Controlling conformations and physical properties of meso-tetrakis(phenylethynyl)porphyrins by ring fusion: Synthesis, properties and structural characterizations

Article abstract of DOI:10.1039/b412688b

The boron trifluoride-catalyzed Rothemund condensations of phenylpropargylaldehyde with 4,7-dihydro-4,7-ethano-2H-isoindole or 3,4-diethylpyrrole in dichloromethane at low temperature give 5,10,15,20-tetrakis(phenylethynyl)porphyrins bearing bicyclo[2.2.2

Full text of DOI:10.1039/b412688b

View Article Online / Journal Homepage / Table of Contents for this issue
A R T I C L E
Controlling conformations and physical properties of
meso-tetrakis(phenylethynyl)porphyrins by ring fusion: synthesis,
properties and structural characterizations
Zhen Shen,†a Hidemitsu Uno,*b Yusuke Shimizua and Noboru Ono*a
a Department of Chemistry, Faculty of Science, Ehime University, 2-5 Bunkyo-cho, Matsuyama,
790-8577, Japan. E-mail: ononbr@dpc.ehime-u.ac.jp; Fax: +81 899279590;
Tel: +81 899279610
b Division of Synthesis and Analysis, Department of Molecular Science, Integrated Center for
Sciences, Ehime University, 2-5 Bunkyo-cho, Matsuyama, 790-8577, Japan.
E-mail: uno@dpc.ehime-u.ac.jp; Fax: +81 899279670; Tel: +81 899279660
Received 17th August 2004, Accepted 30th September 2004
First published as an Advance Article on the web 5th November 2004
The boron trifluoride-catalyzed Rothemund condensations of phenylpropargylaldehyde with
4,7-dihydro-4,7-ethano-2H-isoindole or 3,4-diethylpyrrole in dichloromethane at low temperature give
5,10,15,20-tetrakis(phenylethynyl)porphyrins bearing bicyclo[2.2.2]octadiene and octaethyl substituents, respectively.
The former undergoes a retro Diels–Alder reaction to afford 5,10,15,20-tetrakis(phenylethynyl)benzoporphyrin
quantitatively. The different conformations of the porphyrin periphery were determined by X-ray diffraction and
their redox and spectroscopic properties have been investigated.
9a
precursor for porphyrin synthesis. As shown in Scheme 1,
Introduction
the synthesis of meso-substituted porphyrins was adapted
Porphyrinoids with high-wavelength absorptions have been
according to the procedure developed by Anderson and co-
extensively investigated in recent years due to their potential
workers. 3,4-Diethylpyrrole11 and 4,7-dihydro-4,7-ethano-2H-
isoindole were prepared according to the published pro-
value as photosensitizers in photodynamic therapy (PDT),1
9b
but also as novel optical materials such as fluorescent probes
cedures. 4,7-Dihydro-4,7-ethano-2H-isoindole condensed with
and near-infrared dyes, and as components of photosynthetic
phenylpropynal in dry dichloromethane at −40 ◦C using
antenna arrays.2 Several approaches for the construction of
BF3·OEt2 as catalyst, followed by oxidation with 2,3-dichloro-
red-shifted porphyrinoid systems have been reported, including
5,6-dicyano-1,4-benzoquinone (DDQ) produced BCOD ring-
the introduction of meso-alkynyl substituents,3 the expansion
fused meso-tetrakis(phenylethynyl)porphyrin H2-1 in 10% yield.
of porphyrin chromophores,4 porphyrin linkage isomerizations5
Heating H2-1 at 230 ◦C in vacuo for 30 min give pure meso-
and core modification.6 The steric crowding of the peripheral
tetrakis(phenylethynyl)benzoporphyrin H2-2 quantitatively. The
meso-tetrakis(phenylethynyl)octaethylporphyrin H2-3 was pre-
pared as a main product in 20% yield from 3,4-diethylpyrrole
substituents can cause conformational distortions of porphyrin
rings and also results in the red-shift.7 Recent investigations
on porphyrins with fused aromatic subunits showed that such
using a similar method.
ring expansion produced minor bathochromic shifts to the
Soret absorption except for acenaphthylene fusion.8 On the
other hand, arylethynyl meso-subsituents were found to red-
shift the porphyrin B and Q bands significantly more than
aryl meso-substituents, which is due to the efficient electron
communication between porphyrin and aryl p-systems provided
by the ethynyl group. We have previously reported a convenient
synthetic route to prepare benzoporphyrins via retro Diels–
Alder reaction from the bicyclo[2.2.2]octenediene (BCOD) ring-
fused porphyrins.9 To further extend the conjugation of the por-
phyrin core, we present here the first synthesis and structure char-
acterization of meso-tetrakis(phenylethynyl)benzoporphyrin.
Results and discussion
Synthesis of meso-tetrakis(phenylethynyl)porphyrins
Recently, H. L. Anderson and co-workers have reported that
the boron trifluoride-catalyzed reaction of acetylenic aldehydes
with 3,4-diethylpyrrole generated various meso-alkynyl por-
phyrinoids with contracted and expanded structures.10 Since
the unsubstituted isoindole is too unstable to be used directly
for the preparation of related benzoporphyrins, it occurred
to us to apply the 4,7-dihydro-4,7-ethano-2H-isoindole as its
† Present address: State Key Laboratory of Coordination Chemistry,
Nanjing University, Nanjing 210093, China.
Scheme 1 Reagents and conditions: i, BF3·OEt2; ii, DDQ; iii, Et3N; iv,
230 ◦C, 30 min.
3 4 4 2
O r g . B i o m o l . C h e m . , 2 0 0 4 , 2 , 3 4 4 2 – 3 4 4 7
T h i s j o u r n a l i s
T h e R o y a l S o c i e t y o f C h e m i s t r y 2 0 0 4
©

View Article Online
X-Ray analysis of porphyrins
Single crystals for X-ray analysis were obtained by slow evap-
oration of a mixed solution of CHCl3 and MeOH for Zn-
1 and H2-3, or CHCl3 solution containing a small amount
of pyridine for Zn-2. Their structures were subjected to X-
ray analyses and the results are summarized in Table 1.12
Radial views from the centre of the porphyrins are shown
in Fig. 1. CCDC reference numbers 227105–227107. See
http://www.rsc.org/suppdata/ob/b4/b412688b/ for crystallo-
graphic data in .cif format.
Fig. 1 Distortion diagram of the porphyrins. (a) Zn-1·2MeOH,
−150 ◦C. (b) Zn-2·C5H5N·CHCl3, −70 ◦C. (c) H2-3, −70 ◦C. According
to the numbering sequence, meso-positions are 9, 18, 27 and 36 in
tetrabenzoporphyrin 2 and its precursor 1, but 5, 10, 15 and 20 in
porphyrin 3.
Porphyrin Zn-1. From the systematic absences, the space
group was suggested to be Cc or C2/c. We solved and refined
the structure in both Cc and C2/c space groups. In both cases,
the structures were finally refined without methanol molecules
by several cycles of SHELXL-97 and PLATON-SQUEEZE
programs,13 because even the coordinated methanol molecule
was disordered. As the structure solved in Cc was unstable
during the refinement, the phenyl and porphyrin ring atoms were
tightly restrained and some atoms were treated isotropically.
In the refined structure in Cc, the zinc atom showed out-of-
plane disorder toward the coordinated methanol molecules with
half occupancy. The final R values in the Cc space group were
slightly better than those in the C2/c space group. The PLATON
analysis, however, revealed a centre of symmetry in the structure
of Cc space group with 100% fit. Thus, the centrosymmetric
space group C2/c was chosen. The porphyrin macrocycle of
Zn-1 is slightly wave-structured with a mean plane deviation of
of the benzene rings with the porphyrin planes are 23.4(1)◦,
48.6(2)◦, 53.3(3)◦ and 89.5(1)◦ respectively.
Porphyrin H2-3. The free-base H2-3 adopts a heavily dis-
torted saddle conformation with a maximum displacement
˚
of b-pyrrole carbons from the mean plane of 1.212(2) A
(Fig. 1c and Fig. 4). It is interesting to note that its crys-
tal structure shows obvious in-plane nuclear reorganization
(IPNR).7 Localization of the inner hydogen atom positions
and bond characters was observed (Fig. 5): in compari-
son with H2OETPP (2,3,7,8,12,13,17,18-octaethyl-5,10,15,20-
tetraphenylporphyrin),14 the meso and a-carbon bonds of C4–
C5, C9–C10, C15–C16 and C20–C1 are elongated, with the
˚
average bond distance being 1.426 A for H2-3, while the bond
˚
0.092 A (Fig. 1a). The dihedral angles between the benzene rings
lengths of C5–C6, C10–C11, C14–C15, C19–C20, N2–C9 and
and the porphyrin planes are 15.9(2)◦ and 34.8(2)◦ for the two
types of aryl rings (Fig. 2). These values are much smaller than
N4–C16 are shortened (the average bond distances of C · · · C
˚
and N · · · C for H2-3 are 1.403 and 1.347 A, respectively). The
3a
those for 5,10,15,20-tetra(4-n-butylphenylethynyl)porphyrin,
tilting angles of pyrrole units to the mean porphyrin plane are A:
30.74(7)◦, B: −24.27(6)◦, C: 13.47(6)◦ and D: −27.78(6)◦. This
fact also supports the bond localization in this crystal structure.
The acetylene groups almost lie within the mean planes of the
benzene rings, while the dihedral angles of the benzene rings
with the porphyrin planes are 18.7(1)◦, 22.1(1)◦, 34.0(1)◦ and
36.9(1)◦, respectively.
indicating enhanced conjugation of the benzene plane and the
porphyrin ring through the ethylene bridge.
Porphyrin Zn-2. The structure of Zn-2·C5H5N·CHCl3, as
shown in Fig. 1b, is ruffle-shaped with the maximum displace-
ment of meso-pyrrole carbons from the mean plane of 0.480(3)
˚
A. The isoindole units are almost flat (the mean deviations range
˚
from 0.015 to 0.036 A). In this case, the zinc atom is coordinated
The electronic absorption spectra are given in Fig. 6. The
Soret bands of Zn-1, Zn-2 and Zn-3 are at 494, 528 and 508 nm,
respectively, which are considerably red-shifted compared to
those of meso-unsubstituted Zn-BCOD ring-fused porphyrin
to one pyridine molecule (in the positive region of Fig. 1) and
˚
displaced towards the pyridine ligand by 0.293(1) A from the
mean plane of four nitrogen atoms (Fig. 3). The dihedral angles
Table 1 Crystallographic data for porphyrinsa
Compound
Zn-1·2CH3OH
Zn-2·C5H5N·CHCl3
H2-3
Formula
FW
C76H52N4Zn·2CH3OH
1150.74
−150
C68H36N4Zn·C5H5N· CHCl3
C68H62N4
935.26
−70
1172.92
−70
Temp./◦C
System
monoclinic
C2/c
triclinic
triclinic
¯
¯
Space group
P1
P1
˚
a/A
30.864(8)
11.647(2)
18.709(5)
90
117.893(5)
90
5944(2)
4
0.467
12.6459(5)
16.2904(10)
16.4899(8)
71.236(9)
63.449(8)
68.986(8)
2783.2(2)
2
10.785(2)
14.200(3)
17.438(4)
94.857(4)
102.039(5)
90.567(4)
2601.4(9)
2
˚
b/A
˚
c/A
a/◦
b/◦
c /◦
3
˚
V/A
Z
l/cm−◦1
0.637
27.48
0.069
27.48
2hmax
/
27.48
Unique reflns.
No. obs.
Rint
No. var.
R1
wR(all)
Goodness of
fit
6725
3899
0.067
371
0.102
0.321
1.072
12299
9795
0.033
760
0.059
0.180
1.002
11556
7677
0.037
708
0.070
0.199
1.001
a Mo-Ka was employed.
O r g . B i o m o l . C h e m . , 2 0 0 4 , 2 , 3 4 4 2 – 3 4 4 7
3 4 4 3

View Article Online
Fig. 2 ORTEP plot of the X-ray structure of Zn-1 with thermal ellipsoids shown at 50%. By the PLATON SQUEEZE program, the structure was
refined without methanol molecules.
Fig. 3 ORTEP view of the X-ray structure of Zn-2 with thermal ellipsoids shown at 50%. The disordered phenyl groups with lower occupancies,
chloroform solvent and coordinated pyridine are omitted for clarity.
(400 nm), Zn-tetrabenzoporphyrin (425 nm in THF–pyridine)
and ZnOEP (2,3,7,8,12,13,17,18-octaethylporphyrinato zinc)
(403 nm). The Q bands of Zn-1 (632 and 685 nm), Zn-2 (676 and
737 nm) and Zn-3 (653 and 714 nm) are also in the longer wave-
length region than those of the Zn-BCOD porphyrin (534 and
561 nm), Zn-benzoporphyrin (622 nm) and ZnOEP (569 nm).
The large bathochromic shift (around 100 nm) of the elec-
tronic absorptions of meso-(tetrakisphenylethynyl)porphyrins
demonstrates that the phenylethynyl substituents considerably
enhance the porphyrin conjugation. The absorption of Zn-1
is blue-shifted compared to that of Zn-3. Since the electronic
inductive properties of the ethyl and BCOD ring groups are
thought to be similar, the difference should be primarily due
than H2-3 in solution. The red-shift of the spectrum of Zn-2
compared to that of Zn-1 is most likely due to the extended
electronic conjugation by fused benzene rings.
The redox properties for Zn-1, Zn-2 and Zn-3 were studied
by cyclic voltammetry (Table 2). Zn-1 and Zn-2 showed two
reversible oxidation peaks, while Zn-3 gave only one reversible
peak. The first oxidation potentials of Zn-1, Zn-2 and Zn-3 were
0.34 V, 0.08 V and 0.25 V (vs. Fc/Fc+), respectively. However,
their first reduction potentials were similar, at −1.46 V for Zn-1,
−1.47 V for Zn-2 and −1.46 V for Zn-3. Zn-2 was oxidized at
a much lower potential than Zn-1, indicating that the HOMO
energy level of Zn-2 is considerably increased by fusion with
benzene rings. Since the first reduction potential didn’t change
as much, the HOMO–LUMO separation in Zn-2 is narrowed.
This is in accordance with the red-shifts of the absorption
bands of Zn-2. That Zn-3 is more easily oxidized than Zn-1
1
to the conformational factor. The H NMR chemical shift of
NH in free base H2-1 appears at d −1.72 ppm, whereas that of
H2-3 appears at d 0.26 ppm, indicating that H2-1 is more planar
3 4 4 4
O r g . B i o m o l . C h e m . , 2 0 0 4 , 2 , 3 4 4 2 – 3 4 4 7

View Article Online
Fig. 4 ORTEP plot of H2-3 with thermal ellipsoids shown at 50%. Disordered ethyl and phenyl groups with lower occupancies are omitted for
clarity.
Table 2 Redox potentials of porphyrins Zn-1, Zn-2 and Zn-3.a
Porphyrin
E
1/2(ox)/V
Ep(red)/V
Zn-1
Zn-2
Zn-3
0.34, 0.56
0.08, 0.40
0.25, 0.67b
−1.46
−1.47
−1.46
a In CH2Cl2, c = 10−3 M, 0.1 M TBAP, t = 100 mV s−1, referenced
against Fc+/Fc. b Irreversible peak
distortions and substituent properties can significantly affect the
redox potentials and spectroscopic properties of the porphyrin
macrocycle.
Conclusion
In summary, incorporation of meso-phenylethynyl substituents
and fusion of benzene rings to the porphyrin chromophore con-
siderably changes its redox potential and leads to large red-shifts
in the electronic absorption spectra. The tetrabenzoporphyrins
have not been well studied due to the difficulty of preparation
and their poor solubility in most organic solvents, while BCOD
ring-fused porphyrins are readily available by conventional
and efficient porphyrin syntheses, and can be purified by
recrystallization and/or chromatography. The bulky BCOD
rings not only increase porphyrin solubility by preventing p–
p stacking, but rigidify porphyrin rings to maintain the planar
conformation. They are useful precursors for the construction
of multi-tetrabenzoporphyrin arrays. In addition, we have found
interesting bond localization of the porphyrin skeleton induced
by the ring distortion in a crystalline state of porphyrin H2-3.
Fig. 5 Bond lengths of the H2-3 porphyrin core.
Experimental
Melting points were measured with a Yanagimoto BY-1 melting
point apparatus. Unless otherwise noted, 1H NMR and 13C
NMR spectra were recorded in CDCl3 solution on a JEOL
EX 400 spectrometer at ambient temperature. NMR chemical
shifts are expressed in ppm using TMS as an internal standard,
and coupling constants were measured in Hz. UV-vis spectra
were obtained with Shimadzu UV-2200 spectrometers. Mass
spectra were measured with a JEOL JMS-700 spectrometer (70
eV for EI and m-nitrobenzyl alcohol as the matrix for FAB). El-
emental analysis was performed with a Yanako MT-5 recorder.
Fig. 6 UV-vis spectra of Zn-1 (—), Zn-2 (. . .) and Zn-3 (-·-) in CHCl3.
Inset: absorption spectra of the Q-band region.
may result from the distortion of Zn-3, which destabilizes its
HOMO energy level. This is consistent with the blue-shift of
the Zn-1 absorption bands compared to Zn-3. Conformational
O r g . B i o m o l . C h e m . , 2 0 0 4 , 2 , 3 4 4 2 – 3 4 4 7
3 4 4 5

View Article Online
Cyclic voltammograms were obtained in CH2Cl2–0.1 M TBAP
(tetra-n-butylammonium perchlorate) on a BAS electrochemical
analyzer model BS-1, using a platinum disk as the working
electrode, Ag/AgNO3 as the quasi-reference electrode, and a
platinum wire as the counter electrode. Redox potentials were
referenced internally against ferrocenium/ferrocene (Fc+/Fc).
Measurements were performed under inert atmosphere at room
temperature with a scan rate of 100 mV s−1. THF was distilled
from sodium benzophenone ketyl and dichloromethane was
distilled from CaH2 prior to use. Pyridine was distilled from
(38 mg, 90%) as greenish needles: mp 180 ◦C (decomposed).
dH 2.12–2.17 (16H, m), 6.58 (8H, m), 6.96–7.11 (8H, m), 7.51–
7.65 (12H, m), 8.04–8.06 (8H, m). MS (FAB) m/z: 1086 [M+].
Elemental analysis, calcd (%) for C76H52N4Zn·1.5H2O: C, 81.97;
H, 4.98; N, 5.03. Found: C, 81.71; H, 4.89; N, 4.79. UV-vis, kmax
(CHCl3)/nm (e/dm3 mol−1 cm−1): 494 (2.47 × 105), 631 (1.97 ×
104) and 685 (2.50 × 104).
5,10,15,20-Tetrakis(phenylethynyl)-2,3,7,8,12,13,17,18-octa-
ethylporphyrinato zinc (Zn-3)
˚
CaH2 and stored over 4 A MS. Deuterated solvents were
used without further purification. 3,4-Diethylpyrrole11 and 4,7-
dihydro-4,7-ethano-2H-isoindole9b were prepared according to
published procedures.
The title compound was prepared in quantitative yield by a
method similar to that described above. Greenish crystals, mp
>250 ◦C. dH 1.52 (24H, t, J = 7.3 Hz), 4.01 (16H, q, J = 7.3 Hz),
7.47–7.55 (12H, m) and 7.81–7.83 (8H, m). MS (FAB) m/z: 998
[M+]. Elemental analysis, calcd (%) for C68H60N4Zn: C, 81.79;
H, 6.06; N, 5.61. Found: C, 81.56; H, 6.01; N, 5.53. UV-vis, kmax
(CHCl3)/nm (e/dm3 mol−1 cm−1): 508 (2.49 × 105), 652 (1.61 ×
104) and 714 (1.97 × 104).
9,18,27,36-Tetrakis(phenylethynyl)-3,6,12,15,21,24,30,33-
octahydro-3,6;12,15;21,24;30,33-tetraethano-37H,39H-
tetrabenzoporphine (H2-1)
Boron trifluoride etherate (120 lL, 0.99 mmol) was added to a
stirred solution of phenylpropynal (430 mg, 3.3 mmol) and 4,7-
dihydro-4,7-ethano-2H-isoindole (480 mg, 3.3 mmol) in 350 mL
dry CH2Cl2 under N2 at −40 ◦C. After stirring for 3 h at
−40 ◦C in the dark, the mixture was allowed to warm up to
room temperature overnight. DDQ (749 mg, 3.3 mmol) was
added and the reaction mixture was stirred for an additional
1 h. 1 mL of triethylamine was added and the solvents removed
in vacuo. The residue was purified by column chromatography
on silica gel, eluting with 1% Et3N–CHCl3. The product was
collected as a green fraction. Following evaporation of the
solvents under reduced pressure, the residue was recrystallized
from chloroform–methanol. The title compound was obtained
in 10% yield as a mixture of diastereomers. Greenish crystals,
mp 180 ◦C (decomposed). dH −1.72 (2H, s), 1.98–2.17 (16H,
m), 6.4 (8H, m), 6.92–7.01 (8H, m), 7.54–7.66 (12H, m) and
8.03–8.05 (8H, m). MS (FAB), m/z: 1024 [MH+]. Elemental
analysis, calcd (%) for C76H54N4·2H2O: C, 86.17; H, 5.52; N,
5.29. Found: C, 86.46; H, 5.29; N, 5.15. UV-vis, kmax (CHCl3)/nm
(e/dm3 mol−1 cm−1): 494 (2.47 × 105), 632 (1.86 × 104) and 685
(2.44 × 104).
9,18,27,36-Tetrakis(phenylethynyl)tetrabenzoporphyrinato
zinc (Zn-2)
Zn-1 (20 mg, 0.018 mmol) was heated in a sample tube under
vacuum (10 mmHg) at 230 ◦C for 30 min to give Zn-2. Yield
18 mg, 100% without purification. Green powder, mp >250 ◦C.
dH (C5D5N) 7.48–7.52 (4H, m), 7.60–7.64 (8H, m), 8.07–8.09
(8H, m), 8.18–8.2 (8H, m) and 10.63–10.65 (8H, m). dC (C5D5N)
95.7, 97.6, 104.3, 124.5, 125.6, 127.7, 129.2, 129.6, 131.8, 139.1
and 144.6. MS (FAB) m/z: 973 [M+]. Elemental analysis,
calcd (%) for C68H36N4Zn·1.5H2O: C, 81.55; H, 3.93; N, 5.59.
Found: C, 81.39; H, 3.84; N, 5.51. UV-vis, kmax (CHCl3)/nm
(e/dm3 mol−1 cm−1): 528 (2.39 × 105), 676 (2.05 × 104) and 737
(1.65 × 104).
Acknowledgements
This work was partially supported by Grants-in-Aid for Scien-
tific Research from the Ministry of Education, Culture, Sports,
Science and Technology of Japan and by JSPS postdoctoral fel-
lowship (to Z.S.). We thank the Research Center for Molecular-
Scale Nanoscience (IMS) for carrying out X-ray measurements
(AFC7R-Mercury CCD).
5,10,15,20-Tetrakis(phenylethynyl)-2,3,7,8,12,13,17,18-octa-
ethyl-21H,23H-porphine (H2-3)
BF3·OEt2 (160 lL) was added to a solution of 3,4-diethylpyrrole
(492 mg, 4 mmol) and phenylpropynal (521 mg, 4mmol) in
400 mL dry CH2Cl2 under N2 at −40 ◦C. After stirring for 3 h
at −40 ◦C in the dark, the mixture was allowed to warm up to
room temperature overnight. DDQ (908 mg, 4 mmol) was added
followed by triethylamine (1 mL). The reaction mixture was
purified by column chromatography and recrystallization from
chloroform–methanol. Yield: 200 mg, 20%. Greenish crystals,
mp >250 ◦C. dH 0.26 (2H, s), 1.49 (24H, t, J = 7.3 Hz),
3.94 (16H, q, J = 7.3 Hz), 7.45–7.53 (12H, m) and 7.78–7.80
(8H, m). dC 16.70, 20.66, 91.02, 98.66, 105.04, 124.19, 128.54,
128.71, 130.92, 143.39 and 143.94. MS (FAB) m/z: 936 [MH+].
Elemental analysis, calcd (%) for C68H62N4·H2O: C, 85.68; H,
6.77; N, 5.87. Found: C, 85.57; H, 6.57; N, 5.72. UV-vis, kmax
(CHCl3)/nm (e/dm3 mol−1 cm−1): 502 (1.68 × 105), 607 (1.09 ×
104), 666 (2.39 × 104) and 778 (8 × 103).
References
1 (a) S. B. Brown and T. G. Truscott, Chem. Br., 1993, 29, 955; (b) D.
Dolphin, Can. J. Chem., 1994, 72, 1005; (c) R. Bonnett, Chem. Soc.
Rev., 1995, 24, 19.
2 S. Prathapan, T. E. Johnson and J. S. Lindsey, J. Am. Chem. Soc.,
1994, 115, 7519.
3 (a) H. L. Anderson, A. P. Wylie and K. Prout, J. Chem. Soc., Perkin
Trans. 1, 1998, 1607, and references therein; (b) H. L. Anderson,
Chem. Commun., 1999, 2323; (c) P. N. Taylor, A. P. Wylie, J.
Huuskonen and H. L. Anderson, Angew. Chem., Int. Ed., 1998, 37,
986; (d) S. M. Kuebler, R. G. Denning and H. L. Anderson, J. Am.
Chem. Soc., 2000, 122, 339; (e) T. E. O. Screen, K. B. Lawton, G. S.
Wilson, N. Dolney, R. Ispasoiu, T. Goodson, S. J. Martin, D. D. C.
Bradley and H. L. Anderson, J. Mater. Chem., 2001, 11, 312.
4 (a) J. L. Sessler and A. K. Burrell, Top. Curr. Chem., 1991, 161, 177;
(b) B. Franck and A. Nonn, Angew. Chem., Int. Ed. Engl., 1995, 34,
1795.
5 (a) E. Vogel, M. Kocher, H. Schmickler and J. Lex, Angew. Chem., Int.
Ed. Engl., 1986, 25, 257; (b) P. J. Chmielewski, L. Latos-Grazynski,
K. Rachlewcz and T. Glowiak, Angew. Chem., Int. Ed. Engl., 1994,
33, 779; (c) H. Furuta, T. Asano and T. Ogawa, J. Am. Chem. Soc.,
1994, 116, 767.
9,18,27,36-Tetrakis(phenylethynyl)-3,6,12,15,21,24,30,33-octa-
hydro-3,6;12,15;21,24;30,33-tetraethanotetrabenzoporphyrinato
zinc (Zn-1):
6 (a) M. J. Broadhurst, R. Grigg and A. W. Johnson, J. Chem. Soc. C,
1971, 3681; (b) E. Vogel, W. Haas, B. Knipp, J. Lex and H. Schmickler,
Angew. Chem., Int. Ed. Engl., 1988, 27, 406; (c) T. D. Lash, Angew.
Chem., Int. Ed. Engl., 1995, 34, 2533.
7 R. E. Haddad, S. Gazeau, J. Pecaut, J. Marchon, C. J. Medforth and
J. A. Shelnutt, J. Am. Chem. Soc., 2003, 125, 1253, and references
therein.
Zn(OAc)2·2H2O (100 mg, 0.46 mmol) in MeOH (3 mL) was
added to H2-1 (40 mg, 0.039 mmol) in CHCl3 (10 mL). The
mixture was stirred for 3 h at room temperature. The solution
was washed with water (40 mL) and brine (20 mL), and dried
over anhydrous Na2SO4. After evaporation, the product was
purified by recrystallization from CHCl3–MeOH to give Zn-1
3 4 4 6
O r g . B i o m o l . C h e m . , 2 0 0 4 , 2 , 3 4 4 2 – 3 4 4 7

View Article Online
8 (a) T. D. Lash, J. Porphyrins Phthalocyanines, 2001, 5, 267; (b) T. D.
Lash, Energy Fuels, 1993, 7, 166, and references therein; (c) T. D.
Lash and P. Chandrasekar, J. Am. Chem. Soc., 1996, 118, 8767.
9 (a) S. Ito, T. Murashima and N. Ono, J. Chem. Soc., Perkin Trans.
1, 1997, 3161; (b) S. Ito, T. Murashima, H. Uno and N. Ono, Chem.
Commun., 1998, 1661; (c) S. Ito, N. Ochi, T. Murashima, H. Uno and
N. Ono, Heterocycles, 2000, 52, 399.
12 X-Ray data were processed by CrystalStructure Version 3.6.0
(Rigaku, 3–9-12 Akishima, Tokyo, Japan). Structures were solved by
SIR-97 and then refined by CRYSTALS and/or SHELXL-97. When
the PLATON SQUEEZE program was applied, the data cited in the
text refer to the structures refined by several cycles of SHELXL-97
and PLATON SQUEEZE programs.
13 A. L. Spek, PLATON, A Multipurpose Crystallographic Tool, 2003,
Utrecht University, Utrecht, The Netherlands; A. L. Spek, J. Appl.
Cryst., 2003, 36, 7.
10 A. Krivokapic, A. R. Cowley and H. L. Anderson, J. Org. Chem.,
2003, 68, 1089.
11 L. Sessler, A. Mozaffari and M. R. Johnson, Org. Synth., 1998, 9,
242.
14 A. Regev, T. Galili, C. J. Medforth, K. M. Smith, K. M. Barkigia, J.
Fajer and H. Levanon, J. Phys. Chem., 1994, 98, 2520.
O r g . B i o m o l . C h e m . , 2 0 0 4 , 2 , 3 4 4 2 – 3 4 4 7
3 4 4 7