Polyoxometalate-based inorganic-organic hybrids based on a half rigid N-heterocyclic carboxylate ligand: Syntheses, structures and properties

Three new inorganic-organic hybrids constructed from a half rigid N-heterocyclic carboxylate ligand, K [Ag-3(HL1)(4)](Mo8O26) (1), [Ag-4(HL1)(2)(HL2)(2)(SiMo12O40)] (2) and (H3O)[Ag(L-1)(2)]center dot 2H(2)O (3) [HL1 = 1-(4-carboxylbenzyl)-3-(pyrazine-2-yl)pyrazole; HL2 = 3-(2-pyrazine)pyrazole], were hydrothermally synthesized and characterized. In compound 1, {K[beta-Mo8O26]}(n)(3n-) chains fill in the channels of the 3D supramolecular network. In compound 2, H(L)1 and HL2 coordinate to Ag(I) ions into left- (L) and right-handed (R) helical chains, and (SiMo12O40)(4-) anions link two neighboring helical chains into a 2D layer structure. The crystal structure of compound 3 is stabilized by hydrogen bonds and pi center dot center dot center dot pi interactions, forming a 3D supramolecular network. The luminescent properties of the three compounds have been investigated. In addition, the electrochemical properties of compound 2 have also been investigated. (C) 2020 Elsevier B.V. All rights reserved.