Hydro/solvothermal synthesis and structures of new zinc phosphates of varying dimensionality

Abstract

Hydro/solvothermal reactions of ZnO, HCl, H₃PO₄, 1,4-diazacycleheptane (homopiperazine), and H₂O under a variety of conditions yielded three new organic-inorganic hybrid materials, [C₅N₂H₁₄][Zn(HPO₄)₂]·xH₂O (x = ~0.46), I, [C₅N₂H₁₄] [Zn₃(H₂O)(PO₄)₂(HPO₄)], II, and [C₅N₂H₁₄][Zn₂(HPO₄)₃]·H₂O, III. While I has a one-dimensional structure, II possesses a two-dimensional layered structure, and III has a three-dimensional structure closely related to the ABW zeolitic architecture. All the compounds consist of vertex linking of ZnO₄, PO₄, and HPO₄ tetrahedral units. The fundamental building unit, single four-membered ring (S4R), is present in all the cases, and the observed differences in their structures result from variations in the connectivity between the S4R units. Thus I has a corner-shared S4R forming an infinite one-dimensional chain, II has two corner-shared chains fused through a 3-coordinated oxygen atom forming a strip and a layer with eight-membered apertures, and III has S4R units connected via oxygen atoms to give rise to channels bound by eight T atoms (T = Zn, P) in all crystallographic directions. Crystal data: I, monoclinic, space group = P2₁/n (No. 14), a = 8.6053(3) Å, b = 13.7129(5) Å, c = 10.8184(4) Å, β = 97.946(1)°, V = 1264.35(8) ų, Z = 4; II, monoclinic, space group = P2₁/c (No. 14), a = 11.1029(1) Å, b = 17.5531(4) Å, c = 8.2651(2) Å, β = 97.922(2)°, V = 1595.42(5) ų, Z = 4; III, monoclinic, space group = P2₁ (No. 4), a = 8.0310(2) Å, b = 10.2475(3) Å, c = 10.570(3) Å, β = 109.651(1)°, V = 819.24(3) ų, Z = 2.