Copper Complexes of Some Polyphenols Extracted from Taraxacum officinale and Their Immobilization on Sericite-Based Hybrid Supports

Polyphenolic compounds extracted from Taraxacum officinale (dandelion) were used as natural chelating ligands to synthesize copper–polyphenol complexes, which were subsequently immobilized on sericite to obtain hybrid organic–inorganic materials. The complexes were prepared under controlled pH and temperature conditions, yielding structures with different Cu–polyphenol ratios. Structural characterization confirmed the formation of Cu(II)–polyphenol chelates, partial reduction to Cu(I) species at higher pH values, and the deposition of mixed Cu2O/CuO phases on the layered sericite substrate. Copper–polyphenol superstructures, copper nanoparticles, and copper oxide crystallites were heterogeneously distributed depending on synthesis conditions and metal–ligand ratios. The hybrid materials exhibited modified optical properties, combining the intrinsic reflectance of sericite with UV absorption from polyphenols and copper species. When incorporated into an emulsion matrix, the materials showed promising UV-screening performance, with SPF-equivalent values ranging from 7 to 33 depending on concentration. Antimicrobial evaluation demonstrated that copper–polyphenol complexes displayed enhanced activity against Staphylococcus aureus, Staphylococcus epidermidis, Escherichia coli, and Candida albicans compared to the natural extract, while sericite-supported hybrids retained selective efficacy, particularly against Gram-positive bacteria and C. albicans. These results indicate the potential of dandelion-derived copper complexes and their sericite hybrids as multifunctional bioactive agents for cosmetic dermatology applications.