Photophysical, electrochemical, and photosensitization properties of newly synthesized crown other derivatives of cyanine dyes have been investigated. These dyes exhibit strong absorption in the visible (450-560 nm) range with a solvent-dependent fluorescence quantum yield ranging from 0.006 to 0.11 and adsorb strongly on SnO{sub 2} nanocrystallites. The singlet excited state is readily quenched when adsorbed on SnO{sub 2} nanocrystallites as a result of a charge injection process. The photosensitization properties of these cyanine dyes in extending the photoresponse of SnO{sub 2} semiconductor have been investigated by probing the dependence of photocurrent and photovoltage on the wavelength and intensity of excitation. A maximum photon to photocurrent conversion efficiency of approximately 1% has been observed. 44 refs., 10 figs., 2 tabs.