Probing intraligand and charge transfer excited states of fac-Re(R)(CO)(3)(CO2Et-dppz)(+) (R = py, 4-Me2N-py; CO2Et-dppz = dipyrido3,2a : 2 ',3 ' c phenazine-11-carboxylic ethyl ester) using time-resolved infrared spectroscopy

摘要

The photophysics of fac-Re(R)(CO)(3)(CO2Et-dppz)(+) (R = py(1), 4-Me2N-py (2); CO2Et-dppz = dipyrido3,2a:2 ',3 ' cphenazine-11-carboxylic ethyl ester) was studied with luminescence spectroscopy and time-resolved infrared(TRIR) spectroscopy in the metal carbonyl (2100-1800 cm(-1)) and organic ester (1800-1600 cm(-1)) regions. For 1, the picosecond TRIR spectra in the metal carbonyl region provided evidence for the formation of an intra-ligand IL (pi-pi*) excited state, which partially decays to an equilibrium with the metal-to-ligand charge transfer (MLCT) excited state. For 2 it is evident that both IL (pi-pi*) and MLCT excited states are formed within 2 ps of excitation. The magnitude of the nu(CO) shift in the metal carbonyl region following excitation allows the MLCT excited states to be described more precisely as a d pi(Re) -> p*(phenazine) (MLCT)-M-3 state for 1 and as a dp(Re) -> p*(phenanthroline) (MLCT)-M-3 state for 2.