Polysilylenes with ethynylphenyl substituents

Abstract

Ethynylphenyl-methyldichlorosilane (EPDMS) has been prepared as a new monomer for the synthesis of polysilylenes with triple bonds attached to the catenated Si chain. A series of copolymers with methylphenyldichlorosilane (MPDS) as well as the homopolymer, PEPMS, have been synthesized. The content of ethynylphenyl substituents was quantitatively analyzed by FTIR spectroscopy. The optical properties of the new polymers were studied with respect to potential n-o interaction. No significant bathochromic shift of the UV-absorption maximum could be detected. Unexpectedly, increasing content of incorporated EPMS units led to a decrease of the (a-o*) absorption. The ethynylphenyl-substituted polysilylenes exhibited strong, temperature-dependent fluorescence in solution as well as in films.

Synthesis and Physical Properties of Poly(ethynylmethylsilane) Derivatives

“…1. As already reported [6], the reaction of M1 gave P1 in low yield and generated large amount of the insoluble unidentified solid. In contrast, the reactions of the tolyl derivatives M2 -M4 did not give such insoluble solid.…”

“…The IR spectra of the obtained polymers showed the band of carbon-carbon triple bond stretching at around 2140 -2190 cm -1 to indicate that the ethynyl groups survived the Wurtz reaction condition. The 1 H NMR spectra also supported their structures [6]. EtMgBr was used after the Wurtz reaction in order to deactivate the reactive end groups.…”

“…It was additionally revealed that the introduction of methyl group on a phenyl ring in the side chain hardly affected steric hindrance around the main chain. Frey et al [6] reported 280 nm of π-π* transition and 345 nm of σ−σ* transition for poly(methylphenylsilane-co-phenylethynylmethylsilane) (unit ratio: 51/49), CP(51/49), but we'd like to emphasize the difference of homopolymer of P1 from their copolymer.…”

“…Sodium (stick) and ethynylbenzene derivatives were purchased from Wako Pure Chemical Ind., Ltd. Dehydrated solvents (toluene, ether and tetrahydrofuran, THF) were used as received. Phenylethynyldichloro-(methyl)silane (M1) was synthesized as reported [6]. All dichlorosilanes were distilled twice just before use.…”

“…According to Frey et al [6], CP(51/49) exhibited fluorescence of 480 nm induced by excitation at 345 nm of σ−σ* transition, and no fluorescence done by excitation at 280 nm of π-π* transition. But, for the homopolymer of P1, the fluorescence was observed by excitation at 250 nm of π-π* transition and at 280 nm of σ−σ* transition ( Fig.…”