Cooligomerization of 1,1‐Diethyl‐3,4‐Diphenyl‐2,5‐Dibromo‐1‐Silacyclopenta‐2,5‐Diene with Dichlorodisubstituted‐Silanes Using n ‐Butyllithium and their Photoelectronic Characterizations

Cooligomerization of 2,5‐dibromo‐1,1‐diethyl‐3,4‐diphenyl‐1‐silacyclopenta‐2,5‐diene with dichlorodisubstituted silanes was carried out by using n ‐butyllithium in tetrahydrofuran (THF) to yield poly[(1,1‐diethyl‐3,4‐diphenyl‐1‐silacyclopenta‐2,5‐dienylene)‐ co ‐(disubstituted silylene)]s 6a–g . The stretching frequencies of the dienes in the siloles appeared at 1594–1598 cm −1 in the FT‐IR spectral data of the prepared oligomers. The afforded cooligomers are well soluble in chloroform and THF. Gel permeation chromatography showed that the materials are oligomeric. According to the UV–Vis absorption spectra of the cooligomers in THF, the absorption maximum peaks with molar absorptivities of 7.71 × 10 2 to 1.10 × 10 4 L/(cm mol) were observed at 260–300 nm, indicating red‐shifts of 5–20 nm in comparison with the absorption peaks of 2,5‐dibromo‐1,1‐diethyl‐3,4‐diphenyl‐1‐silacyclopenta‐2,5‐diene. In the fluorescence emission spectra, emission maximum peaks were measured at 375–391 nm and maximum excitation bands at 290–318 nm. These absorption and emission spectra suggest that the prepared copolymers containing 1‐silacyclopenta‐2,5‐dienylene were conjugated following the cooligomer backbone. Cyclic voltammogram traces of 6a showed two oxidation peaks at 0.39 and 1.73 V and two reduction peaks at −0.39 and −1.49 V. Thermogravimetric analyses showed that all of the oligomers were generally thermally stable up to 150 °C, with a weight loss of 0–4% under nitrogen.