ИСТИНА

Effective environmental monitoring is an actual problem of modern society. Most of the existing optical sensors based on chromoionophores, capable of sensitive and highly selective recognition of toxic analytes, and, above all, metal cations, usually work in organic solvents. Therefore, the main trend in the development of environmental monitoring tools is the creation of "intelligent" miniature diagnostic devices operating in aqueous media. Among them, thin-film sensor systems, characterized by compactness, high speed response and availability for analytes are the greatest prospects. Porphyrins are a typical example of compounds that used for creating of sensory systems. In recent years, attention has been paid to the study of the properties of unsymmetrically substituted "push-pull" porphyrins, which combine in their structure substituents with strong electron-donor and electron-withdrawing properties. In the present work, the properties of new representatives of this type of porphyrins are investigated: meso-substituted porphyrins, functionalized with electron-donating (-OC8H17 and -OPhOC8H17) substituents and a diethoxyphosphoryl group, which is a strong electron acceptor. The aggregation properties of solutions of these compounds have been studied, both in the form of zinc complexes and free bases. The conditions for the formation of Langmuir monolayers are determined and their thermodynamic and optical properties are studied. It was found that the monolayers of the free bases of mesityl derivatives, like their solutions, do not exhibit selectivity for cations (mercury, copper, zinc and cadmium), although the times for the formation of complexes for different cations vary significantly. In contrast to solutions and monolayers at the air/water interface, in films of free base porphyrin transferred on a solid substrate (PVC) by the Langmuir-Schaefer (LS) method at 5 mN/m, porphyrins exhibit selectivity for mercury cations. And 30 layer film allows us to fix color changes at binding of mercury cations from aqueous solutions, which is observed for the first time for porphyrin compounds. The high spectral sensitivity of the 5-layer LS films made it possible to determine the content of mercury cations in the aqueous solution at the level of 0.01 mM.