Facile formation of stable crystals with gold-like metallic luster from organic molecules: 1-Aryl-2-(2-thienyl)-5-[5-(tricyanoethenyl)-2-thienyl]pyrroles

Article abstract of DOI:10.1246/bcsj.75.2359

The derivatives of 1-phenyl-2-(2-thienyl)-5-[5-(tricyanoethenyl)-2-thienyl]pyrrole (1a) formed crystals with gold-like or bronze-like metallic luster. When a small substituent is located at the para position of the 1-phenyl group, gold-like lustrous crystals were formed. In contrast, the derivatives of 1 having a longer alkyl chain at the para position of the 1-phenyl group gave bronze-like crystals. The gold-like lustrous crystals have a sheet structure. In the sheet, the molecules of 1 are close to each other via the intermolecular interaction of cyano nitrogen with the hydrogen of the nearest thiophene or pyrrole ring, which enables the side-by-side interaction of the cyano group with the nearest thiophene and pyrrole rings. The bronze-like crystals have a lamella structure of the long alkyl chains that is sandwiched by two π-electron walls. In the wall, the 2-(2-thienyl)-5-[5-(tricyanoethenyl)-2-thienyl]pyrrole moieties are arranged in a ribbon structure to interact to each other. The relationship of the arrangement of the 2-(2-thienyl)-5-[5-(tricyanoethenyl)-2-thienyl]pyrrole moieties with the metallic color of the crystals is discussed.

Full text of DOI:10.1246/bcsj.75.2359

c. Jpn.
© 2002 The Chemical Society of Japan
Bull. Chem. Soc. Jpn., 75, 2359–2370 (2002) 2359
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Headline Articles
Facile Formation of Stable Crystals with Gold-like Metallic Luster from
Organic Molecules: 1-Aryl-2-(2-thienyl)-5-[5-(tricyanoethenyl)-2-
thienyl]pyrroles
02
59
70
SJA8
09-2673
144
K. Ogura et al.
Katsuyuki Ogura,*, # Rui Zhao,† Hiroyuki Yanai, Kazuhiro Maeda,† Ryo Tozawa, Shoji Matsumoto,
and Motohiro Akazome
02
02
Department of Materials Technology, Faculty of Engineering, Chiba University,
1-33 Yayoicho, Inageku, Chiba 263-8522
†Graduate School of Science and Technology, Chiba University, 1-33 Yayoicho, Inageku, Chiba 263-8522
(Received May 27, 2002)
.3
.10
The derivatives of 1-phenyl-2-(2-thienyl)-5-[5-(tricyanoethenyl)-2-thienyl]pyrrole (1a) formed crystals with gold-
like or bronze-like metallic luster. When a small substituent is located at the para position of the 1-phenyl group, gold-
like lustrous crystals were formed. In contrast, the derivatives of 1 having a longer alkyl chain at the para position of the
1-phenyl group gave bronze-like crystals. The gold-like lustrous crystals have a sheet structure. In the sheet, the mole-
cules of 1 are close to each other via the intermolecular interaction of cyano nitrogen with the hydrogen of the nearest
thiophene or pyrrole ring, which enables the side-by-side interaction of the cyano group with the nearest thiophene and
pyrrole rings. The bronze-like crystals have a lamella structure of the long alkyl chains that is sandwiched by two π-elec-
tron walls. In the wall, the 2-(2-thienyl)-5-[5-(tricyanoethenyl)-2-thienyl]pyrrole moieties are arranged in a ribbon struc-
ture to interact to each other. The relationship of the arrangement of the 2-(2-thienyl)-5-[5-(tricyanoethenyl)-2-thien-
yl]pyrrole moieties with the metallic color of the crystals is discussed.
Hitherto, chemists have succeeded in producing metal-like
organic and organometallic materials. These include electron-
conducting polymers1 such as polythiophenes2 and polyacety-
lenes,3 molecular metals that require charge transfer between
two different chemical species,4–6 and highly conducting crys-
tals consisting of single-component neutral nickel complex-
es.7,8 Some organic π-conjugated molecules with relatively
lower molecular weights were known to exhibit metallic luster.
Recently, Cava et al. reported furan- and pyrrole-containing
analogs of 2,2ꢀ:5ꢀ,2ꢁ:5ꢁ,2ꢁꢀ:5ꢁꢀ,2ꢁꢁ-quinquethiophene that
formed golden yellow crystals.9 Holmes et al. synthesized a
fused thiophene, 2,2ꢀ-bi(dithieno[3,2-b:2ꢀ,3ꢀ-d]thiophene)
(BDT) which gave a microcrystalline powder with gold-like
luster.10 The molecules of BDT were shown by X-ray crystal-
lographic analysis to adopt a completely coplanar conforma-
tion with a unique π–π stacking. It was indicated that the me-
tallic luster results mainly from vertical interaction among the
π-molecular orbitals of BDT and intermolecular interaction
between the sulfur atoms. Here, we report novel organic com-
pounds, 1-aryl-2-(2-thienyl)-5-[5-(tricyanoethenyl)-2-thien-
yl]pyrroles (1), which easily form gold-like and bronze-like
lustrous crystals (Fig. 1).
Results and Discussion
Various derivatives of 1-aryl-2-(2-thienyl)-5-[5-(tricyano-
ethenyl)-2-thienyl]pyrroles (1) can be easily synthesized. Re-
action of 1-aryl-2,5-di(2-thienyl)pyrroles (2)11,12 with tetracya-
noethylene occurred at ambient temperature in N,N-dimethyl-
formamide (DMF) to produce many kinds of 1 that are sum-
marized in Scheme 1.13 They are soluble in common organic
solvents such as chloroform, acetone, and THF to give a deep
blue solution because they absorb visible light around the
wavelength of 600–620 nm (Fig. 2). To our surprise, slow
evaporation of the solvent gave crystals with gold-like metallic
luster (Figs. 1a and 1b). All of the compounds except for 1c
exhibited good crystallinity. Interestingly, gold-like lustrous
crystals were formed in the case that the N-substituent of 1 is
the phenyl group having a small substituent (shorter than C3-
chain length) at the para position (1a–1j). Typical photographs
of the crystals are shown in Fig. 1. The crystals have shiny flat
surfaces as if they are metal. The crystals of 1 were entirely
stable in air and no change was observed after being allowed to
stand at ambient temperature for more than three years. The
gold-like lustrous crystals could be easily formed. When one
# Graduate School of Science and Technology

2360 Bull. Chem. Soc. Jpn., 75, No. 11 (2002)
HEADLINE ARTICLES
drop of a CHCl3 solution of 1 was placed on a glass plate,
small crystals were formed as soon as the solvent evaporated.
The typical solid-state UV-vis-NIR diffuse reflection-ab-
sorption spectra of these crystals (1a, 1b, 1d, 1g, and 1j) are
shown in Fig. 3. Instead of the absorption band around 600–
620 nm in solution, strong absorption appeared at longer wave-
lengths, corresponding to the band gap (or exciton) that is be-
low 1.4 eV, in range of infra-red (longer than 900 nm). This
indicates that strong intermolecular interaction among the π-
orbitals of 1 is possible in the crystalline state.14 Generally
speaking, the appearance of a solid depends on the degree of
absorption and reflectance in the visible region of the spec-
trum, where photon energies are in the range of 1.5–3 eV
(800–400 nm wavelength). With a band gap below 1.5 eV, in
the infrared, the solid may appear dark in color or shiny metal-
lic, depending on the reflectivity.14 The present crystals (1a–
1j) are the latter case. Further, strong absorption appeared be-
low 550–540 nm with a maximum at 490–480 nm in the solid
Fig. 1. Typical photographs of gold-like and bronze-like lustrous crystals (see front cover) : a) 1d. b) 1g. c) 1k.
Scheme 1.
Fig. 2. Typical UV-vis absorption spectra of 1: 1a (λmax
=
Fig. 3. UV-vis-NIR diffuse reflection-absorption spectra of
the gold-like lustrous crystals 1a, 1b, 1d, 1g, 1j, and Au
plate (bottom line).
609 nm), 1b (λmax = 621 nm) and 1g (λmax = 610 nm) in
THF (3 × 10−5 M) (1M = 1 mol dm−3).

K. Ogura et al.
Bull. Chem. Soc. Jpn., 75, No. 11 (2002) 2361
Fig. 4. Conformation of the molecule in crystals. a) 1a. b) 1b. c) 1d. d) 1g. e) 1i. f) 1j. The values mean the dihedral angle of the
day in which it is located. The value of 80–90° is the torsion angle between the pyrrole and aryl rings. For the molecules 1a and
1j, the disorder of the terminal thiophene ring was observed. In 1d, all H atoms are omitted for clarity because some H atoms can-
not be assigned precisely due to the disordered propyl group.
Fig. 6. The crystal structure of 1b. a) The coplanar sheet-
like structure. The distance between N and C atoms: a,
3.57 Å; b, 3.45 Å; c, 3.39 Å. The distance between N and
H: d, 2.68 Å; e, 2.61 Å; f, 2.63 Å. b) A side view of the
stacking layers. The layer distance is 3.60 Å (by PXRD).
Fig. 5. The crystal structure of 1a. a) The coplanar sheet-
like structure. The distance between C and N atoms: a,
3.63 Å; b, 3.58 Å; c, 3.33 Å. The distance between H and
N atoms: d, 2.67 Å; e, 2.68 Å; f, 2.56 Å. b) A side view of
thestackinglayers. Thelayer distance is3.60 Å(byPXRD).
held by weak interactions. The molecules in these crystals
adopt a flat conformation as summarized in Fig. 4. The tricya-
noethenyl group, 2,5-thienylene ring, and the central pyrrole
ring are arranged with perfect coplanarity (torsion angle < 3°),
but the terminal thiophene ring was somewhat deviated from
the pyrrole plane. The crystal structures of 1a (Y = H) and 1b
(Y = CH3) are given in Figs. 5 and 6, respectively.
In both of the crystals, the flat molecules form completely
planar sheets which stack to produce the crystal lattice. In the
sheet of 1a (Fig. 5), the molecules are held together with inter-
state spectra of 1a–1j. Consequently, the spectra of the present
crystals in the region of visible light (400–800 nm) resemble
that of gold plate, as shown in Fig. 3.
Fortunately, crystals of sufficient quality for structural stud-
ies were obtained for the compounds 1a, 1b, 1d, 1g, 1i, and 1j.
It is noteworthy that all of these crystals contain two-dimen-
sional layers. As described in the literature,15 this seems to in-
dicate that the molecules in one layer are held together by
strong intermolecular interactions and the adjacent layers are

2362 Bull. Chem. Soc. Jpn., 75, No. 11 (2002)
HEADLINE ARTICLES
1a. The molecules of 1b in the sheet are arranged by means of
the interaction of the cyano nitrogen with the hydrogen of
thiophene (surrounded by a dotted line). Another interaction
was observed between cyano nitrogen and the pyrrole hydro-
gen (d and e). As a result of these interactions, the cyano nitro-
gens are close to the sp2 carbons of pyrrole and thiophene
(marked with a, b, and c: 3.3–3.6 Å). As summarized in Fig. 7,
the crystal structures of 1d, 1g, 1i, and 1j are similar to that of
1b.
Scheme 2.
As mentioned above, 1-aryl-2-(2-thienyl)-5-[5-(tricyanoet-
henyl)-2-thienyl]pyrroles (1k–1p) that have long alkyl groups
at the para position of the central phenyl group formed crystals
with bronze-like metallic luster (Fig. 1c). Their solid-state
UV-vis-NIR diffuse reflection-absorption spectra that are
shown in Fig. 8 are quite different from those of the crystals of
1a–1j that exhibit gold-like metallic luster. Interestingly, the
powder X-ray diffraction patterns of these crystals (Scheme 3)
exhibited intense peaks in the lower-angle region [1k (n = 4),
18.7 Å; 1l (n = 6), 20.4 Å; 1m (n = 10), 24.3 Å; 1n (n = 12),
25.9 Å; 1o (n = 14), 27.9 Å; 1p (n = 16), 29.5 Å]. It is likely
that these intense signals correspond to the layer distance of
molecular interactions between the cyano nitrogen and the hy-
drogen of pyrrole or thiophene (marked with the letters d, e,
and f). Hitherto, a cyano group has been reported to assist the
formation of a sheet structure in a crystal with the aid of inter-
molecular contact with aromatic hydrogen16 or chalcogen at-
oms.17 In the present cases, the cyano nitrogen approaches the
olefinic hydrogen of pyrrole or thiophene ring so that the cy-
ano nitrogens are close to the sp2 carbons of pyrrole and
thiophene (Scheme 2) at many points (marked with a, b, and c:
3.3–3.6 Å).
The sheet structure of 1b (Fig. 6) is different from that of
Fig. 7. The sheet structures (top view) in crystal. a) 1d. Some H atoms could not be assigned so that all H atoms are omitted for
clarity. The disorder of the central carbon of propyl group was observed. b) 1g. c) 1i. d) 1j. The disorder of the terminal
thiophene ring was observed.

K. Ogura et al.
Bull. Chem. Soc. Jpn., 75, No. 11 (2002) 2363
alkyl chain sandwiched between the walls (width: about 15.0/2
Å) that are constructed by stacking of the π-systems of 1, as
depicted illustratively in Fig. 10. The value of 0.91, the coeffi-
cient of n, means that the alkyl chain is not perpendicular to
the wall, which is common to the crystals of 1k–1p bearing a
long alkyl chain. The inclination angle of the alkyl chain is
calculated to be 44°, based on the length of tetradecyl chain
(17.8 Å in the crystal structure of 1o•acetone) and the value of
0.91 × 14 Å. In order to confirm the illustration (Fig. 10), we
concentrated on the formation of single crystals of 1k–1p that
are suitable for X-ray crystallographic analysis. By recrystalli-
zation of 1o (Y = n-C14H29) from acetone, we fortunately ob-
tained single crystals with sufficient quality for structural
study. These crystals include an equimolar amount of acetone.
The PXRD pattern of the single crystals showed a sharp signal
at a lower angle (d = 29.63 Å) together with two sharp signals
(d = 14.87 Å and 9.92 Å). In the crystalline state, the expect-
ed lamella structure of the alkyl chains was observed (Fig. 11).
The lamellas stack to construct the layer of the tetradecyl
chains. The lamella layer was sandwiched between the walls
that consist of 1-phenyl-2-(2-thienyl)-5-[5-(tricyanoethenyl)-
2-thienyl]pyrrole systems. Acetone molecules are located be-
tween the walls. The solid-state UV-vis-NIR diffuse reflec-
tion-absorption spectra are different from those of the gold-
like lustrous crystals of 1a–1d. The metallic luster of the crys-
tal indicates the presence of strong interactions among the π-
systems in the wall. The wall is constructed by stacking of the
ribbon-like structures of 2-(2-thienyl)-5-[5-(tricyanoethenyl)-
2-thienyl]pyrrole π-systems. In the ribbon, the π-systems are
arranged via the so-called hydrogen bond of the cyano nitro-
gen and terminal thiophene hydrogen so that the p-orbital of
cyano group are close enough to the p-orbital of the thiophene
carbon to interact with each other in a side-by-side manner.
Finally, we wish to comment here on the interaction of the
molecular π-orbitals between the neighboring sheets. The in-
teraction seems to be possible because these planar sheets are
close enough (average layer distance: 3.6–3.7 Å by PXRD) to
interact with each other. It was found that the compound
(3)(Chart 1) bearing a long alkyl chain (decyl group) at the
ortho position of the 1-phenyl group also formed crystals with
gold-like metallic luster. In these crystals, two conformers of 3
are paired as depicted in Fig. 12. These pairs were arranged in
a side-by-side manner to form two sheets that were separated
Fig. 8. Typical UV-vis-NIR diffuse reflection-absorption
spectra of the bronze-like lustrous crystals (1l, 1n, and 1p)
and copper foil.
Scheme 3.
the crystal. We could obtain a linear relationship of the length
of alkyl (Y) group with the layer distance (Fig. 9). It is note-
worthy that the layer distances of the gold-like crystals of 1a–d
are almost same (about 3.60 Å) and deviated from the linear
relationship. This line can be represented with an equation:
d = 0.91 × n + 15.0
wherein d and n are the layer distance (Å) and the carbon num-
ber of the alkyl chain, respectively. Thus, we can envisage the
crystal structures of 1k–1p that have a lamella structure of the
Fig. 9. Relationship between the carbon number of the alkyl
Fig. 10. The schematic desctiption of the crystal structure of
(Y) chain and the layer distance in crystals of 1.
the compounds (1k–p) having a long alkyl chain as Y.

2364 Bull. Chem. Soc. Jpn., 75, No. 11 (2002)
HEADLINE ARTICLES
Fig. 11. Crystal structure of 1o•acetone. a) A side view of the crystal. b) The top view of one layer. For simplicity, the acetone mol-
ecules are omitted. The distance between C and N atoms: a, 3.58 Å; b, 3.67 Å. The distance between H and N atoms: c, 2.64 Å.
c) The side view of the plane b).
plays an important role in the origin of the gold-like metallic
luster.
Experimental
General Methods. All chemicals were obtained from com-
mercial suppliers and used without further purification. 1H NMR
spectra were recorded at 300 MHz using a Varian Gemini-2000
NMR spectrometer and chemical shifts were referenced to TMS
Chart 1.
as internal standard. UV-vis absorption spectra were recorded in
THF (concentration: 3 × 10−5 M) (1 M = 1 mol dm−3) on a
by the decyl chain layer. Consequently, a bilayer structure was
constructed (Fig. 13). The molecules of 3 in Chart 1 are
JASCO V-570 spectrophotometer. Solid-state UV-vis-NIR diffuse
reflection-absorption spectra were also recorded on a JASCO V-
enough close to each other via the hydrogen bonding between
the cyano nitrogen and the olefinic hydrogen (Fig. 13a). Since
their solid diffuse reflection-absorption spectra in the visible
light region resembled that of gold plate (Fig. 14), we conclud-
ed that the arrangement of the molecules in a planar sheet
570 spectrophotometer: single crystals were uniformly broken
into powder and then put into a quartz glass cell, and the response
was adjusted to the absorption mode for measurement. Infrared
spectra were measured on a JASCO FT/IR-350 spectrophotome-
ter. Melting points are determined on a hot-stage microscope ap-

K. Ogura et al.
Bull. Chem. Soc. Jpn., 75, No. 11 (2002) 2365
Fig. 12. Conformation of 3 in crystals. a) Two conformations of 3 were paired. The values mean the dihedral angle of the bay in
which it is located. The values 88.7 and 91.1 are the torsion angles between the pyrrole and o-decylphenyl rings. b) The view
from the left bottom of the paired conformations.
Fig. 13. Crystal structure of 3. a) The top view of a layer. The alkyl chains are omitted for simplicity. The distance between C and
N atoms: a, 3.52 Å; b, 3.53 Å; c, 3.55 Å; d, 3.41 Å. The distance between N and H atoms; e, 2.66 Å; f, 2.63 Å; g, 2.63 Å; h,
2.61 Å. b) A side view. c) A side view perpendicular to b).
graphite-monochromated Cu Kα radiation (40 kV, 300 mA). The
spectra were measured between 2° and 50° in the 2θ/θ-scan mode
with steps of 0.01° in 2θ and 4°/min.
Typical Procedure for the Preparation of 1-Aryl-2,5-di(2-
thienyl)pyrrole (2). Method A. A 50 mL three-necked round-
bottomed flask equipped with a Dean-stark trap, a reflux condens-
er (used as one set with the Dean-stark trap), and a nitrogen-filled
balloon was charged with 1,4-di(2-thienyl)-1,4-butanedione
(500 mg, 2.00 mmol) and the corresponding aniline derivative
(8.00 mmol) in 30 mL of 3:1 (v/v) toluene–acetic acid solution.
The reaction mixture was refluxed at 140–150 °C (oil bath temper-
ature) for suitable times (monitored the reaction progress with
TLC) and then cooled to room temperature. After the dark brown
solution was transferred to a 300 mL beaker, a saturated Na2CO3
Fig. 14. UV-vis-NIR diffuse reflection spectra of gold-like
aqueous solution was added to make the reaction mixture basic.
lustrous crystals of 3.
The organic layer was separated and then the aqueous layer was
extracted with toluene (10 mL × 2). The combined organic layers
paratus (Yanaco MP-500D) and are uncorrected. Elemental anal-
ysis was performed by the Chemical Analysis Center of Chiba
University. All powder X-ray diffraction (PDXR) analyses were
taken on a MAC Science MXP powder diffractometer using
were washed with water, dried over anhydrous MgSO4 and then
concentrated in vacuo. The residue was purified by column chro-
matography (silica gel, toluene) and then recrystallized from ace-
tone to afford 2 as a pure product.

2366 Bull. Chem. Soc. Jpn., 75, No. 11 (2002)
HEADLINE ARTICLES
1051, 843, 764, 696 cm−1
Method B. A mixture of 1,4-di(2-thienyl)-1,4-butanedione
(500 mg, 2.00 mmol), the corresponding aniline derivative
(8.00 mmol), and p-toluenesulfonic acid monohydrate (76.2 mg,
0.400 mmol) was heated at 110 °C for 5–24 h under stirring (mon-
itored the reaction progress with TLC) and then cooled to room
temperature. After toluene (20–30 mL) was added to dissolve the
crude product, the insoluble solid was filtered off. The obtained
toluene solution was concentrated in vacuo and then purified by a
procedure similar to that described in method A.
. Anal. Calcd for C18H12FNS2: C,
66.44; H, 3.72; N, 4.30%. Found: C, 66.31; H, 3.62; N, 4.16%.
1-(p-Chlorophenyl)-2,5-di(2-thienyl)pyrrole (2h). Method
A or B, 58% or 74% yield, respectively: pale yellow crystals; mp
1
189.0–190.0 °C; H NMR (CDCl3) δ 6.53 (s, 2H), 6.55 (dd, J =
1.2 and 3.7 Hz, 2H), 6.84 (dd, J = 3.7 and 5.2 Hz, 2H), 7.09 (dd, J
= 1.2 and 5.2 Hz, 2H), 7.24 (d, J = 8.8 Hz, 2H), 7.38 (dd, J =
8.9 Hz, 2H); IR (KBr) 1509, 1490, 1415, 1265, 1091, 1023, 832,
763, 699 cm−1. Anal. Calcd for C18H12ClNS2: C, 63.24; H, 3.54;
N, 4.10%. Found: C, 63.21; H, 3.56; N, 3.94%.
1-Phenyl-2,5-di(2-thienyl)pyrrole (2a). Method B, 83%
yield: pale yellow crystals; mp 180.8–181.5 °C; 1H NMR (CDCl3)
δ 6.51 (dd, J = 1.1 and 3.7 Hz, 2H), 6.54 (s, 2H), 6.81 (dd, J =
3.7 and 5.2 Hz, 2H), 7.05 (dd, J = 1.1 and 5.1 Hz, 2H), 7.30–7.48
(m, 5H); IR (KBr) 1497, 1413, 1349, 1200, 1041, 843, 773,
1-(p-Bromophenyl)-2,5-di(2-thienyl)pyrrole (2i).
Method
A, 78% yield: pale yellow crystals; mp 189.0–190.0 °C; 1H NMR
(CDCl3) δ 6.52 (s, 2H), 6.54 (dd, J = 1.1 and 3.6 Hz, 2H), 6.85
(dd, J = 3.6 and 5.1 Hz, 2H), 7.10 (dd, J = 1.1 and 5.2 Hz, 2H),
7.17 (d, J = 8.7Hz, 2H), 7.54 (dd, J = 8.7 Hz, 2H); IR (KBr)
1508, 1490, 1416, 1265, 1091, 843, 764, 696 cm−1. Anal. Calcd
for C18H12BrNS2: C, 55.96; H, 3.13; N, 3.63%. Found: C, 55.61;
H, 3.03; N, 3.52%.
695 cm−1
. Anal. Calcd for C18H13NS2: C, 70.32; H, 4.26; N,
4.56%. Found: C, 70.02; H, 4.20; N, 4.50%.
1-p-Tolyl-2,5-di(2-thienyl)pyrrole (2b). Method A, 73%
yield: pale brown solid; mp 159.0–160.0 °C; 1H NMR (CDCl3) δ
2.44 (s, 3H), 6.53 (dd, J = 1.1 and 3.7 Hz, 2H), 6.54 (s, 2H), 6.82
(dd, J = 3.6 and 5.1 Hz, 2H), 7.04 (dd, J = 1.1 and 5.1 Hz, 2H),
7.19 (d, J = 8.7 Hz, 2H), 7.22 (d, J = 8.7 Hz, 2H); IR (KBr) 1509,
1420, 1261, 1041, 801, 689 cm−1. Anal. Calcd for C19H15NS2: C,
70.99; H, 4.70; N, 4.36%. Found: C, 70.85; H, 4.86; N, 4.53%.
1-(p-Ethylphenyl)-2,5-di(2-thienyl)pyrrole (2c). Method A,
1-(p-Cyanophenyl)-2,5-di(2-thienyl)pyrrole (2j).
Method
A or B, 18% or 64% yield, respectively: pale yellow needles; mp
211.0–211.5 °C; 1H NMR (CDCl3) δ 6.52 (dd, J = 1.2 and 3.7 Hz,
2H), 6.54 (s, 2H), 6.86 (dd, J = 3.6 and 5.1 Hz, 2H), 7.03 (dd, J =
1.1 and 5.1 Hz, 2H), 7.35 (d, J = 8.8 Hz, 2H), 7.67 (dd, J =
8.7 Hz, 2H); IR (KBr) 2228, 1508, 1412, 1200, 1033, 846, 764,
1
90% yield: pale brown crystals; mp 138.5–139.5 °C; H NMR
702 cm−1
68.12; H, 4.18; N, 7.75%. Found: C, 67.97; H, 3.86; N, 7.76%.
.
Anal. Calcd for C19H12N2S2•0.50CH3COCH3: C,
(CDCl3) δ 1.28 (t, J = 7.6 Hz, 3H), 2.76 (q, J = 7.6 Hz, 2H), 6.51
(dd, J = 1.1 and 5.1 Hz, 2H), 6.52 (s, 2H), 6.79 (dd, J = 3.6 and
5.1 Hz, 2H), 7.04 (dd, J = 1.1 and 3.6 Hz, 2H), 7.23 (br-s, 4H); IR
(KBr) 1514, 1459, 1415, 1200, 1041, 846, 760, 701 cm−1. Anal.
Calcd for C20H17NS2: C, 71.61; H, 5.11; N, 4.18%. Found: C,
71.53; H, 5.09; N, 4.14%.
1-(p-Butylphenyl)-2,5-di(2-thienyl)pyrrole (2k).
Method
A, 86% yield: pale yellow crystals; mp 122.0–123.0 °C; 1H NMR
(CDCl3) δ 0.95 (t, J = 7.3 Hz, 3H), 1.37 (tq-like, 2H), 1.65 (tq-
like, 2H), 2.69 (t, J = 7.7 Hz, 2H), 6.52 (dd, J = 1.1 and 3.6 Hz,
2H), 6.53 (s, 2H), 6.80 (dd, J = 3.6 and 5.2 Hz, 2H), 7.04 (dd, J =
1.1 and 5.1 Hz, 2H), 7.22 (br-s, 4H); IR (KBr) 1510, 1458, 1415,
1-(p-Propylphenyl)-2,5-di(2-thienyl)pyrrole (2d).
Method
A, 85% yield: pale yellow crystals; mp 147.5–148.5 °C; 1H NMR
(CDCl3) δ 0.95 (t, J = 7.3 Hz, 3H), 1.70 (tq-like, 2H), 2.67 (t, J =
7.6 Hz, 2H), 6.52 (dd, J = 1.1 and 3.7 Hz, 2H), 6.53 (s, 2H), 6.80
(dd, J = 3.7 and 5.1 Hz, 2H), 7.04 (dd, J = 1.1 and 5.1 Hz, 2H),
7.22 (br-s, 4H); IR (KBr) 1509, 1413, 1330, 1220, 1032, 831, 760,
1349, 1200, 1041, 846, 763, 693 cm−1
.
Anal. Calcd for
C22H21NS2: C, 72.68; H, 5.82; N, 3.85%. Found: C, 72.48; H,
5.90; N, 3.99%.
1-(p-Hexylphenyl)-2,5-di(2-thienyl)pyrrole (2l). Method A,
69% yield: pale yellow crystals; mp 123.5–124.5 °C; H NMR
1
693 cm−1
.
Anal. Calcd for C21H19NS2: C, 72.16; H, 5.48; N,
(CDCl3) δ 0.89 (t, J = 7.0 Hz, 3H), 1.29–1.50 (m, 6H), 1.70–1.80
(m, 2H), 2.69 (t, J = 7.6 Hz, 2H), 6.52 (dd, J = 1.1 and 3.6 Hz,
2H), 6.53 (s, 2H), 6.80 (dd, J = 3.7 and 5.1 Hz, 2H), 7.03 (dd, J =
1.1 and 5.1 Hz, 2H), 7.21 (br-s, 4H); IR (KBr) 1510, 1467, 1415,
4.01%. Found: C, 71.97; H, 5.45; N, 3.95%.
1-(p-sec-Butylphenyl)-2,5-di(2-thienyl)pyrrole (2e). Meth-
od A, 86% yield: pale yellow crystals; mp 133.0–134.0 °C; H
NMR (CDCl3) δ 0.83 (t, J = 7.3 Hz, 3H), 1.30 (d, 3H), 1.64 (tq-
like, 2H), 2.69 (dq-like, 1H), 6.52 (dd, J = 1.2 and 3.6 Hz, 2H),
6.54 (s, 2H), 6.80 (dd, J = 3.6 and 5.1 Hz, 2H), 7.30 (dd, J = 1.2
and 5.2 Hz, 2H), 7.23 (br-s, 4H); IR (KBr) 1512, 1458, 1416,
1200, 1041, 845, 762, 691 cm−1. Anal. Calcd for C22H21NS2: C,
72.68; H, 5.82; N, 3.85%. Found: C, 72.46; H, 5.82; N, 3.89%.
1-(p-tert-Butylphenyl)-2,5-di(2-thienyl)pyrrole (2f). Meth-
1
1349, 1198, 1040, 836, 759, 690 cm−1
.
Anal. Calcd for
C24H25NS2: C, 73.61; H, 6.43; N, 3.58%. Found: C, 73.65; H,
6.43; N, 3.52%.
1-(p-Decylphenyl)-2,5-di(2-thienyl)pyrrole (2m).
Method
B, 53% yield: pale yellow crystals; mp 107.0–108.0 °C; 1H NMR
(CDCl3) δ 0.88 (t, J = 6.7 Hz, 3H), 1.27 (m, 14H), 1.66 (m, 2H),
2.69 (t, J = 7.7 Hz, 2H), 6.53 (dd, J = 1.4 and 4.1 Hz, 2H), 6.54
(s, 2H), 6.80 (dd, J = 3.7 and 5.1 Hz, 2H), 7.03 (dd, J = 1.1 and
5.1 Hz, 2H), 7.22 (br-s, 4H); IR (KBr) 1509, 1469, 1411, 1350,
1197, 1040, 847, 763, 688 cm−1. Anal. Calcd for C28H33NS2: C,
75.12; H, 7.43; N, 3.13%. Found: C, 75.25; H, 7.49; N, 3.11%.
1
od A, 52% yield: pale yellow crystals; mp 157.0–157.5 °C; H
NMR (CDCl3) δ 0.83 (s, 9H), 6.51 (dd, J = 1.2 and 3.6 Hz, 2H),
6.54 (s, 2H), 6.80 (dd, J = 3.6 and 5.2 Hz, 2H), 7.30 (dd, J = 1.1
and 5.1 Hz, 2H), 7.23 (d, J = 8.7 Hz, 2H), 7.43 (d, J = 8.7 Hz,
2H); IR (KBr) 1512, 1413, 1219, 1111, 1035, 837, 767, 695 cm−1
.
1-(p-Dodecylphenyl)-2,5-di(2-thienyl)pyrrole (2n).
Meth-
1
Anal. Calcd for C22H21NS2: C, 72.68; H, 5.82; N, 3.85%. Found:
C, 72.51; H, 5.82; N, 3.86%.
od A, 69% yield: pale yellow crystals; mp 108.5–109.5 °C; H
NMR (CDCl3) δ 0.88 (t, J = 6.7 Hz, 3H), 1.20–1.38 (m, 18H),
1.61–1.76 (m, 2H), 2.69 (t, J = 7.6 Hz, 2H), 6.52 (dd, J = 1.2 and
3.8 Hz, 2H), 6.54 (s, 2H), 6.80 (dd, J = 3.7 and 5.1 Hz, 2H), 7.03
(dd, J = 1.2 and 5.2 Hz, 2H), 7.22 (br-s, 4H); IR (KBr) 1509,
1470, 1410, 1351, 1199, 1041, 846, 761, 687 cm−1. Anal. Calcd
for C30H37NS2: C, 75.74; H, 7.84; N, 2.94%. Found: C, 75.90; H,
7.86; N, 2.89%.
1-(p-Fluorophenyl)-2,5-di(2-thienyl)pyrrole (2g).
Method
A or B, 62% or 85% yield, respectively: pale yellow crystals; mp
1
198.0–198.5 °C; H NMR (CDCl3) δ 6.53 (s, 2H), 6.56 (dd, J =
1.1 and 3.6 Hz, 2H), 6.84 (dd, J = 3.6 and 5.1 Hz, 2H), 7.08 (dd, J
= 1.1 and 5.1 Hz, 2H), 7.11 (dd, J = 8.4 and 8.8 Hz, 2H), 7.28
(dd, J = 4.9 and 8.9 Hz, 2H); IR (KBr) 1510, 1415, 1222, 1163,

K. Ogura et al.
Bull. Chem. Soc. Jpn., 75, No. 11 (2002) 2367
1-(p-Tetradecylphenyl)-2,5-di(2-thienyl)pyrrole
(2o).
211.5–212.5 °C; 1H NMR (CDCl3) δ 1.35 (t, J = 7.6 Hz), 2.82 (q,
J = 7.6 Hz, 2H), 6.74 (d, J = 4.4 Hz, 1H), 6.79 (dd, J = 1.1 and
3.7 Hz, 1H), 6.89 (dd, J = 3.7 and 5.1 Hz, 1H), 7.03 (d, J =
4.5 Hz, 1H), 7.07 (d, J = 4.3 Hz, 1H), 7.17 (dd, J = 1.1 and 5.1
Hz, 1H), 7.31 (d, J = 8.2 Hz, 1H), 7.42 (d, J = 8.1 Hz, 1H), 7.75
(d, J = 4.5 Hz, 1H); IR (KBr) 2214, 1508, 1458, 1421, 1395,
1247, 1181, 1107, 1051 cm−1; UV-vis (THF, 3 × 10−5 M) λmax
(nm) (ε/M−1 cm−1) 620 (44400). Anal. Calcd for C25H16N4S2: C,
68.78; H, 3.69; N, 12.83%. Found: C, 68.60; H, 3.54; N, 12.55%.
1-(p-Propylphenyl)-2-(2-thienyl)-5-[5-(tricyanoethenyl)-2-
thienyl]pyrrole (1d). Gold-like lustrous crystals; 83% yield:
mp 199.0–200.0 °C (acetone); 1H NMR (CDCl3) δ 1.02 (t, J = 7.3
Hz, 3H), 1.76 (tq-like, 2H), 2.73 (t, J = 7.7 Hz, 2H), 6.74 (d, J =
4.3 Hz, 1H), 6.78 (dd, J = 1.1 and 3.7 Hz, 1H), 6.88 (dd, J = 3.8
and 5.0 Hz, 1H), 6.99 (d, J = 4.5 Hz, 1H), 7.07 (d, J = 4.4 Hz,
1H), 7.16 (dd, J = 1.1 and 5.1 Hz, 1H), 7.30 (d, J = 8.2 Hz, 2H),
7.40 (d, J = 8.2 Hz, 1H), 7.75 (d, J = 4.7 Hz, 1H); IR (KBr) 2213,
1508, 1492, 1451, 1421, 1399, 1362, 1244, 1164, 1107, 1067 cm−
1; UV-vis (THF, 3 × 10−5 M) λmax (nm) (ε/M−1 cm−1) 620
(40300). Anal. Calcd for C26H18N4S2: C, 69.31; H, 4.03; N,
12.43%. Found: C, 69.23; H, 3.86; N, 12.12%.
Method B, 66% yield: pale yellow crystals; mp 110.0–111.0 °C;
1H NMR (CDCl3) δ 0.88 (t, J = 6.7 Hz, 3H), 1.29 (m, 22H), 1.66
(m, 2H), 2.69 (t, J = 7.6 Hz, 2H), 6.52 (dd, J = 1.2 and 3.6 Hz,
2H), 6.53 (s, 2H), 6.80 (dd, J = 3.6 and 5.2 Hz, 2H), 7.03 (dd, J =
1.1 and 5.1 Hz, 2H), 7.22 (br-s, 4H); IR (KBr) 1513, 1468, 1415,
1197, 1040, 846, 764, 688 cm−1. Anal. Calcd for C32H41NS2: C,
76.29; H, 8.20; N, 2.78%. Found: C, 76.09; H, 8.38; N, 2.71%.
1-(p-Hexadecylphenyl)-2,5-di(2-thienyl)pyrrole
(2p).
Method A, 70% yield: pale yellow crystals; mp 113.0–114.0 °C;
1H NMR (CDCl3) δ 0.88 (t, J = 6.7 Hz, 3H), 1.28 (m, 26H), 1.66
(m, 2H), 2.69 (t, J = 7.7 Hz, 2H), 6.52 (dd, J = 1.4 and 3.9 Hz,
2H), 6.53 (s, 2H), 6.80 (dd, J = 3.7 and 5.1 Hz, 2H), 7.03 (dd, J =
1.1 and 5.1 Hz, 2H), 7.21 (br-s, 4H); IR (KBr) 1509, 1465, 1410,
1351, 1198, 1041, 845, 764, 688 cm−1
.
Anal. Calcd for
C34H45NS2: C, 76.78; H, 8.53; N, 2.63%. Found: C, 76.71; H,
8.59; N, 2.56%.
1-(o-Decylphenyl)-2,5-di(2-thienyl)pyrrole.
Method A,
1
79% yield: pale yellow crystals; mp 102.0–103.0 °C; H NMR
(CDCl3) δ 0.87 (t, J = 6.9 Hz, 3H), 1.21 (m, 16H), 2.17 (t, J =
8.0 Hz, 2H), 6.49 (dd, J = 1.1 and 3.7 Hz, 2H), 6.59 (s, 2H), 6.78
(dd, J = 3.7 and 5.1 Hz, 2H), 7.00 (dd, J = 1.1 and 5.1 Hz, 2H),
7.34 (m, 3H), 7.46 (dt-like, 1H); IR (KBr) 1491, 1456, 1427,
1408, 1350, 1158, 1045, 843, 764, 690 cm−1. Anal. Calcd for
C28H33NS2: C, 75.12; H, 7.43; N, 3.13%. Found: C, 75.11; H,
7.47; N, 3.16%.
1-(p-sec-Butylphenyl)-2-(2-thienyl)-5-[5-(tricyanoethenyl)-
2-thienyl]pyrrole (1e). Gold-like lustrous crystals; 89% yield:
mp 188.0–189.0 °C; 1H NMR (CDCl3) δ 0.89 (t, J = 7.3 Hz, 3H),
1.5 (d, 3H), 1.69 (dq-like, 2H), 2.77 (dq-like, 1H), 6.74 (d, J = 4.3
Hz, 1H), 6.76 (dd, J = 1.0 and 3.7 Hz, 1H), 6.87 (dd, J = 3.7 and
5.1 Hz, 1H), 6.97 (d, J = 4.7 Hz, 1H), 7.06 (d, J = 4.3 Hz, 1H),
7.16 (dd, J = 1.0 and 5.1 Hz, 1H), 7.32 (d, J = 8.7 Hz, 2H), 7.40
(d, J = 8.7 Hz, 1H), 7.78 (d, J = 4.7 Hz, 1H); IR (KBr) 2215,
A Typical Procedure for the preparation of 1-aryl-2-(2-thi-
enyl)-5-[5-(tricyanoethenyl)-2-thienyl]pyrroles (1 and 3).
A
mixture of 1-aryl-2,5-di(2-thienyl)pyrrole (0.400 mmol) and
TCNE (0.800 mmol) in 10 mL of anhydrous DMF was stirred for
24 h at room temperature. The reaction mixture was poured into a
saturated NaCl aqueous solution, and the aqueous layer was ex-
tracted with toluene (20 mL × 3). The combined organic layers
were dried over anhydrous MgSO4 and concentrated in vacuo.
The dark blue residue was purified by column chromatography
(silica gel, CHCl3) and then recrystallized from CHCl3 to give the
pure product.
1508, 1499, 1458, 1425, 1402, 1362, 1250, 1170, 1103, 1060 cm−1
;
UV-vis (THF, 3 × 10−5 M) λmax (nm) (ε/M−1 cm−1) 619 (40200).
Anal. Calcd for C27H20N4S2: C, 69.80; H, 4.34; N, 12.06%.
Found: C, 69.47; H, 4.25; N, 11.86%.
1-(p-tert-Butylphenyl)-2-(2-thienyl)-5-[5-(tricyanoethenyl)-
2-thienyl]pyrrole (1f). Gold-like lustrous crystals; 89% yield:
mp 235.5–236.0 °C; 1H NMR (CDCl3) δ 1.42 (s, 9H), 6.74 (d, J =
4.3 Hz, 1H), 6.76 (dd, J = 1.1 and 3.7 Hz, 1H), 6.88 (dd, J = 3.7
and 5.1 Hz, 1H), 7.03 (d, J = 4.5 Hz, 1H), 7.07 (d, J = 4.4 Hz,
1H), 7.16 (dd, J = 1.1 and 5.1 Hz, 1H), 7.32 (d, J = 8.5 Hz, 2H),
7.61 (d, J = 8.5 Hz, 1H), 7.78 (d, J = 4.7 Hz, 1H); IR (KBr) 2212,
1498, 1451, 1423, 1400, 1362, 1321, 1249, 1166, 1108 cm−1; UV-
vis (THF, 3 × 10−5 M) λmax (nm) (ε/M−1 cm−1) 620 (42100).
Anal. Calcd for C27H20N4S2: C, 69.80; H, 4.34; N, 12.06%.
Found: C, 69.80; H, 4.18; N, 11.69%.
1-Phenyl-2-(2-thienyl)-5-[5-(tricyanoethenyl)-2-thienyl]pyr-
role (1a). Yellowish gold-like lustrous crystals; 69% yield: mp
1
248.0–249.0 °C; H NMR (CDCl3) δ 6.74 (d, J = 4.3 Hz, 1H),
6.75 (dd, J = 1.2 and 3.6 Hz, 1H), 6.88 (dd, J = 3.8 and 5.1 Hz,
1H), 6.94 (d, J = 4.5 Hz, 1H), 7.07 (d, J = 4.3 Hz, 1H), 7.17 (dd,
J = 1.0 and 5.1 Hz, 1H), 7.42 (d, J = 7.0 Hz, 2H), 7.61 (dd, J =
7.3 and 7.4 Hz, 1H), 7.68 (d, J = 7.1 Hz, 1H), 7.75 (d, J = 4.5 Hz,
1H); IR (KBr) 2210, 1498, 1451, 1420, 1400, 1363, 1323, 1242,
1178, 1108, 1068 cm−1; UV-vis (THF, 3 × 10−5 M) λmax (nm) (ε/
M−1 cm−1) 613 (54000). Anal. Calcd for C23H12N4S2: C, 67.63;
H, 2.96; N, 13.72%. Found: C, 67.58; H, 2.85; N, 13.68%.
1-(p-Tolyl)-2-(2-thienyl)-5-[5-(tricyanoethenyl)-2-thienyl]-
pyrrole (1b). Gold-like lustrous crystals; 77% yield: mp 222.0–
222.5 °C; 1H NMR (CDCl3) δ 2.51 (s, 3H), 6.74 (d, J = 4.3 Hz,
1H), 6.80 (dd, J = 1.1 and 3.7 Hz, 1H), 6.89 (dd, J = 3.7 and 5.2
Hz, 1H), 7.04 (d, J = 4.5 Hz, 1H), 7.07 (d, J = 4.3 Hz, 1H), 7.17
(dd, J = 1.2 and 5.1 Hz, 1H), 7.29 (d, J = 8.2 Hz, 2H), 7.40 (d, J
= 8.2 Hz, 2H), 7.73 (d, J = 4.5 Hz, 1H); IR (KBr) 2207, 1491,
1450, 1420, 1398, 1362, 1326, 1178, 1162, 1108 cm−1; UV-vis
(THF, 3 × 10−5 M) λmax (nm) (ε/M−1 cm−1) 620 (21300). Anal.
Calcd for C24H14N4S2: C, 68.22; H, 3.34; N, 13.26%. Found: C,
68.12; H, 3.27; N, 13.11%.
1-(p-Fluorophenyl)-2-(2-thienyl)-5-[5-(tricyanoethenyl)-2-
thienyl]pyrrole (1g). Gold-like lustrous crystals; 80% yield: mp
1
246.2–247.0 °C; H NMR (CDCl3) δ 6.73 (d, J = 4.3 Hz, 1H),
6.81 (dd, J = 1.1 and 3.7 Hz, 1H), 6.91 (dd, J = 3.7 and 5.1 Hz,
1H), 7.03 (d, J = 4.5 Hz, 1H), 7.07 (d, J = 4.3 Hz, 1H), 7.19 (dd,
J = 1.1 and 5.1 Hz, 1H), 7.29 (dd, J = 8.4 and 8.8 Hz, 2H), 7.42
(dd, J = 4.9 and 8.9 Hz, 2H), 7.76 (d, J = 4.7 Hz, 1H); IR (KBr)
2206, 1508, 1490, 1397, 1361, 1247, 1163, 1110, 1061 cm−1; UV-
vis (THF, 3 × 10−5 M) λmax (nm) (ε/M−1 cm−1) 610 (35000).
Anal. Calcd for C23H11FN4S2: C, 64.77; H, 2.60; N, 13.14%.
Found: C, 64.63; H, 2.40; N, 12.95%.
1-(p-Chlorophenyl)-2-(2-thienyl)-5-[5-(tricyanoethenyl)-2-
thienyl]pyrrole (1h). Gold-like lustrous crystals; 98% yield:
mp 245.0–245.8 °C; 1H NMR (CDCl3) δ 6.73 (d, J = 4.3 Hz, 1H),
6.79 (dd, J = 1.1 and 3.8 Hz, 1H), 6.91 (dd, J = 3.8 and 5.2 Hz,
1H), 6.98 (d, J = 4.5 Hz, 1H), 7.06 (d, J = 4.3 Hz, 1H), 7.20 (dd,
J = 1.2 and 5.1 Hz, 1H), 7.36 (d, J = 8.8 Hz, 2H), 7.58 (d, J =
1-(p-Ethylphenyl)-2-(2-thienyl)-5-[5-(tricyanoethenyl)-2-
thienyl]pyrrole (1c). Gold lustrous crystals; 70% yield: mp

2368 Bull. Chem. Soc. Jpn., 75, No. 11 (2002)
HEADLINE ARTICLES
8.8 Hz, 2H), 7.76 (d, J = 4.5 Hz, 1H); IR (KBr) 2206, 1514, 1491,
1398, 1362, 1321, 1255, 1163, 1116, 1075 cm−1; UV-vis (THF, 3
× 10−5 M) λmax (nm) (ε/M−1 cm−1) 606 (30000). Anal. Calcd for
C23H11ClN4S2: C, 62.37; H, 2.50; N, 12.65%. Found: C, 62.09; H,
2.29; N, 12.46%.
C33H32N4S2: C, 72.23; H, 5.88; N, 10.21%. Found: C, 72.24; H,
5.92; N, 10.15%.
1-(p-Dodecylphenyl)-2-(2-thienyl)-5-[5-(tricyanoethenyl)-2-
thienyl]pyrrole (1n). Bronze-like lustrous crystals; 70% yield:
mp 138.0–139.0 °C; 1H NMR (CDCl3) δ 0.88 (t, J = 6.7 Hz, 3H),
1.32 (m, 18H), 1.72 (m, 2H), 2.76 (t, J = 7.8 Hz, 2H), 6.73 (d, J =
4.3 Hz, 1H), 6.78 (dd, J = 1.1 and 3.7 Hz, 1H), 6.88 (dd, J = 3.7
and 5.1 Hz, 1H), 6.98 (d, J = 4.7 Hz, 1H), 7.06 (d, J = 4.3 Hz,
1H), 7.16 (dd, J = 1.0 and 5.1 Hz, 1H), 7.30 (d, J = 8.2 Hz, 2H),
7.40 (d, J = 8.4 Hz, 2H), 7.74 (d, J = 4.7 Hz, 1H); IR (KBr) 2215,
1560, 1499, 1458, 1426, 1400, 1248 cm−1; UV-vis (THF, 3 × 10−5
M) λmax (nm) (ε/M−1 cm−1) 619 (42800). Anal. Calcd for
C35H36N4S2: C, 72.88; H, 6.29; N, 9.71%. Found: C, 72.74; H,
6.25; N, 9.68%.
1-(p-Bromophenyl)-2-(2-thienyl)-5-[5-(tricyanoethenyl)-2-
thienyl]pyrrole (1i). Gold-like lustrous crystals; 98% yield: mp
1
251.0–251.8 °C; H NMR (CDCl3) δ 6.72 (d, J = 4.3 Hz, 1H),
6.78 (dd, J = 1.1 and 3.8 Hz, 1H), 6.91 (dd, J = 3.8 and 5.2 Hz,
1H), 6.96 (d, J = 4.5 Hz, 1H), 7.06 (d, J = 4.3 Hz, 1H), 7.20 (dd,
J = 1.1 and 5.1 Hz, 1H), 7.30 (d, J = 8.7 Hz, 2H), 7.73 (d, J =
8.7 Hz, 2H), 7.76 (d, J = 4.5 Hz, 1H); IR (KBr) 2207, 1492, 1450,
1419, 1399, 1362, 1243, 1163, 1107, 1073 cm−1; UV-vis (THF, 3
× 10−5 M) λmax (nm) (ε/M−1 cm−1) 605 (34000). Anal. Calcd for
C23H11BrN4S2: C, 56.68; H, 2.27; N, 11.50%. Found: C, 56.45; H,
2.05; N, 11.37%.
1-(p-Tetradecylphenyl)-2-(2-thienyl)-5-[5-(tricyanoethe-
nyl)-2-thienyl]pyrrole (1o).
Bronze-like lustrous crystals;
1-(p-Cyanophenyl)-2-(2-thienyl)-5-[5-(tricyanoethenyl)-2-
thienyl]pyrrole (1j). Gold-like lustrous crystals; 99% yield: mp
268.0–269.0 °C; H NMR (CDCl3) δ 6.73 (d, J = 4.1 Hz, 1H),
67% yield: mp 138.5–139.5 °C; 1H NMR (CDCl3) δ 0.88 (t, J
= 6.7 Hz, 3H), 1.30 (m, 22H), 1.71 (m, 2H), 2.76 (t, J = 7.8 Hz,
2H), 6.74 (d, J = 4.4 Hz, 1H), 6.78 (dd, J = 1.1 and 3.7 Hz, 1H),
6.88 (dd, J = 3.7 and 5.1 Hz, 1H), 6.98 (d, J = 4.7 Hz, 1H), 7.07
(d, J = 4.3 Hz, 1H), 7.16 (dd, J = 1.2 and 5.1 Hz, 1H), 7.30 (d, J
= 8.4 Hz, 2H), 7.40 (d, J = 8.2 Hz, 2H), 7.75 (d, J = 4.5 Hz, 1H);
IR (KBr) 2214, 1502, 1455, 1403, 1363, 1323, 1248, 1185,
1
6.74 (dd, J = 3.6 and 1.2 Hz, 1H), 6.92 (dd, J = 3.7 and 5.1 Hz,
1H), 6.97 (d, J = 4.5 Hz, 1H), 7.07 (d, J = 4.3 Hz, 1H), 7.22 (dd,
J = 1.1 and 5.1 Hz, 1H), 7.56 (d, J = 8.7 Hz, 2H), 7.77 (d, J =
4.4 Hz, 1H), 7.88 (d, J = 8.8 Hz, 2H); IR (KBr) 2207, 1508, 1491,
1449, 1419, 1397, 1236, 1173, 1107, 1065, 848 cm−1; UV-vis
(THF, 3 × 10−5 M) λmax (nm) (ε/M−1 cm−1) 597 (33000). Anal.
Calcd for C24H11N5S2•0.15CHCl3: C, 64.26; H, 2.49; N, 15.51%.
Found: C, 64.24; H, 2.34; N, 15.66%.
1110 cm−1; UV-vis (THF, 3 × 10−5 M) λmax (nm) (ε/M−1 cm−1
)
620 (41900). Anal. Calcd for C37H40N4S2: C, 73.47; H, 6.67; N,
9.26%. Found: C, 73.14; H, 6.65; N, 9.13%.
1-(p-Hexadecylphenyl)-2-(2-thienyl)-5-[5-(tricyanoethenyl)-
2-thienyl]pyrrole (1p). Bronze-like lustrous crystals; 74%
yield: mp 135.0–136.0 °C; 1H NMR (CDCl3) δ 0.88 (t, J =
6.7 Hz, 3H), 1.28 (m, 26H), 1.70 (m, 2H), 2.76 (t, J = 7.8 Hz,
2H), 6.73 (d, J = 4.3 Hz, 1H), 6.78 (dd, J = 1.1 and 3.7 Hz, 1H),
6.88 (dd, J = 3.7 and 5.1 Hz, 1H), 6.98 (d, J = 4.7 Hz, 1H), 7.06
(d, J = 4.4 Hz, 1H), 7.16 (dd, J = 1.2 and 5.1 Hz, 1H), 7.30 (d, J
= 8.4 Hz, 2H), 7.40 (d, J = 8.4 Hz, 2H), 7.74 (d, J = 4.7 Hz, 1H);
IR (KBr) 2215, 1502, 1456, 1427, 1401, 1348, 1322, 1247,
1-(p-Butylphenyl)-2-(2-thienyl)-5-[5-(tricyanoethenyl)-2-
thienyl]pyrrole (1k). Bronze-like lustrous crystals; 89% yield:
mp 171.5–172.5 °C; 1H NMR (CDCl3) δ 0.99 (t, J = 7.3 Hz, 3H),
1.43 (tq-like, 2H), 1.72 (tq-like, 2H), 2.77 (t, J = 7.9 Hz, 2H),
6.73 (d, J = 4.3 Hz, 1H), 6.78 (dd, J = 1.1 and 3.7 Hz, 1H), 6.88
(dd, J = 3.7 and 5.1 Hz, 1H), 6.98 (d, J = 4.8 Hz, 1H), 7.07 (d, J
= 4.3 Hz, 1H), 7.16 (dd, J = 1.1 and 5.1 Hz, 1H), 7.30 (d, J =
8.4 Hz, 2H), 7.40 (d, J = 8.1 Hz, 1H), 7.74 (d, J = 4.5 Hz, 1H);
IR (KBr) 2217, 1502, 1457, 1428, 1400, 1348, 1322, 1246, 1208,
1209 cm−1; UV-vis (THF, 3 × 10−5 M) λmax (nm) (ε/M−1 cm−1
)
1061 cm−1; UV-vis (THF, 3 × 10−5 M) λmax (nm) (ε/M−1 cm−1
)
620 (41600). Anal. Calcd for C39H44N4S2: C, 74.01; H, 7.01; N,
8.85%. Found: C, 73.78; H, 6.86; N, 8.71%.
620 (33700). Anal. Calcd for C27H20N4S2: C, 69.80; H, 4.34; N,
12.06%. Found: C, 69.61; H, 4.18; N, 11.92%.
1-(o-Decylphenyl)-2-(2-thienyl)-5-[5-(tricyanoethenyl)-2-
thienyl]pyrrole (3). Gold-like lustrous plates; 79% yield: mp
1-(p-Hexylphenyl)-2-(2-thienyl)-5-[5-(tricyanoethenyl)-2-
thienyl]pyrrole (1l). Bronze-like lustrous crystals; 80% yield:
mp 156.0–157.0 °C; 1H NMR (CDCl3) δ 0.91 (t, J = 7.1 Hz, 3H),
0.89–1.43 (m, 8H), 2.76 (t, J = 7.9 Hz, 2H), 6.73 (d, J = 4.3 Hz,
1H), 6.78 (dd, J = 1.1 and 3.7 Hz, 1H), 6.88 (dd, J = 3.7 and
5.1 Hz, 1H), 6.98 (d, J = 4.7 Hz, 1H), 7.06 (d, J = 4.3 Hz, 1H),
7.16 (dd, J = 1.1 and 5.1 Hz, 1H), 7.30 (d, J = 8.4 Hz, 2H), 7.40
(d, J = 8.4 Hz, 1H), 7.74 (d, J = 4.7 Hz, 1H); IR (KBr) 2216,
1503, 1456, 1428, 1401, 1348, 1322, 1247, 1209, 1060 cm−1; UV-
vis (THF, 3 × 10−5 M) λmax (nm) (ε/M−1 cm−1) 618 (22800).
Anal. Calcd for C29H24N4S2: C, 70.70; H, 4.91; N, 11.37%.
Found: C, 70.41; H, 4.75; N, 11.31%.
1-(p-Decylphenyl)-2-(2-thienyl)-5-[5-(tricyanoethenyl)-2-
thienyl]pyrrole (1m). Bronze-like lustrous crystals; 65% yield:
mp 150.0–151.0 °C; 1H NMR (CDCl3) δ 0.89 (t, J = 6.7 Hz, 3H),
1.32 (m, 14H), 1.71 (m, 2H), 2.76 (t, J = 7.9 Hz, 2H), 6.73 (d, J =
4.3 Hz, 1H), 6.78 (dd, J = 1.1 and 3.7 Hz, 1H), 6.88 (dd, J = 3.8
and 5.1 Hz, 1H), 6.98 (d, J = 4.5 Hz, 1H), 7.06 (d, J = 4.4 Hz,
1H), 7.16 (dd, J = 1.2 and 5.2 Hz, 1H), 7.30 (d, J = 8.4 Hz, 2H),
7.40 (d, J = 8.4 Hz, 2H), 7.74 (d, J = 4.5 Hz, 1H); IR (KBr) 2216,
1503, 1456, 1428, 1402, 1362, 1349, 1248 cm−1; UV-vis (THF, 3
× 10−5 M) λmax (nm) (ε/M−1 cm−1) 621 (41700). Anal. Calcd for
1
102.0–103.0 °C; H NMR (CDCl3) δ 0.87 (t, J = 7.0 Hz, 3H),
1.24 (m, 16H), 2.17 (m, 2H), 6.78 (dd, J = 1.2 and 3.8 Hz, 1H),
6.80 (d, J = 4.4 Hz, 1H), 6.87 (dd, J = 3.7 and 5.1 Hz, 1H), 6.99
(d, J = 4.7 Hz, 1H), 7.12 (d, J = 4.4 Hz, 1H), 7.15 (dd, J = 1.2
and 5.1 Hz, 1H), 7.44 (m, 3H), 7.64 (ddd, J = 1.6 and 7.0 and
8.1 Hz, 1H), 7.75 (d, J = 4.7 Hz, 1H); IR (KBr) 2212, 1498, 1452,
1424, 1364, 1346, 1321, 1172, 847, 772 cm−1. UV-vis (THF, 3 ×
10−5 M) λmax (nm) (ε/M−1 cm−1) 620 (43100). Anal. Calcd for
C33H32N4S2: C, 72.23; H, 5.88; N, 10.21%. Found: C, 72.25; H,
5.84; N, 10.19%.
X-ray Crystallography. For compounds 1a, 1b, 1d, 1g, 1i,
and 1j, data collection was performed on a Mac Science MXC18
four-circle diffractometer with graphite monochromated Cu Kα
radiation (λ = 1.54178 Å) using the θ–2θ scan technique. The
structures were solved by direct methods and refined by full-ma-
trix least-squares methods against F (SIR 9218 on a computer pro-
gram package; maXus ver. 1.1 from MAC Science Co. Ltd.). All
non-hydrogen atoms were refined with anisotropic displacement
parameters and hydrogen atoms were refined isotropically. For
the complex 1o•acetone, data collection was performed on a
Brukersmart-1000 CCD diffractometer with graphite monochro-

K. Ogura et al.
Bull. Chem. Soc. Jpn., 75, No. 11 (2002) 2369
α
β
γ
µ

2370 Bull. Chem. Soc. Jpn., 75, No. 11 (2002)
HEADLINE ARTICLES
mated Mo Kα radiation (λ = 0.71013 Å) to a maximum 2θ value
of 57°. The structure was solved by direct methods (SIR 9218) and
refined by full-matrix least-squares methods against F. The non-
hydrogen atoms were refined anisotropically and the hydrogen at-
oms were refined isotropically. All calculations for 1o•acetone
were performed using the teXsan crystallographic software pack-
age (teXsan19 for Windows Ver.1.03) of Molecular Structure Cor-
poration (1997). For compound 3, data collection was performed
on a Mac Science MXC18 four-circle diffractometer with graphite
monochromated Cu Kα radiation (λ = 1.54178 Å) using the θ–2θ
scan technique. The structures were solved by direct methods and
refined by full-matrix least-squares methods against F (SIR 9218
on a computer program package; maXus ver. 3.2.1 from MAC
Science Co. Ltd.). All non-hydrogen atoms were refined anisotro-
pically. One hydrogen atom (H20) was added at calculated posi-
tions and the others on the aromatic rings were located by differ-
ence Fourier synthesis and treated as isotropic contributions ex-
cept that the ones on decyl group were not added. An empirical
absorption correction based on ψ-scans was only applied to crys-
tals 1a, 1b, and 1i. The detailed crystallographic data and struc-
ture refinement parameters are summarized in Table 1. Crystallo-
graphic data (excluding structure factors) for the structures in this
paper have been deposited with the Cambridge Crystallographic
Data Centre as supplementary publication numbers CCDC
191825-191832. Copies of the data can be obtained, free of
charge, on application to CCDC, 12 Union Road, Cambridge
CB2 1EZ, UK [fax: +44-(0)1223-336033 or e-mail: deposit
@ccdc.cam.ac.uk]. The data also were deposited as Document
No. 75046 at the Office of the Editorial of Bull. Chem. Soc. Jpn.
(1974).
5
6
7
J. B. Torrance, Acc. Chem. Res., 12, 79 (1979).
F. Wudl, Acc. Chem. Res., 17, 227 (1984).
A. Kobayashi, H. Tanaka, M. Kumasaki, H. Torii, B.
Narymbetow, and T. Adachi, J. Am. Chem. Soc., 121, 10763
(1999).
8
H. Tanaka, Y. Okano, H. Kobayashi, W. Suzuki, and A.
Kobayashi, Science, 291, 285 (2001).
J. P. Prakka and M. P. Cava, Synth. Met., 68, 275 (1995).
9
10 X.-C. Li, H. Sirringhaus, F. Garnier, and A. B. Holmes, J.
Am. Chem. Soc., 120, 2206 (1998).
11 K. Ogura, H. Yanai, M. Miokawa, and M. Akazome,
Tetrahedron Lett., 40, 8887 (1999).
12 H. Yanai, D. Yoshizawa, S. Tanaka, T. Fukuda, M.
Akazome, and K. Ogura, Chem. Lett., 2000, 238.
13 Hitherto, many derivatives of 2-(tricyanoethenyl)thiophene
have been reported mainly in order to develop efficient second-or-
der nonlinear optical chromophores. For example, a) V. P. Rao, A.
K.-Y. Jen, K. Y. Wong, and K. J. Drost, J. Chem. Soc., Chem.
Commun., 1993, 1118. b) A. K.-Y. Jen, V. P. Rao, K. J. Drost, K.
Y. Wong, and M. P. Cava, J. Chem. Soc., Chem. Commun., 1994,
2057. c) K. Onitsuka, H. Urayama, K. Sonogashira, and F.
Ozawa, Chem. Lett., 1995, 1019. d) V. P. Rao, A. K.-Y. Jen, and
Y. Cai, J. Chem. Soc. Chem. Commun., 1996, 1273. e) C.-F. Shu,
W. J. Tsai, J.-Y. Chen, A. K.-Y. Jen, and Y. Zhang, Chem.
Commun., 1996, 2279. f) C. R. Bu, H. Li, D. Van Derveer, and F.
A. Mintz, Tetrahedron Lett., 37, 7331 (1996).
14 P. A. Cox, “The Electronic Structure and Chemistry of
Solid,” Oxford Science Publications (1987), pp. 38–41.
15 A strategy for the synthesis of molecular crystals contain-
ing two-dimensional layers is discussed: Y.-L. Chang, M.-A.
West, F. W. Fowler and J. W. Lauher, J. Am. Chem. Soc., 115,
5991 (1993). Its related papers: S. Coe, J. J. Kane, T. L. Nguyen,
L. M. Toledo, E. Wininger, F. W. Fowler and J. W. Lauher, J. Am.
Chem. Soc., 119, 86 (1997), and the references cited therein.
16 D. S. Reddy, B. Goud, K. Panneerselvam, and G. R.
Desiraju, J. Chem. Soc., Chem. Commun., 1993, 663.
This work was supported by Grant-in-Aids for “Research
for the Future” Program (JSPS-RFTF96P00304) from the
Japan Society for the Promotion of Science.
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