Nonradiative transition of phosphorescent charge-transfer states of ruthenium(II)-to-2,2′-biquinoline and ruthenium(II)-to-2,2′:6′,2"-terpyridine in the solid state

Temperature-dependent decays of the charge-transfer tripler excited states CCT) of ruthenium(II)) compounds have been investigated in a wide temperature range (77-480 K) for the crystals of Ru(biq)(3)(ClO4)(2), Ru(bpy)(2)- (biq)X-2. 2H(2)O, and Ru(tpy)(2)X-2, (bpy = 2,2'-bipyridine, tpy = 2,2':6',2"-terpyridine, big = 2,2'-biquinoline, X = ClO4-, PF6-). The width of the (CT)-C-1 absorption band and the peak of (CT)-C-3 emission of the Ru(bpy)(2)(biq)X-2. 2H(2)O crystal at 298 K are unchanged from those of the ethanol/methanol solution sample: The (CT)-C-3 of Ru(bpy)(2)(biq)X-2. 2H(2)O and Ru(biq)(3)(ClO4)(2) in the solid state above 370 K are converted to a higher lying excited state, the d-d tripler lowest excited state ((3)(d-d)), with a frequency factor of > 10(13 )s(-1) and an activation energy of > 3100 cm(-1), followed by the rapid degradation of the higher excited state. A small frequency factor (< 10(12) s(-1)) and an activation energy (< 2000 cm(-1)) of the nonradiative decay of (CT)-C-3 for [Ru(tpy)(2)]X-2 in the solid state indicates that the exoergonic intersystem crossing of 3(d-d) to the ground state is the rate-determining process of (CT)-C-3 decay above 200 K.