Molecular Recognition And Sensing Based On Cationic N-heterocycle

Cationic host based N-heterocycle and other related derivatives especially hosts contain cations of imidazole and pyridine have developed rapidly in recent years. These compounds have been widely used in the recognition of ions or small biomolecules because of the unique characters of the cations. In the field of catalyze, imidazoline cations present as the precursor of N-heterocyclic carbenes (NHCs) and thus a large number of metal organic compounds were derived based on it. Numerous studies have been reported owing to their high effective applications in homogeneous catalyzes. Meanwhile, scientists start to do researches on three-dimensional structure derived on the basis of two-dimensional structures and synthesize a series of compounds with interest and potential value. How to design and prepare this system contain functional groups (chirality or fluorescence e.g.) is still a high research value and great importance in supermolecular chemistry. On the basis of this context, this paper contains the following aspects of contents:1. Tripodal luminescence chemosensors based on 1,8-naphthalimide and imidazolium: (1) We have synthesized flexible tripodal luminescence chemosensors based on functionalized naphthalimide group and three imidazolium or pyridinium cations. Probe TIA1 (preorganized tripodal receptor, imidazolium as bridge and 1,8-naphthalimide as signaling subunits) exhibits a selective "turn-on" fluorescent property for ADP over other ribonucleotide polyphosphates. Probes TIA1 and its derivatives TIA2 then successfully applied in living cells imaging for response ADP; (2) In aqueous media, probe TPA1 (preorganized tripodal receptor, pyridinium cations as bridge and 1,8-naphthalimide as signaling subunits) exhibits a selective "turn-on" fluorescent property for maltose over other saccharides. TPA1 was applied in living cells imaging for response maltose, this is the first luminescence probe sensing carbohydrate in living cells; (3) Probe TIPA1 (preorganized tripodal receptor, imidazolium as bridge, piperazine as recognition site and 1,8-naphthalimide as signaling subunits) acted as a dynamic anion-induced ion-pairs sensor and exhibits a selective "turn-on" fluorescent property for CuⅡion-pair (copper perchlorate and copper nitrate) over a wide range of tested metal ions and Cu2+salts ion pairs.2. The construction and catalytic performance of the chiral cyclic N-heterocyclic carbenes compounds:Synthesized a chiral N-heterocyclic carbenes (NHCs) macrocycle compound CNHC as ligand, then first assembled a novel chiral N-heterocyclic carbene silver(Ⅰ) cage CNHC-Ag. Single crystal X-ray structural analysis of this complex shows a cylinder-like structure of two ligands and three Ag+ions. CNHC-Ag could be used as a molecular mircoreactor of Diels-Alder reaction to control the enantioselectivity and asymmetric catalysis of strecker reaction. Then we synthesized an Au complex of this ligand by cation exchange reaction. ESI-MS and NMR shows the same structure as CNHC-Ag.3. Design and synthesis of chiral covalent cage structures derived on the basis of covalent two-dimensional macrocycle structures. Covalent two or three-dimensional organic structures have great value on host-guest chemistry, catalysis, enzyme simulation and so on. Based on the study of chiral N-heterocyclic carbenes (NHCs) macrocycle compound CNHC, this paper synthesized a series of covalent two or three-dimensional compounds, which provide larger cavity and fluorescent function. (1) Chiral imidazolium macrocycle CNHC2 (C63H69N6·3BF4, diameter:1.4 run); (2) Chiral polyhedron cage-like compound CZC (Schiff Base cage-like compound with chiral diaminocyclohexane as vertex and triazole as framework) with long wavelength stoke's shift, fluorescence quantum yieldΦf=21; (3) Chiral polyhedron cage-like compound CAC (Schiff Base cage-like compound with chiral diaminocyclohexane as vertex and triphenylamine as framework),Φf=0.17; (4) First tetrahedron covalent compound CIZ (Schiff Base cage-like compound with chiral diaminocyclohexane as vertex and Tren as framework),Φf=0.15. NMR, MALDI-TOF confirmed the formation of these compounds, the cavity volums calculated by DFT were 4200 A3,3600 A3 and 1600 A3, respectively.