Preparation And Catalytic Properties Of Aromatic Bisimine Palladium And Palladium/Cobalt Bimetallic Self-Assembly Catalytic Monolayer For Suzuki Coupling Reaction

In this paper,aromatic biimine based Si@AI-dbPd and Si@AI-Pd0.33/Co0.66 catalytic monolayers supported on the surface of substrates,such as silicon,quartz and CaF2 were fabricated by self-assembly and characterized.We used Si@AI-dbPd and Si@AI-Pd0.33/Co0.66 to catalyze Suzuki coupling reaction for systematically study of catalytic properties,and the catalytic mechanism was also studied.The main research contents and results are as follows:1.Catalytic monolayer Si@AI-dbPd containing aromatic diimine palladium on the surface of substrates,such as silicon,quartz plate and calcium fluoride was prepared by self-assembly and characterized by water contact Angle(WCA),UV-vis spectroscopy(UV-vis)and Raman spectroscopy(Raman),X-ray photoelectron spectroscopy(XPS),X-ray diffraction(XRD),optical microscope(OM),atomic force microscope(AFM),scanning electron microscope(SEM)and inductively coupled plasma atomic emission spectroscopy(ICP-AES).The catalytic activity of Si@AIdbPd was studied by using Suzuki coupling reaction as a template reaction.Si@AIdbPd showed a high catalytic activity with a turnover number(TON 8581)and a turnover frequency(TOF 1420 h-1).The conjugated system of the aromatic diimine ligand was beneficial to the electron transport,led to improving the reactivity.The catalyst could be recycled for three times.With kinetic study,thermal filtration,catalyst poisoning experiment and In-situ IR,we studied catalytic mechanism.As a result,we found that Si@AI-dbPd was a heterogeneous catalyst occurred on the interface of catalyst.The deactivation mechanism of Si@AI-dbPd during recycling was studied by SEM and WCA.The results showed that,the change of the surface morphology of the Si@AI-dbPd,led to the change of the catalyst micro-environment and deactivation of catalyst.2.Catalytic monolayer Si@AI-Pd/Co with different metal ratios on silicon substrate was fabricated by self-assembly and characterized Si@AI-Pd/Co by WCA and ICP-AES.The catalytic activity of Si@AI-dbPd was studied by using Suzuki coupling reaction as a template reaction.The results showed that different ratios of Pd/Co had a great influence on the catalytic performance of Si@AI-Pd/Co.Si@AIPd0.33/Co0.66 with Pd/Co feeding ratio of 1:2 showed the highest catalytic performance among Si@AI-Pd/Co,with TON(8135)and TOF(2034h-1).Also,coordination mode of the two metals would have a great influence on their catalytic activity.Si@AIPd0.33/CO0.66 has superior substrate suitability and could be recycled for 4 times.Catalytic mechanism was also investigated with catalyst poisoning,kinetic curve study,thermal filtration experiment and XPS.The results showed that Si@AIPd0.33/Co0.66 catalyzed Suzuki reaction was a heterogeneous reaction occurred at the interface of catalyst.