Femtosecond‐Picosecond Laser Photolysis Studies on Proton Transfer Process of Excited 1‐Pyrenol‐Triethylamine Hydrogen Bonding Complex in Solutions

Abstract

Abstract The proton transfer (PT) process in the excited hydrogen bonding (HB) complex of 1‐pyrenol and triethylamine, leading to the formation of a hydrogen‐bonded ion pair (HBIP*) of excited pyrenolate anion and triethylammonium cation, PyO −* ··· H‐N + (C 2 H 5 ) 3 , and subsequent reaction processes of HBIP* in various solvents were investigated by picosecond and femtosecond laser photolysis, as well as by steady‐state absorption and fluorescence measurements. Time constants for the PT process taking place in the time region of a few picoseconds were almost independent of the polarity of the solvent and it was suggested that the intermolecular slow motion in the HB complex, such as the intermolecular vibration and/or the torsional motion of the two moieties, might regulate the PT process. Moreover, the ionic dissociation process following the photoinduced PT process in polar solvent was directly measured. The dynamic behaviors of the excited intermolecular HB complex and underlying mechanisms are discussed by comparing these results with those on the intramolecular photoinduced PT process and with results of investigations of electron transfer systems.