Crystal structure and MAS-NMR study of rehydrated UiO-7

The framework of rehydrated UiO-7 has the ZON type of topology. The crystal structure is described on the basis of high resolution, synchrotron powder X-ray diffraction data. The chemical composition of the unit cell is Al32P 32O128. 62H(2)O. Its dimensions are a = 14.4930(2), b = 14.8731(2) and c = 17.5738(3) Angstrom; space group Pbca. Of the four non-equivalent Al atoms, two have normal tetrahedral coordination, whereas one obtains five-coordin ation and one achieves octahedral coordination on additional bonding to thr ee non-equivalent water molecules. Six more water molecules are located in the channels and are interconnected via hydrogen bonds. These features were confirmed by solid-state (27)AI MAS NMR data. Site assignment of (31)p sig nals is discussed on the basis of P-O-Al angles and Al-coordination. (C) 20 01 Editions scientifiques et medicales Elsevier SAS. All rights reserved.