Activity of upper electron-excited states in bioluminescence of coelenterates

The involvement of upper electron-excited states as the primary excited states into bioluminescence of coelenterates was experimentally verified. A series of fluorescent molecules was used as foreign energy acceptors in this bioluminescent reaction. The fluorescent aromatic compounds – pyrene, 2-methoxy-naphtalene, naphthalene, and 1,4-diphenylbutadiene – were selected, with fluorescent state energies ranging from 26,700 to 32,500 cm−1. Excitation of these molecules by Forster singlet-singlet energy transfer from Sππ∗Sππ∗ of bioluminescence emitter and by light absorption were excluded. The weak sensitized fluorescence of three compounds was found in the course of bioluminescent reaction. Energy of the upper electron-excited states of the bioluminescent emitter was located around 31,000 cm−1. Localization of the primary excitation on a carbonyl group of coelenteramide molecule is discussed. Comparison of the primary excitation in bioluminescent processes of coelenterates and bacteria is provided.