A three-dimensional polymeric potassium complex of 5-sulfonobenzene-1,2,4-tricarboxylic acid: poly[μ-aqua-aqua-μ9-(2,4-dicarboxy-5-sulfonatobenzoato)-dipotassium(I)].

The asymmetric unit in the structure of the title compound, [K2(C9H4O9S)(H2O)2]n, consists of two eight-coordinated K(I) cations, one 2,4-dicarboxy-5-sulfonatobenzoate dianion (H2SBTC(2-)), one bridging water molecule and one terminal coordinated water molecule. One K(I) cation is coordinated by three carboxylate O atoms and three sulfonate O atoms from four H2SBTC(2-) ligands and by two bridging water molecules. The second K(I) cation is coordinated by four sulfonate O atoms and three carboxylate O atoms from five H2SBTC(2-) ligands and by one terminal coordinated water molecule. The K(I) cations are linked by sulfonate groups to give a one-dimensional inorganic chain with cage-like K4(SO3)2 repeat units. These one-dimensional chains are bridged by one of the carboxylic acid groups of the H2SBTC(2-) ligand to form a two-dimensional layer, and these layers are further linked by the remaining carboxylate groups and the benzene rings of the H2SBTC(2-) ligands to generate a three-dimensional framework. The compound displays a photoluminescent emission at 460 nm upon excitation at 358 nm. In addition, the thermal stability of the title compound has been studied.