Tropone-fused, various pi-conjugated polymers (P2-P5) were synthesized by the palladium-catalyzed coupling reaction of 1,4-dibromo-6,8-dimethyl-7H-benzocyclohepten-7-one with aromatic divinyl, diboronic acid, and diethynyl compounds. The molecular orbital calculation of the model compounds was performed to discuss effective conjugation length of the repeating unit of the polymers. The absorption spectra of phenylenevinylene-type polymers shifted to longer wavelengths than the model compounds by about 60 nm. They exhibited green fluorescence [lambda(max)(em) = 544 and 561 nm]. The absorption spectrum of a phenylene-type polymer blueshifted by 10 nm; however, that of a phenyleneethynylene-type polymer redshifted by 83 nm as compared with their model compounds. They showed fluorescence with peak maxima at 457 and 489 nm, respectively. As a result, the absorption spectra of phenylene- and phenylenevinylene-type polymers blueshifted, but that of a phenyleneethynylene-type polymer redshifted by the annulation of tropone onto a benzene ring in the conjugated polymer. (C) 2004 Wiley Periodicals, Inc.