Crystal structures of tricalcium citrates
The crystal structures of calcium citrate hexahydrate, calcium citrate tetrahydrate, and anhydrous calcium citrate have been solved using laboratory and synchrotron X-ray powder diffraction data, and optimized using density functional techniques. Both the hexahydrate and tetrahydrate structures are characterized by layers of edge-sharing Ca coordination polyhedra, including triply chelated Ca. An additional isolated Ca is coordinated by water molecules, and two uncoordinated water molecules occur in the hexahydrate structure. The previously reported polymorph of the tetrahydrate contains the same layers, but only two H2O coordinated to the isolated Ca and two uncoordinated water molecules. Anhydrous calcium citrate has a three-dimensional network structure of Ca coordination polyhedra. The new polymorph of calcium citrate tetrahydrate is the major crystalline phase in several commercial calcium supplements.
- Research Organization:
- Advanced Photon Source (APS), Argonne National Laboratory (ANL), Argonne, IL (US)
- Sponsoring Organization:
- DOE - BASIC ENERGY SCIENCES
- OSTI ID:
- 1459965
- Journal Information:
- Powder Diffraction, Journal Name: Powder Diffraction Journal Issue: 02 Vol. 33; ISSN 0885-7156; ISSN applab
- Publisher:
- Cambridge University Press
- Country of Publication:
- United States
- Language:
- ENGLISH
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