Unusual photophysical properties of substituted carbazoles

Abstract

Photophysical properties of a new class of fluorescent, stable carbazoles (B1-B3, G1-G3, and R1-R2) as a function of excitation wavelength in matrixes and solution are reported. The emission maxima of B1 and B3 and G1-G3 show red shifts (6-16 nm) and substantially increased fluorescence quantum yields with a decrease in temperature from 25 to -10 degrees C. Considerable edge excitation red shift has been observed in B2. The emission of G1 shows both specific and general effects of solvent while intermolecular excitation energy transfer occurs from the naphthyl to the carbazolyl moiety in G3. Lippert-Mataga plots confirm the existence of multiple emitting states in each of these compounds.