Photophysical properties of a β-Carboline Rhenium (I) complex. Solvent effects on excited states and their redox reactivity

The photochemical and photophysical properties of a Re(I) tricarbonyl complex, ClRe(CO)3(nHo)2, where nHo = 9H-pyrido[3,4-b] indole (norharmane), were investigated in solution phase by combination steady state emission spectroscopy, laser flash photolysis (LFP) pulse radiolysis (PR) techniques. These results allowed us to identify study the reactivity β-carboline (nHo) Rhenium(I) complex main excited states. absorption spectrum as well steady-state time-resolved luminescence exhibits marked dependence with solvent properties. experimentally observed corroborated quantum chemical calculations, TD-DFT. most important electronic transitions present all solvents are MLLCTRe(CO)3→nHo1, nHo2 along mixture ILnHo LLCTCl→nHo transitions. relationship between dipole moment polarity was rationalized terms electron density inside outside complex. While is mainly attributed emitting 1ILnHo state, LFP experiments MLCT also detected. species generated either reductive or oxidative conditions compared those obtained PR. Also, quenching rate constant (kq) MV+2 calculated. can efficiently generate singlet oxygen acetonitrile yielding ΦΔ 0.25 ± 0.02. Optoacoustic measurements showed that, after photonic excitation, almost absorbed energy released medium prompt heat. ClRe(CO)3(nHo)2 significant importance relation use this several biomedical fields, such photodynamic therapy photoactivated chemotherapy new alternative therapies regional hyperthermia.