Preparation And Properties Of Self-assembled Nanoparticles Of Porphyrin Derivatives

As a photocatalytic material,porphyrins and their derivatives have very peculiar properties such as light absorption,chemical stability,and accessibility to modifications.There are a variety of uses in photo-catalysis,for instance,light-catalytic decomposition of pollutants,photocatalytic manufacture of hydropower,light-driven therapeutics,etc.The lack of light absorption of porphyrins before 400 nm and between 450 nm and 500 nm,as well as the tendency of porphyrin monomers to aggregate and deviate in solubility,have severely limited the application of porphyrins in photocatalysis.Based on the above deficiencies,appropriate modifications of porphyrins are needed to expand the absorption area for visibility light and to enhance the photocatalytic activity of porphyrins.In this paper,5,10,15,20-tetra(4-aminophenyl)-21 H,23H-porphyrin(TAPP)was formulated by a conventional preparation technique,on the basis of which the porphyrins were modified.Three porphyrin derivatives with Schiff-base structure were synthesized by connecting TAPP with three aldehydes in the manner of Schiff-base.Based on the principle of hydrogen bond self-assembly,the self-assembly behavior of three porphyrin derivatives was investigated.The application of the three porphyrin derivatives and their self-assembly in the field of photocatalysis was investigated.The main investigations of this thesis are as listed below:1.Three new porphyrin derivatives with Schiff-base structure were synthesized from5,10,15,20-tetra(4-aminophenyl)-21 H,23H-porphyrin(TAPP),namely 5,10,15,20-tetra [p-(4-cyanophenylmethylene imino)] phenyl porphyrin(TCy PPP),5,10,15,20-tetra[p-(P-benzylidene)] phenyl porphyrin(Tbe PPP)and 5,10,15,20-tetra [p-(4-pyridylimethylene imino)] phenyl porphyrin(TPy PPP).Due to the modification of porphyrin in the form of Schiff-base,the flow range of electrons in the porphyrin ring was expanded.The adsorption experiments of three new porphyrin derivatives,TCy PPP,Tbe PPP and TPy PPP,were conducted separately under dark conditions.The performance of the adsorption of the three new porphyrin derivatives was higher than that of TAPP,which indirectly indicated that the photocatalytic degradation performance of the three new porphyrin derivatives was better than that of TAPP.2.On the basis of three porphyrin derivatives prepared in the previous stage,the selfassembly experiments of three porphyrin derivatives were carried out by hydrogen bond self-assembly principle.(1)Self-assembly experiments were carried out with tetrahydrofuran solutions of three porphyrin derivatives at the same concentration;(2)The tetra [p-(P-benzylidene)] phenyl porphyrin(Tbe PPP)was used as self-assembly monomer and dichloromethane / tetrahydrofuran solution with different solvent systems was prepared.The adsorption experiments were also performed on the porphyrin self-assemblies.The adsorption results showed that the porphyrin self-assemblies have better adsorption performance on rhodamine B than the three porphyrin derivative monomers,which also indirectly indicates that the porphyrin self-assemblies have better photocatalytic degradation performance than their monomers.3.Photocatalytic degradation experiments were performed on TAPP and three porphyrin derivatives and their self-assemblies.The findings demonstrated that the three new porphyrin derivatives had higher photocatalytic degradation performance than TAPP after the porphyrins were modified.The photocatalytic efficiency of the porphyrin selfassemblies was also significantly higher than that of their monomers,indicating that the self-assembly process resulted in porphyrins with superior light-absorbing properties.In addition,the stability test of the porphyrin derivatives and their self-assemblies was conducted,and the experimental results showed that the porphyrin derivatives and their self-assemblies have good stability of photocatalytic degradation and can be reused for the purpose.Finally,the production of active species in the photocatalytic process was demonstrated using active species trap and the mechanism of photocatalytic degradation was investigated.