Intramolecular hydrogen bonding. VI. The phosphorescence of 9-hydroxyphenalenone in an N-hexane Shpol’skii matrix

Luminescence spectra have been measured for 9-hydroxyphenalenone and its hydroxy-deuterated form in an n-hexane Shpol’skii matrix. Fluorescence spectra from the zero-point level in S1 agree well with those reported for neon matrix by Bondybey et al. [J. Chem. Phys. 80, 5432 (1984)]. However, there is no measurable unrelaxed emission when higher S1 vibrational levels are excited; vibrational relaxation is much faster in n-hexane than in solid neon. Vibrationally resolved phosphorescence spectra are the main new results reported here. The phosphorescence quantum yield for 9-DPO is an order of magnitude stronger than for 9-HPO and the origin band is red shifted by the deuterium substitution. It is proposed that the lowest triplet state is nonplanar.