10398 J. Am. Chem. Soc., Vol. 118, No. 43, 1996
Yamamoto et al.
Table 3. Three-Photon Resonant ø(3) Values, ø(3)max, of Thin Films
of π-Conjugated Polymersa
([M-Cl]+, 40, 40), 159 ([M - Br - Cl]+, 70). IR(cm-1): 3048, 1572,
1460, 1431, 1208, 1093, 1006, 830, 793, 738. Anal. Found: C, 39.4;
H, 1.7; N, 5.2; Br+Cl, 41.8; S, 11.4. Calcd for C9H5NBrClS: C, 39.4;
H, 1.8; N, 5.1; Br+Cl, 42.0; S, 11.7%.
no.
polymer
ø(3)max × 1011, esu λf(max), nm λf(max)/3, nm
1
2
3
4
5
6
7
PThPy
4.9
4.5
4.8
2.1
2.5
0.9
0.7d
1500
1700
1700
1400
1400
1700
500
567
567
467
467
567
BrThPyBr. BrThPyBr was prepared according to the following
procedures a and b. Procedure a was similar to the above described
procedure for the preparation of 2-chloro-5-(5-bromo-2-pyridyl)-
thiophene. The product was separated by column chromatography
(silica gel, ether as eluent). Some oligomers and polymer were also
produced and separated from BrThPyBr. Yield of BrThPyBr was 20%.
Mp 111-112 °C. 1H-NMR (CDCl3, ppm): 8.49 (dd, 0.2 Hz and 0.7
Hz, 1H, 6-H at Py-ring), 7.68 (dd, 2.2 Hz and 8.5 Hz, 1H, 4-H at Py-
ring), 7.31 (dd, 8.5 Hz and 0.7 Hz, 1H, 3-H at Py-ring), 7.17 (d, 4.0
Hz, 1H, H at Th-ring), 6.97 (d, 4.0 Hz, 1H, H at Th-ring). 13C-NMR
(CDCl3, ppm): Py-ring, 150.8 (6-C), 150.3 (2-C), 139.4 (4-C), 119.4
(3-C), 118.9 (5-C); Th-ring, 145.3 (5-C), 131.3 (3-C), 125.1 (4-C), 115.9
(2-C). UV-vis (THF): λmax ) 322 nm. Mass (m/e, relative intensity):
321, 319, 317 (M+, 49, 90, 47), 240, 238 ([M - Br]+, 89, 89), 159
([M - 2Br]+, 100). IR(cm-1): 3046, 1571, 1460, 1424, 1208, 1093,
1007, 831, 791, 738. Anal. Found: C, 34.1; H, 1.6; N, 4.4; Br, 49.8;
S, 10.2. Calcd for C9H5NBr2S: C, 33.9; H, 1.6; N, 4.4; Br, 50.1; S,
10.1%.
Procedure b: BrThPyBr was prepared from 2-(5-bromo-2-pyridyl)-
thiophene (Minato, A.; Suzuki, K.; Tamao, K.; Kumada, M. J. Chem.
Soc., Chem. Commun. 1984, 337). 2-(5-Bromo-2-pyridyl)thiophene
(20.23 g, 84.3 mmol) was dissolved in a mixture of acetic acid (150
mL) and chloroform (75 mL), and the solution was cooled to 0 °C in
an ice-water bath. Then, to the solution was added bromine (13.4 g,
84.3 mmol) dissolved in 20 mL of acetic acid very slowly (ca. 3 h).
The mixture was stirred overnight at room temperature, and a large
amount of white solid was separated. The solvent (chloroform) was
removed under reduced pressure, and the residue was poured into 300
mL of ice-water. After filtration and washing with water, the crude
light yellow solid was dried under vacuum and recrystallized from
propanol and chloroform (1:1). Thus, white crystals of BrThPyBr were
obtained (24.7 g, 92%).
PThQx(diPh)
PThQx(diHep)
PSN11
PSN13
PThb,c
PPyb
a Maximum ø(3), ø(3)max, is observed at an irradiated fundamental
wavelength of λf(max). øf(max)/3 is considered to reflect the position
of a π-π* absorption band contributing to ø(3). Measured with cast
film unless otherwise noted. b ø(3) values for PTh and PPy are estimated
from the ø(3) value measured at a so-called backside mode (cf.
supporting information). Corrected ø(3)max values, which are calculated
from relative ø(3) values against that of PThPy (no. 1), are given.
max
c Measured with vacuum-deposited PTh film.13b d Value measured at
3λmax/λf (or hν/Eg)5c ) 0.95.
accepting units. The copolymers exhibit absorption bands at
longer wavelengths than those of the corresponding homopoly-
mers. A copolymer, PSeN, having the block-type structure gives
rise to the energy-transferred photoluminescence. The copoly-
mers are electrochemically active in both the oxidation (p-
doping) and reduction (n-doping) regions, and the copolymers
of pyridine exhibit unique p-doping and p-undoping behavior,
which can be explained by the EC mechanism. Films of PThPy,
PThQx(diPh), and PThQx(diHep) give relatively large ø(3) values
of about 5 × 10-11 esu at their resonant regions, and the
relatively large ø(3) values are considered to be related to the
CT structure.
Experimental Section
Materials. Solvents were dried, distilled, and stored under N2. 2,5-
Dibromopyridine, 1,4-dibromobenzene, 2,5-dibromothiophene, 2,2′-
bipyridine, triphenylphosphine, o-phenanthroline, and 1,5-cycloocta-
diene were purchased from Tokyo Chemical Industry Co. Ltd.
Ni(cod)2,13 Pd(PPh3)4,5d 2,5-dibromoselenophene,36 2,3-diphenyl-5,8-
dibromoquinoxaline,13 2,3-diheptyl-5,8-dibromoquinoxaline,13c and 2-bu-
tyl-3-phenyl-5,8-dibromoquinoxaline13c were prepared as previously
reported. 2,5-Bis(trimethylstannyl)thiophene and 2,5-bis(trimethyl-
stannyl)furan were prepared by modifying a reported method.37
Monomers. XThPyBr (X ) Cl, Br, and I) was prepared as follows.
ClThPyBr. To a suspension of magnesium turnings (0.224 g, 9.2
mmol) in 5 mL of THF was added 2,5-dichlorothiophene (1.408 g, 9.2
mmol) in 10 mL of THF at room temperature dropwise. Then, the
mixture was allowed to stir at room temperature until magnesium
turnings were consumed completely (ca. 4 h). The produced Grignard
reagent was added to a mixture of 2,5-dibromopyridine (2.30 g, 9.7
mmol) and PdCl2(dppb) (0.061 g, 0.10 mmol) suspended in 30 mL of
THF at -30 °C dropwise. After the addition was finished, the mixture
was stirred overnight from -30 °C to room temperature, and it became
a brown homogeneous solution. After THF was removed under reduced
pressure, the residue was added to 100 mL of water. The aqueous
solution was neutralized by dilute hydrochloric acid and then extracted
with benzene (40 mL × 3). The organic layer was washed with water
and dried over sodium sulfate. After filtration and concentration, the
crude product was recrystallized from 1-propanol. Thus, light yellow
crystals were obtained (2,27 g, yield 90%). Mp 108-109 °C. 1H-
NMR (CDCl3, ppm): 8.55 (d, 2.2 Hz, 1H, 6-H at Py-ring), 7.77 (dd,
2.2 Hz and 8.5 Hz, 1H, 4-H at Py-ring), 7.42 (d, 8.55 Hz, 1H, 3-H at
Py-ring), 7.30 (d, 4.0 Hz, 1H, H at Th-ring), 6.90 (d, 8.55 Hz, 1H, 3-H
at Th-ring). 13C-NMR (CDCl3, ppm): Py-ring, 150.5 (6-C), 150.3 (2-
C), 139.2 (4-C), 119.1 (3-C), 118.7 (5-C); Th-ring; 142.2 (5-C), 133.0
(2-C), 127.3 (4-C), 124.1 (3-C). UV-vis (THF): λmax ) 321 nm. Mass
(m/e, relative intensity): 227, 275, 273 (M+, 20, 100, 73), 240, 238
IThPyBr. 2-(5-Bromo-2-pyridyl)thiophene (2.5 g, 10.4 mmol) was
dissolved in 15 mL of dichloromethane. Then, iodine (1.4 g, 0.55
mmol) and 4.2 mL of 6 M nitric acid were added. The mixture was
refluxed for 2.5 h. After cooling to room temperature, the mixture
was poured into an aqueous solution of sodium thiosulfide and extracted
with chloroform (40 mL × 4). The organic layer was dried over sodium
sulfate and decolored by active carbon. After filtration and concentra-
tion, the crude product was recrystallized from acetone to obtain yellow
flake crystal (3.6 g, yield 95%). Mp 124-125 °C. 1H-NMR (CDCl3,
ppm): 8.57 (d, 2.4 Hz, 1H, 6-H at Py-ring), 7.79 (dd, 8.5 Hz and 2.4
Hz, 1H, H at Th-ring), 7.44 (d, 8.5 Hz, 1H, 3-H at Py-ring), 7.25 (d,
3.9 Hz, 1H, 4-H at Py-ring), 7.19 (d, 3.9 Hz, 1H, H at Th-ring). UV-
vis (THF): λmax ) 327 nm. Mass (m/e, relative intensity): 367, 365
(M+, 100, 100), 240, 238 ([M-I]+, 70, 70), 159 ([M - I - Br]+, 60).
IR(cm-1): 3042, 1562, 1448, 1408, 1362, 1093, 1000, 814, 798, 738.
Anal. Found: C, 29.8; H, 1.4; N, 3.9; Br+I, 56.1; S, 8.6. Calcd for
C9H5NBrIS: C, 29.5; H, 1.4; N, 3.8; Br+I, 56.5; S, 8.8%.
Polymerization. Dehalogenation polycondensations using the zero
valent nickel complexes were carried out in manners similar to those
previously reported.13 Copolymers shown in eq 3, except for PThQx-
(BuPh), were prepared as previously reported.5d PThQx(BuPh) was
prepared in an analogus manner.
PThPy. To a solution of bis(1,5-cyclooctadiene)nickel(0) Ni(cod)2
(0.570 g, 2.07 mmol) in 18 mL of dried DMF at room temperature
was added 2,2′-bipyridine (0.322 g, 2.07 mmol). After stirring for 1
h, BrThPyBr (0.510 g, 1.60 mmol) was added at once directly to the
reaction system. The mixture was allowed to react for 28 h at 60-70
°C. After cooling to room temperature, it was added to 100 mL of 2
M HCl and stirred overnight. After filtration, the reddish brown powder
was washed with a mixture of methanol (60 mL) and concd HCl (10
mL), a warm aqueous solution of EDTA (pH ) 9, then pH ) 3), dilute
ammonia, water, and methanol repeatedly, and dried under vacuum
for 20 h at 80 °C to obtain PThPy (run 1 in Table 1) (0.261 g, yield )
ca. 100%). Anal. Found: C, 65.8; H, 3.0; N, 8.2; Br, 1.9. Mw (light
scattering) ) 5400 calcd for H(Py-Th)33Br: C, 66.9; H, 3.1; N, 8.7;
Br, 1.5. Mw ) 5335 calcd for Br(Py-Th)33Br: C, 65.9; H, 3.1; N,
(36) Gronowitz, S.; Frejd, T. Acta Chem. Scand. B 1976, 30, 313.
(37) van Pham, C.; Macomber, R. S.; Mark, H. B., Jr.; Zimmer, H. J.
Org. Chem. 1984, 49, 5250.