SYNTHESIS AND CHARACTERIZATION OF WELL-DEFINED FULLY CONJUGATED HYPERBRANCHED OLIGOMERS OF BETA,BETA-DIBROMO-4-ETHYNYLSTYRENE

Well-defined dendritic oligomers of poly(beta,beta-dibromo-4-ethynylst yrene) of the first and second generation have been synthesized by a s tepwise synthesis, and characterized. It was found from n.m.r. analysi s and by theoretical calculations that free rotation around formal sin gle bonds is hampered by conjugation. All oligomers were found to be b lue emitters with their emission maxima correlating with the number of repeating units. All dendrimers except dendrimer 12 (beta,beta-bis[be ta',beta'-di(beta '',beta ''-dibromostylyl-4 ''-ethynyl)styryl-4'-ethy nyl]-4-ethynylstyrene) showed two maxima in the excitation spectra. (C ) 1998 Elsevier Science Ltd. All rights reserved.