Synthesis and Characterization of the Novel Transition Metal Phosphite

Inorganic microporous crystal materials have not only the potential applications in catalysis, ion exchange, absorption, molecular recognization, ion conductor, magnetic field, but also have great significance in crystallography and the study of biomineralization.For the past decades, people have been interested in synthesis and application of transition metal phosphate with open framework. And as we know, the structure of HPO32- is similar to that of PO43-, so HPO32- may act as the structure unit to build the open framework. Compared with the research on transition metal phosphate with open framework, the research on transition metal phosphate templated by organic amine is rare. So, in the past few years, people have become interested in the research on transition metal phosphite. Up to now, a lot of phosphite compounds with open framework have been synthesized, such as vanadium phosphite, chromium phosphite, manganese phosphite, iron phosphite, cobalt phosphite and zinc phosphite.Up to now, zinc phosphite play an important role among transition metal phosphite, since decades of zinc phosphite have been synthesized, and zinc-cobalt phosphite is not found up to now .(1) Using metal cobalt and zinc as source materials, and piperazine as template, we first prepared the double metal phosphite (C4H8N2H4)[Zri(3-X) Cox(HPO3)4(H2O)2] (x-0.83) by hydrothermal treatment, which holds new composition and structure. The 3D framework of the compound is constructed by alternately linking MO4 (M = Zn or Co) tetrahedron, ZnO4(H2O)2 octahedron by sharing vertex of pseudo-tetrahedron HPO3. It is noted that the infinite chains comprised of four-ring M2P2O4 in the compound. Due to the non-abound d orbit of the cobalt atom, the compound hold interesting magnetism and potential catalysis properties. Magnetism study suggests that the compound in the range 300K-45K has paramagnetic property and obey the rule of Courier-Weiss. In 300K, u?ff of every cobalt atom is 5.24ub. In addition, pH value is 5-6 that is a key effect factor which affect crystal growth and shape.(2) The hydrothermal reactions of zinc acetic, phosphite, piperazine and water yield3D network (C4HgN2H4)[Zn3(HPO3)4] . And structural investigation suggests that the framework of both compounds is also built from ZnO4 tetrahedron and HPO3 pesduo-tetrahedron by sharing vertex and hold intact four-ring {Zn2P2C>4} chains.phosphite is reported by solvothermal synthesis. And this may give a direction to synthesize zinc phosphite and other metal phosphite. Through a lot of experiment, we find that the following influencing factors played important roles:(l) the rate of reactants mixture. In general, phosphite should be enough, for its reductive property lest it is oxidated to be PO43". (2) The effect of mineralizer: we find that mineralizer still plays an important role in synthesizing zinc