Silica gel coating films doped with Ru(bpy)(3)(2+) complexes were prepared by the sol-gel method from a hydrolyzed tetraethoxysilane solution containing [Ru(bpy)(3)(2+)]Cl-2 . 6H(2)O. UV-visible optical absorption spectra, fluorescence emission spectra, fluorescence efficiency and lifetime, and infrared absorption spectra were measured for the films dried at various temperatures. The fluorescence band attributed to the transition from the metal-to-ligand charge transfer elicited state to the ground state of Ru(bpy)(3)(2+) was found to show blue shift on sol-to-gel film conversion, red shift with increasing drying temperature up to 200 degrees C, and then blue shift again over 200 degrees C. The fluorescence lifetime increased and the fluorescence efficiency decreased with increasing drying temperature. In the as-deposited film, the complexes are thought to be surrounded by the solvent molecules which interact with the silanol groups of the gel network so strongly that the Franck-Condon excited state of the complex may be relaxed to a less extent, giving rise to the blue shift of the fluorescence peak on the sol-to-gel film conversion. During drying up to 200 degrees C the solvent in the gel pores evaporates, leaving the gel pores filled with air; the complexes are just weakly interacting with the gel network, obtaining more freedom of rotation and surrounded by air molecules, which results in the red shift of the fluorescence peak. Over 200 degrees C, the gel pores start to collapse and the complexes are immobilized in the gel network, strongly interacting with and fully surrounded by the silanol groups and/or siloxane chains, which is reflected in the blue shift of the fluorescence peak.