Self-Assembly And Fluorescence Property Of The Metal-Organic Cage-like Compounds

Supermolecular chemistry can be basicly expressed as "Chemistry of two or more chemicals forming a more complex and organized compound through the intermolecular interactions", the macrocyclic, crypt and cage-like molecules which possess cavities and their host-guest chemistry are most important in the study of supermolecular chemistry. The selective inclusion and recognition of specific guest molecular are of great significance in aspects of the host-guest chemistry, catalysis, molecular/ion transport, molecular and supramolecular devices, molecular machines and so on. Recently metal-driven self-assembly of cage-like compounds aroused wide interest because of the variety of coordination geometry, stability of strong coordination and rich photochemical and electrochemical properties.In this paper, a series of cage-like metal-organic compounds has been designed to have not only a different geometry, but also the role of recognition sites with weak signal response group and the corresponding signal transmission and output unit. Therefore, ions could be selectively bond and, demonstrated intuitively through changes of the fluorescence signal, which would have potential applications.1. With flexible maleic hydrazide Schiff base derivatives as a linker to Ce3+as a metal vertex, two spiral metal-organic compounds Ce-CL1 and Ce-CL2 were synthesized by close chelating of Ce3+and the three NO2 tridentate ligands, ESI-MS proved that they can stably exist in solution. The suitable size of the cavities and well-positionedβ-diketone groups within in the cavities proved high selectivity towards Mg2+over other alkali and earth-alkali metals ions and a significant enhancement in fluorescence.2. With rigid semicarbazone Schiff base derivatives as a linker to Zn2+, Cd2+, Co2+, Ni2+ and other transition metal as a metal vertex, four square metal-organic compounds CQ, ZQ, MQ and NQ were synthesized by close chelating of metals and the three N2O tridentate ligands, ESI-MS proved that they can stably exist in solution. For example, the-NH-CO-hydrogen binding site and a fixed geometry of CQ can be used as a fluorescent chemosensor for distinguishing o-phthalate from two other isomers of dicarboxylates, and it can significantly quench the fluorescence.