Fabrication And Heterogeneous Catalytic Properties Of Cyclopalladated Imine And Metallo-Porphyrin Assembly Films

Sustainable green chemistry, high efficientence and atom economy is a major challenge in today’s industrial catalysis. Supramolecular of transition metal complexes can simulate enzyme efficiently to catalyze many reactions under mild condition, but there were some drawbacks, such as lower TON and poor recycling.Preparation of recyclable, highly active and atom economy heterogeneous catalyst immobilzed on suitable supports is a promising access to green chemistry, while providing an ideal template for investigating the mechanism.The main contents include as follow:1. Assembly films of aliphatic and aromatic diimine( 1DIS, 2DIS, 3DIS)immobilized on silicawere prepared by multi-step. Palladium was coordinated with diimine ligands. The length of the chain and the coordination method had a great influence on content of palladium immobilized on silica, in which the content of palladium is in turn from high to low(3DIS,2DIS,1DIS) due to their steric and orientation. The arrangement of diimine molecules on the surface played a great role on catalyzing reaction.2. 1DIS, 2DIS, 3DIS were applied to catalyze Suzuki coupling reaction.The results showed that reaction temperature, time and base has a great influence on the yield and selectivity of Suzuki coupling reaction. The content of palladium immobilized on 1DIS was so low that its catalytic activity is lower. In the case of2 DIS, high catalytic activity of aryl bromides and iodides was acheived, while could hardly catalyze aryl chloride. The imine carbon of 2DIS is easily hydrolyzed because of active hydrogen of α-C, resulting in poor recyclability. 3DIS also showed high catalytic activity for aryl bromides and iodides, and 17% for aryl chloride.3DIS still show high actalytic activity by reused at 8 times.3. We studied the viriation of films’ element relative percentage content and valence state, contact angle, morphology by XPS, static water contact angle, AFM and CV. Mechanism had been proposed based on the experimental results. There was a induction period, aryl halide absorbing, products generated after oxidative addition,metal transition and reductive elimination. The reaction is dynamic equilibrium process of desorption and adsorption. Pre-main reaction was adsorption,latter was desorption, catalytic active species were gradually embedded by products and finally the product desorbed from the film. Morphology of surface of film is a process from ordered to disorder, and finally to ordered during the catalytic process.The reaction actually was a heterogeneous catalysis process, which occurred on the surface of the substrate.4. Mn porphyrin immobilzed on copper-based graphite was used to catalyzecyclohexane’s oxidation and the selectivity and yield were investigated. The optimal conditions was determined as 1.2MPa、150℃.