Based On The Flexible Ligand 6,6 '- The Disulfide Niacin Build Coordination Polymer Synthesis, Structure And Nature Of The Study

Recently, the research of metal-organic coordination polymers has been based on the relationship of structures and functions as a new kind of functional material. In order to obtain the title plymers, we can use the theory of crystal engineering to control the self-assembly of coordination polymers. In this regard, how to design and select the organic ligands and metal ions is the key factor. As we knew, the coordination frameworks constructed from flexible ligand are relatively underdeveloped. It is difficult to predict either the composition or the framework structure constructed from a flexible ligand due to the conformational freedom of flexible ligand in the self-assembly process. However, the special conformation and coordination mode of the flexible ligand might bring on some unprecedented metal-organic coordination polymers frameworks, such as interpenetration or helix structures.In this dissertation, we focus on the flexible carboxylate 6,6'-dithiodinicotinic acid (H2cpds) as the main ligand under the intervention of various transition and lanthanide metal ions. At the same time we introduce the rigid/flexible N-donor ligands as the additional ligand into M-cpds system to obtain eighteen coordination polymers which exhibit fascinating architectures and excellent properties. Furthermore, the factors impact on the structures of coordination polymers have also be represented and discussed.1. We have synthesized a series of coordination polymers using H2cpds, rigid N-donor ligands (pillar N-donor ligand, terminal N-donor ligand) and transition metal ions. They exhibit diverse structures with dimensionalities from OD to 3D interpenetrating network. In sum, when the rigid pillar N-donor ligands were introduced, it could extend the dimensionality of the system of compound. However, the steric hindrance and chelating effects of the terminal ligands can constrain the prolongation of the framework and result in the formation of lower dimensionality. Furthermore, we gain two new compounds 8 and 9 through in situ cleavage of the S-S bond with the solvothermal reactions. In conclusion, the hydrothermal reactions can create more chance for in situ ligand synthesis owing to their relatively critical reaction conditions.2. As a continuation of our previous work, two flexible N-donor ligands (bpa, bpp) are introduced into the synthetic systems. Herein we have obtained four novel coordination polymers with mixed flexible ligands and Zn(II)/Cd(II) metals under the liquid diffusion conditions. The introduction of mixed flexible ligands can lead to the interpenetration or helix structures. Furthermore, the conformations of the flexible N-donor ligands can influence on the frameworks of coordination polymers.3. Reaction of H2cpds with lanthanide metal salts have led to three isostructural coordination compounds {[Ln2(cpds)3(H2O)5]·7H2O}n under hydrothermal conditions. The 3D network with an uncommon two-fold interpenetrating 4-connected CdSO4 structure type constructed by the connection of binuclear [Ln2(CO2)4] unit and H2cpds. It is worth noting that polyrotaxane-like motif is also exhibited in the 3D network.4. We have obtained one special complex {[Cd(cpds)1.5·(H2O)3]·6H2O}n (18) by the reaction of H2cpds and Cd(II) ion under the liquid diffusion condition. The structure of complex 18 is a 16-fold SrS network showing unusual [8+8] mode interpentration. In the whole network, the each 8-fold interpenetrated framework is chiral. As we knew, the 16-fold interpentration is firstly observed in metal-organic coordination frameworks.