20.500.12556/DKUM-98511 Ellagitannins as Al(III) chelators determined binding sites with a predictive model Plant-toxic Al(III) ions released in acidic soils pose a global problem, affecting a substantial portion of agricultural land. One plant defense mechanism against Al(III) ions, which is poorly understood, is the release of organic acids or polyphenols with chelating properties. These compounds include ellagitannins (vescalin, castalin, vescalagin, castalagin, roburin A, and roburin D), whose chelating ability against Al(III) ions was investigated in this study. The formation of coordination compounds was monitored by Job’s method at pH 3.5–5.5. NMR and CD spectroscopy, combined with DFT calculations, were used to determine the binding positions of Al(III) ions on these high-molecular-weight polyphenols. Using information about binding sites and the microscopic protolytic equilibrium of ellagitannins, a model was developed to describe and predict the chelating ability of Al(III) ions by the nonahydroxytriphenoyl and hexahydroxydiphenoyl groups of ellagitannins. This model was then fitted to the experimental Job plots. The obtained stoichiometries and apparent formation constants can be used to predict the Al(III) chelating ability of other ellagitannins with identical structural elements. The developed model can therefore serve as a predictive tool for the removal of Al(III) ions by ellagitannins at various pH values. ellagitannins Al(II) ions chelation model function Job’s method NMR spectroscopy densitty functional calculations elagitanini spektroskopija true false true Elsevier B.V. Angleški jezik Slovenski jezik https://www.sciencedirect.com/journal/spectrochimica-acta-part-a-molecular-and-biomolecular-spectroscopy Članek v reviji 2026-06-17 15:36:49 2026-06-17 15:36:49 2026-07-03 13:32:36 0000-00-00 00:00:00 2026 0 0 14 str. št. članka 128146 Letn. 362 5 Dec. 2026 0000-00-00 Zaloznikova Objavljeno NiDoloceno 2026-03-12 2026-06-28 2026-06-03 54 281198339 10.1016/j.saa.2026.128146 1873-3557 Ellagitannins_as_Al(III)_chelators-Freser-2026.pdf Ellagitannins_as_Al(III)_chelators-Freser-2026.pdf 1 FAF4E362559BF7A017669C1D7F71ACC3 2025fdfefef35ec33bb77068f8c875a62d305256a38efe3f0e0f37b031462478 0ccd006c-6a52-11f1-87c9-00155d580e34 https://dk.um.si/Dokument.php?lang=slv&id=207252 https://doi.org/10.1016/j.saa.2026.128146 0 b39949a7-76d2-11f1-9131-00155d580e34 https://dk.um.si/Dokument.php?lang=slv&id=207876 Fakulteta za kemijo in kemijsko tehnologijo 0 0 0