Spectral characterization of polymer complexes based on poly(3,5,7,3’,4’-pentahydroxyflavone) with some ion metals

The present work focuses on investigating the complexation of some Group II metal ions and Al³⁺ with cross-linked polymers containing built-in fragments of 3,5,7,3’,4’-pentahydroxyflavone (quercetin). It has been studied how the formation of the polymer complexes manifests itself in IR, UV-vis, and fluorescence spectra of polymers. Additionally, the effect of polymer network structure on the spectral parameters of the complexes was analyzed and compared with the complexation of “free” quercetin not bound to the polymer. When a rigid and dense network is formed, metal ions face restricted access to the complexation centers, resulting in a lower concentration of bound metal ions. Moreover, it was found that unlike complexes of “free” quercetin, the complexes of quercetin-containing polymers with Group II ions exhibit extremely weak fluorescence, whereas the polymeric Al³⁺ complexes exhibit significant emission. This finding suggests that quercetin-containing polymers may be promising candidates for use as selective polymeric film indicators for detecting aluminum ions in natural and industrial environments.