Manganese-Vanadate Hybrids: Impact of Organic Ligands on Their Structures, Thermal Stabilities, Optical Properties, and Photocatalytic Activities.

Manganese(II)–vanadate(V)/organic hybrids were prepared in high purity using four different N-donor organic ligands (2,6:2′,2″-terpyridine = terpy, 2,2′-bipyrimidine = bpym, o-phenanthroline = o-phen, and 4,4′-bipyridine = 4,4′-bpy), and their crystalline structures, thermal stabilities, optical properties, photocatalytic activities and electronic structures were investigated as a function of the organic ligand. Hydrothermal reactions were employed that targeted a 1:2 molar ratio of Mn(II)/V(V), yielding four hybrid solids with the compositions of Mn(terpy)V2O6·H2O (I), Mn2(bpym)V4O12·0.6H2O (II), Mn(H2O)(o-phen)V2O6 (III), and Mn(4,4′-bpy)V2O6·1.16H2O (IV). The inorganic component within these hybrid compounds, that is, [MnV2O6], forms infinite chains in I and layers in II, III, and IV. In each case, the organic ligand preferentially coordinates to the Mn(II) cations within their respective structures, either as chelating and three-coordinate (mer isomer in I) or two-coordinate (cis isomers in II and III...