| Supramolecular self-assembly which rely on the non-covalent bond interaction between different molecular units can form highly ordered macromolecular with thermodynamic stability. The coordination bond is widely used as the main driving force to construct metal-ligand macrocycles and polyhedron. Metal-organic macrocycles are important models to realize the process of enzyme catalysis and recognition. These structures discussed exhibit well-defined cavities with gated pores providing specific inner environments for selective uptaking and binding of guest molecules.As the important nitrogen hetero aromatic ring compounds, carbazole and its derivatives containing large conjugated system, the strong electron transfer process and the characteristic of easy to midify, have potencial application value in dye, medicine photoelectric materials and supramolecular recognition. The studies based on the rigid frame of carbazole conjugate system, such as artificial receptor, molecular probe, is increasingly active.On the basis of this context, we use elaborate design synthesis strategy to introduce a variety of weak interaction functional groups to the carbazole frame, constructed relatively open metal-organic macrocycles with transition metal for biological molecules recognition and simulating photocatalysis researches.We introduce aldehyde to the3,6sites which react with2-hydrazo pyridine to form LN. The two-arm bidentate ligand LN coordinate with transition metal Co2+to form [4+4]rhomboid metallacycles, each Co2+coordinated with two LN and two solvent molecules. We get a new structure through the introduction of second ligand4,4’-bipydine to the system which can replace the coordinated solvent molecules. According to the existing building model, we change the coordination atoms of ligand LN to synthetize the new ligand LS, which combine with Ni2+to form simultaneously [2+2] and [3+3] metallacycles, in contrast to LN form [4+4]rhomboid metallacycles.The complex Co-LN-1constructed by LN and Co2+can detect the guest molecules ATP in the acetonitrile and water(4:1) buffer system by utilizing the synergistic effects of electrostatic,π-π stacking, hydrogen-bonding and coordinative interactions inside the cavity.The Co complexes have been widely used in the research about hydrogen production. We construct a noble-metal-free homogeneous system with Co-LN-1as catalyst, fluorescein as the photosensitizer and triethylamine as the sacrificial electron donor, with TON up to500. Co-LN-1with special cavity can encapsulate the fluorescein who also has conjugated system through π-π stacking, efficiently guarantee the electron transfer process in the sysrem and improve the transfer rate, the nature of the host-guest chemistry between them is the main reason of high catalytic efficiency. |
