Research output: Contribution to Journal/Magazine › Journal article › peer-review
Research output: Contribution to Journal/Magazine › Journal article › peer-review
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TY - JOUR
T1 - A solid-state NMR study of lead and vanadium substitution into hydroxyapatite
AU - Pizzala, Helene
AU - Caldarelli, Stefano
AU - Eon, Jean-Guillaume
AU - Rossi, Alexandre Malta
AU - Laurencin, D
AU - Smith, Mark E.
PY - 2009/4/1
Y1 - 2009/4/1
N2 - 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.
AB - 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.
KW - CHEMICAL-SHIFT TENSORS
KW - P-31 NMR
KW - CALCIUM HYDROXYAPATITE
KW - AQUEOUS-SOLUTIONS
KW - CA-43 NMR
KW - V-51 NMR
KW - MAS NMR
KW - H-1 MAS
KW - PHOSPHATES
KW - SPECTRA
U2 - 10.1021/ja808270v
DO - 10.1021/ja808270v
M3 - Journal article
VL - 131
SP - 5145
EP - 5152
JO - Journal of the American Chemical Society
JF - Journal of the American Chemical Society
SN - 1520-5126
IS - 14
ER -