Photophysics and photochemistry of triplet exciplexes between triplet naphthalene derivatives and benzophenone

Abstract

The photophysical and photochemical behaviors in the naphthalene derivatives (RX) and benzophenone (BP or >CO) systems have been studied by means of 355-nm laser photolysis techniques in polar media. At the initial event, the triplet energy transfer (TET) occurs from 3BP* to RX in the nanosecond region. It is found that the following reactions occur effectively in polar media via the triplet exciplexes having loose sandwich-like structures with weak charge-transfer character in the microsecond region: (1) For RNH3+-BP or ROH-BP system, hydrogen atom transfer (HT), for the latter proton-enhanced HT whereas for the former proton-reduced HT, and the more protic hydrogen atom of -NH3+ is more reactive in HT for the HORNH3+-BP system (2) for the ROMe-BP system, proton-induced electron transfer (ET) in the presence of protons. (3) for the RN(Me)2 (or RN(Et2))-BP system, hydrogen-bonding-induced ET in the presence of H2O or methanol.