Studies Of Synthesis, Structure And Coordination Ability Of Dicarboxylic Compounds

Carboxylic acids are the most usefully ligands to build the complex. Carboxyl groups have variety of coordination modes and strong ability of coordination with the metal ions, so they can form the multi-dimensional network structures. These complexes can be used potentially in many fields, such as adsorption separation, catalysis, magnetic materials and optical materials etc. In addition, they can be used to store the gas fuel like methane and hydrogen as the low density porous material, so close attention has been paid to these complexes by more and more chemical researchers. Dicarboxylic compounds have many oxygen atoms, which can coordinate with metal ions, and can form the structural stability and novel functional complex materials. It is important to the development of coordination chemistry, material science and other sciences.Seven bifunctional compounds, such as 1,3-propyl-bis(oxy-3-benzoic acid) (L1), 1,4-butyl-bis(oxy-3-benzoic acid) (L2), 1,3-propyl-bis(oxy-4-benzoic acid) (L3), 1,4-butyl -bis(oxy-3-benzoic acid) (L4), bis(3-fluoro-4-cyano-phenoxy)propane (L5), bis(3-fluoro-4-cyano-phenoxy)ethane (L6), bis(3-fluoro-4-cyano-phenoxy)butane (L7) have been synthesized. The complex [La2(L)2(HL)2] have been synthesized by the reaction of diethyl 1,3-propylidenebis(4-oxybenzoate) and La2(NO3)3·6H2O. Four coordination polymers {[M(HCOO)3] [(CH3)2NH2]}n [M = Co,Ni,Zn,Mn] have been synthesized by the reaction of L1 and transition metal salts in high purity and higher yield under mild hydrothermal conditions. L1 was decomposed into formate in this reaction condition.These compounds have been characterized by EA, IR, TGA and X-ray diffraction analysis. They have similar composition with the difference in the center metal atoms, and all complexes crystallize in the trigonal systems and space groups R-3c. In the crystal structures of all the four compounds, the formats as the bidentate ligand coordinate with the metal atoms to form the octahedral structure. Approximately 6 ?×6 ?×6 ? void exist in {[M(HCOO)3] [(CH3)2NH2]}n, so they can be used as gas-storage materials.