Photoreduction Of Cu(?) And Photocatalytic Click Chemistry Research

The copper(?)-catalyzed azide-alkyne cycloaddition click(CuAAC)reaction is one of the most important reactions based on its highly reliability and selectivity.Heterogeneous catalyst can be separated from a reaction mixture easily and reused multiple times.At the same time,light-induced reactions can be spatially and temporally controlled by focusing photons onto a given area and by varying exposure time,wavelength,and intensity as needed.However,there are few reports about the combination of heterogeneous catalyst and light-induced click reaction.The major works in this thesis are base on heterogeneous light-induced click reaction.Firstly,we fabricated two excellent photocatalysts(CuOx@Nb2O5 and CuOx@TiO2)which could photocatalyze CuAAC under mild conditions with easily product isolation.Secondly,the TIRFM was used to research the catalytic ability of CuOx@Nb2O5 under Single-molecule level,which proved it was a truly heterogeneous process.Thirdly,the commercial catalyst CuOx@Charcoal was modified and characterized on both Single-molecule and Mole level.The results demonstrated that the Single-molecule techniques could be an exceptionally powerful technique to inspire and guide improvements in organic chemistry.Finally,a two-step method to fabricate a large-scale flexible conductive pattern via direct photo-patterning and "volume additive process on demand" theory was developed.The main researches are listed as follows:(1)The fabrications of photocatyst CuOx@Nb2O5 and CuOx@TiO2 by photoreductionThe copper nano-structure was successfully modified on the surface of semiconductor(Nb2O5 and TiO2)by photoreduction.The microstructure of our photocatalyst was characterized by SEM and TEM;the copper valence state and loading were determined by XPS and ICP-OES analysis.The absorption ability of the photocatalysts was characterized by Diffuse Reflectance Spectra.(2)Heterogeneous photocatalytic click chemistryThe catalytic performance of CuOx@Nb2O5 and CuOx@TiO2 was studied in light-induced CuAAC reaction.The new catalysts are air-and moisture-tolerant and can also works under vis-light.The effects of irradiation wavelength,amine and atmosphere were investigated in this light-induced process.Besides,the mechanism of this heterogeneous photocatalytic click chemistry was also proposed.The new catalysts had a wide scope and can be recovered several times.Finally,the CuOx@Nb2O5 and CuOx@TiO2 systems were proved as a heterogeneous process by ICP experiment.(3)From Mole to Molecule:The Single-molecule catalytic research of CuOx@Nb205Here,we used Total Internal Reflection Fluorescence(TIRF)microscopy to enhance the Single-molecular level understanding of CuOx@Nb2O5.The reagents were carefully selected in order to use the Fluorescence Resonance Energy Transfer(FRET)as a probe for successful reaction.The multiple fluorescent emission events have been observed during the click reaction by TIRFM system,which means multiple reactions happened at same catalytic site on Single-molecule level.The results proved that the CuOx@Nb2O5 catalyzed click reaction was a truly heterogeneous process.(4)From Molecule to Mole:Improving heterogeneous copper catalyzed click chemistry using Single-molecule spectroscopyThe commercial catalyst CuOx@Charcoal was modified by different method,and the higher catalytic ability was got after modification.The catalytic performances on Molecule level was investigated by TIRFM system.What's more,the same trend weres found in both Molecule and Mole level.The results demonstrated that the Single-molecule techniques could be an exceptionally powerful technique to inspire and guide improvements in organic chemistry(5)Large-scale flexible conductive copper-silver pattern based on direct photopatterning via volume additive process on demandA two-step method to fabricate a large-scale flexible conductive pattern via direct photo-patterning and "volume additive process on demand" theory was developed.The copper pattern was formed on the surface of the flexible substrate directly by photo-reduction.However,the copper pattern was not conductive due to the discontinuous structure.Fusion growth of particles was achieved via the "volume additive process on demand" to realize the pattern conductivity without sintering.This method is simple,efficient,low-cost and environmentally friendly,especially for heat sensitive substrate to fabricate large-scale conductive pattern.In addition,"volume additive process on demand" theory could be extended to other preparation methods of metal pattern,such as inkjet printing,to meet the new requirement of electronic industry in the future.