Substituent effect on the nonradiative decay rates from 3MLCT excited state of ruthenium(II) complexes: A quantum chemical treatment

The radiationless transition rates from metal-to-ligand charge-transfer excited states of [Ru(phen)3]2+ (phen = 1,10-phnanthroline) and its analogues were investigated in terms of the Huang-Rhys factors (S) using luminescence measurements and quantum chemical calculations. From the luminescence spectral fitting, it was found that not only SM for medium frequency mode but also SL for low frequency mode was significant for the nonradiative process. Huang-Rhys factors predicted by the conventional quantum chemical method were in agreement with the experimental values, SM and SL.