Synthesis And Characterization Of Tryptophan Coordination Polymer And Amino Acid Crystallization Studied By Streaming Potential Measurement

On the basis of L-trp ligand,a series of Fe(â…¡),Co(â…¡),Ni(â…¡),Zn(â…¡),Cd(â…¡) and Mn(â…¡) coordination polymers were synthesized by a hydrothermal or a mixed solvent-thermal method.The products were characterized by spectroscopy.The single crystal structure of six coordination polymers have been resolved by X-ray diffraction.Their thermal stability were investigated.The electrochemical properties of Fe(â…¡),Co(â…¡),Ni(â…¡) and Mn(â…¡)-trp coordination polymers were researched.Through the study on the crystallization process of aqueous solution of amino acids,dicarboxylic acids and complexes by streaming potential method,that will helps to further study on the crystallization or the precipitation process of amino acid complexes and the electrical characteristics on the solid-liquid interface.The research and main conclusion of this dissertation is shown as follows:The coordination polymer of Fe(â…¡) and DL-trp was formed by a hydrothermal method involving Mohr' salt and L-tryptophan.The product was characterized by elemental and thermal analysis,IR and UV spectra,cyclic vohammogram and single-crystal X-ray diffraction. The crystal belongs to the monoclinic system,space group P21/c.The structural analysis shows that the complex assumes a two-dimensional double chain layered structure.The coordination polymer of Co(â…¡) and DL-trp was prepared by a hydrothermal method from hexaaqua-cobaltous perchlorate and L-tryptophan,and was characterized by elemental and thermal analysis,IR and UV spectra,cyclic vohammogram and single-crystal X-ray diffraction. The compound(monoclinic space group P2₁/c) shows a two-dimensional double chain layered structure.The cyrstallized coordination polymer has a centrosymmetric space group. Each Co²⁺ coordinate with a pair of racemes,and the complex is a mesomer.The coordination polymer of Ni(â…¡) and DL-trp was formed by a mixed solvent-thermal method from hexaaquanickel(â…¡) perchlorate and L-tryptophan.It was characterized by elemental and thermal analysis,IR and UV spectra,cyclic vohammogram and single-crystal X-ray difffraction.The crystal belongs to the monoclinic system,space group P2₁/c.The Ni(â…¡) atom is located on an inversion center and has an octahedral coordination geometry formed by four O atoms and two N atoms from D- and L-tryptophan ligands.Each D- and L-tryptophan ligand bridges the Ni(â…¡) atoms through the carboxylate group,leading to a two-dimensional structure parallel to the bc plane.The coordination polymer of Zn(â…¡) and DL-trp was prepared by a mixed solvent-thermal method and characterized by elemental and thermal analysis,IR,UV and ¹HNMR spectra,and single-crystal X-ray diffraction.The compound(monoclinic space group,C2/m) shows a two-dimensional double chain structure.The cyrstallized coordination polymer has a centrosymmetric space group.Each Zn²⁺ coordinate with a pair of racemes,and the complex is a mesomer.The coordination polymer of Cd(â…¡) and DL-trp was successfully prepared by a solvent-thermal method.It was characterized by elemental and thermal analysis,IR and UV spectra,and single-crystal X-ray diffraction.The compound(monoclinic space group P2₁/c) shows a two-dimensional double chain layered structure.The cyrstallized coordination polymer has a centrosymmetric space group.Each Cd²⁺ coordinate with a pair of racemes, and the complex is a mesomer.The coordination polymer of Mn(â…¡) and DL-trp was prepared by a hydrothermal method and characterized by elemental and thermal analysis,IR and UV spectra,cyclic vohammogram and single-crystal X-ray diffraction.The compound(monoclinic space group P2₁/c) shows a two-dimensional double chain layered structure.The cyrstallized coordination polymer has a centrosymmetric space group.Each Mn²⁺ coordinate with a pair of racemes, and the complex is a mesomer.The streaming potential of saturated solution of binary carboxylic acids,which have even carbon atoms,was determined to characterize crystallization under different temperatures.When the temperature was declined to the point where a crystal nucleus appeared,the streaming potential reached the minimum.Thereafter,as the temperature was sequentially lowered,some minicrystals grew,and the streaming potential presented an ascendant tendency.The higher the starting temperature of the acids saturated solution,the higher is the temperature corresponding to the streaming potential minimum.The less the carbon atoms in the acids and the greater the solubility of the acids are,the higher is the temperature of the streaming potential minimum.The streaming potential of saturated solution of Gly,L-Trp and L-GIu were determined to characterize crystallization in cooling process.The influence of solution acidity and the initial temperature to the v-t curve were investigated.The glycine solution has more competitive nucleating ability in higher initial temperature as 30 and 35℃,and less competitive nucleating ability in lower initial temperature as 20 and 25℃.It is shown to the v -t curve of the same initial temperature for the solution of pH=7.0,pH=5.0 and pH=4.0 have more evidently competitive nucleating ability.There is less competitive nucleating ability at isoelectric point.The L-Trp solution has more competitive nucleating ability in lower initial temperature as 20℃,and less competitive nucleating ability in higher initial temperature as 35℃.It is shown to the v-t curve of the same initial temperature for the solution of pH>6.0 have more evidently competitive nucleating ability.There is less competitive nucleating ability at isoelectric point.The L-Glu solution has more competitive nucleating ability below initial temperature 30℃and at isoelectric point(pH=3.15 ).The latter is relevants to the solubility of L-Glu which is smallest at the pH value of isoelectric point and can easily deposit crystalThe streaming potential of saturated solution of K₃[Fe(CN)₆]and K₄[Fe(CN)₆]was determined to characterize crystallization under declining temperature process.When the temperature dropped to the point where crystal nucleus appeared,the streaming potential reached the minimum.Thereafter,the streaming potential presented an ascendant tendency. The higher starting temperature of the complex saturated solution is,the higher temperature corresponding to the value of streaming potential minimum is.The temperature of streaming potential minimum in K₃[Fe(CN)₆]supersaturated solution is lower than that in K₄[Fe(CN)₆] supersaturated solution.