[Ni(C6N2H14)2][Zn4(H2O)(HPO3)5]: A new open-framework zinc phosphite with intersecting 8-, 12- and 16-ring channels

A new three-dimensional (3-D) zinc phosphite with Zn/P ratio of 4/5, [Ni(C6N2H14)2][Zn4(H2O)(HPO3)5] (1), has been prepared by using self-assembled nickel complexes as the structure-directing agents. Its structure is built up from strict alternation of ZnO4 tetrahedra and HPO3 pseudo-pyramids, resulting in an open framework with multi-directional intersecting 8-, 12- and 16-ring channels. The unique nickel complexes Ni(DACH)2 (DACH=1,2-diaminocyclohexane) only involving the cis-DACH acting as ligands are self-assembled under hydrothermal conditions, and act as the structure-directing agents (SDAs) to direct the formation of compound 1. Nickel complexes reside in the channels in a manner that the hydrophobic ends of the cis-DACH molecules exclusively protrude into the 16-ring pores and the amino groups closely interact with the charged inorganic framework through weak H-bonds. The interesting arrangements of nickel complexes imply a feasible approach to the design and synthesis of extra-large pore materials.