POM-based inorganic–organic hybrid compounds: synthesis, structures, highly-connected topologies and photodegradation of organic dyes

Abstract

Four new polyoxovanadate-based organic–inorganic hybrid materials [MnV₂(bpp)₂O₆] (1), [Ag₄V₄(bpp)₄O₁₂]·2H₂O (2) and [M₃V₆(bpp)₄O₁₈·4H₂O]·2H₂O [M = Ni (3), Zn (4), bpp = 1,3-bis(4-pyridyl)propane] have been synthesized under hydrothermal conditions through the self-assembly of transition metal salts, bpp ligands and ammonium metavanadate. Single-crystal X-ray diffraction analyses show that 1 possesses a three-dimensional framework, constructed from arrays of {V₄O₁₂} rings covalently linked through metal–organic units, {Mn(C₁₃H₄N₂)₂}. Compound 2 is an eight-connected self-catenated metal–organic framework, based on bimetallic {Ag₄V₄O₁₂} clusters as nodes. Compounds 3 and 4 are isostructural, both of them exhibit an intriguing 6,10-connected network. The structure of 4, as an example, is based on single zinc atoms as six-connected nodes, as well as bimetallic {Zn₂V₆O₁₈} clusters as ten-connected nodes, defining not only a new topology for three-periodic nets but also the first 6,10-connected framework using heterometallic clusters as nodes. Furthermore, the thermal stabilities and photocatalytic activities of 1–4 have been discussed in detail.