Synthesis, Structural Characterization And Properties Of Coordination Polymers Constructed From Amino Acids And Their Derivatives And Organic Synthesis Of The Corresponding Ligands

In the first part of this dissertion, recent researches on coordination polymers constructed by metal ions and organic ligands are reviewed. The concepts of coordination polymers, framework structures, building blocks and the uncertainty for structure design are discussed, especially for those of chiral coordination polymers.In this thesis, a series of novel coordination polymers and complexes constructed from amino acids and other adjuvant ligands have been synthesized. The crystal structures and properties of them have also been studied. Furthermore, the mediation on structures of coordination polymers via ligands has been explored. In order to reach this aim, several modified aromatic amino acids were synthesized and employed for the construction of new 2D coordination polymers. It was found that the size and shape of our 2D coordination frameworks could be mediated by the ligands to some extent. This thesis mainly consists of five sections.1. A series of modifies amino acids were synthesized. Among them, three aromatic amino acids derivatives molecules: 2-acetylamino-3-(4-amino-phenyl)-propionic acid methyl ester (AAPM), 3E-[5-(2-amino-2- carboxy-ethyl)-2- methoxy -phenyl]-acrylic acid (AMPA) and 3-(4-amino-phenyl)-2- (methoxycarbonylmethyl- amino)-propionic acid methyl ester (AMPM) were successful constructed into the coordinaton polymers.2. The reaction of His with Co(II) salt gives rise to an acentric 3D supramolecule, [Co(D-His)(L-His)]·ClO₄ (1), which is diamagnet. Through the spacer isonicotinate, Co octahedrons are linked to be a centric 2D frameworks, [Co₂(D-His)(L-His)(INT)]·H₂O·ClO₄ (2) , which exhibits paramagnetism property. The tetranucleus clusters, which can be defined as the SBUs of 2, are formed by four simple Co octahedrons. At the same time, four SBUs generate the novel cyclohexane-like chair conformation 16 cobalt nucleus grids. Thus, molecule complex 1 and coordination polymer 2 can be obtained via His and the adjuvant ligands.3. The reactions of Trp with Mn(II) and Zn(II) salts give rise to two centric 2D metal-organic coordination polymers, [Mn(D-Trp)(L-Trp)] ( 3 ) and [Zn(D-Trp)(L-Trp)] (4) . The crystal structures of two compounds are very similar. The rhombic grids are obtained via the linkage of H2N-CH-COO" chains. The magnet measurement displays that 3 is paramagnet and 4 is diamagnet. Additionally, the result of photoacoustic spectroscopy demonstrates that the compound 3 is thermally thick material in R&G model.4. The reactions of Trp with Co(II) and Ni(II) salts give rise to three homochiral metal-organic coordination polymers, [Co₂(L-Trp)₂(Py)₆]·Py·(ClO₄)₂ ( 5 ) , [Ni(L-Trp)(Py)₃]·H₂O·ClO₄ (6) and [Co₂(L-Trp)(INT)₂(H₂O)(ClO₄)] (7) . The chirality of L-Trp induces the homochiralities of these structures. At the same time, the terminal ligand pyridine blocks the increase of dimension. Thus, the dimension can be mediated by the addition of pyridine and isonicotinic acid in our experiment. If D,L-Trp is taken replace of L-Trp, the 3D supramolecule [Co(INT)₂(H₂O)₄] (12) can be obtained.5. Three Phe and Tyr derivatives, 2-amino-3-(4-amino-phenyl)-propionic acid (AAP), 3E-[5-(2-amino-2-carboxy-ethyl)-2-methoxy-phenyl]-acrylic acid (AMPA) and 3-(4-amino-phenyl)-2-(carboxymethyl- amino)-propionic acid (ACP) are chosen to be the ligands. Two of them can be gotten in-situ via hydrolysis of molecules AAPM and AMPM. And then, four kinds of the novel metal-organic frameworks (MOFs) (five structures) can be synthesized. These structures are: [Cd(II)(R-AAP)(Py)(H₂O)]·(ClO₄) (R-8), [Cd(II)(S-AAP)(H₂O)₂]-(ClO₄) (S-9), [Zn₂(II)(R, S-AMPA)(H₂O)] (R, S-10), [Zn₂(II)(R-ACP)(Py)₃]-(ClO₄)₂ (R-11), and inversion twin of R-8. According to the layers discussed above, it's the key trunks and the H₂N-CH-COO^- chain acting as the bridges. Thus, the experimental result is consistent with the assumption that we conceived. Both the size and the shape of the grids in the layers are mediated by the positions of the coordinating function groups at modified amino acids. For convenience, the length of key trunks here is defined as the depth of the ligands, while that of H₂N-CH-COO^- chains is defined as the width. In the layers of 8, 9 and 10, the two sides of one grid are key trunks and H₂N-CH-COO^- chains, respectively. Therefore, the size of grid in such layers is determined not only by the depth but also by the width of ligands. For AAP, the rigidity of the bond between phenyl ring and amino group makes the full elongation of the depth. The size of the grids of 8 and 9 is about 5.0 A × 11.8 A. At the same time, for AMPA, the flexibility of the vinyl bonding makes the partial elongation of the depth and the straight distance of neighboring comers in the grids of 10 is about 4.3 A × 11.4 A. Thus the sizes of such two kinds of layers are almost same. Furthermore, the key trunk of AAP is approximately straight due to the addition of the amino group to the 4-position of Phe, resulting in a distorted rectangle shape of the grids in 8 and 9. Similarly, the key trunk of AMPA is tortuous due to the addition of an acrylic group to the 3-position of modified Tyr, which leads to the formation of a bend rectangle shape of the grids in 10. In sum, the common ground of three kinds of polymers 8, 9 and 10 (four structures) is that the length of the long side is almost two times of that of the short side in the grid when the modified aromatic amino acids are used as spacers. The depth can be expanded by adding a coordinating functional group. On the other hand, the molecule ACP with the long width is designed. In the structure of ACP, the carboxymethyl group is connected to the amino group of Phe for prolonging the width and the other amino group is added at the 4-position of aromatic ring of Phe for prolonging the depth. Therefore the shape of the grids in 4 is a rhombus with a size of 10.0 A × 10.4 A, which is bigger than those of the grids in former four structures. In conclusion, the rational design on adjusting the "depth" and the "width" in the ligands can mediate the size and the shape of the grids in these 2D layers. On the other hand, among these compounds, three pure chiral coordination polymers are obtained due to the inducement of chirality of these modified amino acids. This property makes them being potential NLO materials.