Synthesis and Characterization of New Heterometallic Cobalt-zinc Oxalates Linked by Organic Amines

摘要

Our research interest was related to the synthesis of polynuclear metal complexes containing oxalate as ligand with the aim of obtaining potentially new functional materials and precursors for oxide nanoparticles. Two new heteronuclear complexes Co2Zn2(C_(10)H8N2)(C2O4)4. 2HO, 1, and CoZn(C4H_(10)N2)(C2O4)2. 0.75H2O, 2, were obtained by direct metal-ligand synthesis. Based on Uv-Vis, IR, Raman and elemental analysis, a polymeric tridimensional structure of complexes was established, in which metal-oxalate chains are bridged by 4,4'-dipyridine orpiperazine. Morphological characters have been provedby BET and SEM measurements. Scanning electron microscopy shows particles as assemble of parallel porous sheets for complex 1 and rods and hollow rod-like particles for complex2. The surface area and porosity were evaluated from the nitrogen adsorption-desorption isotherms. Complex 1 presents mesoporous morphology with the surface area of 29.9 m~2/g while complex 2 was also porous, with the surface area of 84.3 m~2/g due to the more complex morphology. Thermo-gravimetric analysis showed that the decomposition proceeds via three well-defined steps up to final residue expressed as cobalt and zinc oxides for both complexes.