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

The divergent synthesis of end-capped silole dendrimers G n -2 n+ 1 Silole ( n = 1−4) using 2,4,6,8-tetramethyl-2,4,6,8-tetravinylcyclotetrasiloxane [Me(CH 2 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 G n- 2 n+ 2 Cl ( 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 GB n -2 n Silole ( n = 1−3) based on phenylethynylmethylsilane (PhC⋮C) 2 Me 2 Si 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 1 H and 13 C{ 1 H} 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.