Secondary fluorescences of 4'-(1-pyrenyl)acetophenone and p-dimethylaminoacetophenone

Abstract

4'-(1-Pyrenyl)acetophenone (PYRA) and p-dimethylaminoacetophenone (DMAA) were investigated in nonpolar and polar protic and aprotic solvents over a wide temperature range. Quantum chemical (INDO/S) calculations of the energies of electronic transitions, oscillator strengths and dipole moments were performed for planar and twisted conformations of both compounds. For DMAA, the experimental results are well explained in terms of the TICT state. In the case of PYRA in polar aprotic solvents, two alternative models are discussed: TICT state formation or inversion of the two low lying singlet states.