A mononuclear platinum(II) complex with ;mixed bpy and H(4)tg(-) ligands, [Pt(H(4)tg-S)(2)(bpy)]center dot 2H(2)O (1a; bpy = 2,2'-bipyridine and H(5)tg = 1-thio-beta-D-glucose), is photoluminescent in the solid state and undergoes facile and reversible removal of solvated water molecules accompanied by changes in its absorption and emission wavelengths. The analogous dmbpy complex, [Pt(H(4)tg-S)(2)(dmbpy)]center dot H2O (2a; dmbpy = 4,4'-dimethyl-2,2'-bipyridine), is also emissive in the solid state, but its absorption and emission spectra remain unchanged after dehydration. X-ray crystallographic analyses revealed that the difference in the chromism of 1a and 2a is due to the difference in their hydrogen-bonding networks, which involve solvated water molecules.