Based On The Preparation And Adsorption Properties Of Tribiphenyl Derivatives Covalent Organic Framework Materials

Covalent organic frameworks(COFs)are a new type of crystalline porous polymers with low density,large specific surface area,controllable pore size and structure.They have shown good application potential in gas storage,organic catalysis and photoelectric sensing.However,the building units of developed COFs materials generally have problems such as difficult synthesis and high cost,which greatly limits the practical application of such materials in various fields.Based on this research status,in this paper intends to synthesize two p-terphenyl derivatives simply and efficiently by one-step synthesis method,and use them as building units to prepare a series of new p-terphenyl COFs materials,and further explore their adsorption properties and influencing factors for heavy metal ions and dyes.Firstly,two p-terphenyl derivatives were synthesized by Suzuki coupling reaction using cheap 2,5-dibromobenzene derivatives with different side groups as substrates.The structure of the prepared p-terphenyl derivatives was characterized by Fourier Transform Infrared spectroscopy and nuclear magnetic resonance hydrogen spectroscopy.Four p-terphenyl COFs materials were synthesized by solvothermal method with the synthesized p-terphenyl derivatives and two amino-containing construction units,and their structure,pore size,morphology and thermal stability were characterized in detail.The adsorption properties of the prepared COFs materials for six heavy metal ions and four dyes were studied by inductively coupled plasma mass spectrometry and UV absorption spectroscopy,respectively.The effects of different structures and reaction conditions on the adsorption properties of p-terphenyl COFs materials for heavy metal ions and dye molecules were further discussed.The results show that the p-terphenyl COFs can be successfully prepared by the economical,simple and efficient one-step synthesis method proposed in this paper.The prepared p-terphenyl COFs materials have large specific surface area,highly ordered crystal structure and good thermal stability,and have regular morphology,uniform pore size distribution and controllable structure.Among them,the three-dimensional COFs material prepared by p-terphenyl derivative p Tp-2 and tetrakis(4-aminophenyl)methane(3D-COF-2)has the largest specific surface area of 614 m~2/g and uniform pore size distribution.The prepared four p-terphenyl COFs materials have good adsorption properties for six heavy metals and four dyes,among which the adsorption effect on mercury ions and cationic dyes(Methylene blue and Rhodamine B)is the best.The adsorption performance of the four p-terphenyl COFs materials is less affected by the change of p H value,and they can still achieve excellent selective adsorption of mercury ions and cationic dyes under the coexistence of other salt solutions.The adsorption process is mainly chemical adsorption,which has the advantages of large adsorption capacity and strong selectivity,indicating that the material has good application potential in the field of adsorption.In addition,the p-terphenyl COFs material with a three-dimensional microporous structure has a larger specific surface area,which makes it have better adsorption performance than the corresponding two-dimensional COFs material,and the reduction of the size of the p-terphenyl derivative side group is beneficial to obtain a COFs material with a more regular crystal structure and a larger pore size.