Heterocyclic annelated di(perylene bisimide): Constructing bowl-shaped perylene bisimides by the combination of steric congestion and ring strain

Article abstract of DOI:10.1021/jo901285k

(Chemical Equation Presented) In this paper, we present the synthesis of S- and N-heterocyclic annelated di(perylene bisimide) with extraordinary doubly bowl-shaped structures. The structures of fused PBI bowls confirmed by singlecrystal X-ray structure a

Full text of DOI:10.1021/jo901285k

pubs.acs.org/joc
Heterocyclic Annelated Di(perylene bisimide): Constructing Bowl-Shaped
Perylene Bisimides by the Combination of Steric Congestion and
Ring Strain
Hualei Qian,†,§ Wan Yue,†,§ Yonggang Zhen,†,§ Simone Di Motta,‡ Eugenio Di Donato,‡
Fabrizia Negri,*,‡ Jianqiang Qu, Wei Xu,† Daoben Zhu,† and Zhaohui Wang*,†
†Beijing National Laboratory for Molecular Sciences, Key Laboratory of Organic Solids, Institute of
‡
ꢀ
Chemistry, Chinese Academy of Sciences, Dipartimento di Chimica “G. Ciamician”, Unversita di Bologna,
Via F. Selmi 2, 40126 Bologna, Italy, and INSTM, UdR Bologna, Italy, §Graduate School of the Chinese
Academy of Sciences, Beijing 100190, China, and BASF Aktiengesellschaft, GVP/C-A030, 67056
Ludwigshafen, Germany
wangzhaohui@iccas.ac.cn; fabrizia.negri@unibo.it
Received June 22, 2009
In this paper, we present the synthesis of S- and N-heterocyclic annelated di(perylene bisimide) with
extraordinary doubly bowl-shaped structures. The structures of fused PBI bowls confirmed by single-
crystal X-ray structure analysis and temperature-dependent 1H NMR are realized by the introduc-
tion of the steric congestion in nonbay regions and by the concurrent formation of the five-membered
heterorings strain in bay regions. On the basis of the geometry obtained from the X-ray analysis, the
maximum POAV1 pyramidalization angle is found in N-heterocyclic annelated diPBI 7, as large as
4.7°, indicating the formation of two PBI bowls with significant curvatures. Furthermore, to assist
the electrochemical and spectroscopic characterization of the two bowl-shaped derivatives and to
assess the influence of heteroatoms on the bowl curvature, quantum-chemically optimized atomic
structures, electronic properties, and optical signatures were computed with density functional
theory.
Introduction
vacuum pyrolysis (FVP)2 or wholly solution-phase synthetic
methods.3 Incorporation of heteroatoms into curved PAHs
has been shown to determine several intriguing properties
associated with the modified π-electron systems and the
potential applications.4 However, up to now, there have
The immense interest surrounding fullerenes has directed
increasing attention toward bowl-shaped polycyclic aro-
matic hydrocarbons (PAHs), also called molecular bowls,
and these have become attractive targets for design and
synthesis.1 In recent years, various molecular bowls, display-
ing curved molecular structures and π-surfaces, extraordin-
ary chemical and physical properties, and unique self-
assembly behavior, have been prepared by either flash
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7803. (b) Seiders, T. J.; Elliott, E. L.; Grube, G. H.; Siegel, J. S. J. Am. Chem.
Soc. 1999, 121, 7804–7813. (c) Sakurai, H.; Daiko, T.; Hirao, T. Science 2003,
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*To whom correspondence should be addressed.
(1) (a) Rabideau, P. W.; Sygula, A. Acc. Chem. Res. 1996, 29, 235–242. (b)
Wu, Y.; Siegel, J. S. Chem. Rev. 2006, 106, 4843–4867. (c) Tsefrikas, V. M.;
Scott, L. T. Chem. Rev. 2006, 106, 4868–4884. (d) Kawase, T.; Kurata, H.
Chem. Rev. 2006, 106, 5250–5273.
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Anthony, J. E. Chem. Rev. 2006, 106, 5028–5048. (c) Wu, Y.; Li, Y.; Gardner,
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DOI: 10.1021/jo901285k
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Published on Web 07/06/2009
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FIGURE 1. PBIs 1, S-PBI 2, and N-PBIs 3 and 4.
been only a few reports on strained aromatic polycycles
including heteroatoms such as S and N in their frameworks.5
Perylene-3,4:9,10-tetracarboxylbisimides 1 (PBIs) have
been intensively investigated primarily in industry as dyes
and pigments6 and recently in electronics and optoelectro-
nics as important n-type materials.7 The extensive interest in
PBIs is due to the versatile optical and electrochemical
properties, the controllable structures and properties, the
chemical and thermal stabilities, and the high electron
affinity.8 The two different types of positions in the aromatic
core of PBIs, namely the bay regions and the nonbay regions,
are depicted in Figure 1. Modifications of PBIs have been
concentrated on the bay regions, whose chemical substitu-
tion can dramatically alter the optical and electronic proper-
ties. Notably, substituents in bay regions can twist the
perylene unit dihedrally out of plane, leading to the dihedral
angle being easily tunable from 0° to 37°.9 Despite this
documented flexibility in the bay region, PBIs with curved
π-structures have been rarely explored. The incorporation of
bowl-shaped structures to n-type chromophores can signifi-
cantly change intermolecular interactions, chemical and
physical properties, and possible applications.
pyrrole rings, respectively. However, the crystal structure of
2 previously reported by our group reveals a planar perylene
˚
core probably because of the long length of C-S bonds (1.78 A)
and, as a consequence, the weak ring strain.10 In contrast
with 2, the DFT optimized structure of 3 shows a deeply
bowl-shaped configuration (see Figure S6 in the Supporting
Information) due to the strong strain resulting from the short
˚
length of C-N bonds (1.41 A). We expected to synthesize 3
by the Buchwald-Hartwig reaction11 of tetrahalogen-PBIs
with an amine. The only observed product was 4 instead of 3
(Supporting Information), indicating the high energy needed
for simultaneously forming two strained pyrrole rings in bay
regions. These findingsdemonstratethe difficulty in preparing
a PBI bowl by modifying the bay regions, suggesting that an
extended aromatic system may be necessary for flexibility and
to reduce the energy costs of making the five-membered ring.
The influence of nonbay regions on structures and proper-
ties of 1 has been neglected mainly because of the difficulty in
modulating PBIs in nonbay regions. Recently, we reported
the CuI-mediated synthesis of di(perylene bisimides) 5
(diPBIs),12 which is the first example demonstrating the
participation of the C-H bond in the nonbay region to the
reaction, and thus it can be regarded as an ideal platform for
investigating the effect of nonbay regions on structures. It
has been demonstrated, by the computed structures of 5 and
their extended trimers, that the steric congestion between H
atoms in the nonbay region and the adjacent O atoms (blue
label in 5 shown in Figure 2) twists the aromatic core to an
out-of-plane configuration.13 Accordingly, we modified our
strategy for the design of PBI bowls, first by introducing the
steric congestion in nonbay regions through the synthesis of
diPBIs and second by including the strained heterorings
in bay regions. Herein we present the synthesis of S- and
N-heterocyclic annelated diPBIs 6 and 7, and confirm their
doubly bowl-shaped structures by single-crystal X-ray struc-
ture analysis and temperature-dependent 1H NMR. Further-
more, the influence of heteroatoms on the bowl curvature,
the optical signatures, and electrochemical properties have
been experimentally determined and rationalized on the
basis of quantum-chemically computed atomic structures,
electronic properties, and optical signatures.
As numerous examples prove the importance of five-
membered rings in the formation of bowl-shaped structures,
our initial strategy for PBI bowls was based on introducing
heteroring strain into two bay regions and using the stress
strain to form curved structures. Thus, we attempted to
prepare 2 and 3 by the incorporation of two thiophene and
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FIGURE 2. DiPBIs 5, S-diPBI 6, and N-diPBI 7.
SCHEME 1. Synthesis of S-diPBI 6 and N-diPBI 7a
a
3
Conditions and reagents: (a) Bu SnSSnBu3, Pd(PPh3)4, toluene, reflux, 12 h, 68%; (b) Pd(OAc)2, PCy3, PhNH2, KOtBu, toluene, reflux, 5 h, 51%.
Results and Discussion
diPBIs by Stille-type and Buchwald-Hartwig reaction, which
have been widely employed in the formationof C-S17 and C-
N18 bonds, respectively. Accordingly, S-heterocyclic anne-
lated diPBI 6 (S-diPBI) was obtained as blue-black solids in
a high yield of 68% by the Pd(PPh3)4-catalyzed reaction of 8
with Bu3SnSSnBu3,10 and N-heterocyclic annelated diPBI 7
(N-diPBI) as green-black solids in a yield of 51% by the
Pd(OAc)2-catalyzed reaction11 of 8 with aniline (Scheme 1).
The structures of 6 and 7 were verified by 1H NMR, 13C NMR
spectroscopy, and MALDI-TOF. Moreover, the synthetic
protocol discussed above reveals that the formation of two
pyrrole rings in the bay regions of diPBIs is much easier than
that for PBIs. A likely reason is the energetically more
favorable formation of five-member rings in the extended
aromatic system.
Computational Details. Atomic structures of 3, 5, 6, and 7
were optimized with density functional theory (DFT) calcu-
lations, using the B3LYP hybrid functional14 with the basis
set limited to 3-21G* owing to the large dimension of the
chromophores. Molecular orbital shapes and energies of 6
and 7 discussed in the text are those calculated at the
optimized cis structures. Orbital pictures were prepared with
Molekel 4.3 visual software.15 Electronic excitation energies
and oscillation strengths were computed for the 60 lowest
singlet excited electronic states of 6 and 7 with time-depen-
dent (TD) DFT calculations. In plotting computed electro-
nic spectra, a Lorentzian line width of 0.1 eV was
superimposed to each computed intensity to facilitate the
comparison with experimental spectra. The computed spec-
tra did not include the vibronic structure associated with
electronic bands and as a result they show a reduced number
of bands compared with the experimental spectra. All quan-
tum-chemical calculations were performed with the Gauss-
ian03 package.16
For the diPBI series, the steric congestion between oxygen
and the neighboring hydrogen atom is expected to result in
two possible conformers, namely, the trans and cis confor-
mer, in which both ends of each PBI unit tilt in different and
the same direction, respectively. To investigate the effect of
the steric congestion and the heterorings strain on structures,
Synthesis and Optimized Structures. Following our strat-
egy, we attempted to prepare S- and N-heterocyclic annelated
(17) (a) Kosugi, M.; Ogata, T.; Terada, M.; Sano, H.; Migita, T. Bull.
^ ꢁ
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W.; Parr, G. G. Phys. Rev. B 1988, 37, 785–789.
(15) Molekel, version 4.3, http://www.cscs.ch/molkel/; Portmann, S.;
€
Luthi, H. P. Chimia 2000, 54, 766.
(16) Frisch, M. J.; et al. Gaussian 03, revision C.02; Gaussian, Inc.,
Pittsburgh, PA, 2003.
(18) (a) Hartwig, J. F. In Handbook of Organopalladium Chemistry for
Organic Synthesis; Negishi, E. I., de Meijere, A., Eds.; Wiley-Interscience:
Weinheim, Germany, 2002. (b) Jiang, L.; Buchwald, S. L. In Metal-Catalyzed
Cross-Coupling Reactions, 2nd ed.; de Meijere, A., Diederich, F., Eds.; John
Wiely & Sons: Weinheim, Germany, 2004.
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FIGURE 3. Equilibrium structures of trans (a) and cis (b) conformers of 5, 6, and 7 computed at the B3LYP/3-21G* level.
quantum chemical calculationswerecarried out on models for
6 and 7 as well as 5 for comparison, featuring methyl
substituents instead of the isopropyl units on the phenyl rings.
For 5-7, low-energy trans and cis conformers were opti-
mized, representing two different out-of-plane deformations
of the two PBI moieties (Figure 3). As shown in Figure 3, PBI
moieties in the trans conformer of 5 are planar, while in the
cis conformer, their aromatic cores are forced to be bent by
the steric congestion in nonbay regions. In the trans con-
former of 6, the aromatic core of each PBI unit is almost
planar, while in the cis conformer, the PBI moieties exhibit a
shallow bowl-shaped structure. In contrast with the trans
conformer of 6, each PBI unit in the trans structure of 7 is
twisted, and compared to the cis conformer of 6, the bowl
shape of the PBI moieties in the cis structure of 7 is strongly
enhanced. These changes are justified by the larger strain
induced by pyrrole rings with respect to thiophene rings.
Notably, for S- and N-diPBI, the computed energies of trans
and cis configurations are much closer than those of diPBI 5
(see Table S1 in the Supporting Information), indicating that
the incorporation of S and N atoms increases the stability of
cis conformers while decreasing that of trans conformers,
leading ultimately to a more stable cis conformer for 7.
Single-Crystal Structures and Bowl Curvatures. Crystals of
S- and N-diPBI suitable for single-crystal X-ray structure
analysis are obtained at room temperature. As revealed by
the crystal structures of 6 and 7 (Figure 4), only cis con-
formers are found in the obtained single crystals. To deter-
mine whether the trans conformers are contained in the
products, we did the temperature-dependent 1H NMR
experiments of 6 and 7 in CDCl3 (Supporting Information)
and only observed slight changes in the chemical shift of
aromatic protons, which correspond to the same isomeric
form and are possibly due to vibrational cooling effects. The
temperature-dependent 1H NMR spectra of both 6 and 7 did
not show a trace of the presence of two isomers. Thus, as
proved by the crystal structures and the temperature-depen-
dent 1H NMR experiments, only the cis conformers of 6 and
7 were obtained in the products of Stille-type and Buchwald
reactions.
regions and the strain induced by the five-membered rings in
bay regions, each PBI unit in 6 and 7, containing perylene
rings with a fused heteroring, exhibits extraordinary bowl-
shaped structures. For both 6 and 7, the two PBI bowls
opening in opposite directions are fully conjugated via the
three C-C bonds in the center. Moreover, the PBI bowls in 6
are much shallower than those in 7, indicating that the strain
˚
induced by C-S bonds (length: 1.76 A) in thiophene rings is
˚
weaker than that by C-N bonds (length: 1.41 A) in pyrrole
rings, in close agreement with the computed C-heteroatom
bond lengths (Supporting Information). Notably, for each
PBI bowl in the crystal structure of 7, one acetone molecule is
on the convex side with a nonbonding C O distance of
˚
3.12 A and two CH2Cl2 molecules on the concave side with
3 3 3
˚
nonbonding C Cl distances of 3.27 and 3.45 A, respec-
3 3 3
tively (see Figure S8 in the Supporting Information).
The curvature was evaluated by the method of π-orbital
axis vector analysis (POAV1)19 based on the geometry
obtained from the X-ray analysis. In S-diPBI, the highest
local curvature, 2.9°, is found on C19 (C19A) that are in the
imide rings, and the average pyramidalization angle for the
carbons of the central benzene ring in the perylene core is
1.0°. Compared with 6, the pyramidalization angles for most
carbons in the aromatic core of 7 are much higher, indicating
the strongly enhanced bowl-shaped structures induced by
pyrrole rings. As shown by the crystal structure of 7, the
highest local curvature, 4.7°, is found on C10 (C10A),
corresponding to one of the β-carbons in the pyrrole rings,
and the average pyramidalization angle for the carbons of
the central benzene ring in the perylene core is 3.1°. These
results are in agreement with the computed structures
(Supporting Information) and the POAV1 analysis provides
further evidence on the enhanced bowl-shaped structure of 7
compared to that of 6, induced by the increased strain
associated with pyrrole rings. It is also suggested that the
curvatures of PBI bowls in the diPBI series can be easily
modified by the introduction of atoms with different radius
in bay regions.
Not only do they significantly alter the structures of the
aromatic core, but the introduction of heteroatoms to diPBI
skeletons also induces highly ordered superstructures. Inter-
estingly, unique ribbons of S-diPBI 6 were observed in the
crystal structure (Figure 5), similarly with those found in the
The crystal structures of S-diPBI 6 and N-diPBI 7 reveal
that both of them have crystallographically imposed inver-
sion symmetry and the steric congestion between H atoms in
nonbay regions and the adjacent O atoms force the neigh-
boring imide rings to adopt an out-of-plane distorted con-
formation (Figure 4). With the steric congestion in nonbay
(19) (a) Haddon, R. C.; Scott, L. T. Pure Appl. Chem. 1986, 58, 137–142.
(b) Haddon, R. C. J. Am. Chem. Soc. 1987, 109, 1676–1685. (c) Haddon,
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FIGURE 4. ORTEP drawing of the molecular structures of 6 (a) and 7 (b) with 30% probability ellipsoids. POAV1 pyramidalization angles
(Θσπ - 90) of one PBI unit based on the crystal structures of 6 and 7 are given: (top) top view and (bottom) side view.
crystal of 2. The inversion-related pairs of S-diPBI molecules
in the crystal of 6 are linked by C3-H3 O1 hydrogen
heteroderivatives featuring five-member rings. The shallow
maximum observed for 5 at ca. 510-520 nm (black dot in the
figure) disappears for 6 and 7 and at the same time a new
electronic transition appears at lower energies (red and blue
triangles in the figure), in the region of the 0-1 vibronic band
associated with the first electronic transition. Inspection of
the wave functions associated with these (black dot and red,
blue triangles) electronic transitions shows a similar orbital
nature. The red shift in bowl-shaped derivatives results from
the modulation of molecular orbital energies (and shapes)
induced by the presence of the heteroatoms forming the five-
member rings.
3 3 3
˚
bonds with H O distances of 2.29 A and C-H O 134.7°
3 3 3
3 3 3
and S1 O1 intermolecular contacts with S O distances
3 3 3
3 3 3
˚
of 3.06 A. The probable reason for the formation of ribbons
in 6 is the subtle influence of sulfur atoms on the molecular
electronic structure.
Absorption Spectra and Electrochemical Properties. The
introduction of S and N atoms to diPBI skeletons leads to a
remarkable change in the electronic absorption spectra. The
blue-black solution of S-diPBI 6 exhibits three major absorp-
tion bands at 411, 584, and 633 nm (εmax=90500 M-1 cm-1
)
with a blue shift of 51 nm relative to 5, as a reflection of the
expanded aromatic core (Figure 6) with a five-atom ring.
Compared with 5, N-diPBI 7 displays hypsochromically
shifted spectra with five major bands at 414, 430, 574, 620,
and 670 nm (εmax=77100 M-1 cm-1). As revealed by the
absorption spectra, the energy of the lowest allowed electronic
transition, namely the optical gap, increases with the incor-
poration of heteroatoms in bay regions.
The TDDFT calculated absorption spectra of 6 and 7 agree
very well with the observed counterpart although the excita-
tion energy of the S0 f S1 transition of 7 is overestimated. The
overestimate results from the limited basis set we were forced
to use because of the size of the systems. Calculations on
similar heteroderivatives of smaller sizes show that an almost
perfect match between computed and observed energies is
obtained employing the larger 6-31+G** basis set.
The frontier orbitals (the highest occupied and the lowest
two unoccupied) of 6 and 7 at the optimized cis structures,
along with a schematic representation of their computed
energies, are depicted in Figure 7. It can be seen that the
incorporation of heteroatoms modifies the shapes of these
orbitals compared with those of 5 (see Figure S13 in the
Supporting Information) although they conserve essentially
the same parentage. The energies of LUMO and LUMO+1
of 6 and 7 are less negative than those of 5 because of the
expanded π-system by heteroatoms.
Similar to 5, the cyclic voltammograms of 6 and 7 exhibit
four reduction waves (Figure 8), revealing that both 6 and 7
are easily reduced and can accept up to four electrons. The
half-wave reduction potentials vs. Fc/Fc+ are -0.62, -0.90,
-1.60, and -1.73 V for 6 and -0.73, -1.01, -1.65, and
-1.85 V for 7. Compared with 5,12 the first reduction
potentials of 6 and 7 are more negative, suggesting an
increased LUMO energy associated with the expansion of
The comparison between computed and observed spectra
shows an interesting feature characterizing the bowl-shaped
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FIGURE 5. Intermolecular interactions in the crystal structure of 6.
FIGURE 6. Top: The TD B3LYP/3-21G* calculated absorption spectra of 5 (black), 6 (blue), and 7 (red) at the optimized cis structures.
Bottom: Absorption spectra of 5 (black), 6 (blue), and 7 (red) in CHCl3.
the conjugated system through the incorporation of a pen-
tagonal ring, in agreement with the computed results (see
Table S1 in the Supporting Information). Due to the stronger
electron-donating properties of nitrogen atoms compared to
sulfur atoms, 7 is more difficult to reduce than 6, in agree-
ment with the calculated LUMO energies. Thus, the electro-
chemical properties as well as the frontier orbital energies can
be easily modulated by incorporating different heteroatoms
into bay regions of diPBI.
The structures of PBI bowls confirmed by single-crystal X-ray
structure analysis are realized by the introduction of the steric
congestion in nonbay regions between hydrogen atoms and
neighboring oxygen atoms and by the concurrent formation
of the five-membered heterorings strain in bay regions. More-
over, on the basis of the geometry obtained from the X-ray
analysis of 6 and 7, the maximum pyramidalization angle is
found in 7, as large as 4.7°, indicating the formation of two
PBI bowls with significant curvatures. The analysis of the
absorption spectra has revealed a unique fingerprint asso-
ciated with the presence of pentagon rings, a marked red shift
of the second allowed electronic transition. Furthermore, the
curvatures, the electronic properties, and the frontier orbitals
Conclusions
Insummary, wehavepresented the facile synthesisof S- and
N-diPBI with extraordinary doubly bowl-shaped structures.
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FIGURE 7. B3LYP/3-21G* computed energies and shapes of the frontier orbitals of S-diPBI 6 (top) and N-diPBI 7 (bottom) at the optimized
cis structure.
FIGURE 8. Reductive cyclic voltammograms of 6 (a) and 7 (b) in CH2Cl2. Scan rate: 0.1 V/s (electrolyte: 0.1 M TBAPF6).
of the PBI bowls can be easily modulated by altering the
covalent radius of the bridged atoms. In light of the accessi-
bility to synthesis and functionalization, the unique doubly
bowl-shaped structures, the controllable curvatures, and the
easily tunable optical and electrochemical properties, hetero-
cyclic annelated diPBIs are promising not only for basic
research in molecular engineering, but also for applications
in materials science.
12 h. After removal of the solvent under vacuum, the crude was
washed with EtOH, dried, dissolved in dichloromethane, and
purified by column chromatography (silica gel, petroleum ether/
CH2Cl2=1:3). Yield 451 mg (68%) of 6 as a blue-black solid.
1H NMR (CDCl3, 300 MHz, 298 K, TMS) δ 10.88 (s, 2H), 10.20
(s, 2H), 9.93 (s, 2H), 7.54 (m, 4H), 7.40 (d, 3J(H,H)=7.8 Hz,8H),
3
3.15 (br, 4H), 2.90 (m, 4H), 1.28 (m, 24H), 1.13 (d, J(H,H)=
6.8 Hz, 12H), 0.87 (d, 3J(H,H)=6.7 Hz, 12H); 13C NMR (CDCl3,
150 MHz, 298 K) δ 164.9, 164.7, 164.6, 163.4, 146.2, 146.1, 140.4,
139.7, 132.0, 131.8, 131.6, 131.5, 131.3, 129.3, 127.3, 125.9, 125.8,
125.0, 124.4, 123.3, 123.1, 121.6, 121.5, 120.1, 119.4, 29.9, 29.4,
24.7, 24.3, 24.2, 24.1. MS (MALDI-TOF) calcd for M- 1474.5,
found 1474.9.
Experimental Section
Synthesis and Characterization. All chemicals were purchased
from commercial suppliers and used without further purifica-
tion unless otherwise specified. Toluene was freshly distilled
from sordium prior to use. Tetrachloro-diPBIs 8 were prepared
according to known procedures.12
S-diPBI 6. Pd(PPh3)4 (156 mg, 0.135 mmol) and Bu3SnSSn-
Bu3 (552 mg, 0.90 mmol) were added to a solution of 8 (700 mg,
0.45 mmol) in toluene under Ar. The mixture was refluxed for
N-diPBI 7. Aniline (110 mg, 1.18 mmol) was added to a
mixture of tetrachloro-diPBIs 8 (250 mg, 0.16 mmol), Pd(OAc)2
(80 mg, 0.36 mmol), PCy3 (70 mg, 0.25 mmol), and KOt-Bu
(200 mg, 1.79 mmol) in 10 mL of toluene under Ar. The mixture
was refluxed for 5 h, and then cooled. After removal of the
solvent under vacuum, the crude was washed with HCl and
extracted with CH2Cl2. The organic layers were separated,
J. Org. Chem. Vol. 74, No. 16, 2009 6281

Qian et al.
JOCArticle
washed with brine, dried over Na2SO4, and purified by column
3
3
˚
γ=90.00°, V=5826.2(12) A , Z=4, Dc =1.362 g/cm , μ=
0.438 mm-1, θ range 1.62-25.00°. Of the 10255 reflections that
were collected, 9157 were unique (Rint=.0.0685), GOF=1.191,
R1=0.0959, wR2=0.2568 for reflections with I > 2σ(I). Largest
chromatography (silica gel, CH2Cl2). Yield 130 mg (51%) of 7
as a black solid. H NMR (CD2Cl2, 300 MHz, 298 K, TMS)
1
3
δ 10.93 (s, 2H), 9.80 (s, 2H), 9.51 (s, 2H), 8.19 (d, J(H,H)=
7.8 Hz, 4H), 7.86 (t, 3J(H,H) = 7.8 Hz, 4H), 7.67 (m, 4H),
7.51 (m, 2H), 7.38 (m, 8H), 3.17 (m, 4H), 2.86 (m, 4H), 1.31
diff. peak and hole, 0.803 and -0.934 e/A .
3
˚
3
3
(d, J(H,H)=6.7 Hz, 12H), 1.14 (d, J(H,H)=6.6 Hz, 12H),
1.08 (m, 24H). 13C NMR (CD2Cl2, 100 MHz, 298 K) δ 165.9,
165.5, 164.6, 146.5, 138.1, 137.1, 132.3, 131.1, 130.2, 128.5,
125.9, 125.5, 124.9, 124.5, 123.9, 123.2, 122.8, 121.6, 121.3,
120.5, 119.4, 29.8, 29.2, 22.8. MS (MALDI-TOF) calcd for
M- 1592.6, found 1592.4.
Acknowledgment. For financial support of this research,
we thank the National Natural Science Foundation of China
(grant nos. 20721061 and 50873106), 973 Program (Grant
2006CB932101), Chinese Academy of Sciences, BASF SE,
and Italian MIUR (funds ex 60%).
Crystallographic Data. S-diPBI 6:. 0.5S-diPBI 0.75CH2Cl2
C6H14, C54.75H52.50Cl1.50N2O4S, Mw =887.72, triclinic, space
3
3
Supporting Information Available: Synthesis and character-
ization of compound 4, MS and H NMR spectra, optimized
1
˚
group P1, a=8.3321(14) A, b=15.291(3) A, c=20.134(4) A,
˚
˚
3
R=73.673(4)°, β=86.124(6)°, γ=85.033(6)°, V=2450.1(7) A ,
structure of 3, crystal structures, temperature-dependent 1H
NMR spectra, selected bond lengths and POAV1 pyramidaliza-
tion angles based on the optimized structures of 6 and 7, a table
with absolute energies, relative energies, MO energies, HOMO-
LUMO gaps, and optical gaps of cis and trans conformations of
5-7, comparison between computed frontier orbitals of 5-7,
complete ref 16, and the Cartesian coordinates of all the
structures optimized. This material is available free of charge
via the Internet at http://pubs.acs.org.
˚
Z=2, Dc=1.203 g/cm3, μ=0.194 mm-1, θ range 1.97-25.00°.
Of the 8605 reflections that were collected, 7110 were unique
(Rint =0.0346), GOF=1.285, R1 =0.0962, wR2 =0.2987 for
reflections with I > 2σ(I). Largest diff. peak and hole, 1.423 and
3
˚
-1.126 e/A .
N-diPBI 7:. 0.5N-diPBI 4CH2Cl2 C3H6O, C61H56Cl8N3O5,
3
3
˚
Mw=1194.69, monoclinic, space group P121/a1, a=18.270(2) A,
˚
˚
b=16.5555(17) A, c=19.663(3) A, R=90.00°, β=101.596(6)°,
6282 J. Org. Chem. Vol. 74, No. 16, 2009