Syntheses Of Meso-porphyrins Modified By Different Substituent Groupsand Its Application Study In Environment Of Water

Due to its controlled structure, high fluorescence quantum yield, largestokes shift, long absorption (λ>400nm) and emission (λ>600nm) wavelength,porphyrins have been extensively used as excellent photosensitizer indyes-sensitized solar cells the detection of trace heavy metal ions in water, andphotocatalytic degradation of organic wastewater.Hence, four free porphyrins and corresponding copper porphyrins modifiedby different substituent groups were synthesized and characterized firstly in thethesis. Then two free porphyrins which were vastly different at polarities wereselected as fluorescence probes in water to detect the trace heavy metal ions(including Zn2+and Cu2+) though the fluorescence spectroscopy. The copperporphyrins showed the enhanced visible absorption. So we used them toimproved the photoactivity of TiO2. The paper was done mainly in the followingaspects:(1) Four free porphyrins modified by different substituent groups:5-(4-hydroxyl)phenyl-10,15,20-tri-phenylporphyrin(H2POH),5-[(4-acetateethyl)methoxy]phenyl-10,15,20-tri-phenylporphyrin(H2PCOOEt),5-[(4-carboxyl)metho-xy]phenyl-10,15,20-tri-phenylporphyrin(H2PCOOH),5,15-di-(4-hydroxyl)phenyl-10,20-di-phenylporphyrin(H2P2-OH) and corresponding copper(Ⅱ) porphyrinswere successfully synthesized and characterized in this thesis. The porphyrinswere characterized by mass spectrum, infrared spectroscopy, ultraviolet-visiblespectrum and1HNMR. The UV-visible spectra indicated that the effect ofdifferent meso-substituent groups on intramolecular electron of porphyrins waslittle.(2) H2POHand H2PCOOEtwere used to detect trace Zn2+and Cu2+in water andthe results showed that H2POHwas fluorescence enhancement probe. In theseparate detection system, the sensitivity of Zn2+was higher than that of Cu2+.However, the selectivity of H2POHwas very low in hybrid detection of Cu2+and Zn2+. On the contrary, H2PCOOEtwas fluorescence quenching probe. In theseparate detection system, the H2POHwas sensitivity to Zn2+and Cu2+.Comparing with H2POH, the H2PCOOEthad a better sensitivity and selectivity inapplication prospects.(3) Eight composite photocatalysts were successfully synthesized andcharacterized by using four free porphyrins and four copper porphyrins whichwas used to sensitize TiO2. The pattern of X-ray diffraction results indicated thatTiO2synthesized by sol-gel method was anatase and porphyrins were loaded onthe surface of TiO2. It was found that sizes of all photocatalysts were nanoscaleand the effect of porphyrins on particle size was very little. The data of scanningelectron microscope and infrared spectroscopy demonstrated the porphyrinsexisted on the surface of TiO2.(4) In photochemical reaction apparatus, the photacatalysis activity of thecatalysts was evaluated by measuring degradation efficiency of4-nitrophenolunder the irradiation of metal halide lamp. The results indicated that the processof all photocatalytic reaction conformed to the kinetics of first order reaction. Inaddition, the decoloration efficiency of CuPOH-TiO2and CuPCOOH-TiO2composite photocatalyst had excellent performance in catalyzing degradation of4-nitrophenol. Based on various factors, the photocatalytic efficiency ofCuPCOOEt-TiO2photocatalysts were the highest.(5) The condition of photocatalytic reaction was changed by adding H2O2and combined influence of porphyrins and H2O2on the photocatalytic reactionwas studied in different composite photocatalysts. The results indicated that4-nitrophenol was degraded by H2O2and a large number of OH was producedafter60min during this process. CuPOHand CuPCOOHhad a better synergisticeffect with H2O2than other porphyrins which indicated that the polarity ofporphyrins was not beneficial to the completely mineralized of4-NP. It wassimilar to the decoloration change of photocatalytic reaction above.