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

摘要

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 Al_(32)P_(32)O_(128) centre dot 62H_2O. Its dimensions are a = 14.4930(2), b = 14.8731(2) and c = 17.5738(3) A; space group Pbca. Of the four non-equivalent Al atoms, two have normal tetrahedral coordination, whereas one obtains five-coordination and one achieves octahedral coordination on additional bonding to three 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)Al MAS NMR data. Site assignment of ~(31)P signals is discussed on the basis of P-O-Al angles and Al-coordination.