Studies On The Synthesis Of New Type Of Molecular Tweezers Under Microwave Irradiation And Molecular Recognition

The study on molecular recognition of artificial receptors is one of the frontiers in bioorganic chemistry. In the dissertation, the efforts were focused on the synthesis of three types of molecular tweezers under microwave irradiation as well as their molecular recognition. Some useful and important new results have been obtained.Eight acridine-aromatic amide molecular tweezers, ten hetero-aromatic Schiff base molecular tweezers and three other molecular tweezers derived from methyl deoxycholate have been synthesized under microwave irradiation. Among them thirteen are new compounds and acridine-aromatic amide molecular tweezers have been designed and synthesized for the first time. The synthetic methods of target compounds have been systemically investigated, and the suitable conditions were chosen. A simple route, with high yield and friendly to environment, have been obtained by microwave irradiation. All these tweezer-type receptors possess different sizes of clefts, different recognition site, different rigidity and flexibility. Their structures were confirmed by IR, 'HNMR, MS and/or element analysis.Molecular recognition properties of these molecular tweezers for some small neutral molecules, such as some aromatic amines and benzophenone, were examined by UV-visible spectra titration. The association constant (Kd) and Gibbs free energy changes (-?G0) were determined. The computer-aided molecular modeling were used to elucidate further the recognition abilities. The results show that 1:1 inclusion complexes are formed for most of molecular tweezer receptors with guests examined. Among the receptors, the Schiff base molecular tweezers showed strong recognition ability for some aromtic amines and benzophenone and the association constant canreach 104M-1. The drive forces of molecular recognition mainly come from non-covalent forces between host and guest, such as H-bond, ? - ? stacking interaction etc. At the same time, the rigidity and flexibility of receptors, micro-environmental effects of different cleft structures, the size/shape-fit and geometry complementary between host and guest also play an important role in recognition process.