Study On Synthesis And Properties Of Triazole Metal-organic Frameworks Materials

Metal-organic frameworks(MOFs)are organic-inorganic hybrid materials.Due to its high specific surface area,adjustable pore size and structure,it is widely used in many fields including organic dye adsorption and heavy metal anions.It has been found that the metal-organic framework adsorbs organic dyes and heavy metal anions through ion exchange or electrostatic interaction.Therefore,this thesis focuses on the design and preparation of ligands,the synthesis of metal-organic frameworks and their research work on dye adsorption and heavy metal anion adsorption.Six novel triazole ligands were designed and synthesized in this thesis.The bis(1,2,4-triazole)-pyridine ligands and copper salt were selected to synthesize five high-dimensional complexes M1-M5 with good structure by hydrothermal method.In this thesis,4-(5-carboxyl-3-pyridine)-1,2,4-triazole and 4-(2,6-dicarboxyl-4-pyridine)-1,2,4-triazole ligands were also selected to synthesize five complexes with different metal salts,in which only zinc nitrate and 4-(5-carboxy-3-pyridine)-1,2,4-triazole can generate two-dimensional M7 under N,N-dimethylformamide as solvent.Both the M6 and M8-M10 structures are zero dimensional.Among them,M3 and M4 are synthesized from copper perchlorate and bis(1,2,4-triazole)-pyridine which results in the formation of three-dimensional porous structure.According to the principle of charge balance,the perchlorate anion are takes place inside the three dimensional pores.The only difference is that oxalic acid is added to the M3 reaction system,which may reduce the copper ion concentration or the pH of the reaction system,so the nitrogen atom on the pyridine ring of M3 does not participate in coordination,and the nitrogen atom on the pyridine ring of M4 participates in coordination.The adsorption of Congo red,Methyl orange,Rhodamine B,Methylene blue,potassium permanganate and potassium dichromate by M3 and M4 found that M3 has the ability to absorb Congo red and dichromate quickly,and M4 has the ability to rapidly adsorb Congo red,permanganate and dichromate.After adsorption for 10 min,the adsorption amount of M3 to Congo red was 10 mg/g.After adsorption for 15 min,the adsorption amount of M4 to Congo red was 10 mg/g.Adsorption for 3 min,the adsorption amount of M4 to potassium permanganate was 25 mg/g,and the adsorption amount of M3 and M4 to potassium dichromate was 25 mg/g.Moreover,the two complexes have better adsorption to Methyl orange,and the adsorption ability to Methyl blue and Rhodamine B is poor.The possible reason is that M3 and M4 belong to the cationic metal organic framework,and the perchlorate anions in the pores undergo ion exchange with anionic dyes and heavy metal anions.Therefore,M3 and M4 have potential application value in adsorbing anionic dyes such as Congo red and heavy metal anions such as dichromate.