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Synthesis and solution studies of the complexes of pyrone analogue ligands with vanadium(IV) and vanadium(V)

TitleSynthesis and solution studies of the complexes of pyrone analogue ligands with vanadium(IV) and vanadium(V)
Publication TypeJournal Article
Year of Publication2002
AuthorsSong, B, Saatchi, K, Rawji, GH, Orvig, C
JournalInorganica Chimica Acta
Volume339
Pagination393-399
Date PublishedNov
Type of ArticleArticle
ISBN Number0020-1693
KeywordsAQUEOUS-SOLUTION, BIS(MALTOLATO)OXOVANADIUM(IV), GLUCOSE, insulin drugs, ION-COORDINATING PROPERTIES, potentiometry, stability constants, vanadium complexes
Abstract

A new potentially tetradentate chelator N,N’-bis(3-hydroxy-6-methyl-2-methylene-4-pyrone)ethylenediamine (H-2(en(ama)(2))), has been synthesized and its protonation constants, as well as those of two other 3-hydroxy-4-pyrone ligands (allomaltol (Hama) and methylmaltol (Hmma)) determined potentiometrically at 25 degreesC and 0.16 M NaCl: pK(a1) = 3.67+/-0.07, pK(a2) = 5.82+/-0.07, pK(a3) = 7.96+/-0.04, pK(a4) = 8.77+/-0.03 for [H-4(en(ama)(2))](2+), pK(a) = 8.04+/-0.02 for Hama and pK(a) = 8.82+/-0.02 for Hmma. Potentiometric pH titrations were also used to measure the stability constants of these ligands with V(IV) and V(V) and to study the structures of the complexes of (en(ama)(2))(2-) in aqueous solution. H-1 NMR was used to assign the protonation constant values to the different protons in H-2(en(ama)(2)). A pM versus pH plot confirmed that H-2(en(ama)(2)) has much stronger complexation than its bidentate analogues, in the same pH range. (C) 2002 Elsevier Science B.V. All rights reserved.

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