A new polymorph in the zinc phosphate Zn2(HPO4)3 family prepared with DABCO as structure-directing agent

A new amine-templated zinc phosphate, [C6H14N2][Zn2(HPO4)3], was prepared by solvothermal synthesis using 1,4-diazabicyclo[2.2.2]octane, dabco, as structure-directing agent. This compound (denoted AU-IV) is a new monoclinic polymorph built from corner sharing ZnO4 and HPO4 tetrahedra forming a framework structure where protonated amine ions coordinate via hydrogen bonds. AU-IV crystallizes from a reaction mixture with the composition, 1Zn(Ac)2:3.89H3PO4:1.94dabco:137H2O (pH 3.47) after several months at RT. The structure of the compound was solved by single crystal X-ray diffraction analysis. [C6H14N2][Zn2(HPO4)3] crystallizes in the monoclinic space group P21/c, a = 14.3142(6) Å, b = 10.0277(4) Å, c = 10.4917(4) Å, β = 94.102(1)°, V = 1502.1(1) Å3. This material is further characterized by solid-state 31P CP/MAS NMR.