Abstract
Fluorescence was examined for the chelates of alkyl and aryl salicylates with boric acid. A significant difference was found in fluorescence intensities and also in fluorescence lifetime between alkyl and aryl esters. This difference was interpreted in terms of the electronic energy levels and the electron distributions in the salicylates calculated with semi-empirical LCAO-SCF-CI method and the method of composite molecule. It was found that in the case of alkyl esters charge-transfer configuration contributes predominantly in the first excited state, whereas in the case of aryl esters locally excited configuration contributes predominantly. The difference in the fluorescence intensities is concluded to be due to the difference in the rates of the non-radiative transition.
