Solvent Mediated Excited State Proton Transfer in Indigo Carmine.

摘要: Excited state proton transfer (ESPT) is thought to be responsible for the photostability of biological molecules, including DNA and proteins, natural dyes such as indigo. However, mechanistic role solvent interaction in driving ESPT not well understood. Here, electronic excited deactivation dynamics indigo carmine (InC) mapped by visible pump-infrared probe two-dimensional electronic-vibrational (2DEV) spectroscopy complemented structure calculations. The observed reveal notable differences between InC a protic solvent, D2O, an aprotic deuterated dimethyl sulfoxide (dDMSO). Notably, acceleration decay D2O (<10 ps) compared dDMSO (130 ps). Our data reveals clear evidence accompanied significant change dipole moment, which found occur dDMSO. We conclude that ability solvents form intermolecular H-bonds with enables ESPT, facilitates rapid nonradiative S1 → S0 transition via monoenol intermediate.