Temperature dependence of dual emission in ruthenium(II) complexes containing 3,3′-bi-1,2,4-triazine derivatives

Three new ruthenium(II) polypyridyl complexes with highly π-deficient ligands, [Ru(bpy)2(btm)]2+ (1), [Ru(bpy)2(btb)]2+ (2) and [Ru(bpy)2(btp)]2+ (3) (bpy = 2,2′-bipyridine, btm = 3,3′-bis(5,6-dimethyl-1,2,4-triazine, btb = 3,3′-bis(5,6-diphenyl-1,2,4-triazine, btp = 3,3′-bis(phenanthro[9,10-e][1,2,4]triazine) were synthesized and characterized. Electrochemical data together with molecular calculations show that the first redox process in these complexes is not bpy based. Complexes 1, 2 and 3 display luminescence in ethanol/methanol (4/1, V/V) at 80 K, and all three complexes exhibit a temperature switch from single (150 K) to dual (80 K) emission behavior.