Synthesis, structure and photophysical properties of three new hemicyanine dyes

Three new hemicyanine dyes that feature a fixed pyridine cation as electron acceptor, trans,trans-4-{4-[4-(N,N-diphenylamino)styryl]styryl}-N-methylpyridinium iodide (1), trans,trans-4-{4-[4-(N-carbazolyl)styryl]styryl}-N-methylpyridinium iodide (2) and trans,trans-4-{4-[2-(benzothiazole-2-yl)ethenyl]styryl}-N-methylpyridinium iodide (3), have been synthesized. The crystal structure of dye 1 was determined. X-ray diffraction analyses reveal that 1 crystal belongs to monoclinic, P21/c space group. Composite materials with these organic dyes doped into polymer-impregnated composite glass were prepared. Photophysical properties of these dyes in various solvents and composite glass were investigated in detail. Generally, photophysical properties of the dyes greatly increase in glass matrices compared with that in solution and there is no obvious fluorescence quenching in high doped concentration. The relationships between molecular structure and photophysical properties of this series of dyes were discussed.