49. (b) Chen, H.;
Cronin, J . A.; Archer, R. D. Inorg. Chem. 1995, 34, 2306. (c) Chiang,
W.; Ho, M. D.; Van Engen, D.; Thompson, M. E. Inorg. Chem. 1993,
32, 2886. (d) Dewar, M. J . S.; Talati, A. M. J . Am. Chem. Soc. 1964,
86, 1592.
Resu lts a n d Discu ssion
1. Syn th esis of Bia r yl Dia ld eh yd e a n d Ar yl Di-
a m in e Mon om er s. We have developed a new method
to synthesize 3,3′-diformyl-2,2′-dihydroxyl-1,1′-biphenyl,7
5, as a monomer to polysalophens (Scheme 2). Treatment
of 2,2′-biphenol with NaH and then with methoxymethyl
(MOM) chloride gave 3. The two OMOM groups of 3
directed ortho metalation8 in the presence of n-BuLi
which after addition of DMF generated 4. Hydrolysis of
the MOM protecting groups of 4 gave the desired biphe-
nol dialdehyde monomer 5. Each step in this synthesis
(6) Dai, Y.; Katz, T. J .; Nichols, D. A. Angew. Chem., Int. Ed. Engl.
1996, 35, 2109.
10.1021/jo001276s CCC: $20.00 © 2001 American Chemical Society
Published on Web 12/21/2000

482 J . Org. Chem., Vol. 66, No. 2, 2001
Zhang et al.
F igu r e 1. Proposed helical structure for poly[(salophen)Ni(II)] complex 9 containing (S)-1,1′-binaphthyl units.
Sch em e 2. Syn th esis of Bip h en yl Dia ld eh yd e
Mon om er
alkynes in the presence of Pd(PPh3)4/CuI produced 7a
and 7b.12 Catalytic hydrogenation of 7a and 7b with Pd
(10%)/C under hydrogen (10 psi) gave the desired mono-
mers 8a and 8b in good yields.
2. Con d en sa tion of th e Op tica lly Active BINOL
Dia ld eh yd e Mon om er (S)-6 w ith Ar yl Dia m in es. In
1994, Brunner and Schiessling reported that when (R)-6
was reacted with (R,R)-1,2-diamino-1,2-diphenylethane,
a polymer was produced, but when (S)-6 was reacted with
(R,R)-1,2-diamino-1,2-diphenylethane, a macrocyclic com-
pound was obtained.13 Thus, the steric structure of the
monomers strongly influences the structure of the con-
densation products.
We have examined the condensation of the optically
active BINOL monomer (S)-6 with the planar 1,2-
phenylenediamine in an effort to generate salophen-Ni-
(II) polymer 9 (Figure 1).14,15 Polymer 9 contains chiral
(S)-binaphthyl units as well as planar (salophen)Ni(II)
units which may generate a helical structure similar to
2.6 However, the reaction of (S)-6 with 1,2-phenylenedi-
amine produced a macrocycle (S,S)-10 rather than a
polymer in very high yield at various concentrations
(Scheme 4). This is similar to the reaction of (S)-6 with
(R,R)-1,2-diamino-1,2-diphenylethane as observed by
Brunner.13 The specific optical rotation of (S,S)-10 is [R]D
) +1561 (c ) 0.3, CH2Cl2). There is a large increase in
optical rotation from (S)-6 to (S,S)-10 accompanied with
a change of the sign.
was about 54-68% yield. The preparation of 5 described
here is a more direct synthesis than the previously
reported.7
The synthesis of 3,3′-diformyl-2,2′-dihydroxy-1,1′-bi-
naphthyl (6) from an O-methylated 1,1′-bi-2-naphthol
(BINOL) was reported before by Brunner et al.9 We have
modified this method by starting with a MOM protected
optically active (S)-BINOL. This synthesis parallels the
preparation of biphenol monomer 5 shown in Scheme 2.
The specific optical rotation of the resulting (S)-6 is [R]D
) -254 (c ) 0.3, CH2Cl2).10
Compound (S,S)-10 was converted to a nickel complex
(S,S)-11 by reaction with 2 equiv of Ni(OAc)2‚4H2O.
Unlike the previously reported (salophen)Ni(II) com-
plexes which are square planar and diamagnetic,1-6,16
complex (S,S)-11 is paramagnetic. The 1H NMR spectrum
of (S,S)-11 does not give any signal in the normal spectral
region. The mass spectrum of (S,S)-11 shows that its
molecular ion (also the base peak) contains two nickel
atoms and two acetate groups. Because of the steric
strain in the macrocycle, it is impossible for (S,S)-11 to
contain two planar (salophen)Ni(II) units. Therefore, a
structure containing a planar (salophen)Ni(II) unit and
a tetrahedral Ni(II) center is proposed for (S,S)-11. The
We have prepared 4,5-dialkyl-substituted 1,2-phe-
nylenediamines 8a and 8b in order to make their
condensation polymers with the biaryl monomers soluble
in organic solvent. Dibromination of 1,2-dinitrobenzene
with bromine in the presence of Ag2SO4 and sulfuric acid
gave 1,2-dibromo-4,5-dinitrobenzene (Scheme 3).11 Cross-
coupling of 1,2-dibromo-4,5-dinitrobenzene with terminal
(12) (a) Tohda, Y.; Sonogashira, K.; Hagihara, N. Synthesis 1977,
777. (b) Sonogashira, K.; Tohda, Y.; Hagihara, N. Tetrahedron Lett.
1975, 4467.
(13) Brunner, H.; Schiessling, H. Angew Chem. Int. Ed. Engl. 1994,
33, 125,
(14) The structure of 9 is generated with the MacSpartan Plus
program.
(15) For a recent review on binaphthyl-based chiral materials, see:
Pu, L. Chem. Rev. 1998, 98, 2405-2494.
(16) (a) Bis-salicylaldehyde-o-phenylenediiminenickel(II) is diam-
agetic in chloroform but paramagenetic in pyridine: Clark, H. C.; Odell,
A. L. J . Chem. Soc. 1955, 3431. (b) Radha, A.; Seshasayee, M.;
Ramalingam, K.; Aravamudan, G. Acta Crystallogr. 1985, C41, 1169.
(7) (a) Moneta, W.; Baret, P.; Pierre, J .-L. J . Chem. Soc., Chem.
Commun. 1985, 899. (b) Moneta, W.; Baret, P.; Pierre, J .-L. Bull. Soc.
Chim. Fr. 1988, 6, 995.
(8) Cox, P.; Wang, W.; Snieckus, V. Tetrahedron Lett. 1992, 33,
2253-2256.
(9) Brunner, H.; Schiessling, H. Bull. Soc. Chim. Belg. 1994, 103,
119.
(10) The reported specific optical rotation for (R)-6: [R]20 ) +248
D
(c ) 0.5, CH2Cl2). Brunner, H.; Goldbrunner, J . Chem. Ber. 1989, 122,
2005.
(11) Ma, L.; Hu, Q. S.; Vitharana, D.; Wu, C.; Kwan, C. M. S.; Pu,
L. Macromolecules 1997, 30, 204.

Chiral (Salophen)Ni(II) Complexes
J . Org. Chem., Vol. 66, No. 2, 2001 483
Sch em e 3. P r ep a r a tion of Alk yla ted Ar yl Dia m in es
Sch em e 4. Con d en sa tion of (S)-6 w ith 1,2-P h en ylen ed ia m in e
tion with the partial formation of a planar (salophen)-
Ni(II) structure in (S,S)-11. It could also be attributed
to additional π-π* transitions involving the metal-
ligand orbitals.18
F igu r e 2. UV spectra of macrocycle (S,S)-10 and its Ni(II)
complex (S,S)-11.
tetrahedral Ni(II) center in (S,S)-11 should be para-
magnetic. (Salen)Ni(II) complexes can become para-
magnetic when they deviate from planarity,17 but non-
planar paramagnetic (salophen)Ni(II) complex was not
reported before.16 In the mass spectrum of (S,S)-11,
another major peak is observed for the loss of a Ni atom
and two AcO groups. This should correspond to a mono-
nuclear planar (salophen)Ni(II) fragment. However, the
reaction of (S,S)-10 with one equivalent of Ni(OAc)2‚4H2O
failed to generate such a mononuclear diamagnetic
complex.
Figure 2 shows the UV spectra of macrocycle (S,S)-10
and nickel complex (S,S)-11. The UV spectra of a
salophen derivative 12 and its Ni(II) complex 13 were
studied by Crawford in 1963.18 Both 12 and 13 have
strong absorptions between 450 and 500 nm. However,
the UV absorptions of macrocycle (S,S)-10 are signifi-
cantly blue shifted from those of 12 with no appreciable
absorption above 450 nm. This indicates that there is
much less conjugation in (S,S)-10. We attribute the
reduced conjugation of (S,S)-10 to the steric congestion
in the macrocycle which disrupts the planarity of the two
salophen units. After coordinated to Ni(II), the resulting
complex (S,S)-11 shows increased absorption in the range
of 420-600 nm. This could be due to increased conjuga-
We have carried out the condensation of (S)-6 with the
alkylated aryl diamine 8b in the presence of Ni(OAc)2‚
4H2O. The addition of Ni(II) made it harder to form
macrocycle so that an oligomer (S)-14 was obtained in
66% yield. The alkyl groups of 8b allow (S)-14 to be
soluble in organic solvents such as THF and chloroform.
The molecular weight of (S)-14 is Mw ) 3600 (PDI ) 1.62)
as determined by gel permeation chromatography (GPC)
relative to polystyrene standards. Our previous study has
shown that the absolute molecular weights of some
binaphthyl polymers determined by laser light scattering
method are often higher than those determined by using
polystyrene standards.19 Thus, we estimate that the
degree of polymerization for (S)-14 should be above 7.
Oligomer (S)-14 is paramagnetic since no NMR signal
in the normal spectra region is observed. This indicate
that there are also nonplanar coordination of Ni(II) units
in this material as observed for macrocycle (S,S)-11. The
UV spectrum of (S)-14 is also similar to that of (S,S)-11.
Therefore, the structure of this oligomer should be
different from that of 9 since the helical structure of 9
requires planar (salophen)Ni(II) coordination.
(17) (a) Holm, R. H. J . Am. Chem. Soc. 1960, 82, 5632. (b) Mockler,
G. M.; Chaffey, G. W.; Sinn, E.; Wong, H. Inorg. Chem. 1972, 11,
1308.
(19) Ma, L.; Hu, Q.-S.; Musick, K.; Vitharana, D.; Wu, C.; Kwan, C.
(18) Crawford, S. M. Spectrochimica Acta 1963, 19, 255.
M. S.; Pu, L. Macromolecules 1996, 29, 5083.

484 J . Org. Chem., Vol. 66, No. 2, 2001
Zhang et al.
Sch em e 5. Con d en sa tion of 5 w ith 8b in th e P r esen ce of Ni(OAc)2‚4H2O
charge-transfer band around 450-600 nm. However, the
near-visible-infrared absorption spectrum (not shown in
Figure 3) of 15 in chloroform (0.01 M) shows broad
absorption bands in the range of 700-1200 nm (ꢀ ) 32-
100) due to the d-d transition of the Ni(II) center. This
is consistent with the existence of nonplanar Ni(II) units
in the polymer.17 The square planar diamagnetic Ni(II)
complexes such as 16 do not have absorption above 700
nm in its near-visible-infrared absorption spectrum.
F igu r e 3. UV-vis spectra of polymer 15 and complex 16 in
chloroform.
3. Con d en sa tion of th e Bip h en ol Dia ld eh yd e
Mon om er 5 w ith Dia m in es. We examined the conden-
sation of the biphenol dialdehyde monomer 5 with
diamine 8b at various concentrations, which however,
only produced a mixture of very low molecular weight
materials and macrocylces. Unlike the reaction of chiral
binaphthyl (S)-6 with 1,2-phenylenediamine, 5 cannot
react with 8b to generate the corresponding macrocycle
with high yield at even high dilutions. Because of this,
Pierre and co-workers had developed a boron-templated
macrocycle synthesis from the condensation of 5 with 1,2-
phenylenediamine.7 To generate the desired polymer, we
conducted the polymerization of 5 with 8b in the presence
of Ni(OAc)2‚4H2O which indeed produced low molecular
weight polymer 15 in 68% yield (Scheme 5). Diamine 8b
with two long-chain alkyl substituents gave a much more
soluble material than diamine 8a that has shorter alkyl
substituents. The molecular weight of 15 is Mw ) 4900
(PDI ) 1.2) as measured by GPC. The estimated degree
of polymerization is above 10. Polymer 15 is also para-
magnetic with no NMR signals detected in the expected
region. This indicates that either only part of the
(salophen)Ni(II) units in 15 are planar or all nonplanar.
A known planar (salophen)nickel(II) complex 16 was
prepared to compare with polymer 15.20 Unlike 15,
complex 16 is a diamagnetic compound and gives well-
defined NMR signals. Figure 3 shows the UV spectra of
polymer 15 and complex 16 in THF. The UV spectrum
indicates that both of the materials contain a broad
4. Cop olym er iza tion of th e Ch ir a l BINOL Mon o-
m er (S)-6 a n d th e Ach ir a l Bip h en ol Mon om er 5
w ith Dia m in e 8b. 2,2′-Substituted 1,1′-binaphthyl mol-
ecules are chiral with restricted rotation around the 1,1′-
bond.16 However, 2,2′-biphenol derivatives are achiral
because the rotation barrier around the 2,2′-pivotal bond
is low. To find out whether the chirality of the binaphthyl
units could induce a helical chiral structure in the
biphenyl-based polymer, we have conducted the co-
condensation of (S)-6 and 5 with 8b in the presence of
Ni(OAc)2‚4H2O (Scheme 6). Table 1 summarizes the
molecular weights of the copolymers. As shown in Table
1, the polymers with more biphenyl units have higher
molecular weights than the polymers with more binaph-
thyl units probably because of the less steric interaction
during the formation of the former materials.
The UV absorption spectra of these copolymers are
compared (Figure 4). As shown in Figure 4, with the
increase of the binaphthyl units in the polymers, there
is significant increase in the absorptions around 250-
340 nm. The circular dichroism (CD) spectra of the
copolymers are also compared (Figure 5). We find that
the increase in the CD maximums at 417-435 nm is
linear with the increase of the chiral binaphthyl contents
in the copolymers (Figure 6). This linear relationship
demonstrates that there is no chiral amplification21 in
(20) Nagar, R.; Sharma, R. C.; Parashar, R. K. Spectrochim. Acta
1990, 46A, 401.
(21) J ha, S.; Cheon, K.-S.; Green, M. M.; Selinger, J . V. J . Am. Chem.
Soc. 1999, 121, 1665.

Chiral (Salophen)Ni(II) Complexes
J . Org. Chem., Vol. 66, No. 2, 2001 485
F igu r e 4. UV spectra of the copolymers.
F igu r e 6. Plot of the molar ellipiticity (at λ ) 417-435 nm)
of the copolymers versus the percentage of the chiral binaph-
thyl unit.
F igu r e 5. CD spectra of the copolymers.
Ta ble 1. Molecu la r Weigh ts of th e Cop olym er s
percentage of the
polymer
chiral binaphthyl (%)
Mw
Mn
PDI
15
17
18
0
5
10
40
100
4900
5400
4400
3400
3600
4000
3400
3900
2600
2200
1.2
1.6
1.1
1.3
1.6
F igu r e 7. (Salophen)Ni(II) units 20-22 that may be present
in the copolymers.
19
(S)-14
Su m m a r y
Polymeric/oligomeric and macrocyclic (salophen)Ni(II)
complexes have been synthesized starting from both an
achiral biphenol dialdehyde and an optically active
BINOL dialdehyde. It was found that these polysalophens
contain paramagnetic nonplanar Ni(II) coordination. This
is different from the previously reported (salophen)Ni-
(II) complexes which are square planar and diamagnetic.
The nonplanar Ni(II) coordination makes the new poly-
meric Ni(II) complexes deviated from a helical structure
proposed for chiral biaryl-based polymers containing
square planar (salophen)Ni(II) units. Copolymerization
of the chiral binaphthyl monomer with the achiral
these poly(salophen-Ni) complex. The chirality of the
binaphthyl units cannot propagate along the biphenyl
polymer chain. This is consistent with the existence of
nonplanar Ni(II) coordination in the polymers which
makes them different from the proposed helical structure
of 9. Thus, the chiral binaphthyl units cannot induce a
main chain helix in the polymer of the achiral biphenyl.
The red-shift from 417 to 435 nm in the CD maximums
going from copolymer 17 to the chiral binaphthyl polymer
(S)-14 is probably due to the increased conjugation of the
(salophen)Ni(II) units from 20 to 22 (Figure 7).
Sch em e 6 Cop olym er iza tion of (S)-6 a n d 5 w ith 8b in th e P r esen ce of Ni(OAc)2‚4H2O

486 J . Org. Chem., Vol. 66, No. 2, 2001
Zhang et al.
dried over Na2SO4. Concentration with a rotary evaporator and
subsequent chromatography on silica gel eluted with hexane/
ethyl acetate (5:1) afforded 4 as colorless crystals in 57% yield
(1.19 g): Rf ) 0.13 (hexane/ethyl acetate ) 5:1); 1H NMR (300
MHz, CDCl3) δ 3.15 (s, 6H), 4.81 (s, 4 H), 7.37 (dd, J ) 0.9,
8.4 Hz, 2 H), 7.67 (dd, J ) 1.8, 7.5 Hz, 2 H), 7.93 (dd, J ) 1.8,
7.8 Hz), 10.43 (s, 2 H); 13C NMR (75 MHz, CDCl3) δ 57.63,
101.19, 124.98, 129.18, 130.28, 132.73, 138.00, 158.19, 190.34.
P r epar ation an d Ch ar acter ization of (S)-3,3′-Difor m yl-
2,2′-bis(m eth oxym eth oxy)-1,1′-bin a p h th yl. The prepara-
tion procedure was the same as that of 4 with the use of (S)-
2,2′-bis(methoxymethoxy)-1,1′-binaphthyl as the starting
material. After workup, the crude product was purified by
column chromatography on silica gel eluted with hexane:ethyl
acetate (4:1). (S)-3,3′-Diformyl-2,2′-bis(methoxymethoxy)-1,1′-
binaphthyl was obtained as a sticky yellow oil in 68% yield:
Rf ) 0.17 (hexane/ethyl acetate ) 4:1); 1H NMR (300 MHz,
CDCl3) δ 2.87 (s, 6H), 4.69 (d, J ) 6.6 Hz, 2 H), 4.73 (d, J )
6.3 Hz, 2 H), 7.22 (d, J ) 8.7 Hz, 2 H), 7.42 (ddd, J ) 0.9, 7.5,
8.1 Hz, 2 H), 7.52 (ddd, J ) 0.9, 6.9, 7.8 Hz, 2 H), 8.08 (d, J )
8.1 Hz, 2 H), 8.62 (s, 2H), 10.55 (s, 2H); 13C NMR (75 MHz,
CDCl3) δ 57.00, 100.60, 125.89, 126.08, 126.26, 128.84, 129.61,
130.05, 130.28, 132.29, 136.68, 154.02, 190.64.
biphenyl monomer demonstrates that the chirality of the
binaphthyl unit is not propagated along the biphenyl
polymer chain. This is consistent with the nonhelical
chain structure of these (salophen)Ni(II) polymers. The
nonlinear optical property of these polymers and macro-
cycles is under investigation.
Exp er im en ta l Section
Unless otherwise noted, all materials obtained from com-
mercial suppliers were used without further purification.
Tetrahydrofuran, diethyl ether, and toluene were distilled from
sodium benzophenone ketyl immediately prior to use. Hexane
was distilled over calcium chloride. Dichloromethane was
distilled over calcium hydride. Ethanol was distilled over Mg
turnings. Thin-layer chromatography was performed on pre-
coated silica gel plates. Silica gel (70-230 and 230-400 mesh)
was used for column chromatography.
NMR spectra were recorded on Varian-300 MHz spectrom-
eter. Mass spectra were recorded either at electron ionization
or at FAB mode using m-nitrobenzyl alcohol (NBA) as the
matrix. Elemental analyses were performed by using a Perkin-
Elmer Series II CHNS/O Analyzer. The UV-vis and visible-
near-infrared spectra were recorded with Cary 5E UV-vis-
NIR spectrophotometer. The CD spectra were recorded with
a J ASCO J -720 spectropolarimeter. Optical rotations were
measured on a J ASCO DIP-1000 polarimeter at 589 nm.
P r ep a r a tion a n d Ch a r a cter iza tion of 2,2′-Bis-
(m eth oxym eth oxy)bip h en yl, 3. Under nitrogen, 2,2′-biphe-
nol (3.72 g, 20 mol) was added to a suspension of NaH (1.15 g,
48 mmol) in THF (40 mL) at 0 °C with stirring. The resulting
solution was stirred at 0 °C for 10 min, and then methoxym-
ethyl chloride (3.65 mL, 48 mmol) was slowly added. The
mixture was allowed to warm to room temperature and stirred
overnight to afford a creamlike mixture. Water was added to
quench the reaction. The organic layer was separated, and the
aqueous layer was extracted with ethyl acetate (30 mL × 3).
The combined organic extracts were washed with brine, and
dried over Na2SO4. After removal of the solvent, the residue
was purified by column chromatography on silica gel. Elution
with hexane/ethyl acetate (5:1) gave compound 3 as a colorless
oil in 54% yield (2.84 g): Rf ) 0.4 (hexane/ethyl acetate ) 5:1);
1H NMR (300 MHz, CDCl3) δ 3.24 (s, 6H), 4.97 (s, 4 H), 6.97
(m, 2 H), 7.10-7.25 (m, 6H); 13C NMR (75 MHz, CDCl3) δ
55.83, 95.20, 115.57, 121.79, 128.65, 129.15, 131.48, 154.88.
P r ep a r a tion a n d Ch a r a cter iza tion of 2,2′-Bis-
(m eth oxym eth oxy)-1,1′-bin a p h th yl.22 The preparation pro-
cedure was the same as that of 3 by using (S)-1,1′-bi-2-
naphthol (BINOL) as the starting material. After workup, the
crude product was purified by column chromatography on
silica gel. Elution with hexane/ethyl acetate (5:1) gave (S)-2,2′-
bis(methoxymethoxy)-1,1′-binaphthyl as a colorless crystal in
P r ep a r a tion a n d Ch a r a cter iza tion of 3,3′-Difor m yl-
2,2′-d ih yd r oxy-1,1′-bip h en yl, 5. After compound 4 (1.0 g, 3.0
mmol) was dissolved in a minimum amount of CH2Cl2, ethanol
(15 mL) and HCl (6 N, 15 mL) were added successively, and
the mixture was heated at reflux for about 10 h. The resulting
yellow solution was concentrated with a rotary evaporator.
Water (30 mL) was then added, and the solution was extracted
with CH2Cl2 (30 mL × 3). The combined extract was dried over
Na2SO4. After removal of the solvent, the residue was purified
by column chromatography on silica gel eluted with hexane/
ethyl acetate (6:1) to give 5 as yellow needle crystals in 68%
1
yield (0.50 g): Rf ) 0.26, (hexane/ethyl acetate ) 6:1). The H
and 13C NMR spectra of 5 match the reported data.7a
P r epar ation an d Ch ar acter ization of (S)-3,3′-Difor m yl-
2,2′-d ih yd r oxy-1,1′-b in a p h t h yl, (S)-6. The preparation
procedure was the same as that of 5 by starting with (S)-3,3′-
diformyl-2,2′-bis(methoxymethoxy)-1,1′-binaphthyl. After work-
up, the crude product was purified by recrystallization from
CH2Cl2/EtOH. This gave (S)-6 as a yellow solid in 90% yield:
1
Rf ) 0.35 (hexane/ethyl acetate ) 4:1). The H NMR data of 5
match the reported data.10
P r ep a r a tion a n d Ch a r a cter iza tion of 4,5-Di(1′-octy-
n yl)-1,2-d in itr oben zen e, 7a . In a drybox, 1,2-dibromo-4,5-
dinitrobenzene (2.0 g, 6.1 mmol), cuprous iodide (0.12 g, 0.61
mmol), and tetrakis(triphenylphosphine)palladium(0) (0.35
mg, 0.31 mmol) were mixed in a Schlenk flask. Triethylamine
(4.0 mL, 28.8 mmol), 1-octyne (1.35 g, 12.2 mmol), and THF
(80 mL) were added successively under nitrogen. The mixture
was further deoxygenated by freeze-pump-thaw three times
(-196 to +25 °C) and was then stirred at room temperature
for 96 h until TLC showed the disappearance of the starting
material. The mixture was filtered, and the precipitate was
washed with ether. The filtrates were combined and concen-
trated by rotary evaporation. The brown oil residue was then
redissolved in ether (50 mL), washed with water and brine,
and dried over Na2SO4. Concentration with a rotary evaporator
and subsequent chromatography on silica gel eluted with
hexane/ethyl acetate (97:3) afforded 7a as a light-yellow solid
in 78% yield (1.84 g): Rf ) 0.33 (hexane/ethyl acetate ) 97:3);
1H NMR (300 MHz, CDCl3) δ 0.91 (t, 6 H, J ) 7.2 Hz), 1.30-
1.35 (m, 8 H), 1.47-1.50 (m, 4 H), 1.62-1.67 (m, 4 H), 2.51 (t,
4H, J ) 7.2 Hz), 7.85 (s, 2 H); 13C NMR (75 MHz, CDCl3) δ
14.24, 20.00, 22.73, 28.42, 28.78, 31.52, 77.35, 102.80, 128.12,
132.07, 140.87; MS (EI) for C22H28N2O4 m/z (relative intensity)
384 (M+, 90).
1
85% yield: Rf ) 0.39, (hexane/ethyl acetate ) 3:1); H NMR
(300 MHz, CDCl3) δ 3.15 (s, 6H), 4.98 (d, J ) 6.6 Hz, 2 H),
5.09 (d, J ) 6.6 Hz, 2 H), 7.14-7.26 (m, 6 H), 7.35 (ddd, J )
1.8, 8.4 Hz, 2 H), 7.58 (d, J ) 9.0 Hz, 2 H), 7.88 (d, J ) 8.1 Hz,
2 H), 7.96 (d, J ) 9.0 Hz, 2 H); 13C NMR (75 MHz, CDCl3) δ
55.78, 95.13, 117.22, 121.24, 124.02, 125.50, 126.25, 127.82,
129.35, 129.83, 133.97, 152.60.
P r ep a r a tion a n d Ch a r a cter iza tion of 3,3′-Difor m yl-
2,2′-bis(m eth oxym eth oxy)bip h en yl, 4. Under nitrogen, n-
butyllithium (2.5 M in hexane, 9.0 mL, 22 mmol) was added
to a solution of 3 (1.73 g, 6.6 mmol) in ether (100 mL) at room
temperature. The mixture was stirred for 2 h, which produced
a gray suspension. After the mixture was cooled to 0 °C, DMF
(1.85 mL, 24 mmol) was added. The reaction mixture was
allowed to warm to room temperature and stirred for 4 h.
Saturated NH4Cl (50 mL) was then added to quench the
reaction. The organic layer was separated, and the aqueous
phase was extracted with ethyl acetate (50 mL × 3). The
combined organic phase was washed with water and brine and
P r ep a r a tion a n d Ch a r a cter iza tion of 4,5-Di(1′-octa -
d ecyn yl)-1,2-d in itr oben zen e, 7b. The preparation procedure
was the same as that of 7a by starting with 1-octadecyne. After
workup, the crude product was purified by chromatography
on silica gel eluted with hexane/ethyl acetate (97:3). This
afforded 7b as a light-yellow solid in 90% yield: Rf ) 0.50
(22) Kitajima, H.; Aoki, Y.; Ito, K.; Katsuki, T. Chem. Lett. 1995,
1113.
1
(hexane/ethyl acetate ) 97:3); H NMR (300 MHz, CDCl3) δ

Chiral (Salophen)Ni(II) Complexes
J . Org. Chem., Vol. 66, No. 2, 2001 487
0.88 (t, 6 H, J ) 6.6 Hz), 1.30 (b s, 48 H), 1.47 (m, 4 H), 1.64
(m, 4 H), 2.50 (t, 4H, J ) 7.2 Hz), 7.85 (s, 2 H); 13C NMR (75
MHz, CDCl3) δ 14.10, 19.81, 22.69, 28.27, 28.93, 29.17, 29.35,
131.86, 140.70; MS (FAB) m/z (relative intensity) 665 (M +
H+, 100). Anal. Calcd. for C42H68N2O4: C, 75.86; H, 10.31; N,
4.21. Found: C, 75.67; H, 10.36; N, 3.97.
P r ep a r a t ion a n d Ch a r a ct er iza t ion of P olym er 15.
Under nitrogen, a solution of 8b (61.2 mg, 0.1 mmol) in THF
(2.0 mL) was slowly added to a mixture of 5 (24.2 mg, 0.1
mmol) and Ni(OAc)2
‚4H O (24.8 mg, 0.1 mmol) in THF (1.0
2
mL) over 10 h via a syringe pump at 70 °C. An additional 40
h reflux resulted in a dark red solution. After removal of the
solvent, the brown residue was redissolved in a minimum
amount of THF and precipitated with absolute ethanol. This
dissolution and precipitation was repeated to give polymer 15
as a dark red solid in 68% yield (60 mg) after drying under
vacuum: UV-vis λmax (THF) nm 500 (ꢀ ) 5.10 × 103), 382 (ꢀ
) 2.05 × 104), 314 (ꢀ ) 2.17 × 104), 251 (3.93 × 104).
P r ep a r a tion a n d Ch a r a cter iza tion of 1,2-Dia m in o-4,5-
d ioctylben zen e, 8a . A solution of 7a (0.77 g, 2.0 mmol) in
MeOH (50 mL) was stirred under hydrogen (10 psi) in the
presence of Pd (10%)/C (85 mg) at room temperature. After
24 h, TLC indicated the consumption of all the starting
material. The reaction mixture was then filtered carefully
through a pad of Celite and washed with diethyl ether. After
removal of the solvent, 8a (0.52 g, 78%) was obtained as a
yellow powder which was pure enough for the subsequent
P r ep a r a tion a n d Ch a r a cter iza tion of P olym er (S)-14.
The preparation procedure was the same as that of 15 by using
(S)-6 as the monomer. Polymer (S)-14 was isolated as a brown
solid in 66% yield (64 mg) after drying under vacuum: UV-
vis λmax (THF) nm 370 (ꢀ ) 1.81 × 104), 260 (ꢀ ) 6.34 × 104);
CD [Θ]λ (4.57 × 10-5 M, THF) 1.25 × 105 (435 nm), -3.42 ×
104 (340 nm), 4.16 × 104 (306 nm), -1.15 × 105 (260 nm).
1
reaction: Rf ) 0.18 (hexane/ethyl acetate/MeOH ) 5:5:1); H
NMR (300 MHz, CDCl3) δ 0.89 (t, J ) 6.9 Hz, 6 H), 1.29 (m,
20 H), 1.51 (m, 4 H), 2.45 (t, J ) 8.1 Hz, 4 H), 3.21 (bs, 4 H),
6.51 (s, 2 H).
P r ep a r a tion a n d Ch a r a cter iza tion of 1,2-Dia m in o-4,5-
d iocta d ecylben zen e, 8b. The preparation procedure was the
same as 8a by hydrogenation of 7b. After workup, the crude
product was purified by flash chromatography on silica gel
eluted with hexane/ethyl acetate (2:1) to afford compound 8bas
a light-yellow solid in 86% yield: Rf ) 0.50 (hexane/ethyl
acetate ) 2:1); 1H NMR (300 MHz, CDCl3) δ 0.88 (t, 6 H, J )
6.9 Hz), 1.25 (b s, 60 H), 1.48 (m, 4 H), 2.44 (t, 4H, J ) 8.4
Hz), 6.50 (s, 2 H); 13C NMR (75 MHz, CDCl3) δ 14.18, 22.69,
29.35, 29.70 (broad intense signal), 31.74, 31.92, 32.08, 117.81,
118.93, 132.41; MS (CI) for C42H80N2 m/z (relative intensity)
613 (M + H+, 100).
P r epar ation an d Ch ar acter ization of Macr ocycle (S,S)-
10. Under nitrogen, a mixture of 1,2-phenylenediamine (43.2
mg, 0.4 mmol) and (S)-6 (136.8 mg, 0.4 mmol) in absolute
ethanol (10 mL) was refluxed for about 10 h to yield a yellow
precipitate. The crude product was filtered at room tempera-
ture and washed with ice-cold ethanol to afford pure 10 as a
yellow solid in 97% yield (160 mg): 1H NMR (300 MHz, CDCl3)
δ 7.10-7.17 (m, 8H), 7.24 (d, J ) 4.2 Hz, 8 H), 7.35 (m, 4 H),
7.84 (m, 4 H), 8.06 (s, 4 H), 8.76 (s, 4 H), 12.48 (s, 4 H); 13C
NMR (75 MHz, CDCl3) δ 116.86, 119.51, 121.42, 123.22,
124.46, 127.45, 127.71, 128.64, 129.04, 134.91, 135.87, 143.75,
154.87, 163.40; MS (CI) m/z (relative intensity) 829 (M + H+,
100); UV-vis λmax (CHCl3) nm 358 (ꢀ ) 3.65 × 104), 314 (ꢀ )
6.58 × 104), 268 (ꢀ ) 1.03 × 105). Anal. Calcd for C56H36N4O4‚
H2O: C, 79.42; H, 4.52; N, 6.61. Found: C, 79.90; H, 4.53; N,
6.57.
P r ep a r a tion a n d Ch a r a cter iza tion of Cop olym er 17.
Under nitrogen, a solution of 8b (61.2 mg, 0.1 mmol) in THF
(2.0 mL) was slowly added to a mixture of 5 (23.0 mg, 0.095
mmol), (S)-6 (1.7 mg, 0.005 mmol) and Ni(OAc)2‚4 H2O (24.8
mg, 0.1 mmol) in THF (1.0 mL) by syringe pump over 10 h at
70 °C. An additional 40 h reflux resulted in a dark red solution.
After removal of solvent, the brown residue was redissolved
in a minimum amount of THF and precipitated with absolute
ethanol twice. Copolymer 17 was isolated as a dark red solid
in 65% yield (57 mg) after drying under vacuum: UV-vis λmax
(THF) nm 514 (ꢀ ) 6.75 × 103), 387 (ꢀ ) 1.97 × 104), 317 (2.08
× 104), 2.59 (3.09 × 104). CD [Θ]λ (4.57 × 10-5 M, THF) 6.49
× 103 (417 nm, the predominate signal).
P r ep a r a tion a n d Ch a r a cter iza tion of Cop olym er 18.
The preparation procedure was the same as that of 17 except
that 5 (21.8 mg, 0.09 mmol) and (S)-6 (3.42 mg, 0.01 mmol)
were used. Copolymer 18 was isolated as a brown solid in 65%
yield (60 mg) after drying under vacuum. UV-vis λmax (THF)
nm 500 (ꢀ ) 5.11 × 103), 383 (ꢀ ) 1.75 × 104), 310 (1.93 ×
104), 251 (3.93 × 104). CD [Θ]λ (4.57 × 10-5 M, THF) 8.23 ×
103 (417 nm, the predominate signal).
P r ep a r a t ion a n d Ch a r a ct er iza t ion of Co-P olym er
19. The preparation procedure was the same as that of 17
except that 5 (14.6 mg, 0.06 mmol) and (S)-6 (13.7 mg, 0.04
mmol) were used. Copolymer 19 was isolated as a brown
solid in 65% yield (61 mg) after drying under vacuum: UV-
vis λmax (THF) nm 381 (ꢀ ) 1.98 × 104), 254 (4.44 × 104); CD
[Θ]λ (4.57 × 10-5 M, THF) 4.17 × 104 (415 nm, the predominate
signal).
P r ep a r a tion a n d Ch a r a cter iza tion of Ma cr ocyclic Ni-
(II) Com p lex (S,S)-11. Under nitrogen, a mixture of (S,S)-
10 (60 mg, 0.07 mmol) and Ni(OAc)2‚4H2O (40 mg, 0.14 mmol)
in absolute ethanol (10 mL) was refluxed for about 10 h to
yield a brown precipitate. The crude product was filtered at
room temperature and washed with ice-cold ethanol to afford
(S,S)-11 as a brown solid: MS (CI) for C60H40O8N4Ni2 m/z
(relative intensity) 1061.1 (M + H+, 100), 885.5 (M - Ni -
2OAc + H+, 60); UV-vis λmax (CHCl3) nm 369 (ꢀ ) 4.64 × 104),
349 (ꢀ ) 4.73 × 104), 310 (ꢀ ) 6.15 × 104), 277 (ꢀ ) 7.69 ×
104).
Ack n ow led gm en t. Support of this work from the
Office of Naval Research (N00014-99-1-0531) is grate-
fully acknowledged. We also thank Dr. Vincent J . Pugh
and Dr. Qiao-Sheng Hu for their assistance in optical
measurements.
J O001276S