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Vanadium complexes with mixed O,S anionic ligands derived from maltol: Synthesis, characterization, and biological studies

TitleVanadium complexes with mixed O,S anionic ligands derived from maltol: Synthesis, characterization, and biological studies
Publication TypeJournal Article
Year of Publication2005
AuthorsMonga, V, Thompson, KH, Yuen, VG, Sharma, V, Patrick, BO, McNeill, JH, Orvig, C
JournalInorganic Chemistry
Volume44
Pagination2678-2688
Date PublishedApr
Type of ArticleArticle
ISBN Number0020-1669
KeywordsBIOCHEMISTRY, BIS(MALTOLATO)OXOVANADIUM(IV), COORDINATION CHEMISTRY, CRYSTAL-STRUCTURE, EPR, IN-VITRO, METAL, OXOVANADIUM(IV)
Abstract

Four mixed O,S binding bidentate ligand precursors derived from maltol (3-hydroxy-2-methyl-4-pyrone) have been chelated to vanadium to yield new bis(ligand)oxovanadium(IV) and tris(ligand)vanadium(III) complexes. The four ligand precursors include two pyranthiones, 3-hydroxy-2- m ethyl-4-pyranthione, commonly known as thiomaltol (Htma), and 2-ethyl-3-hydroxy-4-pyranthione, commonly known as ethylthiomaltol (Hetma), as well as two pyridinethiones, 3-hydroxy-2-methyl-4(H)-pyridinethione (Hmppt) and 3-hydroxy-1,2-dimethyi-4-pyridinethione (Hdppt). Vanadium complex formation was confirmed by elemental analysis, mass spectrometry, and IR and EPR (where possible) spectroscopies. The X-ray structure of oxobis(thiomaltolato)vanadium(IV),VO(tma)(2), was also determined; both cis and trans isomers were isolated in the same asymmetric unit. In both isomers, the two thiomaltolato ligands are arranged around the base of the square pyramid with the V=O linkage perpendicular; the vanadium atom is slightly displaced from the basal plane [V(1) = 0.656(3) angstrom, V(2) = 0.664(2) angstrom]. All of the new complexes were screened for insulin-enhancing effectiveness in streptozotocin-induced diabetes in rats, and VO(tma)2 was profiled metabolically for urinary vanadium and ligand clearance by GFAAS and ESIMS, respectively. The new vanadium complexes did not lower blood glucose levels acutely, possibly because of rapid dissociation and excretion.

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