Spectral properties of 1H-pyrazolo[3,4-b]quinoline substituted with N,N-diethylamine moiety

Photophysical properties of 6-N,N-diethyl-3-methyl-1-phenyl-1H-pyrazol[3,4-b]quinoline (DEPQ), a potential material for electroluminescent applications, were investigated. The absorption and fluorescence spectra and fluorescence lifetimes were recorded in a great number of solvents with different polarity. The red shifts in absorption and fluorescence maxima with the solvent's polarity were observed. Different trends in values of quantum yield for non-polar and polar solvents suggest two different deactivation ways of the excited state, depending on solvent polarity. DEPQ in non-polar solvents emits from locally excited states while deactivation DEPQ in polar solvents indicates charge transfer (CT) fluorescence. Several electro-optical parameters were also calculated.