End-Capped Silole Dendrimers on a Carbosilane Periphery: Potential Electroluminescent Materials^⊥

The divergent synthesis of end-capped silole dendrimers Gn-2n+1Silole (n = 1−4) using 2,4,6,8-tetramethyl-2,4,6,8-tetravinylcyclotetrasiloxane [Me(CH2CH)SiO]4 as a core molecule and allyl alcohol/dichloromethylsilane as a building block is described in this paper. The reaction of the dichloride functionalities of the carbosiloxane dendrimers Gn-2n+2Cl (n = 1−4) with the 1,4-diphenylbutadiene-1,4-dianions (1) provided an effective route for the attachment of silole functionalities to a dendritic periphery. In addition, dendritic siloles GBn-2nSilole (n = 1−3) based on phenylethynylmethylsilane (PhC⋮C)2Me2Si as cores were synthesized. The building blocks of the dendrimers consisted of double bonds (−PhCCHMeSi−) in the inner shell and silole groups on the outermost periphery. The generational limit of the dendrimer for the two-branching type core molecule was found to have eight silole groups for the third generation. All of the dendrimers were characterized by 1H and 13C{1H} NMR, UV spectroscopy, cyclic votammetry (CV), and size exclusion chromatography (SEC). Using this methodology, a series of silole-containing dendrimer systems showing green to greenish-blue fluorescence were synthesized.