Oxovanadium(IV) complexes of carbohydrates: A brief overview

Baran, Enrique J.

doi:10.1016/j.jinorgbio.2008.10.008

Cited by 19 publications

(15 citation statements)

References 70 publications

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“…Its special feature may be assigned to the low intensive, scarcely splitted band at ca 1000 cm −1 , due to the characteristic V = O stretching vibration [3-9]. The visible disappearance of this band in presence of MCCh (starting from the lowest pH 3.54, where potentiometry shows already the share of complexation) may be explained by strong hydrogen-bond interactions between free hydroxyl groups of the carbohydrate ligand and the oxo group of the metal center thus leading to diminution of the V = O bond strength.…”

Section: Resultsmentioning

confidence: 99%

“…The molar D-glucosamine to N -acetyl-D-glucosamine ratio in the chitosan sample is an estimate of the so called degree of deacetylation (DD). The term chitosan is referred to chitin of DD > 60% [1-3]. The degree of deacetylation of the copolymer is usually within the range of 70.0% - 95.0% [4-5].…”

Section: Introductionmentioning

confidence: 99%

“…This non-toxic, biodegradable and biocompatible material has attained great interest in pharmaceutical applications, as versatile drug delivery agent [1-3]. A valuable physicochemical modification of chitosan, used among others as excipient in drug formulations, is microcrystalline chitosan (MCCh), obtained in form of suspension, powder or granules [6-7].…”

Section: Introductionmentioning

confidence: 99%

“…Microcrystalline chitosan shows a number of valuable features as compared with unmodified chitosan: higher absorptivity, chelating capability, higher bioactivity, as well as ability of forming polymer films directly from water slurry. Similarly as it was the case with the previous forms of chitosan, MCCh may be proposed as an effective vehicle for the controlled vanadium release [3]. …”

Section: Introductionmentioning

confidence: 99%

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Coordinative interaction of microcrystalline chitosan with oxovanadium (IV) ions in aqueous solution

Lichawska

Bodek

Jezierska

et al. 2014

Chemistry Central Journal

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BackgroundChitosan, a non-toxic, biodegradable and biocompatible polysaccharide has attained great interest in pharmaceutical applications, as versatile drug delivery agent. Chitosan has been already shown to serve as vehicle for sustained drug release by chitosan-vanadium(IV) complex from a chitosan gel matrix. Therefore, chitosan gel proved to retain vanadium and preserve its insulin-mimetic efficacy. Nevertheless, there is a lack of reports concerning complexing equilibria in aqueous solution, in particular when using the more advantageous microcrystalline form of chitosan (MCCh). Microcrystalline chitosan shows a number of valuable features as compared with unmodified chitosan.ResultsExperimental studies on complexing interaction between a special form of biomaterial - microcrystalline chitosan as ligand, L = MCCh, of two exemplary degrees of deacetylation DD (lower 79.8%; higher 97.7%) with M = oxovanadium (IV) ions have been carried out potentiometrically at four ligand-to-metal concentration ratios (2:1, 5:1, 8:1, 10:1). Among the five hydrolysis equilibria of VO2+ reported up to now in the literature, under the conditions of the present work i.e. aqueous solutions of ionic strength I = 0.1 (KNO3) and temperature 25.0 ± 0.1°C, the predominating one was (VO)2(OH)2 2+ formation: log β20–2 = −7.01(2). Analysis of potentiometric results permitted to note that degree of deacetylation does not essentially influence the coordination mode of the complexes formed. In the case of both the two DD values, as well as for all the ligand-to-metal ratios, formation of hydroxyl deprotonated MLH−1 and ML2H−2 moieties has been confirmed potentiometrically (log β11–1 = −0.68(2) for DD = 79.8% and −0.68(2) for DD = 97.7%, log β12–2 = −7.64(6) for DD = 79.8% and −5.38(7) for DD = 97.7%).ConclusionMicrocrystalline chitosan coordinates the vanadyl ions by the hydroxyl groups. Interaction of MCCh with VO2+ ions in aqueous solution occurs within pH 5–7. Amounts of alkali excessive towards -NH2 are needed to deprotonate the OH groups. Deprotonation occurring at the chitosan hydroxyl groups permits a “pendant” or “bridge” model of coordination with VO(IV). Lack of complexation via deprotonation of amine groups, typical for simple cations and the molybdenum anion, has been indicated also by FTIR spectroscopy and EPR.Graphical AbstractCoordination modes of VO(IV) with microcrystalline chitosan (MCCh): (a)- pendant model, (b)- bridge model

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Coordinative interaction of microcrystalline chitosan with oxovanadium (IV) ions in aqueous solution

Lichawska

Bodek

Jezierska

et al. 2014

Chemistry Central Journal

View full text Add to dashboard Cite

show abstract

“…Baran, 2009). In this context, the interaction of vanadium species with polysaccharides has been scarcely investigated and the available information is so far restricted to VO 2+ complexes of polygalacturonic acid (Branca, Micera, Dessi, & Kozlowski, 1989;Deiana, Erre, Micera, Piu, & Gessa, 1980), chondroitin sulfate A (Etcheverry, Williams, & Baran, 1994) and chitosan (Baran, 2008).…”

Section: Introductionmentioning

confidence: 99%