Synthesis, Characterization, And Photosensitization Study Of Meso-substituted Porphyrins And Metalloporphyrins

For many decades, the porphyrin derivatives attracted great interests and were widely studied in many research areas as for their unique structures and properties. Meanwhile, TiO2 was given high attention and popularity in photocatalysis research area, since 1972 when Fujishima successfully utilized TiO2 electrode to decompose water into hydrogen. The porphyrin-TiO2 organic-inorganic composite have great potential in the field of photocatalysis chemistry, particularly in the aspect of dealing with polluted water. It is verified that porphyrins-TiO2 can efficiently degrade the organic molecules in aqueous solutions and thus purify water utilizing the solar energy. However, the research on porphyrin-TiO2 in photocatalytic degradation is still not complete and systematic, for example, the effects of porphyrin structures and metal ion of metalloporphyrins on potocatalytic efficiency still remain unknown.Hence, we synthesized three long-chain aldehydes, and then six kinds of porphyrins with different substituents, and their corresponding Pt(Ⅱ), Ru(Ⅱ), Sn (Ⅳ) metalloporphyrins. All the compounds were characterized by UV-vis,1HNMR, Elemental Analyses, FT-IR, and MS etc. The metalloporphyrin-TiO2 pohotocatalyst were also prepared and characterized by TEM, XPS, Diffuse reflectance, Raman spectroscopy, FT-IR etc. Through degradation of 4-nitrophenol in aqueous solution under visible and UV-vis light, the photocatalytic efficiency of porphyrin-TiO2 was tested, as to find out the effects of different factors such as the porphyrin structure, the metal ion, the dissolved oxygen, temperature on photocatalysis.The results showed than Pt(Ⅱ) and Sn(Ⅱ) porphyrins can effectively expand the light response of TiO2, and degrade 4-NP in aqueous solution into CO2 and H2O, with good stability, whereas Ru(Ⅱ) porphyrins do not have good sensitization for TiO2; Sn·2OH(4R-o,m,p-TPP) and RuCO(4R-o,m,p-TPP) with axial ligands have the photocatalytic order as:ML(4R-p-TPP)-TiO2> ML(4R-m-TPP)-TiO2> ML(4R-o-TPP)-TiO2, whereas Pt(4R-o,m,p-TPP)-TiO2 is on the contrary; as the number of substituents grow, the sensitization for TiO2 enhaced; the dosage of photocatalyst have an optimal amount; the dissoveld oxygen and temperature have different effects on the system.Besides, water-soluble porphyrins are arousing much more attention in recent years because of their good biochemical activities. In photo dynamic therapy (PDT), water-soluble porphyrins could be both diagnosis drug and photosensitizer, and have advantages in the drug delivery and human body metabolism. Three water-soluble pyridium porphyrins and the corresponding Zn(II), Mn(III) metalloporphyrins were synthesized and characterized by UV-vis, FT-IR, and MS etc., in order to prepare for the further test of PDT.