Syntheses and photophysical properties of fluorescent dibenzofurans, a dibenzothiophene, and carbazoles substituted with bensoxazole and hydroxyl groups to produce excited state intramolecular proton-transfer

Article abstract of DOI:10.1002/jhet.5570320523

Dibenzofurans, a dibenzothiophene, and carbazoles, each substituted with a 2-benzoxazolyl group as well as an ortho-hydroxyl group, were synthesized to produce fluors with fluorescence due to excited-state intramolecular proton-transfer. The orientations for Friedel-Crafts acylation of 3-methoxydibenzothiophene and of the analogous carbazole were determined. The fluors displayed absorption peaks in the 330-385 nm region with molar extinction coefficients up to 57,000. Fluorescence quantum efficiencies of 0.17-0.44 were obtained at wavelengths that had peak values from 540-600 nm. The fluors are of potential use as wavelength shifters in scintillating polystyrene fibers.