Five-membered rings as diazo components in optical data storage devices: an ab initio investigation of the lowest singlet excitation energies

The two lowest singlet excitation energies of 18 azo dyes have been studied by ab initio quantum-chemical methods within the second-order polarization propagator approximation (SOPPA). Various combinations of five-membered ri ngs (furan, thiophene, pyrrole, oxazole, thiazole, and imidazole) have been investigated as diazo components for a potential use in optical das storag e materials. It is found that the diazo compounds with two heterocyclic fiv e-membered rings have pi --> pi* excitation energies corresponding to laser wavelengths in the region 450-500 nm whereas one five-membered ring and a phenyl group as diazo components results in wavelengths in the region 400-3 35 nm. (C) 2000 Published by Elsevier Science B.V.