New efficient laser dyes for operation in the near UV range

Abstract

A series of substituted 2, 6-diphenyl-benzo[1.2d;4.5d′]bisoxazoles(I) and 2, 6-diphenyl-benzo[1.2d;5.4d′]bisoxazoles(II) were synthesized for evaluation as laser dyes. The photophysical properties such as singlet absorption, triplet absorption and fluorescence spectra, the fluorescence quantum yield and fluorescence decay time as well as the laser performance (tuning range, conversion effeciency, photochemical stability) were measured in ethanol or dioxane at room temperature. The success achieved in molecular engineering was demonstrated by its influence on the spectroscopic and photophysical data as well as on the laser performance. Increasing the Stokes' shift by introducing sterical hindrance in the parent compound makes the tuning ranges broader. The substituted 2, 6-diphenyl-benzo[1.2d;4.5d′]bisoxazoles(I) have proved to be a promising new class of photostable laser dyes operating in the near ultraviolet spectral region.