Hydrothermal Synthesis and Crystal Structure of Zn4 (PO4)2(HPO4)2·0.5(C10H28N4)·2H2O, a New Layered Zinc Phosphate with 12-Ring Cavities

Using 1, 4, 8, 11-tetraazacyclotetradecane (cyclam) as a template, a new layered zinc phosphate Zn4(PO4)2(HPO4)2·0.5(C10H28N4)·2H2O (defined as ZnPO-cyclam) with 12ring cavities was synthesized under hydrothermal conditions in a molar ratio ZnO:P2O5:cyclam:H2O=1:2.2:0.5:284.7 at 140°C for 3 days. The gel had a pH 4 at the starting period. The ZnPO-cyclam crystal structure is solved using single-crystal X-ray diffraction data at 293 K. It crystallizes in monoclinic space group P21/c (no.14) with lattice parameters a=15.758(3) ?, b=9.0292(15) ?, c=15.543(3) ?, beta=111.070 (16). V= 2063.7(7) ?3, Z=4, R=0.0392, wR=0.0472, 4166 collected reflections, 2794 observed reflections with I>2sigma(I). The structure of ZnPO-cyclam consists of alternating inorganic and organic layers. The inorganic layers are built up from ZnO4, ZnO3(H2O)2, PO4, and HPO4 with Zn-O-Zn and Zn-O-P bonds. The protonated cyclam molecules in which the four nitrogen atoms are all protonated form the organic layers. Strong hydrogen bonding exists between the inorganic-organic layers, and there are 12-ring cavities in the inorganic layers, in which the template cyclam molecules reside.