Polyphosphate

Polyphosphates are salts or esters of polymeric oxyanions formed from tetrahedral PO₄ (phosphate) structural units linked together by sharing oxygen atoms. Polyphosphates can adopt linear or a cyclic ring structures. In biology, the polyphosphate esters ADP and ATP are involved in energy storage. A variety of polyphosphates find application in mineral sequestration in municipal waters, generally being present at 1 to 5 ppm.GTP, CTP, and UTP are also nucleotides important in the protein synthesis, lipid synthesis, and carbohydrate metabolism, respectively.

Structure

Structure of triphosphoric acid

Structure of triphosphoric acid

Polyphosphoric acid

Polyphosphoric acid

Cyclic trimetaphosphate

Cyclic trimetaphosphate

Adenosine diphosphate (ADP)

Adenosine diphosphate (ADP)

The structure of tripolyphosphoric acid illustrates the principles which define the structures of polyphosphates. It consists of three tetrahedral PO₄ units linked together by sharing oxygen centres. For the linear chains, the end phosphorus groups share one oxide and the others phosphorus centres share two oxide centres. The corresponding phosphates are related to the acids by loss of the acidic protons. In the case of the cyclic trimer each tetrahedron shares two vertices with adjacent tetrahedra.