Coordination and Bonding Aromatic Interaction-driven Self-Assembly toward Conductive Porous Molecular Frameworks

概要

In this dissertation, three type compounds, PMC-ring-M (M = Zn, Ni, Co), PMC- R-X (X = Cl, Br), and MX chain complex of [Pt(bpam)2Cl]Cl22H2O, were presented and studied through crystal structure, optical property, conductive property and magnetic property and so on. All of them were related to the bonding-aromatic interaction.

In chapter 2, PMC-ring compounds were discussed by the crystal structure and physical properties. To rich the architecture of PMC compounds, the pyrazole group was the pendent group in NDI, namely NDI-Hpz. The pyrazole group has one hydrogen donor and one N for coordination with metal ions, so the flexibility and propensity to form the angular coordination geometry of the pyrazole group made it a good candidate for metallacycle formation in PMC. In addition, the hydrogen bonds could stabilize the structure, so the NDI-Hpz was selected as the ligand. Finally, the expected structure was realized by the electrochemical approach in which the isolated hexagonal metallacycles were densely stacked alternatively with a sequence of ABC to construct a 3D network with 1D helical π-stacked columns and 1D pore channels. And the chemical formula of PMC-ring-Ni was further determined by the elemental analysis and TGA as [Ni(NDI-Hpz)(dma)2(NO3)]·1.8DMA·2H2O. The short π-π distance of 3.174 Å implied the existence of NDI radicals that were confirmed by the solid-state absorption spectra and ESR spectrum. Moreover, the PXRD patterns of PMC-ring compounds with different metal ions showed an isostructural geometry. Meanwhile, the temperature dependence of electrical conductivity of all PMC-ring compounds displayed a semiconductive behavior and the conductivity was slightly higher than PMC-1. Although the improvement of the robustness remains to be addressed, the concept of using metallacycle as a building block provides a new platform for developing electrically conductive porous molecular materials.

In chapter 3, to realize the thermal and air stability in the PMC field, the 1,2,4- triazole group was chosen as the terminal group in NDI. By contrast to Hpz, the triazole group has two coordination sites, higher symmetry, and a stronger electron- withdrawing effect. In addition, the triazole group was favorable to form the meta- halide chain structure that would enhance thermal stability. In this work, two synthetic methods were used to obtain the same PMC compounds, solvothermal and electrochemical approaches, which was confirmed by the PXRD patterns. The single crystals were acquired by the solvothermal method and SXRD analysis showed that the interpenetrated 3D coordination bonded framework was formed with 1D rhombic channels and 1D Cd-Cl zigzag chain due to the triazole group which led to a longer π- π distance of 3.554 Å. The crystalline powders were synthesized by electrolysis and measured by the PXRD with different halide ions which showed an isostructural architecture. Moreover, the solid-state absorption spectra displayed larger CT bands in PMC-R compounds than PMC-ring-Ni due to the longer π-π distance and smaller charger transfer integral which resulted in a lower conductivity, and both of them showed a semiconductive behavior. Otherwise, PMC-R compounds showed better thermal stability than PMC-1 and PMC-ring compounds up to 150 ˚C and better air stability that was confirmed by the unchanging absorption bands after PMC-R-Cl was exposed to air for 20 days.

In chapter 4, the novel synthetic strategy, mechanochemical method, was provided to synthesize the starting materials, [Pt(bpam)2]X2 (X = Cl, Br, I), which was analyzed by the 1H NMR and SXRD. The single crystal of PtCl chain complex, [Pt(bpam)2Cl]Cl22H2O, was synthesized by the acetone diffusion into the [Pt(bpam)2]Cl2 solution. SXRD analysis revealed that the PtCl chain had a mixed- valence state and a long Pt-Pt distance of 7.115 Å due to the π-stacked arrays of aromatic rings of ligand. Along with hydrogen bonds between Cl and N-H of ligand, the π-stacking interaction enhanced the stability of crystal structure. Moreover, the tri- metal complex was synthesized by the liquid-liquid diffusion ([Pt(bpam)2Zn2Cl6]). The selective coordination with metal ions make it possible to synthesize 2D or 3D MX- chain framework.