Macromolecules, Vol. 35, No. 15, 2002
Oligo- and Poly(thienylphenylamine)s 5783
added dropwise to a solution of PT1N (1.0 g, 2.0 mmol) in
CH2Cl2 (40 mL) and AcOH (20 mL). The reaction solution was
stirred at room temperature for 1 h. Saturated aqueous
NaHCO3 solution was added, and the product was extracted
with CH2Cl2. The organic layer was washed with brine, dried
(Na2SO4), and evaporated. Purification of the residue by
column chromatography (silica gel; hexane-CH2Cl2 7:1) fur-
nished unchanged PT1N (271 mg; 21%), 1BrPT1N (508 mg;
44%), and 2BrPT1N (272 mg; 27%). 1BrPT1N: 1H NMR (400
MHz, CDCl3) δ 6.96 (d, J ) 4.0 Hz, 1H), 6.99 (d, J ) 4.0 Hz,
1H), 7.05 (dd, J ) 3.6, 5.2 Hz, 2H), 7.10 (d, J ) 8.8 Hz, 2H),
7.11 (d, J ) 8.8 Hz, 4H), 7.23 (dd, J ) 3.6, 5.2 Hz, 4H), 7.39
(d, J ) 8.8 Hz, 2H), 7.51 (d, J ) 8.8 Hz, 4H). 13C NMR (100
Hz, CDCl3) δ 110.6, 122.5, 122.6, 124.1, 124.3, 124.6, 126.6,
127.0, 128.1, 128.3, 129.6, 130.9, 144.0, 145.7, 146.4, 147.0.
FAB-MS [m/z] ) 569 (M + 2). 2BrPT1N: 1H NMR (400 MHz,
CDCl3) δ 6.96 (d, J ) 4.0 Hz, 2H), 6.99 (d, J ) 4.0 Hz, 2H),
7.05 (dd, J ) 3.6, 5.2 Hz, 1H), 7.10 (d, J ) 8.8 Hz, 4H), 7.11
(d, J ) 8.8 Hz, 2H), 7.23 (dd, J ) 3.6, 5.2 Hz, 4H), 7.39 (d, J
) 8.8 Hz, 4H), 7.51 (d, J ) 8.8 Hz, 2H). 13C NMR (100 Hz,
CDCl3) δ 110.7, 122.5, 122.6, 124.3, 124.4, 124.8, 126.6, 127.0,
128.1, 128.5, 129.8, 130.9, 144.0, 145.6, 146.2, 146.8. FAB-MS
[m/z] ) 647(M + 2).
(b) P r epar ation of th e Mon o-Stan n yl-Su bstitu ted P T1N
Bis(t h ien ylp h en yl)(4-t r im et h ylst a n n ylt h ien ylp h en yl)-
a m in e. To a THF solution (25 mL) of PT1N (502 mg, 1.02
mmol) was added n-butyllithium (1.3 mL, 2.04 mmol) dropwise
at -78 °C. The mixture was stirred at room temperature for
5 min. Tri-n-butyltin chloride (0.55 mL, 2.04 mmol) was added
dropwise at -78 °C, and the mixture was stirred at room
temperature for 5 min. Water was added, and the product was
extracted with EtOAc. The organic layer was washed with
brine, dried (Na2SO4), and evaporated. Purification of the
residue by column chromatography (silica gel treatment with
10%Et3N-hexane; hexane) furnished 1-Sn(n-Bu)3PT1N (320
mg; 40%). 1H NMR (270 MHz, CDCl3) δ 0.91 (t, J ) 7.3 Hz,
9H), 1.12 (m, 6H), 1.36 (m, 6H), 1.58 (m, 6H), 7.06 (d, J ) 3.8
Hz, 2H), 7.11 (d, J ) 8.4 Hz, 6H), 7.12 (d, J ) 3.6 Hz, 1H),
7.23 (d, J ) 3.8 Hz, 4H), 7.36 (d, J ) 3.6 Hz, 1H), 7.49 (d, J )
8.4 Hz, 4H), 7.52 (d, J ) 8.4 Hz, 2H).
Dim er . Under N2, 1SnPT1N (104 mg, 0.13 mmol) in THF
(10 mL) was added dropwise to the mixture of 1BrPT1N (75.9
mg, 0.13 mmol) and Pd(PPh3)4 (7.7 mg, 6.65 µmol). The
reaction mixture was refluxed for 1 h and cooled at room
temperature. The reaction solution was diluted with THF, and
the product was purified by column chromatography (silica gel;
hexane-THF 8:1) furnished dimer (115 mg; 88%). 1H NMR
(400 MHz, C4D8O) δ 7.04 (dd, J ) 3.9, 5.4 Hz, 4H), 7.14 (d, J
) 8.8 Hz, 12H), 7.22 (d, J ) 3.9 Hz, 2H), 7.31 (d, 10H), 7.57
(d, J ) 8.8 Hz, 12H). 13C NMR (100 MHz, C4D8O) δ 123.4,
124.2, 125.1, 125.3, 125.4, 127.2, 127.6, 127.7, 128.0, 128.8,
129.5, 136.2, 142.7, 144.0, 146.5, 146.7. MALDI-TOF MS )
980.
Tr im er a n d Tetr a m er . (a ) Tr im er : Following the above
procedure for the dimer using 2BrPT1N (30 mg, 0.46 µmol),
1SnPT1N (175 mg, 224 µmol), and Pd(PPh3)4 (5.3 mg, 4.62
µmol) in THF (40 mL), the trimer was obtained. Purification
by column chromatography (silica gel; hexane-THF 6:1)
produced the trimer (24 mg; 35%). 1H NMR (400 MHz,
CD2Cl2) δ 7.08 (dd, J ) 3.6, 5.2 Hz, 5H), 7.15 (d, J ) 8.8 Hz,
18H), 7.18 (dd, J ) 3.6 Hz, 4H), 7.21 (d, J ) 3.6 Hz, 4H), 7.27
(d, J ) 5.2 Hz, 5H), 7.29 (d, J ) 3.6 Hz, 5H), 7.55 (d, J ) 8.8
Hz, 18H). 13C NMR (100 MHz, C4D8O) δ 123.4, 124.2, 125.0,
125.1, 125.3, 125.5, 127.3, 127.7, 128.7, 130.0, 130.7, 131.2,
137.1, 137.9, 143.7, 145.0, 147.6, 147.9. MALDI-TOF MS )
1470.
127.7, 128.7, 130.0, 130.2, 130.7, 137.1, 137.2, 143.7, 143.8,
145.0, 147.6, 147.9. MALDI-TOF MS ) 1959.
Syn th esis of P olym er s. (a ) Ch em ica l Oxid a tive P o-
lym er iza tion . The branched polymers, pPT1Nc, pPT2Nc, and
pPT3Nc, were obtained in 97-98% yield by chemical oxidative
polymerization of PT1N, PT2N, and PT3N with ferric chloride
as the oxidant in CH2Cl2. FeCl3 (389 mg, 2.4 mmol) was added
to the PT1N solution (5 mL of CH2Cl2). The reaction solution
was stirred for 4 h at room temperature under N2. The reaction
solution was then precipitated into MeOH (500 mL) and
filtered. The solid was reduced from the oxidizing form by a 1
N NH3 methanol solution and filtered. This procedure was
repeated five times. The polymer, pPT1Nc, was obtained in
97% yield (401 mg). The same procedures were employed for
the polymerization of PT2N and PT3N. The concentrations of
PT2N and PT3N in the reaction mixture were 16.9 and 6.25
mM, respectively, because of solubility limitations. pPT2Nc
and pPT3Nc were each obtained in 98% yield.
(b) Electr opolym er ization of Tr is(th ien ylph en ylam in e)-
s. The electropolymerization of the monomers (1 mM) was
carried out by cyclic potential sweeps in the range from 0 to
1.1 V vs Ag/Ag+ on a Pt disk electrode (φ ) 2 mm) using same
apparatus and instruments as that for cyclic voltammetry. The
supporting electrolyte was tetrabutylammonium tetrafluo-
roborate (0.2 M). The solvent was a mixture of acetonitrile and
dichloromethane [v/v: 10/1 (PT1N), 1/1 (PT2N), and 1/10
(PT3N)].
Resu lts a n d Discu ssion
Syn th esis of Mon om er s12-19 a n d Oligom er s. As
precursors to the branched polymers, the tris[4-(2-
oligothienyl)phenyl]amines (PT1N, PT2N, and PT3N)
with a thienyl, bithienyl, or terthienyl group were
synthesized (Scheme 1). The synthesis of PT1N was
carried out through the cross-coupling reaction of the
MgBr-substituted thiophene with tris(bromophenyl)-
amine using a Pd catalyst. PT1N was isolated in 79%
yield. PT1N was successfully brominated at the 4-posi-
tion of the thienyl group with NBS. A similar procedure
for PT1N was used to synthesize PT2N. Brominated
PT1N reacts with the Grignard thiophene to yield PT2N
in 76%. Terthiophene boronic acid for the Suzuki
coupling reaction was prepared by the reaction of
lithium terthiophene with triethyl borate in the pres-
ence of 1 N HCl. The Suzuki coupling with tris-
(bromophenyl)amine using a Pd catalyst produced PT3N
in 32% yield. PT3N has poor solubility compared to that
of the starting materials, such as tris(bromophenyl)-
amine and terthienylboronic acid. During the reaction
PT3N is precipitated in MeCN. PT3N can then be
isolated by filtration. These monomers were character-
ized by NMR and IR spectra, mass spectrometry, and
elemental analysis.
As monomers of the analogous linear polymers, which
were used for a comparison with the branched poly-
mers, bis(thienylphenyl)(4-methylthienylphenyl)amine
(MePT1N) and bis(thienylphenyl)(4-bromophenyl)amine
(Br-PT1N) were also synthesized through cross-coup-
ling using a Pd catalyst. BrPT1N was also synthesized
using the same procedure as for PT1N. The cross-
coupling of the MgBr-substituted methylthiophene with
BrPT1N produced MePT1N.
As model compounds, the dimer, trimer, and tetramer
of PT1N were prepared in order to investigate their
electrochemical properties and spectra. The oligomers
of PT1N were synthesized through cross-coupling of the
Br-substituted PT1N and the stannyl-substituted one
using a Pd catalyst. As raw materials for the dimer and
trimer, the mono- and dibromo-substituted PT1N de-
rivatives were prepared in one pot by bromination in
(b) Tetr a m er : 3BrPT1N (25.3 mg, 32 µmol), 1SnPT1N (150
mg, 192 µmol), and Pd (PPh3)4 (5.0 mg, 4.23 µmol) in THF (67
mL) were used and purification by column chromatography
(silica gel; hexane-THF 4:1) produced the tetramer (6.0 mg;
1
10%). H NMR (400 MHz, CD2Cl2) δ 7.08 (dd, J ) 3.5, 5.1 Hz,
6H), 7.15 (d, J ) 8.8 Hz, 24H), 7.18 (d, J ) 3.6 Hz, 6H), 7.21
(d, J ) 3.6 Hz, 4H), 7.22 (d, J ) 3.6 Hz, 2H), 7.27 (d, J ) 5.1
Hz, 6H), 7.28 (d, J ) 3.5 Hz, 6H), 7.55 (d, J ) 8.8 Hz, 24H).
13C NMR (Hz, C4D8O) δ 123.4, 124.3, 125.1, 125.5, 127.3, 127.6,