Barbalat D. Synthesis and chemical-analytical characteristics of new 6,7-dihydroxybenzopyrylium derivatives and their application in combined spectrophotometric methods of analysis

The dissertation is devoted to synthesis and study of properties of new analytical organic reagents - derivatives of 6,7-dihydroxybenzopyrylium, as well as research of their interaction with molybdenum (VI), establishment of optimal conditions of complexation and development of methods of cloud point extraction extraction and determination of Mo (VI). A number of 2,4 substituted derivatives of 6,7-dihydroxybenzo[b]pyrylium were synthesized and 8 of which were obtained for the first time. The structure of the synthesized compounds was confirmed by IR, Raman, NMR spectroscopy and mass spectrometry. Using the approaches of tristimulus colorimetry and spectrophotometry involving quantum chemical calculations, a detailed scheme of acid-base transformations in solutions of the obtained 6,7-dihydroxybenzo[b]pyrylium derivatives was proposed and the ionization constants of the corresponding functional groups were determined. New analytical forms based on complexes of synthesized reagents with Mo(VI) have been studied and identified. The optimal complexation conditions and corresponding chemical-analytical characteristics have been established. For the first time, the possibility of combining cloud point extraction at room temperature for the preconcentration of Mo(VI) in the form of complexes with 6,7-dihydroxybenzo[b]pyrylium derivatives with spectrophotometric detection was shown. New analytical forms based on Mo(VI) complexes with synthesized 2,4-substituted derivatives of 6,7-dihydroxybenzo[b]pyrylium, which are the basis for the development of simple, sensitive and environmentally attractive methods for its spectrophotometric determination with cloud point extraction preconcentration. The developed combined spectrophotometric methods were tested in the analysis of water samples of different categories, food products, pharmaceuticals and plant materials.