Crown-linked porphyrin systems

Full text of DOI:10.1021/jo001700p

J . Org. Chem. 2001, 66, 4419-4426
4419
Cr ow n -Lin k ed P or p h yr in System s
Sandhya A. Duggan,1 Gary Fallon,1
Steven J . Langford,*,1 Vei-Lin Lau,1
J acqueline F. Satchell,1 and Michael N. Paddon-Row2
School of Chemistry, Monash University, Clayton,
Victoria, Australia 3800, and School of Chemistry,
University of New South Wales, Kensington,
New South Wales, Australia 2052
s.langford@sci.monash.edu.au
F igu r e 1. The general structure of our crown-ether-based
multiporphyrin systems.
Received December 4, 2000
(Revised Manuscript Received March 21, 2001)
which contain porphyrin subunits antipodally displaced
on the macrocycle. System 1 (Figure 1) is representative
of the types that we wish to synthesize. By varying the
size of the crown ether, we can modulate the center-to-
center distances between the porphyrin rings. Molecular
modeling has been used to determine the approximate
center-to-center distances in the extended forms of 1
(Figure 1) for m ) 0-3 to be 15-26 Å. Both the 12C4
and 18C6 analogues of 1 have porphyrin-to-porphyrin
distances that are comparable to that found between the
special pair (SP) and bacteriopheophytin (BPh) in the
photosynthetic reaction center for the purple bacteria
Rhodopseudomonas viridis.9 Larger derivatives of 1
incorporating 24C8 and 30C10 crown ether systems will
allow the addition of structural10,11 and chromophoric12
auxiliaries to be complexed within the cavity. Here, we
report the first synthesis of free-base analogues of 1
involving 18-crown-6, 24-crown-8, and 30-crown-10 bridges,
monofunctionalized dibenzocrown ethers and some open
chain polyether analogues. X-ray crystallography has
been used to characterize the tetranitro analogue of
DB30C10sa precursor to 1.30C10. Complexation of
1.24C8 with (C6H5CH2)2NH2PF6 illustrates the potential
use of organic cations as structural auxiliaries.
In tr od u ction
The success of the photosynthetic reaction center3 as
a transducer of light into chemical potential depends
primarily on the assembly being able to exert strict
control over a number of design features, such as the
separation and orientation of the various redox centers
and the nature of the medium separating them. There-
fore, an important aspect of designing artificial photo-
synthetic devices based particularly on the multiporphy-
rin arrays found in light harvesters and in the initial
processes of such reaction centers, is the selection of an
appropriate organizing principle that will control these
same features.4 Multiporphyrin systems in which the
porphyrin subunits are interlinked using covalent bonds
have produced an array of elegant structures, some of
which display reaction-center-like processes.4,5 However,
a disadvantage of using these arrays as potential energy
transduction devices6 usually lies in their synthesis,
which is not trivial and can be extremely difficult and
expensive to realize on a large scale. These difficulties
may be overcome by employing molecular recognition
events to facilitate the association and orientation of the
porphyrinic chromophores.7
Resu lts a n d Discu ssion
Our approach to a series of multiporphyrin arrays is
through crown ether systems8 of the type 3n-crown-n
Our strategy has centered about an efficient means of
attaching potent chromophores, such as the porphyrins,
* To whom correspondence should be sent. Phone: + 03 9905 4569.
Fax: + 03 9905 4597.
(1) Monash University.
(2) University of New South Wales.
(3) Deisenhofer, J .; Epp, O.; Miki, K.; Huber R.; Michel, H. Nature
1985, 318, 618.
(8) Other multichromophoric crown ether systems have been pre-
pared in the past with success: (a) Thanabal, V.; Krishnan, V. J . Am.
Chem. Soc. 1982, 104, 3643. (b) Iyoda, T.; Morimoto, M.; Kawasaki,
N.; Shimidzu T. J . Chem. Soc., Chem. Commun. 1991, 1480. (c) Yoon,
D. I.; Berg-Brennan, C. A.; Lu, H.; Hupp, J . T. Inorg. Chem. 1992, 31,
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10.1021/jo001700p CCC: $20.00 © 2001 American Chemical Society
Published on Web 05/23/2001

4420 J . Org. Chem., Vol. 66, No. 12, 2001
Notes
Sch em e 1
a
b
HNO3, CH2Cl2, r.t., 88%. HNO3, CH2Cl2, 0 °C, 81%. c HNO3, H2SO4, CH2Cl2, r.t. 63-96%.
to a crown ether system. We decided to take advantage
of tetraarylporphyrin-2,3-diones such as 4,13 which have
served us well in the past as a means of making highly
rigid multichromophoric systems which undergo efficient
ET14 and EnT15 processes. Condensation of the porphyrin-
2,3-dione 4 with an ortho-diamine functionalized crown
would lead to the desired crown ether appended porphy-
rin systems. Commercially available DB18C6, DB24C8,
and DB30C1016 were nitrated17 (HNO3, H2SO4, CH2Cl2)
using a biphasic system (Scheme 1) to yield the corre-
sponding TNDB18C6,18 TNDB24C8, and TNDB30C10 as
bright yellow solids in excellent yield. This nitration is
stepwise, forming the two intermediate isomeric dinitro-
crown-ethers19 in which one nitro group has been added
to each of the catechol rings. At room temperature this
reaction is fast in the presence of an excess of HNO3. The
1,2,4-substitution pattern of each catechol ring in DN3nCn
is borne out by the splitting patterns seen in the 1H NMR
spectrum of such samples. The DN3nCn is the major
isolable product (>80% yield) when (a) only nitric acid is
added to a CH2Cl2 solution of crown ether or (b) a dilute
CH2Cl2 solution (HNO3, H2SO4, CH2Cl2) is used. The rate
for the second nitration is much slower and can be easily
monitored by 1H NMR spectroscopy in particular, the
eventual presence of a four proton singlet at ca. δ 7.5.
The aromatic substitution pattern of the desired tetrani-
tro-crown ethers was supported by X-ray crystallography.
Yellow crystals suitable for X-ray analysis were grown
by slow evaporation of a solution of TNDB30C10 in
MeCN.21 Clearly indicated is the 1,2,4,5-arrangement of
the nitro and alkoxy groups on both benzene units of the
crownsconsistent with the 1H NMR spectra of this series
of molecules. There was no appreciable sign of intramo-
lecular π-π stacking interactions between the aromatic
moieties22 nor was there any solvent (MeCN) included
within the crystal lattice. Interestingly enough, all at-
tempts to nitrate the 2,3-dibromocrown ether 220 under
the same conditions failed to give any of the correspond-
ing 12,13-dinitrocrown ether. Controlled nitration of 2
was possible (Scheme 1), yielding the 12-nitro-2,3-dibro-
mocrown ether 3 in 81% yield after recrystallization.
Compound 3 became central to our strategy of appending
a single porphyrin unit to the crown ethers.
Reduction of the crown ethers TNDB18C6, TNDB24C8,
and TNDB30C10 (NH2NH2‚H2O, Pd/C, EtOH) under
anaerobic conditions gave the colorless and highly air-
sensitive TADB18C6, TADB24C8, and TADB30C10,
respectively (Scheme 2). Two approaches to the conden-
sation of these amines with 4 to form the target photo-
active crowns were made. Initially, the putative tetraami-
nocrown ethers were condensed (after filtration of the
catalyst) with a deoxygenated solution of the porphyrin-
2,3-dione 4 in CH2Cl2 (Scheme 2). However, a shortcom-
ing of this reaction sequence was the presence of excess
hydrazine hydrate, which is able to condense with 4,
forming undesirable side-products. We have recently
found it more efficient to precipitate the tetra-amines
from the ethanol solution as the highly stable and
(13) (a) Crossley, M. J .; King, L. G. J . Chem. Soc., Chem. Commun.
1984, 921. (b) Crossley, M. J .; Burn, P. L.; Langford, S. J .; Prashar, J .
K. J . Chem. Soc., Chem. Commun. 1995, 1921.
(14) (a) Antolovich, M.; Oliver, A. M.; Paddon-Row, M. N. J . Chem.
Soc., Perkin Trans. 2 1989, 783. (b) Ranasinghe, M. G.; Oliver, A. M.;
Rothenfluh, D. F.; Salek, A.; Paddon-Row, M. N. Tetrahedron Lett.
1996, 37, 4797. (c) J olliffe, K. A.; Bell, T. D. M.; Ghiggino, K. P.;
Langford S. J .; Paddon-Row, M. N. Angew. Chem., Int. Ed. Engl. 1998,
37, 915. (d) J olliffe, K. A.; Langford, S. J .; Oliver, A. M.; Shephard, M.
J .; Paddon-Row, M. N. Eur. J . Chem. 1999, 5, 2518.
(15) J olliffe, K. A.; Langford, S. J .; Ranasinghe, M. G.; Shephard,
M. J .; Paddon-Row, M. N. J . Org. Chem. 1999, 64, 1238.
(16) We have decided to use acronyms to describe our poly-nitro and
poly-amino systems. For example, TNDB18C6 relates to the TetraNitro
derivative of DiBenzo-18-Crown-6.
(20) van Nostrum, C. F.; Picken, S. J .; Schouten, A.-J .; Nolte, R. J .
M. J . Am. Chem. Soc. 1995, 117, 9957.
(17) (a) Ungaro, R.; El Haj, B.; Smid, J . J . Am. Chem. Soc. 1976,
98, 5198. (b) Rogers, R. D.; Henry, R. F.; Rollins, A. N. J . Inclusion
Phenom. 1992, 13, 219. (c) Forget, S.; Verber M.; Strzelecka, H. Mol.
Cryst. Liq. Cryst. 1995, 258, 263.
(18) Chang, S. H.; Cho, S. A. J . Korean Chem. Soc. 1988, 32, 71.
(19) Feigenbaum, W. M.; Michel, R. H. J . Polym. Sci. A 1971, 9,
817.
(21) Crystal data for C28H36N4O18: MW ) 716.61, monoclinic, P21/
c, a ) 13.9862(6) Å, b ) 7.5273(4) Å, c ) 15.4139(7) Å, â ) 104.874-
(3)°, V ) 1568.4(1) Å3, Z ) 2, T ) 123 ( 1 K, µ(Mo KR) ) 1.28 cm-1
,
Dcalcd ) 1.517 gcm-3
, R ) 6.3% for 2545 observed independent
reflections. Hydrogen atoms were treated as idealized contributions.
(22) Hunter, C. A.; Sanders, J . K. M. J . Am. Chem. Soc. 1990, 112,
5525.

Notes
J . Org. Chem., Vol. 66, No. 12, 2001 4421
Sch em e 2
attributed to the uncomplexed species resonate at the
same δ values as they do in the H NMR spectra of the
1
individual components and the stoichiometry of the
complex is readily determined as 1:1 by integration of
relevant probe protons on both the host and guest species.
This situation is clearly one of slow kinetics between
complexation and decomplexation at 300 MHz and 300
K. The observation of both signals attributable to com-
plexed and uncomplexed species allows for the determi-
nation of the association constants (Ka) by single point
analysis.11c The high value obtained (Ka ) 105 M-1) is
consistent with the results obtained by both Stoddart’s
and Gibson’s groups for [Bn2NH2]+PF6 with DB24C8.11
The addition of CD3SOCD3 (20%) to the NMR sample
leads to complete decomplexation.
Our approach to the formation of crown ethers and
their derivatives bearing a single porphyrin group, e.g.
9 and 15, began by investigating the cyclization of the
polyether derivatives 5.24 Compounds 9 and 15 are
pivotal to any derivatization by allowing the introduction
of electrophiles25 or other electron acceptors to the crown
ether periphery. Diacetates 5 were chosen as our starting
point for three reasons. First, the acidic conditions of the
nitration of the unprotected diol would surely lead to a
range of byproducts, the diacetate is easily formed,24 and
the acetate group is easily removed under the subsequent
reduction conditions. The diacetates 5a and 5b were
nitrated cleanly (Scheme 4) in high yield after purifica-
tion by column chromatography to give bright yellow oils
that solidified on standing. Deprotection of 6 (K2CO3,
MeOH) followed by tosylation (TsCl, NEt3, CH2Cl2) of the
diol 7, gave the bistosylate 8 in high yield. All attempts
to cyclize 8 with catechol under differing conditions of
base, solvent, and temperature failed to give any of the
corresponding dinitro-DB18C6. This observation was
consistent with literature reports on the effect of nucleo-
philic ring cleavage of nitro crown ethers by alcoholic
bases.18 Using a similar synthetic strategy to that
outlined for 1, compounds 6a and 6b were subjected to
reduction (NH2NH2‚H2O, Pd/C, EtOH) followed by con-
densation with 4 to yield 9a and 9b, respectively (Scheme
4), in excellent yield. In this case, the highly nucleophilic
nature of the hydrazine allows the hydroxy groups to be
regenerated during this reaction sequence.
Alternatively, we proposed that the desired regiose-
lectivity in 15 could be introduced into a dibenzocrown
ether by way of appropriate blocking groups (Scheme 5).
Nitration of 2 (Scheme 1) proceeded smoothly and in high
yield. Hydrazine reduction of 3 yielded the amine 11,26
in which removal of the bromo groups were also observed.
This was surprising in light of our earlier results on rigid-
norbornylogous bridged systems where debromination
did not occur under similar conditions.14a The debromi-
nation posed a potential problem in itself. The highly
activated nature of the two aromatic units within the
crown ether meant that the subsequent functionalization
might not occur ortho to the amino group. Interestingly,
there have been no reports in the literature of regiose-
lectivity in electrophilic aromatic substitution between
activated dibenzo-crown ether units. Protection of the
amine (Ac2O, CH2Cl2) allows for the regiospecific nitra-
tion of 12 ortho to the acetamide group in high yield.
a
b
Hydrazine hydrate, Pd/C, EtOH, reflux, Ar. Concentrated
HCl, EtOH. c 4, CH2Cl2, reflux. 4, pyridine, reflux, 36-63% for
2 steps.
d
crystalline tetrahydrochloride salts.23 In each case, the
resulting condensation products were purified by column
chromatography (silica) to yield the free-base porphyrin-
appended crown ethers 1 as bright purple solids in good
yield. The 400 MHz 1H NMR spectrum of 1.18C8 is
shown in Figure 2. The spectrum is well resolved and
clearly indicates the symmetrical nature of the molecule.
UV-vis spectra of 1.3nCn (n ) 6,8,10) were identical
(λmax (CDCl3): 430, 524, 596, 649 nm), indicating little
electronic coupling between the porphyrin units in the
ground state.
One of our long-term goals is to assemble nanometer-
sized multiporphyrin arrays using a structural auxiliary
and 1 as a scaffold. Molecular modeling suggests that
such arrays will closely mimic, in terms of porphyrin-to-
porphyrin distance, the arrangement between the special
pair, BChl and BPhe, within the reaction center of the
purple bacteria. To determine this study’s viability, we
investigated the complexation of 1.24C8 with [Bn2NH2]+-
-
PF6 in CDCl3 at 300 K. Equimolar mixes of the two
components display the 1:1 complex formed between
these two species, and both uncomplexed 1.24C8 and
[Bn2NH2]+PF6 within the 1H NMR spectrum. The signals
(24) Hiratani, K.; Aiba, S. Bull. Chem. Soc. J pn. 1984, 57, 2657.
(25) Diederich, F.; J onas, U.; Gramlich, V.; Herrmann, A.; Ringsdorf,
H.; Thilgen, C. Helv. Chim. Acta 1993, 76, 2445.
(23) Aqueous solutions of the tetrahydrochloride salt have a limited
shelf life, darkening considerably over a two day period.
(26) J eong, K.-S.; Cho, Y. L. Bull. Korean Chem. Soc. 1994, 15, 705.

4422 J . Org. Chem., Vol. 66, No. 12, 2001
Notes
1
F igu r e 2. 400 MHz H NMR spectrum of 1.18C6 in CDCl3 at 300 K.
-
Sch em e 3. P r elim in a r y Com p lexa tion Stu d y betw een 1.24C8 a n d [Bn 2NH2]+P F 6 in CDCl3
None of the alternate isomers, where nitration occurs in
the other ring, were observed. This regiospecificity was
somewhat surprising taking into account steric effects
known for the acetamide group, the competition between
the equally strong directing groups, and the size of the
incoming electrophile.27 Deprotection of 13 (1M HCl, 60
°C, 3 days) occurred cleanly to give the nitroamine 14 as
an orange solid in excellent yield. Reduction of 14 (NH2-
NH2‚H2O, Pd/C, EtOH) and condensation with 4 gave 15
in 76% yield as a bright purple solid (Scheme 5).
Con clu sion
Our work describes an efficient method for the syn-
thesis of a series of porphyrin-appended crown ether
(27) Advanced Organic Chemistry, 4th Ed.; March, J ., Ed.; Wiley:
New York, 1992; p. 513.

Notes
J . Org. Chem., Vol. 66, No. 12, 2001 4423
Sch em e 4
a
b
d
HNO3, H2SO4, CH2Cl2, r.t. 92-95%. MeOH, K2CO3, 15 min. c TsCl, NEt3, CH2Cl2, 0 °C, 72%. Catechol, base, solvent. e Hydrazine
hydrate, Pd/C, EtOH, reflux, Ar. f 4, CH2Cl2, reflux, 84-86% for 2 steps.
Sch em e 5
Exp er im en ta l Section
Gen er a l Meth od s. Chemicals were purchased from Aldrich
and used as received. Solvents were dried and reagents were
purified where necessary using literature methods.29 Thin-layer
chromatography (TLC) was carried out on aluminum sheets
precoated with Merck 5735 Kieselgel 60F. Column chromatog-
raphy was carried out using Kieselgel 60 (0.040-0.063 mm
mesh, Merck 9385). Melting points are uncorrected. Microanaly-
ses were carried out within the Chemistry Department, Uni-
versity of Otago, New Zealand. Low resolution mass spectra were
recorded on a micromass platform spectrometer (QMS, quad-
rupole mass electrospray) and high-resolution mass spectra were
recorded on a Bruker BioApex 47e Fourier transform mass
spectrometer equipped with an Analytica ESI source. In both
cases, samples were prepared as either aqueous methanol or
dichloromethane solutions. Nuclear magnetic resonance (NMR)
spectra were recorded at 300 MHz for proton frequency and 75
MHz for carbon frequency using the DEPT pulse sequence.
Reflection data were measured with an Enraf-Nonius Kap-
paCCD diffractometer at 123 K using graphite monochromated
Mo KR radiation (λ ) 0.71069 Å). Reflections with I > 3σ(I) were
considered observed. The structure was determined by direct
methods.
Syn th esis of TNDB-3n -cr ow n -n . Gen er a l P r oced u r e. To
a stirred solution of DB-3n-crown-n (0.4-1.2 mmol) in dichlo-
romethane were added dropwise concentrated nitric acid (1 mL)
and, after 5-10 min, concentrated sulfuric acid (0.5 mL). The
reaction mixture was stirred at room temperature for 2-4 days.
a
b
Hydrazine hydrate, Pd/C, EtOH, reflux, Ar, 96%. Ac2O, r.t.,
86%. c HNO3, CH2Cl2, 0 °C, 80%. 1 M HCl, 60 °C, 3 days, 72%.
e Hydrazine hydrate, Pd/C, EtOH, reflux, Ar. f 4, CH2Cl2, reflux,
76% for 2 steps.
d
2,3,12,13-T e t r a n it r o -6,7,9,10,17,18,20,21-o c t a h y d r o -
5,8,11,16,19,22-h e x a o x a d ib e n zo [b ,k ]c y c lo o c t a d e c e n e
(TNDB18C6) was synthesized from DB18C6 (0.55 g, 1.20
mmol), by nitration over 2 days. The product precipitated out of
solution, pure, as a fine yellow powder (0.73 g, 96%), which was
obtained by filtering the reaction mixture, washing with water,
and drying in the oven. Mp 228-229 °C. ESI HRMS (+ve):
Found m/z 563.0866 [M + Na]+ (Calculated for molecular
formula C20H20N4O14Na, 563.0874). 1H NMR (300 MHz, CD3-
CN): δ 3.90-3.92 (8H, m, OCH2), 4.27-4.31 (8H, m, OCH2), 7.53
(4H, s, ArH). 13C NMR (75 MHz, d6-DMSO): δ 69.3, 70.3, 109.3,
136.9, 151.8.
2,3,16,17-T e t r a n it r o -6,7,9,10,12,13,20,21,23,24,26,27-
d od eca h yd r od ib en z[b,n ]-1,4,7,10,13,16,19,22-oct a oxa cy-
clotetr a cosin (TNDB24C8) was synthesized from DB24C8
(0.41 g, 0.90 mmol) by nitration over 4 days, after which
dichloromethane was added (30 mL) and the organic layer
collected, washed with water (2 × 30 mL), and dried over
anhydrous sodium sulfate. The mixture was filtered and the
solvent removed under reduced pressure to afford a yellow
grainy solid (0.55 g, 96%). Mp 197-198 °C. ESI HRMS (+ve):
Found m/z 651.1416 [M + Na]+ (Calculated for molecular
systems in which the catechol unit of the crown ethers
are fused to two â-pyrrolic positions of the porphyrin
periphery. Critical to this strategy was the preparation
of crown ethers bearing ortho-amine groups. In the case
of the doubly appended systems 1, tetranitration, the
subsequent reduction and condensation were achieved in
high yield in 3 steps from commercially available starting
materials. We have also demonstrated for the first time
the regiospecific nitration of a dibenzocrown ether bear-
ing five activating groups. This regiospecificity leads to
the efficient preparation of the singularly appended
crown ether 15. We are at present investigating ways of
incorporating other electron accepting groups into 1 using
9 and 15 as precursors, making metalated variants of 1
to investigate ET and EnT processes,28 and investigating
the ability of systems 1, 9, and 15 to act as fluorescent
sensors for a range of organic and metal cations.
(28) (a) Rege P. J . F.; Williams, S. A.; Therien, M. J . Science 1995,
269, 1409. (b) Harriman, A.; Sauvage, J .-P. Chem. Soc. Rev. 1996, 41.
(29) Purification of Laboratory Chemicals, 3rd ed.; Perrin, D. D.,
Armarego, W. L., Eds.; Pergamon Press: New York, 1988.

4424 J . Org. Chem., Vol. 66, No. 12, 2001
Notes
formula C24H2N4O16Na, 651.1398). 1H NMR (300 MHz, CD3-
CN): δ 3.70 (8H, s, OCH2), 3.83-3.87 (8H, m, OCH2), 4.26-
4.29 (8H, m, OCH2), 7.52 (s, 4H, ArH). 13C NMR (75 MHz,
CDCl3): δ 69.7, 70.7, 71.9, 109.0, 136.9, 151.7.
dichloromethane/hexane to elute any unreacted 4 (56.6 mg) and
subsequently 2:98 and 4:96 methanol/dichloromethane mixtures.
1.30C10 was obtained as a red-purple solid (86.0 mg, 63% based
on recovered 4). Mp > 350 °C. ESI HRMS (+ve): Found m/z
1813.7138 [M + H]+ (Calculated for molecular formula C116
-
2,3,19,20-Tet r a n it r o-6,7,9,10,12,13,15,16,23,24,26,27,29,-
30,32,33-h exa d eca h yd r od iben zo[b,q]-1,4,7,10,13,16,19,22,-
25,28-d eca oxa cyclotr ia con tin (TNDB30C10) was synthe-
sized from DB30C10 (217 mg, 0.40 mmol), by nitration over 2
days, after which dichloromethane was added (30 mL) and the
organic layer collected, washed with water (2 × 30 mL), and
dried over anhydrous sodium sulfate. The mixture was filtered,
the solvent removed under reduced pressure, and the resulting
solid dried in the oven for 0.5 h to afford a yellow grainy solid,
which was recrystallized from an acetonitrile solution (133.9 mg,
46%). Mp 165-166 °C. ESI HRMS (+ve): Found m/z 739.1912
[M + Na]+ (Calculated for molecular formula C28H36N4O18Na,
739.1922). 1H NMR (300 MHz, CDCl3): δ 3.58-3.68 (16H, m,
OCH2), 3.83-3.86 (8H, m, OCH2), 4.25-4.28 (8H, m, OCH2), 7.40
(4H, s, ArH). 13C NMR (75 MHz, CDCl3): δ 69.8, 70.3, 71.1, 71.5,
109.2, 136.8, 151.8.
H93N12O10, 1813.7138). Found m/z 1835.6930 [M + Na]+ (Cal-
culated for molecular formula C116H92N12O10Na, 1835.6957); λmax
(CHCl3): 384 sh (log ꢀ, 5.13), 430 (5.58), 524 (4.70), 559 (4.19),
1
596 (4.36), 649 nm (3.55). H NMR (300 MHz, CDCl3): δ -2.68
(4H, br s, inner NH), 3.76-3.82 (8H, m, OCH2), 3.87-3.93 (8H,
m, OCH2), 4.02-4.10 (8H, m, OCH2), 4.32-4.37 (8H, m, OCH2),
7.02 (4H, s, ArH), 7.74-7.88 (24H, m, meso-ArH), 8.07-8.20
(16H, m, meso-ArH), 8.64 (s, 4H, â-pyrrolic H), 8.89-8.90 (8H,
m, â-pyrrolic H). 13C NMR (75 MHz, CDCl3): δ 69.3, 69.8, 71.1,
71.5, 108.9, 109.0, 117.1, 121.6, 127.0, 127.6, 128.0, 128.1, 133.8,
134.0, 134.2, 134.7, 138.0, 138.2, 139.8, 142.1, 142.3, 146.3, 151.4,
152.4, 154.8.
4,5-Din itr o-1,2-bis(2-(2-(2-a cetoxy(eth oxyeth oxy))))ben -
zen e 6a . To 5a 22 (4.12 g, 10.8 mmol) were added concentrated
nitric acid (8 mL, 177.8 mmol), dichloromethane (50 mL), and
concentrated sulfuric acid (4 mL, 73.5 mmol). The mixture was
stirred for 2 days and then quenched by addition of ice water
(100 mL). The organic layer was collected, washed with a sodium
carbonate solution (5%, 70 mL) and water (2 × 70 mL), then
dried over anhydrous sodium sulfate and filtered, and the solvent
removed under reduced pressure to give 6a as a yellow oil which
solidified on standing (4.71 g, 95%). The product was chromato-
graphed on silica (ethyl acetate/hexane; 2:1). Mp 48-49 °C. ESI
HRMS (+ve): Found m/z 483.1231 [M + Na]+ (Calculated for
molecular formula C18H24N2O12Na, 483.1227). 1H NMR (300
MHz, CDCl3): δ 2.04 (6H, s, COCH3), 3.75 (4H, t, J ) 4.5 Hz,
OCH2), 3.90 (4H, t, J ) 4.5 Hz, OCH2), 4.22 (4H, t, J ) 4.5 Hz,
OCH2), 4.30 (4H, t, J ) 4.5 Hz, OCH2), 7.43 (2H, s, ArH). 13C
NMR (75 MHz, CDCl3): δ 20.8, 63.2, 69.1, 69.3, 69.7, 108.9,
136.4, 151.3, 170.6. Anal. Calcd for C18H24N2O12: C, 45.2; H, 4.3;
N, 7.5. Found C, 45.3; H, 4.2; N, 7.6.
Syn th esis of 1. Gen er a l P r oced u r e. To a tetranitrodibenzo-
3n-crown-n (0.19-0.68 mmol) was added degassed ethanol (10
mL), Pd/C (100 mg), and degassed hydrazine hydrate (20 drops).
The mixture was stirred and heated to reflux in an overnight
reaction under an argon atmosphere, in darkness. Upon comple-
tion, the reaction mixture was filtered, under argon, though a
plug of Celite into a round-bottom flask containing degassed
dichloromethane (40 mL) and 2,3-dioxo-5,10,15,20-tetraphenyl-
chlorin 4. The Celite plug was washed with a further amount of
dichloromethane (10 mL). This mixture was then heated to
reflux under an argon atmosphere and allowed to react over-
night. TLC was used to monitor the reaction’s progress. Once
complete, the solvent was removed from the completed reaction
mixture under reduced pressure to give a red/purple solid that
was purified by column chromatography.
1.18C6 was synthesized from TNDB18C6 (102.9 mg, 0.19
mmol) and 4 (156.8 mg, 0.24 mmol). Chromatography: chloro-
form, then increasing to 7%, N,N-dimethylformamide in chlo-
roform. The first band to elute was unreacted 4 (88.1 mg), the
second band was the targeted bis-porphyrin, which was isolated
as a red-purple solid. The product was then recrystallized from
a methanol and dichloromethane mixture and filtered to yield
1.18C6 as fine red-purple crystals (52.9 mg, 51% based on
recovered 4). Mp > 350 °C. ESI HRMS (+ve): Found m/z
4,5-Din itr o-1,2-bis(2-(2-(2-a cetoxy(eth oxyeth oxy))))ben -
zen e 6b. The compound was formed from 5b22 (1.30 g, 4.6 mmol)
in a manner similar to that described above for 6a (1.39 g, 92%).
Mp 108-110 °C. ESI MS (+ve): Found m/z 395.0 [M + Na]+.
1H NMR (300 MHz, CDCl3): δ 2.09 (6H, s, COCH3), 4.34 (4H,
m, OCH2), 4.45 (4H, m, OCH2), 7.39 (2H, s, ArH). 13C NMR (75
MHz, CDCl3): δ 21.1, 62.3, 68.4, 109.4, 137.0, 151.4, 170.8.
4,5-Din itr o-1,2-bis(2-(2-(2-tosyloxy(eth oxyeth oxy))))ben -
zen e 8. To a solution of 6a (1.02 g, 2.20 mmol) in MeOH (50
mL) was added K2CO3 (0.56 g, 4.05 mmol) and the mixture
stirred at room temperature for 15 min. Once complete, the
mixture was filtered to remove any excess K2CO3 and then the
filtrate was extracted into dichloromethane (100 mL), washed
with water (3 × 30 mL), and dried (Na2SO4) and the solvent
removed under vacuum at ambient temperature. The diol 7 was
isolated as a yellow solid (0.74 g, 89%) and used without further
purification. 1H NMR (300 MHz, CDCl3): δ 3.67, 4H, m, OCH2),
3.73, 4H, m, OCH2), 3.96, 4H, m, OCH2), 4.27, 4H, m, OCH2),
7.38, 2H, s, ArH. ESI MS (+ve): Found m/z 399.2 [M + Na]+.
To an ice cold solution of 7 (0.74 g, 1.96 mmol) and triethylamine
(0.59 g, 5.87 mmol) in dry dichloromethane (50 mL) was added
TsCl (0.83 g, 4.31 mmol) and the reaction allowed to proceed
overnight at 4 °C. Once complete, the organic solution was
washed with 1 M HCl (2 × 20 mL) and then water (1 × 20 mL),
dried (Na2SO4), and the solvent removed under vacuum. The
residue was chromatographed on silica (EtOAc/hexane; 2:1) to
yield 8 (0.75 g, 72%) as a yellow oil. ESI MS (+ve): Found m/z
707.2 [M + Na]+; ESI HRMS (+ve): Found m/z 707.1196 [M +
Na]+ (Calculated for molecular formula C28H32N2O14S2Na,
707.1187). 1H NMR (300 MHz, CDCl3): δ 2.43 (6H, s, CH3), 3.77
(4H, t, J ) 4.6 Hz, OCH2), 3.87 (4H, t, J ) 4.1 Hz, OCH2), 4.16
(4H, t, J ) 4.6 Hz, OCH2), 4.23 (4H, t, J ) 4.1 Hz, OCH2), 7.32
(4H, d, J ) 8.2 Hz, ArH), 7.37 (2H, s, ArH), 7.77 (4H, d, J ) 8.2
Hz, ArH). 13C NMR (75 MHz, CDCl3): δ 20.8, 63.2, 69.1, 69.3,
69.7, 108.9, 136.4, 151.3, 170.6.
819.3061 [M
C108H78N12O6:
+
2H]2+ (Calculated for molecular formula
1638.6167, C54H38N6O3: 819.3038); λmax
(CHCl3): 384 sh (log ꢀ, 5.13), 430 (5.58), 524 (4.70), 559 (4.19),
596 (4.36), 649 nm (3.55). H NMR (400 MHz, CDCl3): δ -2.69
1
(4H, br s, inner NH), 4.21-4.25 (8H, m, OCH2), 4.38-4.42 (8H,
m, OCH2), 7.05 (4H, s, ArH), 7.70-7.92 (24H, m, meso-ArH),
8.12-8.22 (16H, m, meso-ArH), 8.63 (4H, s, â-pyrrolic H), 8.80-
8.94 (8H, ABq, J ) 4.8 Hz, â-pyrrolic H). 13C NMR (100 MHz,
CDCl3): δ 68.5, 69.8, 104.6, 108.5, 114.3, 116.9, 121.4, 126.8,
127.4, 127.8, 127.9, 133.8, 134.0, 134.5, 139.6, 140.8, 146.1, 150.3,
151.2, 152.1, 154.6.
1.24C8 was synthesized from TNDB24C8 (74.1 mg, 0.12
mmol) and 4 (88.1 mg, 0.14 mmol). Chromatography: 3:2
dichloromethane/hexane to elute any unreacted 4 (36.7 mg) and
subsequently 2:98 methanol/dichloromethane mixture. 1.24C8
was obtained as a red-purple solid (24.5 mg, 36% based on
recovered 4). Mp > 350 °C. ESI HRMS (+ve): Found m/z
1725.6564 [M + H]+ (Calculated for molecular formula C112
-
H85N12O6, 1725.6613). Found m/z 1747.6351 [M + Na]+ (Calcu-
lated for molecular formula C112H84N12O6Na, 1747.6433); λmax
(CHCl3): 384 sh (log ꢀ, 5.13), 430 (5.58), 524 (4.70), 559 (4.19),
1
596 (4.36), 649 nm (3.55). H NMR (300 MHz, CDCl3): δ -2.65
(4H, br s, inner NH), 3.95-4.00 (8H, m, OCH2), 4.07-4.14 (8H,
m, OCH2), 4.32-4.40 (8H, m, OCH2), 7.03 (4H, s, ArH), 7.60-
7.88 (24H, m, meso-ArH), 8.00-8.22 (16H, m, meso-ArH), 8.66
(4H, s, â-pyrrolic H), 8.87-8.96 (8H, m, â-pyrrolic H). 13C NMR
(75 MHz, CDCl3): δ 62.0, 68.8, 69.3, 121.7, 126.9, 127.0, 127.1,
127.6, 128.1, 128.1, 128.2, 134.3, 134.7, 138.0, 138.1, 139.8, 141.3,
142.2, 142.3, 146.2, 151.5, 151.9, 154.6.
9a . To 6a (260 mg, 56.37 mmol) were added degassed ethanol
(15 mL), Pd/C (78.3 mg), and hydrazine hydrate (0.5 mL, 16.05
mmol). The mixture was degassed to remove traces of oxygen,
then stirred and heated to reflux overnight under argon, in
1.30C10 was synthesized from TNDB30C10 (57.7 mg, 0.08
mmol) and 4 (105.1 mg, 0.16 mmol). Chromatography: 3:2

Notes
J . Org. Chem., Vol. 66, No. 12, 2001 4425
darkness. Upon completion, the reaction mixture was filtered
though a plug of Celite into a solution of 4 (250 mg, 38.44 mmol)
in dichloromethane (50 mL). The Celite plug was washed with
a further amount of dichloromethane (20-30 mL). This mixture
was then heated to reflux under an argon atmosphere, and
allowed to react overnight. TLC was used to monitor the reaction
progress. Once complete, the solvent was removed under reduced
pressure to yield a dark red-purple solid. This was purified using
column chromatography (dichloromethane and consequently
Me2CO/CH2Cl2; 1:3), to yield 9a as a dark red-purple solid (300
mg, 86%). Mp 294-295 °C. ESI HRMS (+ve): m/z 925.3727 [M
+ H]+ (Calculated for molecular formula C58H49N6O6H, 925.3714);
sodium carbonate solution (2 × 30 mL) and water (2 × 30 mL)
and dried (Na2SO4). The dichloromethane was removed under
vacuum to yield the desired product 12 (99 mg, 86%) as a bright
yellow solid. An analytically pure sample was recrystallized from
dichloromethane. Mp 185-186 °C. ESI MS (-ve): m/z 553.2 [M
+ Cl]-. 1H NMR (300 MHz, CDCl3): δ 2.28 (s, 3H, CH3), 4.01
(m, 8H, OCH2), 4.18 (m, 6H, OCH2), 4.28 (m, 2H, OCH2), 6.74
(d, 1H, J ) 8.5 Hz, ArH), 6.86 (m, 4H, ArH), 7.28 (s, 1H, NH),
7.26 (d, 1H, J ) 1.6 Hz, ArH). 13C NMR (75 MHz, CDCl3): δ
24.9, 68.5, 68.7, 69.8, 105.4, 111.6, 113.1, 121.5, 133.7, 144.5,
148.3, 148.7, 168.5. Anal. Calcd for C22H27NO7.CH2Cl2: C, 54.9;
H, 5.8; N, 2.8. Found C, 54.8; H, 6.0; N, 2.9.
947.3536 [M + Na]+ (Calculated for molecular formula C58
48N6O6Na, 947.3533). 1H NMR (300 MHz, CDCl3): δ -2.63 (2H,
-
3-Nit r o-6,7,9,10,17,18,20,21-oct a h yd r o-5,8,11,16,19,22-
h exaoxadiben zo[a ,j]cyclooctadecen -2-yl Acetam ide 13. Con-
centrated nitric acid (2 equiv, 25 µL) was added to a stirring
solution of acetamide 12 (78 mg, 0.19 mmol) in an ice bath. This
was left to stir overnight, and reaction progress was monitored
by TLC (by disappearance of starting materials). Once complete,
the reaction mixture was washed with a saturated sodium
carbonate solution (2 × 30 mL) and water (2 × 30 mL), dried
(Na2SO4), and the solvent removed in vacuo. The nitro-acetamide
13 (69 mg, 80%) was recrystallized from chloroform. Mp 226-
227 °C. ESI MS (+ve): m/z 485.3 [M + Na] +. 1H NMR (300 MHz,
CDCl3): δ 2.28 (s, 3H, COCH3), 4.01 (s, 8H, OCH2), 4.15 (m,
6H, OCH2), 4.28 (t, 2H, J ) 3.4 Hz, OCH2), 6.87 (m, 4H, ArH),
7.65 (s, 1H, ArH), 8.46 (s, 1H, ArH), 10.75 (s, 1H, NH). 13C NMR
(75 MHz, CDCl3): δ 26.2, 68.1, 68.2, 68.9, 69.1, 69.3, 69.4, 70.0,
70.1, 103.6, 108.0, 112.5, 121.2, 128.3, 132.4, 143.8, 148.5, 155.5,
169.5. Anal. Calcd for C22H26N2O9.0.5CHCl3: C, 51.7; H, 5.2; N,
5.3. Found C, 51.6; H, 5.3; N, 5.2.
H
br s, inner NH), 3.76-3.80 (8H, m, OCH2), 4.05 (4H, m, OCH2),
4.35 (4H, m, OCH2), 7.05 (2H, s, ArH), 7.72-7.87 (12H, m, meso-
ArH), 8.14-8.22 (8H, m, meso-ArH), 8.69 (2H, s, â-pyrrolic H),
8.91 (4H, ABq, J ) 5.1 Hz, â-pyrrolic H). 13C NMR (75 MHz,
CDCl3): δ 20.7, 20.9, 21.1, 25.7, 108.8, 117.0, 121.6, 126.9, 127.5,
123.0, 128.1, 134.1, 134.6, 137.9, 137.9, 139.6, 142.0, 142.1, 146.0,
150.0, 151.3, 151.7, 168.0, 171.0, 173.8.
9b was formed from 6b (250 mg, 0.66 mmol) and 4 (370 mg,
0.57) in a similar procedure to yield 6b (384 mg, 80%). Mp >300
°C. ESI HRMS (+ve): Found m/z 837.3154 [M + H]+ (Calculated
for molecular formula C54H41N6O4, 837.3189). 1H NMR (300
MHz, CDCl3): δ -2.59 (2H, br s, inner NH), 4.10-4.13 (4H, m,
OCH2), 4.30-4.33 (4H, m, OCH2), 7.13 (2H, s, ArH), 7.72-7.89
(12H, m, meso-ArH), 8.13-8.23 (8H, m, meso-ArH), 8.70 92H,
s, â-pyrrolic H), 8.92 (4H, AB q, J ) 5.1 Hz, â-pyrrolic H). 13C
NMR (75 MHz, CDCl3): δ 61.1, 71.2, 110.1, 117.1, 121.6, 126.8,
126.9, 127.6, 128.0, 128.1, 128.2, 134.1, 134.6, 137.9, 138.2, 139.7,
142.1, 142.2, 149.2, 151.6, 152.2, 154.9, 173.4.
3-Nit r o-6,7,9,10,17,18,20,21-oct a h yd r o-5,8,11,16,19,22-
h exa oxa d iben zo[a ,j]cycloocta d ecen -2-yl Am in e 14. Nitro-
acetamide 13 (31 mg, 0.06 mmol) was dissolved in absolute
ethanol (3 mL), and hydrochloric acid was added (10 drops, 1
M). The reaction mixture was allowed to stir under argon.
Reaction progress was monitored by 1H NMR. On completion,
dichloromethane (10 mL) was added to the reaction mixture and
it was washed with sodium carbonate (2 × 20 mL) and water (2
× 20 mL) and dried with sodium sulfate. The solvent was
removed under vacuum to yield 14 as a bright yellow solid (23
mg, 72%) which was recrystallized from dichloromethane. Mp
75-76 °C. ESI MS (+ve): m/z 443.3 [M + Na]+. 1H NMR (300
MHz, CDCl3): δ 4.01 (s, 8H, OCH2), 4.01 (m, 8H, OCH2), 4.13
(m, 8H, OCH2), 4.15 (m, 6H, OCH2), 6.13 (s, 1H, ArH), 6.21 (s,
broad, 2H, NH), 6.87 (m, 4H, ArH), 7.47 (s, 1H, ArH). 13C NMR
(75 MHz, CDCl3): δ 68.3, 68.5, 68.9, 69.3, 69.6, 70.0, 70.1, 70.2,
99.8, 107.7, 112.9, 113.1, 121.2, 121.4, 121.5, 140.8, 142.9, 148.5,
148.7, 156.5. Anal. Calcd for C20H24N2O8.CH2Cl2: C, 5.0; H, 5.1;
N, 5.5. Found C, 50.0; H, 5.1; N, 5.4.
2,3-Dibr om o-13-n itr o-6,7,9,10,17,18,20,21-octa h yd r o-5,8,-
11,16,19,22-h exa oxa d iben zo[a ,j]cycloocta d ecen e 3. Con-
centrated nitric acid (57 µL, 0.9 mmol, 2 equiv) was added to a
stirring solution of dibromo-dibenzo-18-crown-6 1118 (229 mg,
0.4 mmol) in dichloromethane (5 mL) and allowed to stir
overnight. The reaction mixture was then washed with
a
saturated solution of sodium carbonate (2 × 30 mL) and water
(2 × 30 mL) and dried with sodium sulfate. The dichloromethane
was removed under vacuum to yield the mono-nitrated product,
which was recrystallized in chloroform to give rise to 12 (202
mg, 81%) as a pale yellow solid. Mp 216-218 °C. ESI MS (+ve):
m/z 586.0 [M + Na]+. 1H NMR (CD3CN): δ 3.85 (t, 8H, J 6.2
Hz, OCH2), 4.08 (m, 4H, OCH2), 4.21 (m, 4H, OCH2), 7.03 (d,
1H, J ) 9.0 Hz, ArH), 7.17 (s, 2H, ArH), 7.73 (d, 1H, J ) 2.7
Hz, ArH), 7.88 (dd, 1H, J ) 9.0 Hz, J ) 2.6 Hz, ArH). 13C NMR
(CDCl3): δ 68.8, 68.9, 69.0, 69.3, 69.4, 100.2, 107.4, 114.5, 117.1,
117.2, 118.4, 141.3, 148.3, 148.8. Anal. Calcd for C20H21NO8Br2:
C, 42.6; H, 3.8; N, 2.4. Found C, 42.5; H, 3.8; N, 2.2.
6,7,9,10,17,18,20,21-Oct a h yd r o-5,8,11,16,19,22-h exa oxa -
d iben zo[a ,j]cycloocta d ecen -2-yl Am in e 11. Nitro-dibenzo-
18-crown-6, 12 (201.5 mg, 0.36 mmol), and 10% palladium on
carbon (112 mg) were combined in absolute ethanol (20 mL) and
stirred, under argon. This mixture was allowed to reflux and
hydrazine hydrate (20 drops) was added dropwise. The reaction
was monitored by TLC and, on completion, was hot filtered
through Celite and the solvent removed under reduced pressure.
Dichloromethane (100 mL) and water (50 mL) were added to
the residue, and the aqueous layer was extracted with dichlo-
romethane (50 mL). The organic layer was washed with water
(2 × 30 mL) and dried (Na2SO4) and the solvent removed under
reduced pressure. The product 11 (129 mg, 96%) was isolated
as a white solid. Mp 156-158 °C, lit.26 159-163 °C. ESI MS
(+ve): m/z 398.2 [M + Na]+. 1H NMR (300 MHz, CDCl3): δ 4.02
(m, 8H, OCH2), 4.10 (m, 4H, OCH2), 4.16 (m, 4H, OCH2), 6.21
(dd, 1H, J ) 8.4 Hz, J ) 2.60 Hz, ArH), 6.29 (d, 1H, J ) 2.6 Hz,
ArH), 6.88 (m, 4H, ArH), 6.70 (d, 1H, J ) 8.4 Hz, ArH). 13C NMR
(75 MHz, CDCl3): δ 68.8, 69.1, 70.1, 70.2, 70.5, 102.7, 107.5,
113.6, 113.8, 121.5, 121.6, 148.8.
P or p h yr in -Cr ow n 15. Degassed ethanol (5 mL) was added
to 14 (45 mg, 0.107 mmol), Pd/C (50 mg), and hydrazine hydrate
(5 drops). The mixture was stirred and heated to reflux in an
overnight reaction under an argon atmosphere, in darkness.
Upon completion, the reaction mixture was filtered under argon,
through a plug of Celite, into a round-bottom flask containing
degassed dichloromethane (10 mL) and 2,3-dioxo-5,10,15,20-
tetraphenylchlorin 4 (30 mg, 0.0466 mmol). The Celite plug was
washed with a further amount of dichloromethane (2 mL). This
mixture was then heated to reflux under an argon atmosphere,
and allowed to react overnight. TLC was used to monitor the
reaction’s progress. Once complete, the solvent was removed in
vacuo and the sample was purified by column chromatography
to give 15 as a red/purple solid (35 mg, 76% yield). Mp > 350
°C. ESI MS (+ve): m/z 999.3 [M + H]+. 1H NMR (300 MHz,
CDCl3): δ -2.61 (s, 2H, inner NH), 4.09 (m, 4H, OCH2), 4.15
(m, 4H, OCH2), 4.19 (m, 4H, OCH2), 4.35 (m, 4H, OCH2), 6.87
(m, 4H, ArH), 7.02 (s, 2H, ArH), 8.17 (m, 4H, meso-ArH), 8.24
(m, 4H, meso-ArH), 8.71 (d, 2H, J ) 8.8 Hz, â-pyrrolic), 8.93 (d,
4H, J ) 8.8 Hz, â-pyrrolic). 13C NMR (75 MHz, CDCl3): δ 68.7,
69.1, 69.8, 70.5, 108.5, 113.4, 117.2, 121.5, 121.7, 127.0, 127.1,
127.6, 128.0, 128.1, 128.2, 134.2, 134.3, 134.7, 138.0, 138.3, 139.8,
142.2, 142.3, 146.4, 148.8, 151.4, 152.3, 154.9.
6,7,9,10,17,18,20,21-Oct a h yd r o-5,8,11,16,19,22-h exa oxa -
d iben zo[a ,j]cycloocta d ecen -2-yl Aceta m id e 12. To a solution
of the amine 11 (107 mg, 0.29 mmol) in anhydrous dichlo-
romethane (10 mL) was added acetic anhydride (58 mg, 2 equiv).
The resulting mixture was stirred at room temperature under
argon for 2 h. More dichloromethane (20 mL) was added to the
reaction mixture, and it was then was washed with a saturated
Ack n ow led gm en t. This research was funded by the
Special Monash University Research Fund (SMURF)

4426 J . Org. Chem., Vol. 66, No. 12, 2001
Notes
bond lengths and angles, anisotropic thermal parameters for
TNDB30C10, and copies of 1H and 13C NMR spectra for
TNDB18C6, TNDB24C8, TNDB30C10, and 8. This material
is available free of charge via the Internet at http://pubs.acs.org.
and by the Australian Research Council’s Small Grant
Scheme. An ARC Senior Research Fellowship (to M.N.P.-
R.) is also gratefully acknowledged.
Su p p or tin g In for m a tion Ava ila ble: Tables of crystal
data, structure solution and refinement, atomic coordinates,
J O001700P