Absorption and Fluorescence Spectra of Aqueous Solutions of Disodium Cromoglycate

Abstract

ABSTRACT In the AM1 approximation, we calculated the molecular geometry and energetic structure of an individual molecule of disodium cromoglycate and its conformers as well as measured their absorption and fluorescence spectra in aqueous solutions of different concentrations. The calculation of electron transitions gives the lowest two π-π* transitions and one n-π* for the unit aromatic chromophore which is slightly split in a cromoglycate dianion containing two aromatic blocks. These transitions are found to correspond to the low intensive absorption band at 330 nm and fluorescence at 384 nm upon low concentration. It is established that the increase in the concentration leads to the aggregation and hence to the essential splitting of absorption bands and appearance of the fluorescence at 485 nm.