Synthesis and Properties of Novel σ−π-Conjugated Polymers with Alternating Organosilicon and [2.2]Paracyclophane Units in the Main Chain

Abstract

Novel σ−π-conjugated polymers (8a−c) that have alternating organosilicon and [2.2]paracyclophane units in the polymer backbone were synthesized by polycondensation of dichlorodisilanes (5a,b) or dichlorosilane (5c) with bifunctional lithium acetylide derived from 4,16-diethynyl[2.2]paracyclophane (4) and butyllithium, and their optical and thermal properties were investigated. A self-standing thin film of the polymer was obtained easily by casting from a CHCl3 solution. All polymers were thermally stable in the solid state. The polymers showed delocalization of the π-electron through the Si−Si bonds and the through-space of the [2.2]paracyclophane moiety. σ−π Conjugation between the disilanylene unit and the π-electron system with a paracyclophane core was not significantly effective, which suggests sufficient delocalization of the π-electron along the diethynyl[2.2]paracyclophane unit.