Influence of annelation by benzene ring on electronic absorption spectra and on character of the singlet π‐π* transitions at polynuclear p‐quinones

Abstract

Aromatic polynuclear pquinones and their derivatives have been studied using their electronic absorption and luminescence spectra and their basicity. The data were used to provide a basis for the study of the relationships between the structure and the spectral characteristics.

Low-Lying Electronic States, Spectroscopy, and Photophysics of Linear Para Acenequinones

“…12 Kunavin and Shvekhgeimer reported that the lr3(n,z*) state energies of dicarbonyl compounds depend both on the presence of vinyl groups conjugated with carbonyl groups and on the mutual position of carbonyl groups in a molecule.lo6 As is seen in Figure 8, the energy levels of the lowest order spin-orbit and vibronic perturbations of the singlet and triplet states. Hartmann and Lorenz first showed that the carbonyl group in quinones interrupted the n-electron delocalization and that the position of the first singlet ~tn* transition was determined by the size of the aromatic subsystem ( m or n in Q [ n~, n l ) .~~ Nepras and Titz have attempted to provide a quantitative interpretation for Hartmann's observation using a PPP method.12 The l(n,z*) electronic spectra have been interpreted in terms of the local and charge-transfer transitions of the aromatic subsystem.…”

“…66 Nepras and Titz have attempted to provide a quantitative interpretation for Hartmann's observation using a PPP method. 12 The l{it,7i*) electronic spectra have been interpreted in terms of the local and charge-transfer transitions of the aromatic subsystem. They stated that the lowest \n,n*) state energies in acenequinones depend not only on the size of the larger aromatic subsystem but also on the size of smaller one.…”

“…They stated that the lowest \n,n*) state energies in acenequinones depend not only on the size of the larger aromatic subsystem but also on the size of smaller one. 12 Kunavin and Shvekhgeimer reported that the L3(n,.T*) state energies of dicarbonyl compounds depend both on the presence of vinyl groups conjugated with carbonyl groups and on the mutual position of carbonyl groups in a molecule. 106 As is seen in Figure 8, the energy levels of the lowest co£ oo^co^cajcco Figure 8.…”

“…89 Such an observation has been confirmed also by decay measurements as exemplified in Figure 13. At high total pressure, the fluorescence of Q [1,0] and Q[0,0] exhibits a single exponential decay with the lifetime being identical with the phosphorescence lifetime, but as the pressure is reduced the decay curve becomes a double exponential, with the lifetime of the fast decay component being pressure dependent and that of the slow one being identical with the phosphores-PRESSURE (Torr) Figure 12. Pressure dependence of 4>f and 4>p for Q[0,0] and Q[1,0] vapors.…”