The Preparations And Properties For Catalysis Of Metallic Nanoclusters Templated By PAMAM-Dendrimers

PAMAM Dendrimers become a hot spot having a nano-cavity and large number of functional groups. PAMAM-dendrimers have been synthesized successfully by divergent method with the Michael addition and Acylamidation reaction. 4.5G PAMAM was characterized to be the target molecular structure using Infrared spectroscopy(IR) and Ultraviolet-Visible spectrophotometer.To study furtherly the purification problems of PAMAM, Entraining agent (n-heptane) were selected, the results showed that the degree of purity of PAMAM were greatly improved, the yield of 4.5G PAMAM fell from 108.9% to 101.3%. As the generation increased, the greater difficulty in purification.PAMAM with nanometer cavity is an excellent templated material. The Ag nanoclusters were prepared under the conditions of time 36h, n(Ag)/n(PAMAM) 30, which were well-stabilized with degree of dispersion and smaller diameter. The Ag nanoclusters were very stable under the temperature of 45℃. The Pd nanoclusters were also successfully prepared under the condition of time 36h and n(Pd2+)/n(PAMAM) 60. The complexing reaction mechanism between Pd2+ or Ag+ and polyamide-Dendrimers were coordinated with the interior tertiary amine groups of PAMAM.Cinnamic acid is a very important intermediate for organic synthesis. There are some problems of higher reaction temperature and lower efficiency in the homogeneous phase Heck reaction for the synthesis of cinnamic acid which was difficult in the separation of catalyst. For this reason, we adopted Palladium nanoclustes within PAMAM templates as analog homogeneous catalysts. The reaction conditions of Heck reaction of Iodobenzene with Acrylic acid were determined. The optimal reaction conditions were reaction temperature 40℃, 4.0804gPhI, 2.8824gAA, 0.015g catalyst, 2.5298gEt3N, reaction time 4h, the yield was 67%, TON=1875, TOF=469h-1. This kinds of Catalysts were easily separated by nano-filtration and reused three times without significant reduction in yield.The innovation of this thesis was that a new purirafication method was proposed and the analog homogeneous catalyst PAMAM templated Palladium nanoclustes was used in Heck reaction with potential prospect in the future.