Fluorescence reactions of the third group cations with monoazo substituted derivatives of chromotropic acid

Fluorimetry, spectrophotometry, and quantum chemistry have been used for studying the mechanism of the formation of fluorescing complexes of the third group cations (Sc, Al, La, In, Y) with chromotropic acid monoazosubstituents. Previously, the complexes have not been studied as fluorimetric reagents. Fluorescing complexes have different quantum yield of fluorescence which drops sharply in the series Al→Ga→Sc→In→Y from 34 to 0.015%. The presence of substituents SO3H, AsO(OH)2, COOH, PO(OH)2 in o-position with respect to azogroup, as well as the absence of any substituent, leads to disappearance of fluorescent effects during interaction with ions of metals. The results of quantum-chemical calculating electron structure of possible complexes and energy of s→s transitions are given. Molecular diagrams of the main state of fluorescing complex are presented. It has been established that with increasing ionic radius in the series of the third group cations the formation of fluorescing complexes is hundered. The possibility of analytical application of the reagents studied has been considered