Photoluminescence of trans-1,2-Di(2-naphthyl)ethylene: Conformation Isomerism and Validity of the Kennard Relation

trans-1,2-Di(2-naphthyl)ethylene (DNE) exists in liquid solutions as a mixture of three conformers which have relatively high stability in the excited state, do not convert into each other during the excited state lifetime, and thus behave as individual compounds. This behavior results in the dependence of the luminescence spectrum on the excitation wavelength and in nonexponential luminescence decay. Recently, it has been shown theoretically that the Kennard relation should hold for the excitation-emission matrix in the case of any luminophore in the thermodynamically equilibrium state independent of complexity of the luminescence properties. It has been experimentally shown in this study that the Kennard relation does hold for DNE solutions.