Self-Assembly, Structural Diversity and Properties of L-histidine-containing Chiral Zinc(II), Nickel(II) and Cadmium(II) Metal Compounds

• Main Author: 柯思妤
• Other Authors: 呂光烈
• Format: Others
• Language: zh-TW
• Published: 2013
• Online Access: http://ndltd.ncl.edu.tw/handle/93353191176790163831

碩士 === 國立臺灣師範大學 === 化學系 === 101 === The goal of this study was to develop a self-assembly synthetic strategy for the preparation of metal–organic coordination polymers using L-2-amino-3-(1H-imidazol-4-yl)propanic acid (L-histidine), 4,4’-bipyridine (bipy) and 5,5’-bipyrimidine (bpym) in combination with different transition metal ions. The solid state structures of the products were characterized by FT-IR spectroscopy, elemental analysis, thermogravimetric analysis and single-crystal X-ray diffraction methodology. The reaction of L-histidine with Zn(II) or Ni(II) ions leads to the formation of neutral monomeric compounds, [M(L-his)2]H2O (M = Zn (1), Ni (2)). In 1, the Zn(II) centers are coordinated by two N atoms of two different imidazoles and two N atoms of the NH2 groups of two L-histidine ligands to form a tetrahedral geometry. In 2, the nickel(II) centers are coordinated to two L-histidine ligands in a tridentate fashion through N, NH2 and O to furnish an octahedral geometry. In another reaction, when Cd(II) ion is allowed to react with 4,4’-bipyridine and L-histidine, in the present of perchlorate (ClO4 ) or nitrate (NO3 ), the coordination polymers {[Cd(bipy)(L-his)(H2O)](ClO4)}n (3), {[Cd(bipy)(L-his)(H2O)](NO3)H2O}n (4), respectively, are formed. The molecular structures of 3 and 4 reveal that the L-histidine acts as a bridging ligand, adopting a bis-chelating coordination mode through the N atom of the NH2 group and four O atoms of carboxylates to form a 1-D chain. The 4,4’-bipyridine ligands are then connected with each chain to afford a 2-D layered structure. In these series, the de-/ad-sorption behavior of coordinated water molecules and guest water molecules are supported by TGA technology. The results show that the process is reversible when the system is exposed to water vapor. In particular, the chemical and physical adsorption behavior of 4 can be clearly differentiated from the TGA patterns. When Cd(NO3)2 or Cd(ClO4)2 is reacted with 5,5’-bipyrimidine and L-histidine, the coordination polymers {[Cd(bpym)0.5(L-his)(H2O)](NO3)C2H5OH}n (5) and {[Cd(bpym)0.5(L-his)(H2O)](ClO4)H2O}n (6), respectively, are formed. In 5 and 6, the Cd(II) centers are coordinated with L-histidine ligands in a tetradentate coordination mode via the N atom of imidazole, the N atom of an NH2 group and two carboxylate O atoms to form a 1-D chain. In addition, 5,5’-bipyrimidine is connected to each chain of 5 and 6 via cis- and trans form, respectively, to form a 2-D layer and a 3-D structure. Key word：chiral, L-histidine, metal-organic framework, self-assembly.