Spectrophotometric investigation on the complexation between chromo- and fluoroionophores containing aza-15Crown-5 moiety and alkaline and alkaline-earth metal ions

A series of new styryl dyes containing N-phenyl-aza-15-Crown-5 moiety is synthesized and their complexation and spectroscopic properties are studied together with the parent macrocyclic compound and related benzothiazolic derivative. Stability constants of the corresponding Ca2+, Sr2+, Ba2+ complexes obtained in dry acetonitrile solution are determined spectrophotometrically. Two different mathematical approaches are developed enabling the spectrophotometric determination of stability constants in the cases when ligand and complex absorption bands are overlapping and the complex spectrum cannot be obtained experimentally.