polyanionen

Polyanions are chemical species that carry more than one negative charge. They can be small inorganic ions composed of several negatively charged atoms, or larger organic or inorganic macromolecules with repeating negatively charged groups. The shared feature is a net negative charge that governs their solubility, binding properties, and reactivity, especially their strong affinity for positively charged counterions.

Inorganic polyanions include phosphate (PO4^3-), sulfate (SO4^2-), and polyphosphates such as pyrophosphate (P2O7^4-). Silicate species (SiO3^2-), and polyoxoanions formed from metal-oxide clusters, such as certain tungstate or molybdate assemblies, are also classified as polyanions.

Organic and biopolymeric polyanions include nucleic acids (DNA and RNA) with a charged phosphate backbone, as well as polyanionic carbohydrates (alginate, carrageenan) and synthetic polymers like polyacrylates, which bear carboxylate groups.

Polyanions form salts with cations (for example, Na+, Ca2+) and exhibit properties determined by charge density and hydration. They commonly engage in electrostatic interactions with positively charged molecules, ions, and proteins, influencing processes in biology, chemistry, and materials science. In biological systems, polyanions contribute to the structure and function of nucleic acids and extracellular matrices and participate in mineralization. In materials chemistry, they are used as ligands, templates, catalysts, or functional components in energy storage and catalysis.