title: Structure of the calcium pyrophosphate monohydrate phase (Ca2P2O7·H2O): towards understanding the dehydration process in calcium pyrophosphate hydrates.
abstract: Calcium pyrophosphate hydrate (CPP, Ca(2)P(2)O(7) · nH2O) and calcium orthophosphate compounds (including apatite, octacalcium phosphate etc.) are among the most prevalent pathological calcifications in joints. Even though only two dihydrated forms of CPP (CPPD) have been detected in vivo (monoclinic and triclinic CPPD), investigations of other hydrated forms such as tetrahydrated or amorphous CPP are relevant to a further understanding of the physicochemistry of those phases of biological interest. The synthesis of single crystals of calcium pyrophosphate monohydrate (CPPM; Ca(2)P(2)O(7) · H2O) by diffusion in silica gel at ambient temperature and the structural analysis of this phase are reported in this paper. Complementarily, data from synchrotron X-ray diffraction on a CPPM powder sample have been fitted to the crystal parameters. Finally, the relationship between the resolved structure for the CPPM phase and the structure of the tetrahydrated calcium pyrophosphate β phase (CPPT-β) is discussed.
authors.affiliation: CIRIMAT, UMR 5085 INPT-CNRS-UPS, Université de Toulouse, ENSIACET, Toulouse, France.
authors.forename: Pierre
authors.initials: P
authors.lastname: Gras
authors.affiliation: CEMES-CNRS UPR 8011, Toulouse, France.
authors.forename: Nicolas
authors.initials: N
authors.lastname: Ratel-Ramond
authors.affiliation: Laboratoire de Génie Chimique, UMR 5503 CNRS-INPT-UPS, Université de Toulouse, Toulouse, France.
authors.forename: Sébastien
authors.initials: S
authors.lastname: Teychéné
authors.affiliation: CIRIMAT, UMR 5085 INPT-CNRS-UPS, Université de Toulouse, ENSIACET, Toulouse, France.
authors.forename: Christian
authors.initials: C
authors.lastname: Rey
authors.affiliation: Synchrotron SOLEIL, L'Orme des Merisiers, Saint-Aubin, Gif-sur-Yvette, France.
authors.forename: Erik
authors.initials: E
authors.lastname: Elkaim
authors.affiliation: Laboratoire de Génie Chimique, UMR 5503 CNRS-INPT-UPS, Université de Toulouse, Toulouse, France.
authors.forename: Béatrice
authors.initials: B
authors.lastname: Biscans
authors.affiliation: CIRIMAT, UMR 5085 INPT-CNRS-UPS, Université de Toulouse and Université Paul Sabatier, Toulouse, France.
authors.forename: Stéphanie
authors.initials: S
authors.lastname: Sarda
authors.affiliation: CIRIMAT, UMR 5085 INPT-CNRS-UPS, Université de Toulouse, ENSIACET, Toulouse, France.
authors.forename: Christèle
authors.initials: C
authors.lastname: Combes
mesh_terms: D001031:Apatites / Q000737:chemistry*; D002130:Calcium Phosphates / Q000737:chemistry*; D002131:Calcium Pyrophosphate / Q000737:chemistry*; D003890:Desiccation; D010710:Phosphates / Q000737:chemistry*; D014961:X-Ray Diffraction
chemical_list: D001031:Apatites; D002130:Calcium Phosphates; D010710:Phosphates; C022045:octacalcium phosphate; C494369:calcium phosphate, dihydrate; D002131:Calcium Pyrophosphate
keywords: calcium pyrophosphate hydrates; crystal structure; pathological calcification; powder diffraction; structure determination; synchrotron study