Construction Of 2D Photoactive COFs And Their Strcture-Property Relationship

The structure affects the property and application of materials.Thus,the structure-activity relationship study has emerging as an important issue for the design and modification of functional materials.Covalent Organic Frameworks(COFs)are crystalline porous networks.Owning to their tunable functionalities,regular pore structure,and extended ?-conjugation networks,COF materials can be applied in lots of hot fields,such as gas adsorption/separation,heterogeneous catalysis,energy storage,chemical sensing and optoelectricity etc.Although these molecule-based materials provide them with many advantages in the study of the structure-property relationship,the relationships between COF structure,light absorption,and catalytic activity are still unknown.In this paper,we focused on the structure-property relationship of 2D COF materials.For comparison,a series of 2D photoactive COFs were constructed and applied as fluorescent sensors and photocatalysts.Accordingly,our main research work is summarized as follows:1.Two tetraphenyl ethylene-based COFs(COF-LZU44 and COF-LZU45)were constructed via the SchifF's base chemistry to study their optical properties.Our results reveal that the two COFs are 2D layered-stacking structures and composed of two kinds of 1D channel with different sizes.COF-LZU44 and COF-LZU45 can absorb the visible light well and catalyze the Aza-Henry reaction under light.Additionally,contributed to the dihydroxyl groups,COF-LZU45,to some extent,could response to Ag+,Zn2+ and Cu2+.This study indicated that the substituent groups have significant effects on the optical properties of 2D COFs.2.In order to further insight into the effects on the photoelectric property of COFs caused by different substituent groups,a number of 2D COFs which possess the similar skeletons and pore sizes but with different side chains or inner cores were synthesized.The UV/Vis diffuse reflectance spectrum demonstrated that these 2D COFs exhibited good absorption ability forvisible light.In combination with the band-gaps and photocatalytic activities of the 2D COFs partial relationships between the COF structure and photoactivity were obtained,which provide some theoretic basis for the construction of photoactive COF materials.