Formation of metal-assisted stable double helices in dimers of cyclic bis-tetrapyrroles that exhibit spring-like motion

Article abstract of DOI:10.1002/chem.201001605

Bidipyrrin-bridged macrocycles, prepared from Ni^II-bridged dipyrrinbased nanorings by intramolecular oxidative biaryl coupling reactions, yielded [2+4]-type Zn^II-assisted stable twisted-ring dimers comprising two double helices. These [2+4]-type metal complexes can be optically resolved by chiral HPLC and exhibit tunable electronic and optical properties as a result of spring-like motions. The double helices behave as glue to connect two macrocycles and as the screws of hinges to form thermally responsive synchronized spring systems.

Full text of DOI:10.1002/chem.201001605

FULL PAPER
DOI: 10.1002/chem.201001605
Formation of Metal-Assisted Stable Double Helices in Dimers of
Cyclic Bis-Tetrapyrroles that Exhibit Spring-Like Motion
Takashi Hashimoto,[a] Takuma Nishimura,[a] Jong Min Lim,[b] Dongho Kim,[b] and
Hiromitsu Maeda*[a, c]
Abstract: Bidipyrrin-bridged macrocycles, prepared from NiII-bridged dipyrrin-
based nanorings by intramolecular oxidative biaryl coupling reactions, yielded
[2+4]-type ZnII-assisted stable twisted-ring dimers comprising two double helices.
These [2+4]-type metal complexes can be optically resolved by chiral HPLC and
exhibit tunable electronic and optical properties as a result of spring-like motions.
The double helices behave as glue to connect two macrocycles and as the screws
of hinges to form thermally responsive synchronized spring systems.
Keywords: chirality · coordination
compounds heterocycles
macrocycles · self-assembly
·
·
Introduction
In most cases the optical resolution of such racemic mix-
tures, which would provide various valuable chiral clusters,
is not easy to achieve,[7] especially in the case of metal-assist-
ed helices, because of fairly weak metal–ligand interactions.
As potential building subunits of helical assemblies, linear
tetrapyrrole ligands, bidipyrrins, that is, directly linked dipyr-
rin dimers,[8,9] can be used to fabricate metal complexes, in-
cluding [2+2]-type ZnII-assisted double helices[10] as well as
roughly square-planar complexes formed with NiII, CuII, and
PdII[11] (Scheme 1). Because of the coordination properties
of dipyrrins as monoanionic bidentate ligands, bidipyrrin–
ZnII double helices are electronically neutral and therefore
their enantiomers would be isolated from the racemic mix-
ture by facile protocols such as chiral HPLC. However,
The control of chirality in metal-assisted assemblies[1] is an
important issue in the production of promising catalysts for
asymmetric synthesis.[2] In addition, chirality-amplified mac-
romolecular systems have attracted considerable attention
since Lee and co-workers reported the temperature-depen-
dent conformational changes in the single helical springs of
coordination polymers.[3] As small discrete systems,[4] ThIV-
assisted quadruple-stranded bis-bidentate helicates were
found by Xu and Raymond[5] and self-organized CuI-bridged
double helices were developed by Nitschke and co-workers
using nitrogen-containing aromatic ligands.[6] In many cases
the chirality in metal–ligand clusters can be controlled by
auxiliaries such as the chiral substituents of ligand mole-
cules. On the other hand, metal coordination itself affords
racemic forms of chiral assemblies based on achiral ligands.
[a] T. Hashimoto, T. Nishimura, Prof. Dr. H. Maeda
College of Pharmaceutical Sciences
Institute of Science and Engineering
Ritsumeikan University, Kusatsu 525-8577 (Japan)
Fax : (+81)77-561-2659
E-mail: maedahir@ph.ritsumei.ac.jp
[b] J. M. Lim, Prof. Dr. D. Kim
Department of Chemistry, Yonsei University
Seoul 120-749 (Korea)
[c] Prof. Dr. H. Maeda
PRESTO, Japan Science and Technology Agency (JST)
Kawaguchi 332-0012 (Japan)
Supporting information for this article is available on the WWW
under http://dx.doi.org/10.1002/chem.201001605.
Scheme 1. Metal coordination modes of bidipyrrin as the parent struc-
ture.
Chem. Eur. J. 2010, 16, 11653 – 11661
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there have been no reports of optically resolved bidipyrrin-
based double helices presumably due to their fragility even
though they are constructed of electronically compensating
of enantiomers under specific conditions. For example, 1a–c
show a slow transition between enantiomers in CHCl3 at
room temperature, presumably due to the existence of a
trace amount of electron-pair donor species as well as the
electron-pair donating nature of CHCl3 itself. The transi-
tions occur over several hours and so temporary optical res-
olutions were performed. However, it is difficult to establish
fixed conditions using CHCl3 and to estimate exact kinetic
parameters for the racemization processes. The fragility of a
single lock was also suggested by the ligand-exchange be-
havior of 1a and 1b in CHCl3 in which the ligand-exchanged
mass of these double helices was observed. In THF, 1a–c
maintain their enantiomeric purities at room temperature
but exhibit a slow transition to the racemic state at 608C,
possibly due to the electron-pair donating nature of THF
that is suitable for metal coordination. In THF at 608C, no
ligand exchange between bidipyrrin–ZnII complexes were
observed. Therefore the racemization can be considered to
occur through a first-order reaction: The kinetic parameters
(k) of the racemization of 1a,c at 608C were estimated to be
4ꢁ10À5 and 9ꢁ10À6 sÀ1, respectively, which are possibly de-
pendent on the electron-donating aryl substituents and are
correlated with the metal-coordination ability of the pyrrole
nitrogen atom. Furthermore, aliphatic 1c, which is soluble in
hydrocarbon solvents as a monomer according to its UV/Vis
absorption spectrum, does not show diminished CD signals
in hexane even at 608C because of the very weak coordina-
tion properties of the solvent. On the other hand, amphi-
philic 1d, which is soluble in water and forms aggregates
mainly on the scale of 180 and 330 nm at 20 and 808C, re-
spectively, as observed by dynamic light-scattering (DLS)
measurements, shows racemization behavior in aqueous so-
lution at 908C. Apart from inert solvents such as hexane,
ZnII-assisted bidipyrrin double helices show transitions be-
tween enantiomers in various solvents, at least at high tem-
peratures. Although further investigations should be made,
including the determination of intermediates or transition
states during racemization, the fragility of bidipyrrin-based
double helices was demonstrated.
À
N Zn bonds. Stimulated by the fascinating but almost unex-
plored properties of bidipyrrins, we have investigated the
formation, topological control, and properties of these opti-
cally resolved and stable helical structures.
Results and Discussion
Properties of ZnII-assisted double helices based on meso-ar-
ylbidipyrrin derivatives: Initially we attempted to reveal the
detailed properties of ZnII-coordinated bidipyrrin-based
double helices. To explore the possibility of their optical res-
olution and to examine their stabilities as pure enantiomers
in various solvents, the double-helical ZnII complexes (1a–
d) of meso-arylbidipyrrins, including hexadecyloxy- and trie-
thyleneglycol (TEG)-substituted derivatives, were prepared
by an oxidative biaryl coupling reaction of NiII complexes of
the corresponding dipyrrins and subsequent demetalation
and ZnII complexation (Figure 1a). The double helices 1a–d
can be optically resolved by chiral HPLC (Daicel IA,
hexane/CH2Cl2/Et2NH=95:5:0.5 for 1a,b, hexane/CH2Cl2 =
7:1 for 1c, and hexane/THF/Et2NH=50:50:0.1 for 1d). In
solution, the optically pure double helices 1a–d, which show
CD signals after resolution, were transformed into mixtures
The double helical structure of meso-phenyl 1a was re-
vealed by single-crystal X-ray analysis (Figure 1b), which
showed the absence of significant interactions between p-
conjugated moieties in the solid state.[12] Single-crystal analy-
sis of 1a revealed temperature-dependent behavior in the
double helical structure with ZnII–ZnII distances of 3.243
and 3.254 ꢂ at 123 and 297 K, respectively. This observation,
the reduced heights of the double helix and the extended
widths at 123 K compared with those a 297 K, suggests that
the bidipyrrin-based double helices can be useful building
blocks of stimuli-responsive chiral systems not only in the
solid state but also in solution, which would enable more dy-
namic spring-like motions. In fact, the double helix of 1a ex-
1
hibits significant changes in its H NMR and UV/Vis absorp-
tion spectra as the temperature varies: from 60 to À608C,
the resonance of, for example, the pyrrole a-CH at 7.22 ppm
is shifted upfield to 7.01 ppm in CDCl3 and the absorbance
at lmax =572 nm increased by around 1.9-fold in CHCl3 as a
Figure 1. a) ZnII coordination of meso-arylbidipyrrin derivatives and
b) the ORTEP drawing (ellipsoids drawn at the 50% probability level) of
the single-crystal X-ray structure of 1a (M type, front view).
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Double Helices in Dimers of Cyclic Bis-Tetrapyrroles
FULL PAPER
result of the flexibility of the double helix. However, it is
not easy to discuss the detailed temperature-dependent heli-
cal motions by CD spectral changes because of racemization
in this solvent.
temperature for 5 h, we obtained brown and red solids of
[1+2]-type NiII and CuII complexes 3a and 3’a in yields of
91 and 40%, respectively. In sharp contrast, the treatment
of 4a,b with ZnACTHNUTRGNE(UNG OAc)2 (10 equiv) for 5 h in CHCl3 resulted
in the formation of ZnII-bridged [2+4]-type dimers 5a,b, as
revealed by 1H NMR spectroscopy (see below) and
MALDI-TOF MS, as green solids in yields of 71 and 60%,
Synthesis and characterization of bidipyrrin-based macrocy-
cles and metal complexes: One of the effective strategies for
forming stable bidipyrrin double helices is the coordination
of multiple (more than two) ZnII ions. As candidate ligand
molecules for such multinuclear complexes, covalently
linked cyclic bis-bidipyrrins (cBDPR, 4a,b) were obtained
as dark-blue solids in yields of 78 and 48% (two steps) by a
biaryl coupling of NiII nanorings (mmm-DPR2Ni2, 2a,b)[13]
and subsequent demetalation of 3a,b (Scheme 2). In con-
trast to 2a,b, which exhibit temperature-dependent para-
magnetic 1H NMR shifts because of the distortion of the
square-planar coordination, 3a,b show diamagnetic features
due to the approximate square-planar coordination of NiII.
respectively. Similarly, treatment with CdACTHNURGTNEUNG(OAc)2 under ap-
propriate conditions also resulted in the formation of the
MALDI-TOF MS peak of the [2+4]-type complex. The ad-
dition of 1.0 equiv of ZnACTHNUTRGNE(NUG OAc)2 to 4a led to the formation
of complicated mixtures, including intermediate complexes
such as [2+2]- and [2+3]-type complexes, as a result of a
small amount of metal cations for [2+4]-type complexation.
No ligand exchange was observed for 5a and 5b on heating
at reflux in CHCl3 and toluene, whereas the addition of
acids such as aq. HCl readily led to the demetalation of 5a
to give 4a. The UV/Vis absorption spectra of 4a, protonated
4a, 3a, 3’a, and 5a in CHCl3 were quite distinct with absorp-
tion maxima (lmax) at 410, 587, and 724 nm for 4a, 440 and
691 nm for protonated 4a, 412, 575, and 845 nm for 3a, 467,
575, and 769 nm for 3’a, and 424 and 655 nm (br) for 5a
(Figure 2). Fluorescence emission of 5a in CHCl3 was ob-
served at 822 nm (lex =655 nm, FF =0.006). The electronic
nature of 5b is very similar to that of 5a, as illustrated by
the lmax at 425 and 651 nm (br) and the lem at 822 nm (lex =
651 nm, FF =0.006) in CHCl3.
By treating 4a with NiACHTUNGRTENNUG(OAc)2 and CuAHCTUTGNERNN(UGN OAc)2 (10 equiv in
each) in CHCl3 and stirring the resultant solution at room
The 1H NMR spectrum of 5a in [D8]THF exhibited 22
unique peaks arising from the helical structure formed on
ZnII complexation in the absence of diastereomers (Fig-
ure 3a). Furthermore, from the DOSY analysis of 3a, 4a,
Figure 2. UV/Vis absorption spectra and colors (inset) in CHCl3 of a) 4a
(red) and protonated 4a (blue) and b) 3a (brown), 3’a (yellow), and 5a
(green).
Scheme 2. Formation of metal complexes of bidipyrrin-based macrocy-
cles.
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H. Maeda et al.
Figure 3. a) 1H NMR spectrum of 5a in [D8]THF (600 MHz, 608C) with the correlations suggested by 1H–1H ROESY experiments and b) optimized
structure of 5a (M type) at the DFT level of theory.
and 5a we observed that these complexes have diffusion co-
efficients of 5.1ꢁ10À10, 6.8ꢁ10À10, and 3.8ꢁ10À10 m2 sÀ1, re-
spectively. These values reflect the different sizes of these
complexes. The structural optimization of 5a at the B3LYP/
6-31G** level of theory[14] supports the formation of [2+4]-
type structures (Figure 3b). The dihedral angles between the
dipyrrin moieties are 65.5–65.88, whereas the ZnII–ZnII dis-
tances in the double helices and across the inner pore are
3.59 and 7.61 ꢂ, respectively. Furthermore, the neighboring
phenylethynyl spacers are quite strained with a dihedral
angle of 35.48. With the assistance of the optimized struc-
ture, all the proton signals were assigned on the basis of
1H–1H COSY and ROESY experiments, which showed cor-
relations between the pyrrole b-CH and phenyl o-CH at the
meso position. The variable-temperature (VT) NMR spectra
of 5a in [D8]THF in the range of À60 to +608C showed
temperature-dependent upfield shifts in many of the protons
along with downfield shifts (Dd=0.057, 0.052, 0.008, 0.022,
and 0.016 ppm) in the protons assigned to the meso-aryl-H
(Hj and Hl), external pyrrole a-CH (Hn), and inner “bipyr-
role” units (Hs and Hu). In particular, the chemical shifts of
the external pyrrole-CH of 5a (Hn, Hp, and Hv) exhibited
behavior similar to that of the pyrrole-CH of 1a (Figure 1b).
Figure 4. a) VT CD spectra of 5a in 2-methyl-THF (2.8ꢁ10À6 m at RT)
and possible conformational changes (inset) and b) the corresponding
Chemical shift changes in 1a are larger than those in 5a,
which suggests that in solution the double helix of 1a is
more flexible than that of 5a. Furthermore, XAFS revealed
that the distances between two neighboring ZnII in 1a and
5a are 3.17 and 3.24 ꢂ, respectively, in a matrix of 2-methyl-
THF at À1638C, which suggests the formation of double
helices.
In contrast to 1a–d, the interlocked complexes 5a,b re-
tained their enantiopurity after optical resolution by chiral
HPLC (Daicel IA, hexane/CHCl3/Et2NH=80:20:0.1). This
suggests that unstable double helices of bidipyrrin could be
stabilized by dual locks, as observed in the case of 5a,b. The
enantiomers of 5a in 2-methyl-THF exhibited Cotton effects
in the CD spectra with lmax at 336, 424, 618, 664, and
772 nm. The VT CD spectral changes of each enantiomer of
5a,b in 2-methyl-THF revealed stronger Cotton effects at
low temperatures because of a possible fastening of the
pitches of the ZnII-bridged double helices as springs (Fig-
ure 4a). These changes correlated well with the correspond-
ing UV/Vis absorption (Figure 4b) and fluorescence spectral
changes. Such temperature-dependent spectral changes of
5a,b were also observed in CHCl3, THF, and toluene. In 2-
methyl-THF, 5a,b shows similar UV/Vis and CD spectral
VT UV/Vis absorption spectra.
changes, even below the glass transition temperature (Tg), to
those in solution, whereas the fluorescence emissions are
significantly enhanced below the Tg. Furthermore, the small-
er dihedral angles at the bipyrrole units, which indicate the
fastening of helical pitches, should provide enhanced ab-
sorption bands at low temperatures. The temperature-de-
pendent changes in the helical pitches are consistent with
the changes observed in the solid-state structures of 1a, as
discussed above. The CD changes that are dependent on the
states of the helical pitches contrast those observed for equi-
libria between helical diastereomers or folding–unfolding
oligomers.[15,16] To the best of our knowledge, this is the first
example of temperature-dependent spring-like motions of
metal complexes in which the enantiomeric purity of the
helices is retained.
Photophysical properties tunable by external stimuli: The
fluorescence lifetimes of 5a in 2-methyl-THF at different
temperatures were estimated from time-correlated single-
photon counting (TCSPC) measurements. In the case of
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Double Helices in Dimers of Cyclic Bis-Tetrapyrroles
FULL PAPER
(CH2Cl2); 1H NMR (600 MHz, CDCl3, 208C): d=7.61 (t, J=1.2 Hz, 2H;
ArH), 7.55–7.54 (m, 4H; ArH), 7.51–7.46 (m, 6H; ArH), 7.00 (d, J=
4.2 Hz, 2H; pyrrole-H), 6.77 (d, J=4.2 Hz, 2H; pyrrole-H), 6.58 (dd, J=
4.2, 1.2 Hz, 2H; pyrrole-H), 6.41 ppm (dd, J=4.2, 1.8 Hz, 2H; pyrrole-
H); UV/Vis (CHCl3): lmax (eꢁ10À5)=587 nm (0.23mÀ1 cmÀ1); MS
(MALDI-TOF): m/z (%): calcd for C30H23N4: 439.19 [M+H]+; found:
439.1 (100), 440.1 (19).
metal-free 4a, fluorescence dynamics revealed a single
decay component of 0.48 ns at 248C and an increased decay
component at low temperatures (1.9 ns at À1968C). In con-
trast, at high temperatures, 5a exhibited two decay compo-
nents (0.040 and 0.60 ns at 248C) whereas at low tempera-
tures the fast decay component of 5a disappeared with the
lifetime of the second component increasing (3.0 ns at
À1968C). This indicates that 5a has a second relaxation
pathway from the excited to the ground state that is absent
in 4a. Note also that this relaxation pathway is blocked at
low temperatures. From these observations it can be con-
cluded that the fast decay component of 5a is a result of the
flexible spring-like motion, which can be controlled by ex-
ternal stimuli.
ZnII complex of Ph-BDPR (1a): [Zn
ACHTUGNRTEN(NUGN OAc)2·2H2O] (17.1 mg, 0.08 mmol)
was added to CHCl3 solution (5 mL) of Ph-BDPR (14.2 mg,
a
0.032 mmol) and the mixture was stirred at room temperature for 3 h.
The solvent was evaporated to dryness and the residue was purified by
silica gel column chromatography (Wakogel C300, CHCl3) and recrystal-
lized from CHCl3/hexane to afford 1a (8.5 mg, 53%) as a purple solid.
Rf =0.82 (CH2Cl2); 1H NMR (600 MHz, CDCl3, 208C): d=7.48–7.43 (m,
8H; ArH), 7.40–7.38 (m, 4H; ArH), 7.25–7.22 (m, 4H; ArH), 7.10 (d,
J=7.8 Hz, 4H; ArH), 7.06 (m, 4H; pyrrole-H), 6.57 (dd, J=4.8, 1.2 Hz,
4H; pyrrole-H), 6.42 (d, J=4.2 Hz, 4H; pyrrole-H), 6.37 (d, J=4.2 Hz,
4H; pyrrole-H), 6.29 ppm (dd, J=4.2, 1.2 Hz, 4H; pyrrole-H); UV/Vis
(CHCl3): lmax (eꢁ10À4)=425 (5.5), 471 (1.8), 574 (3.5), 614 (3.2), 634 nm
(3.1mÀ1 cmÀ1); MS (MALDI-TOF): m/z (%): calcd for C80H40N8Zn2:
1000.20 [M]+; found: 1000.2 (46), 1001.2 (48), 1002.2 (96), 1003.2 (77),
1004.2 (100), 1005.3 (63), 1006.3 (42), 1007.2 (36), 1008.2 (19).
Conclusion
All the measurements have revealed that the ZnII-assisted
double helices of 5a,b behaved not only as glue to connect
two covalently linked nanorings but also as the fairly stable
screws of hinges that exhibit thermally responsive synchron-
ized spring motions. As observed in this investigation, dual-
interlocked double helical assemblies assisted by metal cat-
ions are essential to form stimuli-responsive chiral macro-
molecular systems and materials.
ZnII complex of pTol-BDPR (1b): [Zn
ACHTUNGTRENNUNG
0.40 mmol) was added to a CHCl3 solution (5 mL) of 5,5’-diAHCTUNGTRENNUNG
pyrrin (pTol-BDPR)[9b] (39.9 mg, 0.08 mmol) and the mixture was stirred
at room temperature for 2 h. The solvent was evaporated to dryness and
the residue was purified by silica gel column chromatography (Wakogel
C300, CHCl3) and recrystallized from CHCl3/hexane to afford 1b
1
(41.1 mg, 90%) as a purple solid. Rf =0.84 (CH2Cl2); H NMR (600 MHz,
CDCl3, 208C): d=7.35 (dd, J=7.8, 1.8 Hz, 4H; ArH), 7.19 (d, J=7.8 Hz,
4H; ArH), 7.04–7.03 (m, 4H; ArH), 7.00–6.98 (m, 8H; ArH, pyrrole-H),
6.58 (dd, J=4.2, 1.2 Hz, 4H; pyrrole-H), 6.42 (d, J=4.2 Hz, 4H; pyrrole-
H), 6.36 (d, J=3.6 Hz, 4H; pyrrole-H), 6.27 (dd, J=4.2, 1.2 Hz, 4H; pyr-
role-H), 2.45 ppm (s, 12H; CH3); UV/Vis (CHCl3): lmax (eꢁ10À5)=425
(0.68), 470 (0.19), 574 (0.37), 614 (0.37), 634 nm (0.36mÀ1 cmÀ1); MS
(MALDI-TOF): m/z (%): calcd for C80H40N8Zn2: 1056.26 [M]+; found:
1056.3 (56), 1057.3 (45), 1058.3 (90), 1059.3 (73), 1060.3 (100), 1061.3
(70), 1062.3 (55), 1063.3 (36), 1064.3 (18), 1065.3 (10).
Experimental Section
General procedures: The starting materials were purchased from Wako
Chemical Co., Nacalai Chemical Co., and Aldrich Chemical Co. and
used without further purification unless otherwise stated. UV/Vis spectra
were recorded on a Hitachi U-3500 spectrometer. Fluorescence spectra
and quantum yields were recorded on a Hitachi F-4500 fluorescence
spectrometer for ordinary solutions and on a Hamamatsu Quantum
Yields Measurements System for Organic LED Materials C9920-02, re-
spectively. CD spectra were recorded on a JASCO J-720W spectrometer.
NMR spectra used for the characterization of the products were recorded
on a JEOL ECA-600 600 MHz spectrometer. All NMR spectra were ref-
erenced to solvent. Electrospray ionization mass spectra (ESIMS) were
recorded on a Bruker microTOF spectrometer using positive- and nega-
tive-mode ESI-TOF methods. Matrix-assisted laser desorption/ionization
time-of-flight mass spectra (MALDI-TOF MS) were recorded on a Shi-
madzu AXIMA-CFR plus spectrometer in the positive mode. Fast atom
bombardment mass spectra (FABMS) were recorded using a JEOL
GCmate instrument in the positive ion mode with a 3-nitrobenzylalcohol
matrix. TLC analyses were carried out on aluminium sheets coated with
silica gel 60 (Merck 5554). Column chromatography was performed on
Sumitomo alumina KCG-1525, Wakogel C-200, and C-300.
5-(3,4,5-Trihexadecyloxyphenyl)dipyrrin (3OC16Ph-DPR): A THF solu-
tion (5 mL) of DDQ (26.5 mg, 0.116 mmol) was added to a THF solution
(5 mL) of 5-(3,4,5-trihexadecyloxyphenyl)dipyrromethane[17] (100 mg,
0.106 mmol) and the mixture was stirred at room temperature for 30 min.
The solvent was evaporated to dryness and the residue was purified by
alumina (CH2Cl2) and silica gel column chromatography (Wakogel C300,
CH2Cl2/hexane=2:1) and recrystallized from CHCl3/MeOH to afford
3OC16Ph-DPR (61.3 mg, 0.096 mmol, 61%) as an orange solid. Rf =0.40
(CH2Cl2/hexane=2:1); 1H NMR (600 MHz, CDCl3, 208C): d=7.63 (s,
2H; pyrrole-H), 6.71 (d, J=4.2 Hz, 2H; pyrrole-H), 6.70 (s, 2H; ArH),
6.40 (m, 2H; pyrrole-H), 4.05–3.94 (m, 6H; OCH2), 1.81–1.76 (m, 6H;
CH2), 1.51–1.25 (m, 78H; CH2), 0.89–0.86 ppm (m, 9H; CH3); UV/Vis
(CH2Cl2): lmax (eꢁ10À5)=437 nm (0.16mÀ1 cmÀ1); MS (MALDI-TOF):
m/z (%): calcd for C63H108N2O3 [M]+: 940.84; found: 940.8 (100), 941.8
(48).
NiII complex of 3OC16Ph-DPR ([3OC16Ph-DPR2·Ni]): [Ni
ACTHNUTRGEN(UGN OAc)2·4H2O]
(707 mg, 2.84 mmol) was added to a CHCl3 solution (20 mL) of 3OC16Ph-
DPR (1.337 g, 1.42 mmol) and the mixture was stirred at room tempera-
ture for 4 h. The mixture was then washed with brine, extracted with
CHCl3, and dried over anhydrous Na2SO4. The solvent was removed
under vacuum and recrystallized from CHCl3/MeOH to afford [3OC16Ph-
DPR2·Ni] quantitatively as a metallic-green solid. Rf =0.45 (CH2Cl2);
1H NMR (600 MHz, CDCl3, 208C): d=8.91 (s, 4H; pyrrole-H), 7.23 (d,
J=4.2 Hz, 4H; pyrrole-H), 6.84 (d, J=4.2 Hz, 4H; pyrrole-H), 6.64 (s,
4H; phenyl-H), 4.05–3.92 (m, 12H; OCH2), 1.81–1.76 (m, 12H; CH2),
1.52–1.25 (m, 156H; CH2), 0.89–0.86 ppm (m, 18H; CH3); UV/Vis
(CH2Cl2): lmax (eꢁ10À5)=473 nm (0.43mÀ1 cmÀ1); MS (MALDI-TOF):
m/z (%): calcd for C126H214N4NiO6 [M]+: 1937.59; found: 1937.6 (80),
1938.6 (100), 1939.6 (84), 1940.6 (45), 1941.6 (22).
5,5’-Diphenylbidipyrrin (Ph-BDPR): DDQ (49.2 mg, 0.22 mmol) was
added to a toluene solution (15 mL) of a NiII complex of 5-phenyldipyr-
rin [(Ph-DPR)2·Ni] (89.8 mg, 0.18 mmol) and the mixture was heated at
reflux temperature for 12 h. The solvent was evaporated to dryness and
the residue was purified by silica gel column chromatography (Wakogel
C300, CHCl3) and evaporated to afford the NiII complex of 5,5’-diphenyl-
bidipyrrin [Ph-BDPR·Ni] as a brown solid. A 12m aq. HCl (3 mL) solu-
tion was added to a CHCl3 solution (5 mL) of [Ph-BDPR·Ni] (17.8 mg,
0.036 mmol) and the mixture was stirred at room temperature for 1 h.
The reaction mixture was diluted with aq. NaHCO3 (10 mL), dried over
anhydrous Na2SO4, and evaporated to dryness. The solution was evapo-
rated to afford Ph-BDPR (14.2 mg, 92%) as a blue solid. Rf =0.83
Chem. Eur. J. 2010, 16, 11653 – 11661
ꢀ 2010 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.chemeurj.org
11657

H. Maeda et al.
NiII
complex
of
5,5’-bis(3,4,5-trihexadecyloxyphenyl)bidipyrrin
dryness and the residue was purified by alumina (CH2Cl2) and silica gel
column chromatography (Wakogel C300, 7% MeOH/CH2Cl2) to afford
3TEGPh-DPR (202.6 mg, 0.29 mmol, 72%) as an orange oil. Rf =0.25
(7% MeOH/CH2Cl2); 1H NMR (600 MHz, CDCl3, 208C): d=7.63 (s,
2H; ArH), 6.75 (s, 2H; pyrrole-H), 6.67 (d, J=4.2 Hz, 2H; pyrrole-H),
6.40 (d, J=4.2 Hz, 2H; pyrrole-H), 4.26–4.14 (m, 6H; OCH2), 3.86–3.52
(m, 30H; CH2), 3.38–3.36 ppm (m, 9H; CH3); UV/Vis (CHCl3): lmax (eꢁ
10À5)=437 nm (0.09mÀ1 cmÀ1); MS (MALDI-TOF): m/z (%): calcd for
C36H54N2O12: 706.37 [M]+; found: 706.4 (100), 707.4 (35).
([3OC16Ph-BDPR·Ni]): p-Chloranil (12.5 mg, 0.051 mmol) was added to
a toluene solution (30 mL) of [3OC16Ph-DPR2·Ni] (16.4 mg, 8.46 mmol)
and the mixture was heated at reflux overnight. The solvent was evapo-
rated to dryness and the residue was purified by silica gel column chro-
matography (Wakogel C300, CH2Cl2/hexane=1:2) and recrystallized
from CH2Cl2/MeOH to afford [3OC16Ph-BDPR·Ni] (10.3 mg, 5.32 mmol,
63%) as
a
brown solid. Rf =0.45 (CH2Cl2/hexane=1:2); 1H NMR
(600 MHz, CDCl3, 208C): d=6.89 (m, 2H; pyrrole-H), 6.85 (d, J=
4.2 Hz, 2H; pyrrole-H), 6.77 (s, 4H; ArH), 6.62 (d, J=4.2 Hz, 2H; pyr-
role-H), 6.43 (m, 2H; pyrrole-H), 5.98 (s, 2H; pyrrole-H), 4.07–3.98 (m,
12H; OCH2), 1.84–1.74 (m, 12H; CH2), 1.53–1.25 (m, 156H; CH2), 0.89–
0.86 ppm (m, 18H; CH3); UV/Vis (CH2Cl2): lmax (eꢁ10À5)=419 nm
(0.37mÀ1 cmÀ1); MS (MALDI-TOF): m/z (%): calcd for C126H212N4NiO6
[M]+: 1935.57; found: 1935.6 (48), 1936.6 (100), 1937.6 (96), 1938.5 (87),
1939.6 (65), 1940.5 (40).
NiII complex of 3TEGPh-DPR ([3TEGPh-DPR2·Ni]): [Ni
ACTHNUTRGEN(UGN OAc)2·4H2O]
(286 mg, 1.15 mmol) and Na2CO3 (158 mg, 1.15 mmol) were added to a
CHCl3 solution (15 mL) of 3TEGPh-DPR (202.6 mg, 0.29 mmol) and the
mixture was stirred at room temperature overnight. The mixture was
then washed with brine, extracted with CH2Cl2, and dried over anhydrous
Na2SO4. The solvent was removed under vacuum to afford 3TEGPh-
DPR (168.6 mg, 0.11 mmol, 80%) as an orange solid. Rf =0.25 (7%
1
5,5’-Bis(3,4,5-trihexadecyloxyphenyl)bidipyrrin (3OC16Ph-BDPR): A 12m
aq. HCl solution (20 mL) was added to a CHCl3 solution (3 mL) of
[3OC16Ph-BDPR·Ni] (8.2 mg, 4.23 mmol) and the mixture was stirred at
room temperature for 30 min. The mixture was then washed with
Na2CO3, extracted with CHCl3, and dried over anhydrous Na2SO4. The
solvent was evaporated to dryness and the residue was recrystallized
from CHCl3/hexane to afford 3OC16Ph-BDPR quantitatively as a green
solid. Rf =0.30 (CHCl3); 1H NMR (600 MHz, CDCl3, 208C): d=7.59 (s,
2H; pyrrole-H), 6.99 (d, J=4.2 Hz, 2H; pyrrole-H), 6.88 (d, J=4.2 Hz,
2H; pyrrole-H), 6.75 (s, 4H; ArH), 6.70 (m, 2H; pyrrole-H), 6.42 (m,
2H; pyrrole-H), 4.07–3.97 (m, 12H; OCH2), 1.83–1.78 (m, 12H; CH2),
1.53–1.25 (m, 158H; CH2), 0.89–0.86 ppm (m, 18H; CH3); UV/Vis
(CHCl3): lmax (eꢁ10À5)=594 nm (0.46mÀ1 cmÀ1); MS (MALDI-TOF): m/z
(%): calcd for C126H214N4O6 [M+H]+: 1880.66; found: 1879.7 (67), 1880.7
(100).
MeOH/CH2Cl2); H NMR (600 MHz, CDCl3, 208C): d=8.84 (s, 4H; pyr-
role-H), 7.20 (s, 4H; pyrrole-H), 6.81 (d, J=3.0 Hz, 4H; pyrrole-H), 6.69
(s, 4H; ArH), 4.24–4.13 (m, 12H; OCH2), 3.84–3.54 (m, 60H; CH2),
3.38–3.37 ppm (m, 18H; CH3); UV/Vis (CHCl3): lmax (eꢁ10À5)=475 nm
(0.31mÀ1 cmÀ1); MS (MALDI-TOF): m/z (%): calcd for C72H106N4NiO24
:
1468.65 [M]+; found: 1468.7 (100), 1469.7 (98), 1470.7 (76), 1471.6 (48),
1472.7 (22).
NiII complex of 5,5’-bis(3,4,5-tri-TEG-phenyl)bidipyrrin ([3TEGPh-
BDPR·Ni]): p-Chloranil (158 mg, 0.645 mmol) was added to a toluene so-
lution (150 mL) of [3TEGPh-DPR2·Ni] (158 mg, 0.107 mmol) and the
mixture was heated at reflux overnight. The solvent was then evaporated
to dryness and the residue was purified by silica gel column chromatogra-
phy (Wakogel C300, 3% MeOH/CH2Cl2) to afford [3TEGPh-BDPR·Ni]
(76.9 mg, 0.052 mmol, 49%) as a brown solid. Rf =0.60 (3% MeOH/
CH2Cl2); 1H NMR (600 MHz, CDCl3, 208C): d=6.85 (m, 2H; pyrrole-
H), 6.82 (s, 4H; ArH), 6.81 (s, 2H; pyrrole-H), 6.63 (d, J=4.2 Hz, 2H;
pyrrole-H), 6.43 (m, 2H; pyrrole-H), 5.96 (s, 2H; pyrrole-H), 4.27–4.18
(m, 12H; OCH2), 3.88–3.53 (m, 60H; CH2), 3.39–3.36 ppm (m, 18H;
CH3); UV/Vis (CH2Cl2): lmax (eꢁ10À5)=416 nm (0.29mÀ1 cmÀ1); MS
ZnII complex of 3OC16Ph-BDPR ([3OC16Ph-BDPR2·Zn2], 1c): [Zn-
ACHTUNGTRENNUNG(OAc)2·2H2O] (94 mg, 0.432 mmol) was added to a CHCl3 (15 mL) solu-
tion of 3OC16Ph-BDPR (203.7 mg, 0.108 mmol) and the mixture was
stirred at room temperature for 3 h. The mixture was then washed with
brine, extracted with CHCl3, dried over anhydrous Na2SO4, and evaporat-
ed to dryness. The residue was recrystallized from CHCl3/hexane to
afford [3OC16Ph-BDPR2·Zn2] (184.6 mg, 0.095 mmol, 88%) as a green
solid. Rf =0.30 (CH2Cl2/hexane=1:2); 1H NMR (600 MHz, CDCl3,
208C): d=6.86 (s, 4H; pyrrole-H), 6.72 (d, J=1.2 Hz, 4H; ArH), 6.70 (d,
J=4.2 Hz, 4H; pyrrole-H), 6.47 (d, J=4.2 Hz, 4H; pyrrole-H), 6.42 (d,
J=4.2 Hz, 4H; pyrrole-H), 6.32 (d, J=1.2 Hz, 4H; ArH), 6.21 (m, 4H;
pyrrole-H), 3.99–3.91 (m, 16H; OCH2), 3.52–3.50 (m, 4H; OCH2), 2.94–
2.90 (m, 4H; OCH2), 1.80–1.76 (m, 16H; CH2), 1.64–1.24 (m, 292H;
CH2), 0.89–0.86 ppm (m, 36H; CH3); UV/Vis (CHCl3): lmax (eꢁ10À5)=
427 nm (1.35mÀ1 cmÀ1); MS (MALDI-TOF): m/z (%): calcd for
C252H424N8O12Zn2: 3883.14 [M]+; found: 3883.1 (18), 3884.1 (36), 3885.0
(66), 3886.0 (76), 3887.0 (92), 3888.0 (100), 3888.9 (82), 3889.9 (55),
3890.9 (42), 3891.9 (16).
(MALDI-TOF): m/z (%): calcd for C72H104N4NiO24
found: 1466.6 (100), 1467.6 (88), 1468.7 (54), 1469.7 (26).
:
1466.64 [M]+;
5,5’-Bis(3,4,5-tri-TEG-phenyl)bidipyrrin (3TEGPh-BDPR): TFA (3 mL)
was added to a CHCl3 solution (30 mL) of [3TEGPh-BDPR·Ni] (70 mg,
0.048 mmol) and the mixture was stirred at room temperature for 3 h.
The mixture was then washed with Na2CO3, extracted with CHCl3, and
dried over anhydrous Na2SO4. The solvent was evaporated to dryness
and the residue was purified by silica gel column chromatography (Wako-
gel C300, 4% MeOH/CH2Cl2) to afford 3TEGPh-BDPR (30.9 mg,
0.022 mmol, 46%) as
a green solid. Rf =0.40 (6% MeOH/CH2Cl2);
1H NMR (600 MHz, CDCl3, 208C): d=7.60 (s, 2H; pyrrole-H), 6.99 (d,
J=4.2 Hz, 2H; pyrrole-H), 6.84 (d, J=4.2 Hz, 2H; pyrrole-H), 6.80 (s,
4H; ArH), 6.65 (m, 2H; pyrrole-H), 6.41 (m, 2H; pyrrole-H), 4.26–4.17
(m, 12H; OCH2), 3.87–3.52 (m, 60H; CH2), 3.39–3.36 ppm (m, 18H;
CH3); UV/Vis (CHCl3): lmax (eꢁ10À5)=593 nm (0.40mÀ1 cmÀ1); MS
(MALDI-TOF): m/z (%): calcd for C72H106N4O24: 1410.72 [M]+; found:
1410.7 (100), 1411.7 (70).
5-(3,4,5-Tri-TEG-phenyl)dipyrromethane (3TEGPh-DPM): 3,4,5-Tri-
TEG-benzaldehyde[18] (1.78 g, 2.93 mmol) was dissolved in pyrrole
(1.22 mL, 17.6 mmol) and CH2Cl2 (10 mL) and degassed by bubbling
with nitrogen for 30 min. Trifluoroacetic acid (22 mL, 0.293 mmol) was
added and the solution was stirred under N2 at room temperature for
30 min and then quenched with triethylamine (1 mL). The remaining pyr-
role was removed by vacuum distillation with gentle heating. The residue
was purified by silica gel column chromatography (Wakogel C300, 5%
MeOH/CH2Cl2) to afford 3TEGPh-DPM (284.4 mg, 0.40 mmol, 14%) as
a yellow oil. Rf =0.50 (5% MeOH/CH2Cl2); 1H NMR (600 MHz, CDCl3,
208C): d=8.10 (s, 2H; NH), 6.69 (m, 2H; pyrrole-H), 6.48 (s, 2H; ArH),
6.14 (m, 2H; pyrrole-H), 5.92 (s, 2H; pyrrole-H), 5.36 (s, 1H; meso-H),
4.12–4.07 (m, 6H; OCH2), 3.79–3.52 (m, 30H; CH2), 3.37–3.36 ppm (m,
9H; CH3); MS (MALDI-TOF): m/z (%): calcd for C36H56N2O12: 708.38
[M]+; found: 708.4 (100), 709.4 (38).
ZnII complex of 3TEGPh-DPR ([3TEGPh-DPR2·Zn2], 1d): [Zn-
AHCTNUGTERN(GNUN OAc)2·2H2O] (16.8 mg, 0.0764 mmol) was added to a CH2Cl2 solution
(20 mL) of 3TEGPh-BDPR (27 mg, 0.0191 mmol) and the mixture was
stirred at room temperature for 3 h. The mixture was then washed with
brine, extracted with CH2Cl2, dried over anhydrous Na2SO4, and evapo-
rated to dryness. The residue was purified by silica gel column chroma-
tography (Wakogel C300, 15% MeOH/CH2Cl2) to afford [3TEGPh-
DPR2·Zn2] (15.6 mg, 5.27 mmol, 55%) as a green solid. Rf =0.75 (15%
1
MeOH/CH2Cl2); H NMR (600 MHz, CDCl3, 208C): d=6.83 (s, 4H; pyr-
role-H), 6.75 (d, J=1.2 Hz, 4H; pyrrole-H), 6.62 (d, J=4.2 Hz, 4H; pyr-
role-H), 6.44 (s, 8H; ArH), 6.30 (d, J=1.8 Hz, 4H; pyrrole-H), 6.21 (m,
4H; pyrrole-H), 4.21–4.10 (m, 16H; OCH2), 3.83–3.50 (m, 124H; CH2),
3.39–3.34 (m, 36H; CH3), 3.25–3.24 ppm (m, 4H; CH2); UV/Vis (CHCl3):
lmax (eꢁ10À5)=427 nm (0.72mÀ1 cmÀ1); MS (MALDI-TOF): m/z (%):
calcd for C144H208N8O8Zn2 [M]+: 2945.26; found: 2945.3 (14), 2946.3 (38),
5-(3,4,5-Tri-TEG-phenyl)dipyrrin (3TEGPh-DPR):
A THF solution
(15 mL) of DDQ (100 mg, 0.44 mmol) was added to a THF solution
(15 mL) of 3TEGPh-DPM (284.4 mg, 0.40 mmol) and the mixture was
stirred at room temperature for 15 min. The solvent was evaporated to
11658
www.chemeurj.org
ꢀ 2010 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Chem. Eur. J. 2010, 16, 11653 – 11661

Double Helices in Dimers of Cyclic Bis-Tetrapyrroles
FULL PAPER
2947.3 (61), 2948.3 (78), 2949.3 (100), 2950.3 (88), 2951.3 (68), 2952.3
(53), 2953.3 (32), 2954.3 (16), 2955.3 (8).
role-H), 6.44 (dd, J=4.2, 2.4 Hz, 4H; pyrrole-H), 5.96 ppm (brs, 4H; pyr-
role-H); UV/Vis (CHCl3): lmax (eꢁ10À5)=412 (0.68), 575 (0.22), 845 nm
(0.17mÀ1 cmÀ1); MS (MALDI-TOF): m/z (%): calcd for C80H44N8Ni2:
1232.24 [M]+; found: 1232.2 (56), 1233.2 (69), 1234.2 (100), 1235.2 (81),
1236.2 (64), 1237.2 (45), 1238.2 (15), 1239.2 (13), 1240.2 (7).
2-tert-Butyl-1,3-bis(3-formylphenylethynyl)benzene (tBuPh-mmm-FOR):
A mixture of 3-bromobenzaldehyde (0.38 g, 2.04 mmol), 1-tert-butyl-3,5-
diethynylbenzene (0.35 g, 1.92 mmol), triethylamine (0.3 mL, 4.1 mmol),
NiII complex of the mono-oxidative coupling derivative of bis-bidipyrrin
([4’a·Ni2]): The fraction following that of 3a was recrystallized from
CHCl3/hexane to afford [4’a·Ni2] (21.5 mg, 10%) as a brown solid. Rf =
0.32 (CH2Cl2); 1H NMR (600 MHz, CDCl3, 208C): d=9.12 (s, 4H; pyr-
role-H), 7.77–7.72 (m, 4H; ArH), 7.68–7.60 (m, 10H; ArH, pyrrole-H),
7.55–7.43 (m, 8H; ArH), 7.40–7.34 (m, 6H; ArH), 6.83–6.70 (m, 6H; pyr-
role-H), 6.65 (d, J=4.2 Hz, 2H; pyrrole-H), 6.61 (d, J=4.2 Hz, 2H; pyr-
role-H), 6.46 (dd, J=4.2, 1.2 Hz, 2H; pyrrole-H), 6.41 (dd, J=3.6,
1.2 Hz, 2H; pyrrole-H), 5.98 ppm (m, 2H; pyrrole-H); UV/Vis (CHCl3):
lmax (eꢁ10À5)=430 (0.61), 560 (0.14), 845 nm (0.11mÀ1 cmÀ1); MS
(MALDI-TOF): m/z (%): calcd for C80H46N8Ni2: 1234.26 [M]+; found:
1234.3 (53), 1234.3 (66), 1235.3 (100), 1236.3 (72), 1237.3 (43).
[PdCl2ACHTUNGTRENNUNG(PPh3)2] (17.5 mg, 0.02 mmol), triphenylphosphine (3.8 mg,
0.01 mmol), and CuI (1 mg, 0.005 mmol) in dry THF (10 mL) was heated
at reflux under nitrogen for 64 h. The reaction mixture was diluted with
CH2Cl2 (50 mL), washed with 0.01m aq. EDTA (80 mL), dried over
Na2SO4, and evaporated to dryness. The residue was purified by silica gel
column chromatography (Wakogel C300, 30% hexane/CH2Cl2) and re-
crystallized from CH2Cl2/hexane to afford tBuPh-mmm-FOR (72.1 mg,
24%) as a dark-red oil. Rf =0.47 (CH2Cl2); 1H NMR (600 MHz, CDCl3,
208C): d=10.03 (s, 2H; CHO), 8.06 (s, 2H; ArH), 7.87 (d, J=7.8 Hz,
2H; ArH), 7.79 (d, J=7.8 Hz, 2H; ArH), 7.57–7.54 (m, 5H; ArH),
1.37 ppm (s, 9H; CH3); MS (FAB): m/z (%): calcd for C28H22O2: 390.16
[M]+; found: 389.7 (100), 390.7 (97).
NiII complex of tBuPh-cBDPR (3b): p-Chloranil (173.6 mg, 7.10 mmol)
was added to a CHCl3 solution (14 mL) of 2b (95.4 mg, 0.07 mmol) and
the mixture was heated at reflux for 50 h. The solvent was evaporated to
dryness and the residue was purified by alumina (CHCl3) and silica gel
column chromatography (Wakogel C300, CHCl3) and recrystallized from
CHCl3/hexane to afford 3b (87.3 mg, 92%) as a brown solid. Rf =0.86
2-tert-Butyl-1,3-bis(3-dipyrrolylmethylphenylethynyl)benzene
(tBuPh-
mmm-DPM): Aldehyde tBuPh-mmm-FOR (120 mg, 0.31 mmol) was dis-
solved in pyrrole (6.0 mL) and degassed by bubbling with nitrogen for
10 min. Trifluoroacetic acid (6.0 mL, 0.035 mmol) was added and the solu-
tion was stirred under N2 at room temperature for 40 min and then
quenched with triethylamine (0.4 mL). The remaining pyrrole was re-
moved by vacuum distillation with gentle heating. The residue was puri-
fied by silica gel column chromatography (Wakogel C300, 1% Et3N/
CH2Cl2) and recrystallized from CH2Cl2/hexane to afford tBuPh-mmm-
1
(CH2Cl2); H NMR (600 MHz, CDCl3, 208C): d=7.72 (s, 4H; ArH), 7.66
(dt, J=7.8, 1.2 Hz, 4H; ArH), 7.57–7.51 (m, 12H; ArH), 7.46 (dd, J=7.8,
7.2 Hz, 4H; ArH), 6.84 (dd, J=4.2, 1.2 Hz, 4H; pyrrole-H), 6.68 (m, 4H;
pyrrole-H), 6.61 (m, 4H; pyrrole-H), 6.44 (dd, J=4.2, 1.2 Hz, 4H; pyr-
role-H), 5.96 (m, 4H; pyrrole-H), 1.38 ppm (s, 18H; CH3); UV/Vis
(CHCl3): lmax (eꢁ10À5)=414 (0.79), 565 (0.27), 846 nm (0.21mÀ1 cmÀ1);
MS (MALDI-TOF): m/z (%): calcd for C88H60N8Ni2: 1344.36: [M]+;
found: 1344.4 (53), 1345.4 (76), 1346.4 (100), 1347.4 (78), 1348.4 (57),
1349.4 (33), 1350.4 (14).
1
DPM (117 mg, 61%) as a light-yellow solid. Rf =0.44 (CH2Cl2); H NMR
(600 MHz, CDCl3, 208C): d=7.98 (brs, 4H; NH), 7.49–7.21 (m, 11H;
ArH), 6.73 (m, 4H; pyrrole-H), 6.17 (m, 4H; pyrrole-H), 5.94 (m, 4H;
pyrrole-H), 5.49 (s, 2H; meso-H), 1.33 ppm (s, 9H; CH3); MS (FAB):
m/z (%): calcd for C44H38N4: 622.31 [M]+; found: 622.4 (100), 623.4 (71).
2-tert-Butyl-1,3-bis(dipyrrolylphenylethynyl)benzene
(tBuPh-mmm-
DPR): DDQ (28.0 mg, 0.12 mmol) was added to a THF solution (15 mL)
of dipyrromethane tBuPh-mmm-DPM (38.4 mg, 0.06 mmol) and the mix-
ture was stirred at 08C for 20 min. The solvent was evaporated to dryness
and the residue was purified by alumina (5% MeOH/CH2Cl2) and silica
gel column chromatography (Wakogel C200; 5% MeOH/CH2Cl2) to
afford tBuPh-mmm-DPR (37.3 mg, 98%) as a brown solid. Rf =0.24
(CH2Cl2); 1H NMR (600 MHz, CDCl3, 208C): d=7.69–7.44 (m, 15H;
ArH, pyrrole-H), 6.61 (m, 4H; pyrrole-H), 6.41 (m, 4H; pyrrole-H),
1.34 ppm (s, 9H; CH3); UV/Vis (CHCl3): lmax (eꢁ10À5)=435 nm
(0.30mÀ1 cmÀ1); MS (FAB): m/z (%): calcd for C44H34N4: 618.28 [M]+;
found: 619.0 (100), 620.0 (65).
NiII complex of tBuPh-mmm-DPR (2b): Pyrene (3.9 mg, 0.02 mmol) and
[NiACHTUNGTRENNUNG(OAc)2·4H2O] (9.6 mg, 0.04 mmol) were added to a CHCl3 solution
(20 mL) of dipyrrin tBuPh-mmm-DPR (23.9 mg, 0.04 mmol) and the mix-
ture was heated at reflux for 46 h. The solvent was evaporated to dryness
and the residue was purified by silica gel column chromatography (Wako-
gel C200; 3% MeOH/CHCl3) and recrystallized from CHCl3/hexane to
Cyclic bis-bidipyrrin cBDPR (4a): A 12m aq. HCl solution (10 mL) was
added to a CHCl3 solution (10 mL) of 3a (69.7 mg, 0.056 mmol) and the
mixture was stirred at room temperature for 1 h. The reaction mixture
was then diluted with aq. NaHCO3 (50 mL), dried over Na2SO4, and
evaporated to dryness. The solution was recrystallized from CHCl3/
hexane to afford 4a (58.4 mg, 92%) as a blue solid. Rf =0.11 (CH2Cl2);
1H NMR (600 MHz, CDCl3, 208C): d=7.72–7.65 (m, 14H; ArH), 7.54–
7.42 (m, 12H; ArH), 7.38 (t, J=7.8 Hz, 4H; ArH), 6.87 (brs, 2H; pyr-
role-H), 6.78 (brs, 2H; pyrrole-H), 6.65 (brs, 2H; pyrrole-H), 6.60 (brs,
2H; pyrrole-H), 6.45 (brs, 2H; pyrrole-H), 6.32 ppm (brs, 2H; pyrrole-
H); UV/Vis (CHCl3): lmax (eꢁ10À5)=410 (0.49), 587 (0.66), 724 nm
(0.34mÀ1 cmÀ1); MS (ESI-TOF): m/z (%): calcd for C80H49N8: 1121.41
[M+H]+; found: 1121.41 (100), 1122.42 (92), 1123.42 (38), 1124.43 (15).
Cyclic bis-bidipyrrin tBuPh-cBDPR (4b):
A 12m aq. HCl solution
(5 mL) was added to CHCl3 solution (5 mL) of 3b (35.5 mg,
a
0.026 mmol) and the mixture was stirred at room temperature for 1 h.
The reaction mixture was then diluted with aq. NaHCO3 (20 mL), dried
over Na2SO4, and evaporated to dryness. The solution was recrystallized
from CHCl3/hexane to afford 4b (26.8 mg, 83%) as a blue solid. Rf =0.12
(CH2Cl2); 1H NMR (600 MHz, CDCl3, 208C): d=7.72–7.65 (m, 8H;
ArH), 7.57–7.55 (m, 6H; ArH), 7.50–7.49 (m, 4H; ArH), 7.46 (t, J=
7.8 Hz, 4H; ArH), 6.87 (brs, 2H; pyrrole-H), 6.78 (brs, 2H; pyrrole-H),
6.66 (brs, 2H; pyrrole-H), 6.60 (brs, 2H; pyrrole-H), 6.45 (brs, 2H; pyr-
role-H), 6.32 (brs, 2H; pyrrole-H), 1.39 ppm (s, 18H; CH3); UV/Vis
(CHCl3): lmax (eꢁ10À5)=411 (0.52), 588 nm (0.66mÀ1 cmÀ1); MS
(MALDI-TOF): m/z (%): calcd for C88H65N8: 1233.53 [M+H]+: 1233.5
(100), 1234.5 (82), 1235.5 (44), 1236.5 (12).
afford 2b (17.1 mg, 66%) as
a white solid. Rf =0.90 (5% MeOH/
CH2Cl2); 1H NMR (600 MHz, CDCl3, 208C): d=9.34 (brs, 8H; pyrrole-
H), 7.62–7.57 (m, 10H; ArH, pyrrole-H), 7.52 (m, 4H; ArH), 7.44–7.43
(m, 4H; ArH), 7.41–7.36 (m, 8H; ArH), 6.77 (brs, 8H; pyrrole-H),
1.37 ppm (s, 18H; CH3); UV/Vis (CHCl3): lmax (eꢁ10À5)=478 nm
(0.92mÀ1 cmÀ1); MS (MALDI-TOF): m/z (%, observed with the use of
2,5-dihydroxybenzoic acid as matrix): calcd for C88H64N8Ni2: 1348.40
[M]+; found: 1348.1 (14), 1349.4 (60), 1350.4 (81), 1351.5 (95), 1352.5
(100), 1353.5 (67), 1354.5 (51), 1355.5 (28).
NiII complex of cyclic bis-bidipyrrin cBDPR (3a): p-Chloranil (403.0 mg,
1.64 mmol) was added to a CHCl3 solution (40 mL) of 2a[12b] (202.7 mg,
0.16 mmol) and the mixture was heated at reflux for 46 h. The solution
was purified by alumina (CHCl3) and silica gel column chromatography
(Wakogel C300, CHCl3) and recrystallized from CHCl3/hexane to afford
3a (171.8 mg, 85%) as a brown solid. Rf =0.85 (CH2Cl2); 1H NMR
(600 MHz, CDCl3, 208C): d=7.75 (s, 2H; ArH), 7.72 (s, 4H; ArH), 7.65
(dt, J=7.2, 1.2 Hz, 4H; ArH), 7.54–7.52 (m, 8H; ArH), 7.46 (dd, J=7.8,
7.2 Hz, 4H; ArH), 7.38 (t, J=7.8 Hz, 2H; ArH), 6.83 (dd, J=4.8, 1.2 Hz,
4H; pyrrole-H), 6.68 (m, 4H; pyrrole-H), 6.62 (d, J=2.4 Hz, 4H; pyr-
CuII complex of cBDPR (3’a): Cu
ACTHNUTRGNEN(UG OAc)2 (24.6 mg, 0.14 mmol) was added
to a CHCl3 solution (5 mL) of bidipyrrin 4a (15.2 mg, 0.014 mmol) and
the mixture was stirred for 25 h at room temperature. The solvent was
evaporated to dryness and the residue was purified by silica gel column
chromatography (Wakogel C300, CHCl3) and recrystallized from CHCl3/
hexane to afford 3’a (8.4 mg, 50%) as an orange solid. Rf =0.81
(CH2Cl2); UV/Vis (CHCl3): lmax (eꢁ10À5)=467 (0.69), 769 nm
(0.49mÀ1 cmÀ1); MS (MALDI-TOF): m/z (%): calcd for C80H44N8Cu2:
Chem. Eur. J. 2010, 16, 11653 – 11661
ꢀ 2010 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.chemeurj.org
11659

H. Maeda et al.
1242.23 [M]+; found: 1242.2 (83), 1243.2 (78), 1244.2 (100), 1245.2 (80),
1246.2 (44), 1247.2 (24), 1248.2 (8).
ZnII complex of cBDPR (5a): [Zn
ACHTNUTRGNEUG(N OAc)2·2H2O] (7.6 mg, 0.03 mmol) was
Debye–Scherrer camera with a camera length of 543 mm was used with
an imaging plate as detector and the diffraction pattern was obtained
with a 0.018 step in 2q. The exposure time of the X-ray beam was 10 s for
the melted sample of 1c sealed in a quartz capillary.
added to a CHCl3 solution (13 mL) of bidipyrrin 4a (21.1 mg, 0.03 mmol)
and the mixture was stirred for 25 h at room temperature. The solvent
was evaporated to dryness and the residue was purified by silica gel
column chromatography (Wakogel C300, CHCl3) and recrystallized from
CHCl3/hexane to afford 5a (15.8 mg, 68%) as a green solid. Rf =0.82
(CH2Cl2); 1H NMR (600 MHz, CDCl3, 208C): d=7.68 (s, 4H; ArH),
7.53–7.50 (m, 8H; ArH), 7.44 (d, J=7.8 Hz, 4H; ArH), 7.39 (dd, J=7.8,
7.2 Hz, 4H; ArH), 7.33–7.29 (m, 8H; ArH), 7.22 (dt, J=8.4, 1.2 Hz, 4H;
ArH), 7.17 (s, 4H; ArH), 7.13 (d, J=4.2 Hz, 4H; pyrrole-H), 7.04 (s, 4H;
pyrrole-H), 6.99 (dd, J=7.8, 7.2 Hz, 4H; ArH), 6.93 (d, J=7.8 Hz, 4H;
ArH), 6.75 (s, 4H; pyrrole-H), 6.67 (d, J=3.6 Hz, 4H; pyrrole-H), 6.40–
6.38 (m, 12H; pyrrole-H), 6.34 (d, J=4.2 Hz, 4H; pyrrole-H), 6.30 (d,
J=4.2 Hz, 4H; pyrrole-H), 6.28 ppm (d, J=4.2 Hz, 4H; pyrrole-H); UV/
Vis (CHCl3): lmax (eꢁ10À5)=424 (2.13), 655 nm (0.84mÀ1 cmÀ1); MS
(MALDI-TOF): m/z (%): calcd for C160H88N16Zn4: 2488.45 [M]+; found:
2488.4 (6), 2489.3 (14), 2490.4 (31), 2491.4 (46), 2492.4 (70), 2493.3 (79),
2494.3 (98), 2495.3 (100), 2496.3 (100), 2497.3 (80), 2498.3 (72), 2499.3
(52), 2500.3 (38), 2501.3 (27), 2502.4 (14), 2503.3 (8).
Dynamic light scattering: DLS measurements were taken with a Malvern
Zetasizer Nano-ZS differential light-scattering instrument.
HPLC: Chiral HPLC analyses were performed with a Shimadzu LC-20A
instrument with Daicel Chiralpak IA column.
Time-resolved fluorescence decay measurements: Time-resolved fluores-
cence lifetime experiments were performed by the time-correlated single-
photon counting (TCSPC) technique. As the excitation source we used a
Ti:sapphire laser (Mai Tai BB, Spectra-Physics), which provides a repeti-
tion rate of 800 kHz with ~100 fs pulses generated by a home-made
pulse-picker. The output pulse of the laser was frequency-doubled by a
1 mm thickness of a second harmonic crystal (b-barium borate, BBO,
CASIX). The fluorescence was collected with a microchannel plate pho-
tomultiplier (MCP-PMT, Hamamatsu, R3809U-51) equipped with a ther-
moelectric cooler (Hamamatsu, C4878) connected to a TCSPC board
(Becker & Hickel SPC-130). The overall instrumental response function
was about 25 ps (the full-width at half-maximum (fwhm)). A vertically
polarized pump pulse from a Glan-laser polarizer was used to irradiate
samples and a sheet polarizer, set at an angle complementary to the
magic angle (54.78), was placed in the fluorescence collection path to
obtain polarization-independent fluorescence decays.
ZnII complex of tBuPh-cBDPR (5b): [Zn
ACHTNUTRGENG(UN OAc)2·2H2O] (38.8 mg,
0.18 mmol) was added to a CHCl3 solution (7 mL) of bidipyrrin 4b
(21.8 mg, 0.018 mmol) and the mixture was stirred for 13 h at room tem-
perature. The solvent was evaporated to dryness and the residue was pu-
rified by silica gel column chromatography (Wakogel C300, CHCl3) and
recrystallized from CHCl3/hexane to afford 5b (15.8 mg, 68%) as a green
solid. Rf =0.64 (CH2Cl2); 1H NMR (600 MHz, CDCl3, 208C): d=7.69 (s,
4H; ArH), 7.54–7.51 (m, 8H; ArH), 7.46 (t, J=1.8 Hz, 4H; ArH), 7.39
(t, J=7.8 Hz, 4H; ArH), 7.34 (dt, J=8.4, 1.2 Hz, 8H; ArH), 7.17 (dt, J=
9.0, 1.2 Hz, 8H; ArH), 7.13 (dd, J=4.2, 0.6 Hz, 4H; pyrrole-H), 7.05 (t,
J=1.2 Hz, 4H; pyrrole-H), 6.98 (t, J=7.2 Hz, 4H; ArH), 6.92 (dt, J=7.2,
1.8 Hz, 4H; ArH), 6.73 (m, 4H; pyrrole-H), 6.69 (dd, J=4.2, 1.2 Hz, 4H;
pyrrole-H), 6.39–6.37 (m, 12H; pyrrole-H), 6.31–6.28 (m, 12H; pyrrole-
H), 1.37 ppm (s, 36H; CH3); UV/Vis (CHCl3): lmax (eꢁ10À5)=425 (1.83),
651 nm (0.81mÀ1 cmÀ1); MS (MALDI-TOF): m/z (%): calcd for
C176H120N16Zn4: 2712.70 [M]+; found: 2712.7 (3), 2713.8 (5), 2714.8 (10),
2715.8 (24), 2716.8 (37), 2717.8 (60), 2718.8 (74), 2719.8 (94), 2720.7
(100), 2721.8 (98), 2722.7 (92), 2723.7 (78), 2724.7 (56), 2725.7 (40),
2726.7 (27), 2727.7 (15), 2728.7 (11), 2729.7 (6), 2730.7 (4).
XAFS measurements: The fluorescent XAFS measurements were per-
formed at the Zn K-edge at BL-9A of the Photon Factory of the High
Energy Accelerator Research Organization (KEK).[22] The 19-element
SSD was used as the fluorescent detector. The sample solution was
added to a brass cell sealed with Kapton windows and placed in a cryo-
stat after freezing in liquid nitrogen. The EXAFS oscillations c(k) given
in Figure 37 of the Supporting Information were extracted by using the
program REX2000 (Rigaku) to obtain the Fourier transforms given in
Figure 38 of the Supporting Information. The area from 0.9–3.2 ꢂ was
Fourier-filtered to determine the bond distances for a fixed coordination
number.
Acknowledgements
Structure optimization: DFT calculations on 1a and 5a were carried out
by using the Gaussian 03 software package[14] and an HP Compaq dc5100
SFF computer.
This work was supported by a Grant-in-Aid for Young Scientists (B, No.
19750122) and Scientific Research on Innovation Areas (“Coordination
Programming” Area 2107, No. 22108533) from the Ministry of Educa-
tion, Culture, Sports, Science, and Technology (MEXT) and the Ritsu-
meikan R-GIRO project (2008-2013). We thank Prof. Atsuhiro Osuka,
Eiji Tsurumaki, and Taro Koide, Kyoto University, for X-ray analysis,
Prof. Hiroshi Shinokubo and Dr. Satoru Hiroto, Nagoya University, for
ESI-TOF MS, Prof. Tomohiro Miyatake, Ryukoku University, for
FABMS, Prof. Yasuhiro Inada and Dr. Misaki Katayama, Ritsumeikan
University, for XAFS (BL-9A at the Photon Factory), Dr. Sono Sasaki
(at present, Kyoto Institute of Technology) and Dr. Hiroyasu Masunaga,
JASRI/SPring-8, for synchrotron XRD analysis, and Prof. Hitoshi Tamia-
ki, Ritsumeikan University, for various measurements. T.H. thanks the
JSPS for a Research Fellowship for Young Scientists and a Nishio Memo-
rial Scholarship.
X-ray crystallography: Data was collected on a Rigaku RAXIS-RAPID
diffractometer for 1a, refined by full-matrix least-squares procedures
with anisotropic thermal parameters for the non-hydrogen atoms. The hy-
drogen atoms were calculated in ideal positions. Structures were solved
by using the Crystal Structure crystallographic software package[19] and
SIR97,[20] and refined by full-matrix least-squares on F2 with anisotropic
displacement parameters for the non-hydrogen atoms using SHELXL-
97.[21] Crystals of 1a were obtained from CH2Cl2. Crystal data for 1a
(123 K): C60H40N8Zn2, Mw =1003.74, monoclinic, P21/n (no. 14), a=
13.345(3),
4766.8(19) ꢂ3, T=123(2) K, Z=4, 1calcd =1.399 gcmÀ3
1.057 mmÀ1
reflections collected=44617, independent reflections=
b=16.390(3),
c=22.258(5) ꢂ,
b=101.737(9)8,
V=
,
mACHTUGNTR(EUNNNG MoKa)=
,
10893, R1 =0.0355, wR2 =0.0799, GOF=1.023 [I> 2s(I)]. Crystal data
for 1a (293 K): C60H40N8Zn2, Mw =1003.74, monoclinic, P21/n (no. 14),
a=13.453(3), b=16.452(3), c=22.320(6) ꢂ, b=101.137(9)8, V=
[1] For selected books on metal-assisted assemblies, see: a) Transition
Metals in Supramolecular Chemistry (Ed.: J.-P. Sauvage), Wiley,
New York, 1999; b) Metal-Containing and Metallosupramolecular
Polymers and Materials (Eds.: U. S. Schubert, G. R. Newkome, I.
Manners),. ACS, Washington, 2006.
[2] For recent reviews, see: a) D. Fiedler, D. H. Leung, R. G. Bergman,
K. N. Raymond, Acc. Chem. Res. 2005, 38, 349–360; b) M. Shibasa-
ki, M. Kanai, S. Matsunaga, N. Kumagai, Acc. Chem. Res. 2009, 42,
1117–1127.
4846.9(19) ꢂ3, T=293(2) K, Z=4, 1calcd =1.376 gcmÀ3
,
mACHTUNGTRENNUNG
1.039 mmÀ1
,
CCDC-768146 and -768147 contain the supplementary crystallographic
data for this paper. These data can be obtained free of charge from The
Cambridge Crystallographic Data Centre via www.ccdc.cam.ac.uk/data_
request/cif.
X-ray powder diffraction experiments: High-resolution XRD analysis
was carried out by using a synchrotron radiation X-ray beam with a
wavelength of 1.00 ꢂ on BL40B2 at SPring-8 (Hyogo, Japan). A large
[3] H.-J. Kim, D. Lee, H.-S. Park, M. Lee, J. Am. Chem. Soc. 2007, 129,
10994–10995.
11660
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ꢀ 2010 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Chem. Eur. J. 2010, 16, 11653 – 11661

Double Helices in Dimers of Cyclic Bis-Tetrapyrroles
FULL PAPER
[4] For recent reviews, see: a) J. R. Nitschke, Acc. Chem. Res. 2007, 40,
103–112; b) R. W. Saalfrank, H. Maid, A. Scheurer, Angew. Chem.
2008, 120, 8924–8956; Angew. Chem. Int. Ed. 2008, 47, 8794–8824.
[5] J. Xu, K. N. Raymond, Angew. Chem. 2006, 118, 6630–6635; Angew.
Chem. Int. Ed. 2006, 45, 6480–6485.
[6] a) D. Schultz, F. Biaso, A. R. M. Shahi, M. Geoffroy, K. Rissanen, L.
Gagliardi, C. J. Cramer, J. R. Nitschke, Chem. Eur. J. 2008, 14,
7180–7185; b) V. E. Campbell, X. de Hatten, N. Delsuc, B. Kauff-
mann, I. Huc, J. R. Nitschke, Chem. Eur. J. 2009, 15, 6138–6142.
[7] a) T. E. Wood, N. D. Dalgleish, E. D. Power, A. Thompson, X. Chen,
Y. Okamoto, J. Am. Chem. Soc. 2005, 127, 5740–5741; b) J. M. C.
Kerckhoffs, J. C. Peberdy, I. Meistermann, L. J. Childs, C. J. Isaac,
C. R. Pearmund, V. Reudegger, S. Khalid, N. W. Alcock, M. J.
Hannon, A. Rodger, Dalton Trans. 2007, 734–742.
10025; b) H. Maeda, T. Hashimoto, Chem. Eur. J. 2007, 13, 7900–
7907.
[14] Gaussian 03, Revision D.02, M. J. Frisch, G. W. Trucks, H. B. Schle-
gel, G. E. Scuseria, M. A. Robb, J. R. Cheeseman, J. A. Montgom-
ery, Jr., T. Vreven, K. N. Kudin, J. C. Burant, J. M. Millam, S. S.
Iyengar, J. Tomasi, V. Barone, B. Mennucci, M. Cossi, G. Scalmani,
N. Rega, G. A. Petersson, H. Nakatsuji, M. Hada, M. Ehara, K.
Toyota, R. Fukuda, J. Hasegawa, M. Ishida, T. Nakajima, Y. Honda,
O. Kitao, H. Nakai, M. Klene, X. Li, J. E. Knox, H. P. Hratchian,
J. B. Cross, C. Adamo, J. Jaramillo, R. Gomperts, R. E. Stratmann,
O. Yazyev, A. J. Austin, R. Cammi, C. Pomelli, J. W. Ochterski, P. Y.
Ayala, K. Morokuma, G. A. Voth, P. Salvador, J. J. Dannenberg,
V. G. Zakrzewski, S. Dapprich, A. D. Daniels, M. C. Strain, O.
Farkas, D. K. Malick, A. D. Rabuck, K. Raghavachari, J. B. Fores-
man, J. V. Ortiz, Q. Cui, A. G. Baboul, S. Clifford, J. Cioslowski,
B. B. Stefanov, G. Liu, A. Liashenko, P. Piskorz, I. Komaromi, R. L.
Martin, D. J. Fox, T. Keith, M. A. Al-Laham, C. Y. Peng, A. Na-
nayakkara, M. Challacombe, P. M. W. Gill, B. Johnson, W. Chen,
M. W. Wong, C. Gonzalez, J. A. Pople, Gaussian Inc., Wallingford
CT, 2004.
[8] For books and a review on dipyrrins, see: a) H. Fischer, H. Orth,
Die Chemie des Pyrrols, Vol. 2, Akademische Verlagsgesellschaft,
Leipzig, 1937; b) H. Falk, The Chemistry of Linear Oligopyrroles
and Bile Pigments, Springer, Vienna, 1989; c) T. E. Wood, A.
Thompson, Chem. Rev. 2007, 107, 1831–1861.
[9] For the synthesis of bidipyrrins, see: a) M. Brçring, Synthesis 2000,
ˇ
´
1291–1294; b) H. S. Gill, I. Finger, I. Bozidarevic, F. Szydlo, M. J.
Scott, New J. Chem. 2005, 29, 68–71.
[15] For example, see: H. Katagiri, Y. Tanaka, Y. Furusho, E. Yashima,
Angew. Chem. 2007, 119, 2487–2491; Angew. Chem. Int. Ed. 2007,
46, 2435–2439.
[16] CD changes that depend on guest-stimulated helical pitch stretching
have recently been reported: K. Miwa, Y. Furusho, E. Yashima, Nat.
Chem. 2010, 2, 444–449.
[10] For ZnII-assisted double helices of bidipyrrins, see: a) Y. Zhang, A.
Thompson, S. J. Rettig, D. Dolphin, J. Am. Chem. Soc. 1998, 120,
13537–13538; b) M. Brçring, S. Link, C. D. Brandt, E. C. Tejero,
Eur. J. Inorg. Chem. 2007, 1661–1670.
[11] a) M. Brçring, C. D. Brandt, J. Lex, H.-U. Humpf, J. Bley-Escrich,
J.-P. Gisselbrecht, Eur. J. Inorg. Chem. 2001, 2549–2556; b) M. Brçr-
ing, C. D. Brandt, J. Bley-Escrich, J.-P. Gisselbrecht, Eur. J. Org.
Chem. 2002, 910–917.
[12] a) The solid-state structure of 1a is similar to the first example of an
X-ray-analyzed meso-aryl-bidipyrrin ZnII complex by Prof. Shinoku-
bo (private communication); b) by X-ray diffraction (XRD) analysis,
1c also showed solid-state lamella assemblies arising from van der
Waals interactions between alkoxy units. As observed in the crystal
structure of 1a, the solid-state absorption spectrum suggests no no-
table interactions between the p moieties, ZnII-assisted double heli-
cal parts, of 1c.
[17] F. Cheng, A. Adronov, Chem. Eur. J. 2006, 12, 5053–5059.
[18] C. B. Nielsen, J. Johnsen, J. Arnbjerg, M. Pittelknow, S. P. Mcllroy,
P. R. Ogilby, M. Jorgensen, J. Org. Chem. 2005, 70, 7065–7079.
[19] CrystalStructure: Crystal Structure Analysis Package, Rigaku and
Rigaku/MSC, The Woodlands, 2000.
[20] SIR97: A program for crystal structure solution: A. Altomare, M. C.
Burla, M. Camalli, G. L. Cascarano, C. Giacovazzo, A. Guagliardi,
A. G. G. Moliterni, G. Polidori, R. Spagna, J. Appl. Crystallogr.
1999, 32, 115–119.
[21] SHELXL-97: Programs for Crystal Structure Analysis, G. M. Shel-
drick, University of Gçttingen (Germany), 1998.
[22] M. Nomura, A. Koyama, Nucl. Instrum. Methods Phys. Res. Sect. A
2001, 467–468, 733–736.
[13] For metal coordination chemistry of phenylethynyl-bridged dimeric
dipyrrins, see: a) H. Maeda, M. Hasegawa, T. Hashimoto, T. Kaki-
moto, S. Nishio, T. Nakanishi, J. Am. Chem. Soc. 2006, 128, 10024–
Received: June 8, 2010
Published online: August 23, 2010
Chem. Eur. J. 2010, 16, 11653 – 11661
ꢀ 2010 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.chemeurj.org
11661