Two-dimensional Porphyrin MOFs Adsorption Of Dyes And Enzyme-like Catalysis

Porphyins are macrocyclic compounds composed of four conjugated pyrroles by methylene.It has been widely used in biology,chemistry and physics,because of its special chemical structure and photoelectric properties.Porphyrin-based metal-organic framework?Por-MOFs?is a new type of porous material with large surface area,highly ordered porosity and the characteristics of porohyrins,exhibiting excellent properties in gas storage separation,catalytic and water treatment,which have received considerable attention in recent years.In this paper,two-dimensional?2D?structure of the MOF materials were constructed from Cu metal node and porphyrin as the basic building block,the application of the Por-MOFs as an absorbent and enzyme-like in dye treatment was studied in detail.Metal-organic frameworks?MOFs?of copper-tetrakis-?4-carboxyphenyl?-porphyrin?CuTCPP?were prepared by a facile solvothermal route.The nanosheets with 2D ultrathin structure and larger specific surface area show higher adsorption capacity for rhodamine B?Rh B?,compared with the 3D bulk MOF of CuTCPP.The interaction between the 2D MOF nanosheets and rhodamine B?Rh B?was investigated based on spectroscopic methods.The UV-vis absorption,steady state,and time-resolved fluorescence studies reveal that the fluorescence of Rh B is efficiently quenched by 2D CuTCPP nanosheets,and the mechanism of quenching process is totally the static quenching by the formation of ground state Rh B–CuTCPP nanosheets complex with an apparent association constant of 3.953×10³ M^-1.Higher-order aggregate may also be involved in the complexation.The thermodynamic studies demonstrate that the Rh B-CuTCPP nanosheets interaction is a spontaneous process and driven by electrostatic and hydrophobic forces.Cu-FeTCPP MOFs with peroxidase activity were synthesized by solvothermal method,in which 5,10,15,20-tetrakis?4-carboxyphenyl?iron porphyrin?FeTCPP?is used as organic ligand,copper nitrate is metal node.The color reaction of colorless3,3',5,5'-tetramethylbenzidine?TMB?was used to demonstrate that Cu-FeTCPP MOFs have peroxidase-like catalytic activity and are able to catalyze the production of hydroxyl radicals by H₂O₂?·OH?,and then oxidizes TMB into TMB⁺.The Michaelis constant K_m was obtained by the kinetic fit of the enzymatic reaction.Compared with FeTCPP and 3D Cu-FeTCPP MOFs,the K_m value of the 2D Cu-FeTCPP MOFs nanosheets in the smallest,so it has the best affinity for the substrate and the highest enzyme activity.Cu-FeTCPP MOFs nanosheets and TMB were used to construct an H₂O₂ detection colorimetric sensing system.It has an excellent linear detection range in the range of 5-1000?M H₂O₂ concentration,and the limit of detection?LOD?is 2.09?M.Cu-FeTCPP MOFs were used to catalytically degrade the Congo red,shows good catalytic degradation capability.Cu-FeTCPP MOFs nanosheets were grown to the modified PET membrane by secondary growth method,through enzymatic catalysis performance laying a foundation for the combination of catalysis and membrane process.