Hydrothermal synthesis and characterization of a new zinc phosphate [Zn2.5(HPO4)2(PO4)][C6H10N2] • 5H2O

A new two-dimensional zinc phosphate, [Zn-2.5(HPO4)(2)(PO4)][C6N2H10] center dot 5H(2)O (denoted in the following as ZnP-2AMP), with alternating inorganic and organic layers has been synthesized hydrothermally using 2-aminomethylpyridine (2AMP) as the structure-directing agent. This compound represents the first structure with a Zn/P ratio of 5/6. The structure of this compound, determined by single crystal X-ray diffraction, consists of anionic parallel [Zn-2.5(HPO4)(2)(PO4)(H2O)(2)](2-) sheets built up from ZnO4, ZnO2(H2O)(4), PO4 and HPO4, alternating with thick slabs of organic molecules (C6H10N2)(2+) and water molecules, the octahedral ZnO2(H2O)(4) being enclosed in each [4(6)8(2)12(2)] cage. The organic cations are linked to the anionic sheets through hydrogen bonds. Solid-state C-13 and P-31 MAS NMR spectroscopies are in agreement with the X-ray structure. Ab initio calculations allow the partial attribution of phosphorus and carbon signals to the independent crystallographic sites and to the various atoms of the organic groups. Additional characterization of the compound has also been performed by IR spectroscopy and TG-DTA analyses. (C) 2006 Elsevier Ltd. All rights reserved.