Chasing the Elusive Dihydrogen Phosphate

Chemists of KFU have synthesized a series of molecular receptors capable of selective binding of dihydrogen phosphate anions.

Supramolecular chemistry aims to design systems for analysis, such as molecular sensors, reagents for selective extraction or selective transport of anions and cations. One of the tasks that analytical sensors are used for is detection of tetrahedron oxygen-containing anions. Many of such anions are detrimental to the environment and must be selectively extracted from industrial sewage. Selective phosphate and hydrogen phosphate sensors are also of use to biochemists – these ions play an important role in metabolism (for instance, the ATP-ADP cycle).

Currently existing selective sensors for phosphate and hydrogen phosphate anions are far from perfect. In particular, the sensors using hydrogen binding can hardly distinguish between dihydrogen phosphate ions, acetate ions, and fluoride ions, which makes their practical use for analyzing intracellular processes challenging.

Ivan Stoikov, Professor in the Department of Organic Chemistry of KFU, and his group have decided to catch dihydrogen phosphate with the help of a pillararene platform. Pillararenes are macrocyclic compounds consisting of hydroquinone fragments that are bound together in a para position. Pillararenes are close in structure to other macrocyclic compounds that have already established themselves in supramolecular chemistry – calixarenes and cucurbiturils.

The researchers have managed to produce new derivatives of pillararenes by adding N-phenyl and N-alkyl fragments to the basic structure of pillararene. Such a process has proved to be beneficial to the resulting compounds’ ability to selectively detect some ions. Pillararenes modified by N-phenyl groups have demonstrated very strong binding with dihydrogen phosphate anions, and those with N-alkyl groups selectively detect dihydrogen phosphate ions in the presence of fluorides and acetates.

As Associate Professor Liudmila Yakimova hopes, this result is but the first step in the advent of a reliable detecting technology for dihydrogen phosphate ions.