Studies On Benzoxazole Fluorescent Sensors For Cations And Mechanism Of The Oxida-tive Addition Of Aryl Halide To Gold (â… ) Complexes

As an important branch of the supermolecular chemistry, the fluorescence mo-lecular switch has developed rapidly and attracted interests by the chemists. In thisdissertation, the functional design and the molecular recognition of benzoxazole fluo-rescent receptors were studied.A series of fluorescent probes with double benzoxazole fluorescen groups linkedcrown ether or open chain polyester were designed and synthesed. According to themetal ion titration test, it was found that there is no good selectivity to the particularmetal ion and the further identification was given up.Gold catalysts have attracted considerable interests in recent years because oftheir high activity and selectivity in catalyzed reactions. They showed different chrac-teristics in many reactions, such as hydrogenation, oxidation and cycloaddition reac-tions, etc.Here, DFT calculations under B3LYP were performed to investigated the role theligands affecting the oxidative addition reaction of the aryl halides to Au(â… ) complexes.We provide a theoretical basis for the catalysts designing. The results show that thecomplex [Au (ppy)] is prefer to the oxidative addition reactions of aryl halide com-pared to the complexes [Au(dpe)]+and [Au(NHC)Cl]. The coordination of elec-tron-rich nitrogen to gold center play a key role to stabilize the transition stateTSppy(2-3)and the oxidative addition products3ppy. The electron-deficient feature ofcomplex [Au(dpe)]~+increase the relative energies of the transition states TSdpe(2-3)andthe oxidative additive products3dpe. For the complex [Au(NHC)Cl], the great defor-mation-energies result in the very high barriers for the oxidative addition reactions ofaryl halide.