A series of monomeric and dimeric cyanine dyes belonging to the thiazole orange family have been prepared via an improved synthetic procedure, by the reaction of the monomethine dye containing an iodoalkyl group with tertiary diamine linkers under microwave irradiation. The effects of microwave power and irradiation time on yield were examined. The electronic absorption and steady-state fluorescence spectra of prepared dyes have been investigated. Fluorescence properties indicate significance in singlet oxygen sensitization and make the present compounds potential candidates in the area of photodynamic therapy.