The synthesis and crystal structure of a new open-framework zincophosphate UiO-17

Abstract

A novel three-dimensional open-framework zincophosphate 2[N₂C₄H₁₂]²⁺[Zn₇(H₂O)₂(PO₄)₆]^4– has been synthesised hydrothermally, and characterised by powder and single crystal X-ray diffraction, thermogravimetric analysis and solid state ³¹P MAS and ¹³C CP MAS NMR spectroscopy. The compound crystallises in the monoclinic space group C2/c with a = 16.134(3), b = 8.241(2), c = 22.860(5) Å, β = 104.05(3)°, V = 2948.4(10) Å³ and Z = 4. The open framework contains a two-dimensional staggered eight-membered ring channel system running along [001] and [011] in which diprotonated piperazinium cations reside. The framework consists of ZnO₄ and PO₄ tetrahedral units, in addition there are ZnO₄(H₂O) trigonal bipyramids which together with Zn–O–Zn bonding lead to an interrupted framework rather than alternating ZnO₄ and PO₄ linkages. The framework is an example of symmetry matching between template and framework as a symmetry element of piperazine constrains the framework structure.