Pizzala, Helene, Caldarelli, Stefano, Eon, Jean-Guillaume, Rossi, Alexandre Malta, Laurencin, Danielle and Smith, Mark E.. (2009) A solid-state NMR study of lead and vanadium substitution into hydroxyapatite. Journal of the American Chemical Society, Vol.131 (No.14). pp. 5145-5152. ISSN 0002-7863

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Abstract

A systematic study on cationic and anionic substitution in hydroxyapatite structures was carried out, with the aim of understanding the impact of ion exchange on the crystalline structure and properties of these materials. Lead and vanadium were chosen for the exchange, due to their known effects on the redox and catalytic properties of hydroxypatites. Hydroxyapatites with variable Pb and V contents, Pb-x- Ca10-x(VO4)y(PO4)(6-y)(OH)(2) (x = 0, 2, 4, 6, 8 and 10 for y = 1; y = 0, 0.5, 1, 2, 3 and 6 for x = 10) were synthesized and characterized by NMR spectroscopy. Solid-state NMR allowed an analysis of the chemical environment of every ion after substitution into the hydroxyapatite network. Ca-43 and 207 Pb NMR spectra at different lead concentrations provided clear evidence of the preferential substitution of lead into the Ca(II) site, the replacement of the Ca(I) site starting at x = 4 for y = 1. Two NMR distinguishable Pb(I) sites were observed in Pb-10(PO4)(6)(OH)(2), which is compatible with the absence of a local mirror plane pi rpendicular to the c direction. In contrast with P-31 NMR, for which only small variations related to the incorporation of Pb are observed, the strong change in the V-51 NMR spectrum indicates that lead perturbs the vanadium environment more than the phosphorus one. The existence of a wide variety of environments for OH in substituted apatites, is revealed by H-1 NMR, and the mobility of the water molecules appears to vary upon introduction of lead into the structure.

Item Type:	Journal Article
Subjects:	Q Science > QC Physics Q Science > QD Chemistry
Divisions:	Administration > Vice Chancellor's Office Faculty of Science > Physics
Library of Congress Subject Headings (LCSH):	Magnetic resonance imaging, Magnetic resonance microscopy, Hydroxyapatite, Phosphates, Lead, Vanadium, Substitution reactions
Journal or Publication Title:	Journal of the American Chemical Society
Publisher:	American Chemical Society
ISSN:	0002-7863
Date:	15 April 2009
Volume:	Vol.131
Number:	No.14
Number of Pages:	8
Page Range:	pp. 5145-5152
Identification Number:	10.1021/ja808270v
Status:	Peer Reviewed
Publication Status:	Published
Access rights to Published version:	Restricted or Subscription Access
Funder:	Programa CAPES/Cofecub, France. Ministère des affaires étrangères et européennes (MAEE), Provence-Alpes-Côte d'Azur (France) (PACA), Conselho Nacional de Desenvolvimento Científico e Tecnológico [ National Council for Scientific and Technological Development (Brazil)] (CNPq), Engineering and Physical Sciences Research Council (EPSRC), University of Warwick, CAPES (Organization : Brazil)
Grant number:	436/03 (CAPES/Cofecub)
URI:	http://wrap.warwick.ac.uk/id/eprint/28162

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