Combined cluster quantum chemical MINDO/3 and ab initio study on zinc phosphate structures

Semiempirical MINDO/3 and ab initio calculations were performed to mimic di fferent synthesis routes of zinc phosphates (ZPO) having four-, six- and ei ght-member ring structures. The Zn/P ratio remained equal to unity while th e ZPO followed a strict alternating tetrahedral connectivity. Two different basis sets, i.e., 3-21G* and 6-31G**, were used. It was found that the for mation of the ZPO structure is energetically highly favored when the buildi ng blocks that compose the structure interacts according to a deep acid-bas e neutralization. The Lewis acid sites (LAS) formed from the most stable pr ecursor ZPO structure display high activity in binding with Lewis base mole cules such as CO. Both the blue-shift of the adsorbed CO stretching mode an d its adsorption energy with the LAS shows that the Lewis acidity of ZPO is not less than that of pure ZnO.