Synthesis And Properties Of Carboxyl/ Hydroxyporphyrin Frameworks

Metal-organic frameworks(MOFs),as an emerging star crystalline porous material,are characterized by structural diversity,high specific surface area and porosity,and designability.As a branch of metal-organic frameworks,metalloporphyrin frameworks not only have the general characteristics of MOFs,but also have some unique characteristics due to the introduction of porphyrin molecules with special structures and properties.In this paper,a series of novel crystalline porous complexes have been constructed using carboxyporphyrins,hydroxylated carboxyporphyrins and phenolic porphyrins,and their properties have been studied.The specific work is as follows:1.On the basis of the work of the research group,Zr PP-n-H2(n=1 and 2)and Zr PP-1-M(M=Fe,Ni,Cu,Zn,Mn and Co)porphyrin porous Complexes constructed by the phenolic porphyrin ligands THPP(THPP=5,10,15,20-tetrakis(3,4,5-trihydroxyphenyl)porphyrin)and THBPP(THBPP=5,10,15,20-tetrakis(3,4,5-trihydroxybiphenyl)porphyrin were used to study their non-linear optical properties and optical limiting properties at 532 nm laser wavelength with different pulse energies.The results showed that the length of porphyrin ligand could not improve the optical limiting performance of the material,however,when the center of porphyrin ring was chelated with manganese,iron,cobalt,nickel,copper,zinc metal ions,especially manganese and cobalt,its optical limiting performance was greatly improved,which indicated that anchoring metal ions in porphyrin ring could improve the optical limiting performance of porphyrin-based MOFs.This work may provide a new perspective for the application of metal porphyrin-based MOFs in laser protection.2.Because pure phenolic porphyrins are difficult to obtain high crystalline MOFs that can be used for X-ray single crystal diffraction,we synthesized a hydroxyl-functionalizedcarboxyporphyrinligandT³CPP-OH,(T³CPP-OH=5,5',5'',5'''-(porphyrin-5,10,15,20-tetrayl)tetrakis(2-hydroxybenzoic acid),which possesses both carboxyl and hydroxyl groups(phenol groups).By using this ligand,we constructed two novel crystalline porous complexes Ca-T³CPP-OH-1,Ca-T³CPP-OH-2 with uncoordinated hydroxyl groups.A series of characterizations were carried out,and the structural analysis showed that there were a large number of uncoordinated hydroxyl groups in the structure,and a large number of water and solvent molecules existed between the layers.Uncoordinated hydroxyl groups can form hydrogen bond networks with water molecules or other solvent molecules and have the function of promoting proton conduction.Therefore,we studied the proton conductivity of this kind of materials,and the results showed that Ca-T³CPP-OH-2 exhibited excellent proton conductivity under high humidity conditions,and the conductivity could reach 1.4 x10^-3 S cm^-1at 25?and 98%relative humidity.3.To further explore the application of porphyrin MOF in clean energy,we successfully constructed three novel crystal complexes,Ni-TCPP-1,Ni-TCPP-2,Ni-TCPP-3 by using carboxyporphyrin TCPP(TCPP=meso-Tetra(4-carboxyphenyl)porphine),and characterized them in a series of methods.Ultraviolet-visible spectroscopy analysis showed that the compound had visible light absorption characteristics.And the photocurrent test showed that all three compounds had photocurrent response ability.At the same time,we analyzed the energy band structure of this compound by Tauc plot combined with Mott-Schottky test,and found that this compound has a suitable energy band for photocatalytic dioxide reduction.Further,we found that the compound had carbon dioxide adsorption effect by gas adsorption test.This indicates that the material has the potential of photocatalytic carbon dioxide reduction.Therefore,we tested the photocatalytic carbon dioxide reduction of compound Ni-TCPP-3.It was found that this new porous material,as a heterogeneous co-catalyst,has high photocatalytic reduction performance for CO2 with the photosensitizer.The Ni TCPP-3 exhibits a CO production rate of 11?mol h^-1,and the compound showed good selectivity for the reduction product CO,with a selectivity of 97%.4.In order to obtain highly stable porphyrin MOFs with high valence ion coordination,we synthesized a rare titanium-based crystalline porous complex Ti-TCPP based on carboxyporphyrin TCPP by a two-step method.In the two-step synthesis process,Ti₆ clusters based on p-aminobenzoic acid were synthesized as precursors first,and then Ti₆clusters and TCPP were reacted to obtain the compound Ti-TCPP.It was found that the compound was isomorphic with PCN-221.The characterized the morphology and adsorption properties of the compound was performed.The synthesis of this compound not only expands the diversity of Ti-MOFs structure,but also provides a good reference for the synthesis of Ti-MOFs.