AMINO-ACID DERIVATIVES OF LAYERED ZIRCONIUM-PHOSPHATES - ALPHA-ZIRCONIUM L-(-SERINEPHOSPHATE AND ZIRCONIUM L-(+)-SERINEPHOSPHATE PHOSPHATES())

A layered derivative of a-zirconium phosphate containing 1-(+)-serine covalently attached to the inorganic layer has been prepared by allowi ng Zr fluoro complexes to decompose in the presence of 1-(+)-phosphose rine. On the basis of thermogravimetric weight loss and C,H,N elementa l analyses, the layered compound obtained has been formulated as Zr[HO OCCH(NH2)CH2OPO3](2). The X-ray powder diffraction pattern has been in dexed with a monoclinic cell(a = 5.3737 Angstrom, b = 9.3231 Angstrom, c = 14.510 Angstrom, beta = 96.99 degrees, Z = 2). FT-IR absorption s pectra show that the serine groups attached to the inorganic layers ar e present as zwitterions. Thermal decomposition commences at ca. 250 d egrees C and occurs in two steps: the first is due to a decarboxylatio n reaction, with the formation of the amino derivative Zr(NH2CH2CH2OPO 3)(2), while the second is associated with pyrolysis of the organic mo iety, leading to ZrP2O7. Despite the presence of the amino acid functi on in the interlayer region, the compound does not show intercalation ability towards cations or anions or polar species. However, compounds with a certain degree of microporosity and possessing ion-exchange an d adsorption properties have been obtained by replacing some of the ph osphoserine groups of the compound by HPO4 groups, to produce the mixe d layered derivatives Zr[HOOCCH(NH2)CH2OPO3](2-x)(HPO4)(x).