Structure of monoclinic dicalcium pyrophosphate tetrahydrate

Davis, Nicki L.; Mandel, Gretchen S.; Mandel, Neil S.; Dickerson, Richard E.

doi:10.1007/bf01171054

Cited by 14 publications

(12 citation statements)

References 18 publications

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“…The pyrophosphate anion has general characteristics similar to the other two known calcium pyrophosphate hydrate structures (Mandel, 1975;Davis et al, 1985). PÐO B distances are signi®cantly longer than PÐO T and the PÐO B ÐP angle of 134 is relatively small (B denotes bridging, and T terminal).…”

Section: Structure Descriptionmentioning

confidence: 73%

“…The -polymorph of the calcium pyrophosphate tetrahydrate thus shows a largely different structure from the -polymorph (Davis et al, 1985), although both have the same space-group symmetry. The structure of the former is a distinctly layered one with only the hydrogen bonds between the layers, while is characterized by a three-dimensional framework structure with the water molecules inside the channels formed by calcium pyrophosphate polyhedra structure.…”

Section: Figurementioning

confidence: 98%

“…The relation between the number of bonded water O atoms (nOW) and the V S /V P ratio for the Ca coordination polyhedra with CN7. The coordinations are from: 1 -Ca 2 P 2 O 7 (Webb, 1966); 2 t-CPPD (Mandel, 1975); 3 m-CPPT (Davis et al, 1985); 4 m-CPPT (this article).…”

Section: Figurementioning

confidence: 99%

“…Besides t-and m-CPPD, a tetrahydrate, Ca 2 P 2 O 7 Á4H 2 O (denoted CPPT) is common in precipitates formed in vitro around neutral and acidic pH. The tetrahydrate is also polymorphic, with one monoclinic form with a known structure (Davis et al, 1985) and another form previously supposed to be orthorhombic from the microscopic investigation of crystal morphology (Brown et al, 1963) and indexing of powder patterns (Mandel et al, 1988). However, the present study shows this form to be monoclinic as well, but even if the space group is the same the structures are largely different.…”

Section: Introductionmentioning

confidence: 99%

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Structure of the β form of calcium pyrophosphate tetrahydrate

Balić-Žunić¹,

Christoffersen²,

Christoffersen³

2000

Acta Crystallogr Sect B

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-Ca 2 P 2 O 7 Á4H 2 O is monoclinic, P2 1 /c, a = 12.287 (6), b = 7.511 (3), c = 10.775 (5) A Ê , and = 112.54 (1) . Five of the terminal O atoms from a pyrophosphate group bind to Ca atoms, together with O atoms from three of the water molecules. The fourth H 2 O forms only hydrogen bonds. Both Ca atoms have coordination number 7 and show characteristics between those of a capped octahedron and a pentagonal bipyramid. The analysis of coordination distortions suggests that regularity and volume ef®ciency of a Ca coordination polyhedron increases with the number of bound water O atoms. The structure is layered after {100}, re¯ected also in the morphology of crystals which are formed as extremely thin plates. The central parts of the layers are formed by chains of Ca coordination polyhedra which run along the b axis and are interconnected by pyrophosphate groups. Water molecules form the surfaces of the layers. A peculiar auto-inhibition of growth from supersaturated solutions is supposed to be caused by a direct attachment of CaP 2 O 7 2À and P 2 O 7 4À to the water molecules on the surfaces of layers. Ca 2 P 2 O 7 Á4H 2 O is known in two polymorphs. The unit-cell volume of the form compared with that of suggests that the former is a low-temperature modi®cation.

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Section: Structure Descriptionmentioning

confidence: 73%

Section: Figurementioning

confidence: 98%

Section: Figurementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Structure of the β form of calcium pyrophosphate tetrahydrate

Balić-Žunić¹,

Christoffersen²,

Christoffersen³

2000

Acta Crystallogr Sect B

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“…The different structures of the calcium pyrophosphate hydrates elucidated indicate significant differences in the environment of the pyrophosphate ions. 1,3,4 In particular, the P-O-P angle of the anion could change from 123.1u for the FTIR spectroscopy could also be an important characterisation technique for calcium pyrophosphate hydrates, with the geometry of the ion affecting the bands observed on the spectrum. Each compound provides a specific spectrum.…”

Section: Characterisationmentioning

confidence: 99%

Crystallisation of a highly metastable hydrated calcium pyrophosphate phase

et al. 2013

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International audienceA simple and fast synthesis method was set up to obtain pure hydrated calcium pyrophosphate (CPP)phases of biological interest. This work focused on a specific phase synthesised at 25 uC and pH 4.5 in a stirred tank reactor. Powder X-ray diffraction, FTIR spectroscopy, scanning electron microscopy and thermogravimetric analyses revealed that the phase is unknown but presents similarities with a monoclinic tetrahydrated CPP phase (Ca2P2O7?4H2O, m-CPPT b phase) synthesised under the same conditions of pH and temperature. Characterisation of the unreferenced phase (u-CPP) has been performed, especially to better identify its composition, structure and stability, as well as its possible relation to the m-CPPT b phase or to other hydrated CPP phases

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Synthesis and Characterisation of Hydrated Calcium Pyrophosphate Phases of Biological Interest

et al. 2013

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The details of a synthesis method for biologically relevant hydrated calcium pyrophosphates (CPPs, Ca 2 P 2 O 7 ·nH 2 O) has been elucidated. Control of the pH (from 3.6 to 5.8) and the temperature (from 25 to 90°C) during the synthesis enabled the preparation of four pure CPP phases within one hour without intermediates: monoclinic and triclinic calcium pyrophosphate dihydrate (CPPD, Ca 2 P 2 O 7 ·2H 2 O), which are the two CPP phases detected in vivo in joints of arthritic patients, monoclinic tetrahydrate β (CPPT, Ca 2 P 2 O 7 ·4H 2 O) and an amorphous phase (a-CPP, Ca 2 P 2 O 7 ·nH 2 O). Four domains corresponding to the four different phases of hydrated calcium pyrophosphate were identified; a-CPP was synthesised over a very wide pH and temperature range (up to 90°C) within the domain of synthesis conditions explored, including physiological conditions (pH 7.4 and 37°C). The as-synthesised hydrated CPP phases were characterised by complementary techniques (powder X-ray diffraction, FTIR and Raman spectroscopy, scanning electron microscopy and thermogravimetry) and chemical analyses. Rietveld refinement analyses of the as-synthesised crystalline phases were performed, and[a] CIRIMAT,

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Structure of monoclinic dicalcium pyrophosphate tetrahydrate

Cited by 14 publications

References 18 publications

Structure of the β form of calcium pyrophosphate tetrahydrate

Structure of the β form of calcium pyrophosphate tetrahydrate

Crystallisation of a highly metastable hydrated calcium pyrophosphate phase

Synthesis and Characterisation of Hydrated Calcium Pyrophosphate Phases of Biological Interest

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