Design,synthesis And Catalytic Applications Of Supported?Nitrogen-containing Heterocyclic Gold Catalysts

As one of the important members of precious metal catalysts,gold catalysts have attracted more and more scholars'attention due to their special catalytic properties.Among them,homogeneous gold catalysts with excellent catalytic performance have been well developed in recent years.However,the homogeneous gold catalyst has the disadvantages of poor stability and difficulty in recovery,which not only hinders the further development of the gold catalyst but also causes certain pollution to the environment.Based on the consideration of improving the stability of the catalyst,saving cost and reducing environmental pollution without affecting its catalytic activity,the gold complex with Nitrogen-containing heterocyclic ligand as the skeleton and a series of supported gold catalysts were designed and studied.The main research contents and results are as follows:?1?The eighteen-membered ring binuclear gold?III?complex based on pyridinyl thienyl triazole structure was synthesized for the first time and structurally determined by X-ray crystallography.Then the thermogravimetric analysis showed that the complex has strong thermal stability which proved that the nitrogen-containing heterocyclic ligand can stabilize the gold catalyst.This new gold catalyst?PTT-Au?bearing the unsymmetrical thienyl-pyridinyl-triazole ligand showed high catalytic activity,could synthesize enone compounds in high yield.?2?An efficient and simple method for the in situ preparation of highly active gold nanoparticles on nitrogen-doped graphene was designed and developed with thienylbenzotriazole gold as the precursor and no reductants.The newly developed gold nanocomposites was characterized by XRD,EDS,XPS,SEM,TEM and other characterizations.This gold nanocomposite?TTA-Au-NG?can effectively catalyze the borrowing hydrogen reactions of ketones and alcohols,alcohols and alcohols,amines and alcohols,and amines and amines in water and mechanism investigations were carried out to better discuss this catalyst system and these reactions.Finally,the catalyst was verified to have recyclability and cycleability through repeated experiments.?3?A composite nano-gold catalyst?PA-Au-PCS?prepared by in-situ preparation of polycyanostyrene polymer?PCS?as a carrier and pentazole gold as a precursor in ethanol reflux was designed and synthesized.The newly developed gold nanocomposites was characterized by XRD,EDS,XPS,SEM,TEM and other characterizations.In addition,it was observed that this catalytic system was successful achieved the application on the synthesis of cinnoline derivatives and hydration reactions in high yields,and at the same time mechanism investigation was conducted to better under these transformation and catalyst system.Finally,we carried out repeated experiments on the catalyst and found that the catalyst was also recyclable and cyclic.?4?The composite nano-gold catalyst PA-Au-TiO₂ was prepared in situ by using one-pot method with pentazole gold as the precursor,ethanol as solvent.Next,the catalysts were characterized by SEM,EDS and XPS.Then the catalyst was applied to the synthesis reaction of aromatic ketone and aromatic ether.It was found that the catalyst has good catalytic activity for both types of reactions,and it was found that the catalyst also has certain recyclability through the repeated experiments.