Effect of pH on the emission and absorption characteristics of 2,3-dicyano-p-hydroquinone

Abstract

Ultraviolet/visible absorption spectra, fluorescence emission spectra and fluorescence lifetimes have been measured for aqueous solutions of 2,3-dicyano-1,4-hydroquinone at various pH values. The dianion, anion and neutral species were all seen both in absorption and emission and pK values for the equilibria between these species in the ground and excited singlet state have been deduced. In strongly acidic solutions, absorption, tentatively ascribed to a protonated hydroquinone, is also observed.