Electronic spectra of some isoindolone derivatives

Abstract

The absorption (293 K), luminescence and excitation spectra (293 and 77 K) of 12b-p-tolyl-perhydro-1,3-benzoxazino[2,3-a]isoindolone (1) and 2-(2-hydroxyethyl)-1-p-tolyl-4,5,6,7-tetrahydro-3(1H)-isoindolone (2) were examined in solution, and the luminescence and excitation spectra were examined in polycrystalline form. An analysis of the electronic spectra indicates that the lowest excited singlet and triplet electronic state in these molecules are of the ππ*-type. The large probability of intersystcm conversion to triplet state appears in the polycrystallinc form of 2 and solution of 1. The rotation of the tolyl group in 2 due to excitation at room temperature, causes internal degradation of the excited singlet state and an absence of fluorescence. The molecules keep their solid state conformation in solution, too, at least in the ground electronic state.