Intercalation of an oxalatooxoniobate complex into layered double hydroxide and layered zinc hydroxide nitrate

A Zn/Al layered double hydroxide with molar ratio of 3 was prepared by coprecipitation in alkaline pH and used as a matrix to intercalate the ionic complex diaquadioxalatooxoniobate(V) (DDON), derived from NH4[NbO(C2O4)(2)(H2O)(2)]center dot 2H(2)O. In a similar way, the layered zinc hydroxide nitrate, Zn-5(OH)(8)(NO3)(2)center dot 2H(2)O, was synthesized, preexpanded with azelate ions (-OOC(CH2)(7)COO-), and then intercalated with the niobium complex. For both layered matrices, the results from X-ray powder diffactometry, Fourier transform infrared spectroscopy, and thermal analysis (TG/s-DTA) indicate the presence of the oxalate ion. In addition, results from X-ray photoelectron and Raman spectroscopy indicate the presence of the niobium center bonded to oxygen atoms. Finally, diffuse reflectance UV-vis spectroscopy suggests that the niobium centers are coordinated to oxalate ions. This is the first report of the intercalation of niobium into a layered matrix. (c) 2008 Elsevier Inc. All rights reserved.