Luminescence of microcrystals and solutions of 8-azagona-1,3,5(10),13-tetraene-12,17-dione

We present the results of the investigation of delayed luminescence of 2,3-methoxy-8-azagona-1,3,5(10),13-tetraene-12,17-dione (8,9-dimethoxy-1,2,3,5,6,10b,11,12-octahydrocyclopentane[5,6]pyrido[2,1-a]isoquinoline-1,12dione) in solid solutions. Dual delayed luminescence with maxima in the region of 400 and 500 nm depending on the excitation wavelength has been revealed. It is shown that the observed delayed luminescence is a phosphorescence of individual molecules of the substance (short-wavelength luminescence) and molecular pairs (long-wavelength luminescence) resulting from the dipole-dipole (Coulomb) interaction of strongly polarized molecules. The conclusion has been drawn that the spectral features observed for the solutions of 8-azasteroids are due to both individual molecules and their aggregates. (C) 2002 Elsevier Science B.V. All rights reserved.