Theoretical Studies of the Electronic Structure and Spectroscopic Properties of [Ru(Htcterpy)(NCS)_3]~(3-)

摘要

The ground-and excited-state structures of [Ru(Htcterpy)-(NCS)3]~(3-)(1H)(tcterpy = 4,4',4"-tricarboxy-2,2':6',2"-terpyr-idine)are optimized by the DFT and CIS methods,respectively.Absorption and emission spectra in the gas phase and in solution(ethanol and water)are predicted at the TD-DFT/ B3LYP level.Experimental spectra are roughly reproduced by our calculated results.In ethanol solution,the HOMOs of the absorption spectra are dominated by d orbitals of the ruthenium atom and thiocyanate ligands,and the LUMOs possess pi*(tcterpy)character with considerable carboxyl contribution.In the theoretically simulated absorption spectra,the first four bands are attributed to Ru/NCS->PI*(tcterpy)charge-transfer(MLCT/LLCT)transitions,whereas the fifth one with the strongest intensity arises from intraligand tcterpy pi->pi* charge transfer(ILCT)mixed with some O(p_z)->terpy charge transfer(LLCT).Our calculations reveal that the MLCT/LLCT absorption bands in water are blue-shifted with respect to those in ethanol,agreeing with experimental observations.This can be rationalized by a decreased dipole moment in the excited state.The phosphorescent emissions are calculated to occur at 724,711,and 691 nm in the gas phase,in ethanol,and in water,respectively,all with the same ~3LMCT/~3LLCT character.