Y. Wang et al. / Journal of Organometallic Chemistry 696 (2011) 1874e1878
1877
stronger emission than M1, may be ascribed to the weak
conjugation. As shown in Table 2, the quantum yields ( ) of P1, P2
and P3 are 0.19, 0.28 and 0.37, respectively. All the data is higher
than that of M1 (only 0.09), suggest that the conjugation can
effectively enhance the emission efficiency. Some published papers
report the similar instances [18,19], silylene-functional conjugated
polymers were synthesized via acyclic diene metathesis conden-
sation. The authors find that the fluorescence quantum yields of the
polymers (on a repeat unit basis) are 5-fold higher than the model
s
e
p
respectively. Fluorescence quantum yields were measured using
quinine sulfate in 0.1 N H2SO4
F
(
F
¼ 54.6%) as standard. TGA was
carried out under nitrogen flow at a heating rate of 10ꢁ C/min on
a MettlerToledo SDTA-854 TGA system. DSC measurements were
performed with MettlerToledo DSC822 series. Elemental analysis
was measured on a Vario EI Ⅲ elemental analyzer. The average
molecular weight of the polymers was determined in THF (1 ml/
min) at 40ꢁ C by waters 515 liquid chromatograph equipped with
the refractive-index detector and three Styragel columns, and using
the standard polystyrene for calibration.
sep
compound and ascribe the phenomenon to the influence of
interaction. So we think that the results indicate the weak
conjugation in our obtained polymers.
s
e
p
se
p
4.2. Preparation of 1,4-diazidobenzene
In summary, the results of both UVevis and PL measurements
verify the weak conjugation of the obtained polymers. The
similar spectra suggest that the side groups on the silicon atom had
little effect on the photoproperties of the polymers.
se
p
The mixture of 1,4-diiodobenzene (3.30 g, 10.0 mmol), NaN3
(1.56 g, 24.0 mmol), CuSO4 (0.16 g, 1.0 mmol), ascorbate acid (0.35 g,
2.0 mmol), Na2CO3 (0.21 g, 2.0 mmol), L-proline (0.23 g, 2.0 mmol),
DMSO (9 ml) and H2O (1 ml) was stirred in dark for 24 h at 65ꢁ C.
Then the mixture was extracted with ethyl acetate (200 ml) and
washed with H2O (3 ꢂ 100 ml), dried over MgSO4, filtered and
distilled under reduced pressure. The crude product was purified
by a silica gel column using petroleum ether as an eluent to give
1,4-diazidobenzene as a light yellow crystalline, which is light-
sensitive (turn to brownish when exposed to light) and should be
stored in the dark (Yield: 56%).
2.3. Thermal properties
Fig. 6 shows thermal stability of P1eP3 with heating rate of
10ꢁ C/min under N2 atmosphere. The polymers only exhibit
moderate heat-resistant properties. The temperature of 5% weight
loss based on initial weight (Td5) of P1 is only 201ꢁ C, which may be
related to the thermal decomposition of SieCH3 groups. Obviously,
the SiePh groups have better thermal stability than SieCH3 groups,
so the polymer P3 with two phenyl groups attached on silicon
atoms shows the best thermal stability among these polymers, and
the Td5 and final weight residue at 800ꢁ C are 272ꢁ C and 79.5%,
respectively. The polymers were also investigated by DSC
measurement, but no obvious glass transition temperature (Tg) and
melting points (Tm) were found for any polymer.
1H NMR ( in CDCl3) 7.01 (s); 13C NMR (
d d in CDCl3) 120.4,
136.8 ppm; FT-IR (KBr plate) 2125 cmꢀ1(eN3).
4.3. Preparation of model compound (M1)
Trimethylsilylacetylene (0.10 g, 1 mmol), 1,4-diazidobenzene
(0.16 g, 1 mmol), copper iodide (0.01 g, 5 mol %), pyridine (0.5 ml)
and DMF (2 ml) was stirred for 24 h at 60ꢁ C under dark. Then the
mixture was poured into ethyl acetate (100 ml) and washed with
H2O (3 ꢂ 50 ml), dried over MgSO4, filtered and distilled under
reduced pressure. The crude product was purified by a silica gel
column using petroleum ether as an eluent to give M1 as a pale
yellow solid (Yield: 63%).
3. Conclusion
We have successfully prepared Poly[silylene-(1,2,3-triazol-4-yl)-
1,4-phenylene]s from diethynylsilanes and diazidobenzene via
CuAAC step-growth polymerization. The polymers showed unique
UVevis and PL properties, which indicated the weak
s
ep
conjuga-
1H NMR (
d
in DMSO-d6) 8.84 (s, 1H), 7.95 (d, 2H, J ¼ 9.0 Hz), 7.34
tion between the silylene and aromatic heterocycle. The fluore-
scence emission spectrum was observed in visible blue region (ca.
430 nm), and the emission intensity and quantum yield were
(d, 2H, J ¼ 9.0 Hz), 0.32 (s, 9H); 13C NMR (
d in DMSO-d6) 147.2, 140.4,
134.5, 129.6, 122.7, 121.4, ꢀ0.11 ppm; FT-IR (KBr plate) 3143, 3071,
2103, 1508, 1253 cmꢀ1; Anal. Calc. for C11H14N6Si: C, 51.16; H, 5.43;
N, 32.56. Found: C, 51.25; H, 5.23; N, 32.81%.
enhanced due to the sep interaction of the polymer main chains.
The present results provided a facile and cheap method to obtain
optical polymeric materials containing organosilicon groups. Other
4.4. Preparation of polymers (P1eP4)
sep conjugated polymers with different organosilicon or aromatic
units in backbone are currently in progress.
4. Experimental
The mixture of diethynyldimethylsilane (0.05 g, 0.5 mmol),
1,4-diazidobenzene (0.08 g, 0.5 mmol), copper iodide (0.01 g, 5 mol
%), pyridine (0.5 ml) and DMF (2 ml) was stirred for 24 h at 60ꢁ
C
under dark. The mixture was poured into ethyl acetate (200 ml) and
washed with H2O (3 ꢂ 100 ml), and the organic layer was dried over
MgSO4, filtered and distilled under reduced pressure. The residue
was poured into vigorously stirred petroleum ether (100 ml) to
afford P1 as beige precipitate (Yield: 71%).
4.1. General
Anhydrous tetrahydrofuran (THF) and diethyl ether (Et2O) were
freshly distilled over sodium and benzophenone before use.
Compound 1,4-diazidobenzene was prepared by modifying
the reported procedure [20,21]. Diethynyldimethylsilane, diethynyl-
methylphenylsilane and diethynyldiphenylsilane were prepared
from reported papers elsewhere [22,23]. Dipropargyldiphenyl silane
was obtained according to the published literature [24]. Trime-
thylsilylacetylene and other chemicals were purchased from Aldrich
and used as received unless otherwise noted.
FT-IR spectra was recorded with a Bruker Tensor27 spectro-
photometer. 1H NMR and 13C NMR spectra were measured using
CDCl3 and DMSO-d6 as solvent on Bruker AVANCE-300 NMR
Spectrometer. UVevis absorption and fluorescence spectra were
analyzed with UV-7502PC and ISS K2-Digital spectrophotometer,
1H NMR (
6H); 13C NMR (
d in DMSO-d6) 8.88 (s, br, 2H), 8.00 (m, 4H), 0.43 (s,
d
in DMSO-d6) 148.5, 141.6, 135.9, 121.8, ꢀ2.5 ppm;
FT-IR (KBr plate) 3121, 1661, 1517, 1259, 837, 800 cmꢀ1; Anal. Calc.
for (C12H12N6Si)n: C, 53.73; H, 4.48; N, 31.34. Found: C, 53.47; H,
4.63; N, 31.76%.
The polymers P2, P3, P4 were prepared in a similar procedure to
P1. Data for P2: yellow solid (Yield: 65%); 1H NMR (
d
in DMSO-d6)
8.92 (s, br, 2H), 7.96 (m, 4H), 7.53 (m, 2H), 7.39 (m, 3H), 0.43 (m,
3H); 13C NMR (
in DMSO-d6) 149.2, 142.1, 137.5, 135.2, 134.8, 129.5,
d
127.9, 122.5, ꢀ2.8 ppm; FT-IR (KBr plate) 3130, 3070, 1667, 1510,
1258 cmꢀ1; Anal. Calc. for (C17H14N6Si)n: C, 61.82; H, 4.24; N, 25.45.
Found: C, 61.25; H, 4.43; N, 25.87%.