Self-assembly of four one-dimensional molybdenum(V) phosphates linked by strontium and transition metal

Four reduced molybdenum(V) phosphates, [(py)2(Himi)4][FeII2SrMo12O24(OH)6(H2O)8(H2PO4)2(HPO4)4(PO4)2]·4H2O 1, (H2bpp)2[CoII2Sr2Mo12O24(OH)6(H2O)8(H2PO4)2(HPO4)2(PO4)4]·6H2O 2, [(Hpy)(Himi)][Ni(H2O)6][Ni2Sr2Mo12O24(OH)6(H2O)8(H2PO4)2(HPO4)2(PO4)4]·4H2O 3, (H2imi)2[Zn2Sr2Mo12O24(OH)6(H2O)6(H2PO4)2(HPO4)2(PO4)4]·3H2O 4 (imi = imidazole, bpp = 1,3-bi(4-pyridyl)-propane, py = pyridine), have been obtained by hydrothermal methods. These structures were determined by single-crystal X-ray diffraction analysis and were further characterized by elemental analysis, IR, and TG analysis. All the compounds contain the [P4Mo6O31]12− (abbreviated as [P4Mo6]) polyoxoanions as building blocks, which are further connected into the sandwich-type dimeric units by various transition metal (TM) ions. In compound 1, the dimeric {Fe[P4Mo6]2} units are bonded by an heterometallic {SrFe} binuclear unit to form 1-D string. In compounds 2–4, the dimeric {(TM)[P4Mo6]2} units are linked by new {Sr2TM} trinuclear fragments into one-dimensional (1-D) chains. All the 1-D chains are further packed into various three-dimensional (3-D) supramolecular assemblies via strong hydrogen-bonding interactions. Furthermore, the electrochemical activities of compounds 1–4 and magnetic properties of compounds 1–3 are reported.