Organic templates in zincophosphate synthesis: Zn5(PO4)2(HPO4)4·H2O·2H2N2C6H12, containing two distinct eight-ring channels and Zn3(PO4)(HPO4)2· HN2C6H12, containing tetrahedral three-rings and Zn–N bonds

Abstract

The hydrothermal syntheses, single-crystal X-ray structures and some properties of two new microporous, anionic, zinc phosphate frameworks encapsulating organic cations are described. Zn₅(PO₄)₂(HPO₄)₄·H₂O·2H₂N₂C₆H₁₂(ZnPO/dab-C) crystallizes in the triclinic space group P(No. 2) with a= 9.366(1)Å, b= 9.882(1)Å, c= 19.183(2)Å, α= 85.406(3)°, β= 85.029(3)° and γ= 114.485(3)°, V= 1596.51 ų and Z= 2, with R(F)= 7.11% for 4095 observed reflections [I > 3σ(I)], Zn₃(PO₄)(HPO₄)₂·HN₂C₆H₁₂(ZnPO/dab-D) is orthorhombic, space group P2₁2₁2₁(No. 19), a= 11.095(2)Å, b= 16.413(2)Å, c= 8.263(1)Å, V= 1505.61 ų, Z= 4, with R(F)= 5.71% for 1321 observed reflections [I > 3σ(I)].

Both of these new materials consist of a three-dimensional network of tetrahedrally coordinted zinc and phosphorus atoms, linked through oxygen atom vertices, to form two different open structures. ZnPO/dab-C contains two distinct one-dimensional eight-ring channels (one regular, one squashed), occupied by extraframework, protonated, 1,4-diazabicyclo[2.2.2]octane (DABCO, [H₂N₂C₆H₁₂]²⁺) molecules. ZnPO/dab-D is a new framework type containing ‘bridged’ three-rings of tetrahedra. The DABCO molecule coordinates to the framework in this phase via Zn–N links. ³¹P MAS NMR data for these two materials are presented, and may be interpreted using a simple bond-strength model.