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

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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 Å3 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 Å3, 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.