Funct. Mater. 2025; 32 (4): 685-693.
Synthesis and spectral properties of alginic acid polymers modified by flavonol fragments
Research Institute of Chemistry at V.N. Karazin Kharkiv National University, 4 Svobody Sq., Kharkiv 61022, Ukraine
The article is devoted to the development of a method for the synthesis of polymers based on alginic acid modified with flavonol fragments and the study of the spectral properties of the obtained compounds. The conditions for the direct esterification reaction of alginic acid with 7-hydroxyflavonol and 4′-hydroxyflavonol are described. The reaction demonstrates the regioselectivity: it leads to the formation of ester bridges between the polymer chain and flavonols involving the 7-hydroxy- and 4′-hydroxy groups, while esterification of the 3-hydroxy group of flavonols does not occur. This allows keeping the spectral properties of flavonol fragments, the ability to complex, and intramolecular proton transfer in the excited state. It was shown that the absorption and fluorescence spectra of the modified polymers are similar to the neutral forms of free flavonols. The results obtained will enable the use of flavonol-containing alginate polymers in the gel phase for the detection and accumulation of metal ions, for examination of solvent′s polarity, and for medical practice as a depot for the slow release of biologically active flavonoids.
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