Ca8HPO42PO465H2O

Ca8HPO42PO465H2O is a condensed chemical formula that corresponds to octacalcium phosphate (OCP), with the more explicit standard formula Ca8(HPO4)2(PO4)4·5H2O. OCP is a hydrated calcium phosphate mineral and an important precursor in biomineralization, often acting in the pathway toward hydroxyapatite in biological systems.

Structure and composition: OCP consists of layers of calcium and phosphate arranged in alternating blocks, with phosphate groups present as both HPO4^2- and PO4^3- units. The crystal structure includes interlayer water, giving it a hydrated character. The conventional representation denotes five water molecules per formula unit.

Occurrence and formation: OCP forms by precipitation from aqueous solutions containing calcium and phosphate under specific conditions of pH and ion activity, and it can appear during biomineralization processes in bones and teeth. It is also synthesized in laboratory settings for research and industrial purposes.

Stability and transformation: In many environments, octacalcium phosphate is metastable and can transform to hydroxyapatite over time or under heating. The rate and extent of transformation depend on factors such as temperature, pH, and the presence of impurities or dopants. This transformation is relevant to both natural bone development and the processing of calcium phosphate biomaterials.

Applications and significance: OCP is studied as a precursor to biological hydroxyapatite and as a component in calcium phosphate ceramics and coatings for bone repair and dental applications. Its solubility and resorption characteristics can be manipulated for medical implants and controlled-release systems.

Notes: The given condensed formula is a representation of the standard octacalcium phosphate composition. The canonical form is Ca8(HPO4)2(PO4)4·5H2O.