首页 | 本学科首页   官方微博 | 高级检索  
     检索      


VO2+ complexation by bioligands showing keto-enol tautomerism: a potentiometric, spectroscopic, and computational study
Authors:Sanna Daniele  Varnágy Katalin  Timári Sarolta  Micera Giovanni  Garribba Eugenio
Institution:Istituto CNR di Chimica Biomolecolare, Trav. La Crucca 3, I-07040 Sassari, Italy.
Abstract:The interaction of VO(2+) ion with ligands of biological interest that are present in important metabolic pathways--2-oxopropanoic acid (pyruvic acid, pyrH), 3-hydroxy-2-oxopropanoic acid (3-hydroxypyruvic acid, hydpyrH), oxobutanedioic acid (oxalacetic acid, oxalH(2)), (S)-hydroxybutanedioic acid (l-malic acid, malH(2)), and 2,3-dihydroxy-(E)-butanedioic acid (dihydroxyfumaric acid, dhfH(2))--was described. Their complexing capability was compared with that of similar ligands: 3-hydroxy-2-butanone (hydbut) and 3,4-dihydroxy-3-cyclobutene-1,2-dione (squaric acid, squarH(2)). All of these ligands (except l-malic acid) exhibit keto-enol tautomerism, and the presence of a metal ion can influence such an equilibrium. The different systems were studied with electron paramagnetic resonance (EPR) and UV-vis spectroscopies and with pH potentiometry. Density functional theory (DFT) methods provide valuable information on the relative energy of the enol and keto forms of the ligands both in the gas phase and in aqueous solution, on the geometry of the complexes, and on EPR and electronic absorption parameters. The results show that most of the ligands behave like α-hydroxycarboxylates, forming mono- and bis-chelated species with (COO(-), O(-)) coordination, demonstrating that the metal ion is able to stabilize the enolate form of some ligands. With dihydroxyfumaric acid, the formation of a non-oxidovanadium(IV) complex, because of rearrangement of dihydroxyfumaric to dihydroxymaleic acid (dhmH(2)), can be observed. With 3-hydroxy-2-butanone and 3,4-dihydroxy-3-cyclobutene-1,2-dione, complexation of VO(2+) does not take place and the reason for this behavior is explained by chemical considerations and computational calculations.
Keywords:
本文献已被 PubMed 等数据库收录!
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号