Unexpectedly High Acidity of Water-Soluble Phosphacoumarins
Ivanenko T.Yu. Zalaltdinova A.V. Darmagambet K.Kh. Gerasimova M.A. Sadykova Y.M. Levandovski V.D. Gazizov A.S. Akylbekov N.I. Appazov N.O. Burilov A.R. Lutoshkin M.A.
December 2025Multidisciplinary Digital Publishing Institute (MDPI)
Chemistry (Switzerland)
2025#7Issue 6
In this work, we report the one-pot synthesis and characterization of four water-soluble 2-hydroxybenzo[e][1,2]oxaphosphinine 2-oxides. The compounds were obtained by cascade reactions of (2-ethoxyvinyl)phosphonic dichloride with phenol or naphthol derivatives, and their acid–base, structural, and photophysical properties were investigated using a combination of experimental and computational methods. These compounds exhibit UV– vis absorption maxima at 209–341 nm and fluorescence maxima at 300–394 nm. Notably, these cyclic phosphonic acids exhibit unusually strong acidity with pKa values from −1.3 to 0, comparable to mineral acids; complete protonation is not achieved even in concentrated HCl. The acidity trends and spectra were further analyzed by DFT using both explicit and implicit solvation models.
absorption , Cox-Yeates method , DFT , emission , phosphacoumarins
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Institute of Chemistry and Chemical Technology, Federal Research Center «Krasnoyarsk Science Center of the Siberian Branch of the Russian Academy of Science», Akademgorodok 50/24, Krasnoyarsk, 660036, Russian Federation
Siberian Federal University, Svobodny pr. 79, Krasnoyarsk, 660041, Russian Federation
Arbuzov Institute of Organic and Physical Chemistry, Federal Research Center «Kazan Scientific Center», Russian Academy of Science, Arbuzova Str., 8, Kazan, 420088, Russian Federation
Laboratory of Engineering Profile “Physical and Chemical Methods of Analysis”, Korkyt Ata Kyzylorda University, Aiteke bi Str. 29A, Kyzylorda, 120014, Kazakhstan
Institute of Chemistry and Chemical Technology
Siberian Federal University
Arbuzov Institute of Organic and Physical Chemistry
Laboratory of Engineering Profile “Physical and Chemical Methods of Analysis”
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