Function Oriented Metal Organic Gels And Their Composites

As a new porous material,metal organic gels(MOGs)refer to a supramolecular organic gel with metal elements introduced.Compared with the traditional gels,the introduction of metal elements and the coordination bonds between metal and organic ligands bring many unique properties to the gel system,which have potential applications in the fields of sensing,homogeneous catalysis,gas adsorption and separation.However,due to the excessive factors affecting the gel process and the uncertainty of the structure,it is still a great challenge to rationally design new functional MOGs and their composite materials.In this paper,the application of transition metal based MOGs and their composite materials in heterogeneous organic catalysis,photocatalytic hydrogen production and fluorescence sensing are studied in this paper,including the following parts:In the second chapter,the properties of noble metal nanoparticles loaded with transition metal-based metal MOGs were investigated.In situ impregnation reduction method was employed to load the silver nanoparticles(Ag NPs)into the gel channel to obtain the composite material Ag@MOG,and the hydrogenation reaction of nitrophenol was used as a probe to study the activity of Ag@MOG in heterogeneous catalytic reaction.The kinetic study shows that the catalytic activity of composite material for three kinds of nitrophenol is different,which can be attributed to the difference in the diffusion rate of the reaction substrates in the composite.The method of using MOGs as the carrier of noble metal nanoparticles not only can be further extended to other gel systems,but also enrich the application field of MOGs.The third chapter of this paper is followed by the second chapter.Three kinds of composite material,Pt@MOG,Pd@MOG and Pt-Pd@MOG were prepared by using MOGs as carrier.Firstly,the composite material Pt@MOG is used as the research object.By sensitizing the composite by using Rh B solution,Pt@MOG can be stimulated by the visible light to catalyze hydrogen production in an aqueous solution containing 10% volume fraction of triethanolamine.The influence of the solution concentration of Rh B on the hydrogen production rate was further explored,and the best concentration was found to be around 150 ppm.On this basis,we further study the effect of photocatalytic hydrogen producing active center on the hydrogen production rate.The composite materials are sensitized by using eosin Y(EY)solution,and the hydrogen production rate of the composites is studied under the same conditions by using Pt@MOG,Pd@MOG and Pt-Pd@MOG as the research object.It is found that the hydrogen production rate of composite materials has the following relationship: Pt-Pd@MOG > Pt@MOG > Pd@MOG,which can be attributed to the synergy between bimetallic catalysts.We believe that our work will inspire more researchers to design and synthesize functional nanoparticles-gel composites.In the fourth chapter of this thesis,the ion replacement in MOF is borrowed,the rare earth based MOG(MOG(Eu))is obtained by metal replacement in the precursor of transition metal based MOG(MOG(Al)).As expected,the sample after replacement have good fluorescence properties.By elemental analysis of the sample,it is found that there is no complete replacement.Only some of the metal centers in the precursor are replaced by rare earth ion.In terms of the luminescence and sensing applications of the material,a small amount of rare earth ions can achieve target effect is a good result.,which is the advantage of the rare earth ion as the photoactive center of the luminescent material.Further studies showed that MOG(Eu)had good selective detection for nitroimidazole antibiotics and p-nitrophenol.In the same way,we use rare earth ion Tb to replace the metal center of precursor and obtain the material(MOG(Tb))with good luminescence properties,which proves the feasibility of the post synthesis ion replacement in the MOGs.This is the first example of MOG to achieve ion replacement,opening new doors for functional applications and design of MOGs.We have reason to believe that this work will attract more researchers to start studies of functional development and design of MOGs.The results of this part are published in the famous international magazines Inorganic Chemistry Frontiers(2018,5(1): 120-126)and European Journal of Inorganic Chemistry(2018,2018(2): 186–193).