SPECTRAL STUDIES OF LIGHT-SENSITIVE CROWN-CONTAINING DYES IN SOLUTIONAND IN POLYMOLECULAR, LANGMUIR-BLODGETT LAYERS

A comparative spectral study of the complexation of two crown-containi ng dyes (structures 1 and 2) with calcium in solution and in polymolec uIar Langmuir-Blodgett layers was carried out. The binding constants w ith Ca in solution were measured. The logarithms of the binding consta nts are 12.8 for structure 1 and 8.02 for structure 2 (the binding con stant for the Ca-EDTA complex is 10.57). The complex of compound 1 wit h Ca is four orders of magnitude more stable in solutions than the com plex of compound 2. Therefore, the addition of EDTA results in dissoci ation of only the complex of 2 with Ca (the absorption band shifts to the initial position). The complex of 1 with Ca becomes less stable in polymolecular Langmuir-Blodgett layers due to the dissociation in EDT A solution when exposed to light with lambda = 400 nm. The complex of 2 with Ca behaves almost the same way in polymolecular Langmuir-Blodge tt layers and in solution.