Synthesis, Characterization And Properties Of Axially Substituted Silicon Phthalocyanines Photosensitizers

Silicon phthalocyanines (SiPcs) are phthalocyanines (Pcs) covalented with silicon at the center. It is well known that the planar aromatic system of Pcs made them easy to aggregate and slightly soluble in common organic solvents, resulting in the negative effects of photodynamic therapy. Pcs can be modified with functional groups to improve solubility; SiPcs can be subsitituted both peripherally and axially because of the hexacoordinated silicon. The functionalization of axial position enhances steric hindrance to weaken the tendency of aggregation. Besides, SiPcs possesses advantages such as favorable biocompatibility, relatively high yield and purity. So far, there are less studies about SiPcs.In this thesis, four axially substituted silicon phthalocyanines have been synthesized and characterized. Their photophysical chemical properties and in vitro photodynamic activities are also studied. The results are as follows:1. Four axially substituted silicon phthalocyanines are synthesized from dichloro silicon phthalocyanine:[(1-carboxyl ethyl ester)methoxy]2-silicon phthalocyanines,[(5-carboxyl methyl ester)pentyloxy]2-silicon phthalocyanines,[(4-carboxyl methyl ester)phenoxy]2-silicon phthalocyanines,[methoxy]2-silicon phthalocyanines, which have been characterized through NMR (1H,13C), UV-Vis spectra, ESI-HRMS, IR and Element Analysis.2. The single crystal of SiPcs were obtained by vapor diffusion method at room temperature. The single crystal of [(1-carboxyl ethyl ester)methoxy]2-phthalocyanines and [methoxy]2-phthalocyanines are suitable for X-ray diffraction analysis. These two SiPcs are both triclinic, space group P-1. The methoxy of [methoxy]2-silicon phthalocyanines could rotate to some extent.3. Photostability of these axially substituted SiPcs and Zinc phthalocyanine (ZnPc) in DMF were studied via UV-Vis spectra. SiPcs show much higher photostability than ZnPc with only a little degradation during the illumination. Fluorescence quantum yield (ΦF) and singlet oxygen yield (ΦΔ) of these four SiPcs were also studied; among them [methoxy]2-silicon phthalocyanine shows the best photophysical chemical properties with ΦF=0.46and ΦΔ=0.50, respectively.4. In vitro cytotoxicity and fluorescence imaging of these four SiPcs were studied in Hela and Siha cells. Results show good repeatability were achieved in these two cell lines with the dose-dependence phototoxicity and low medial lethal concentration (IC50) values.[(1-carboxyl ethyl ester)methoxy]2-phthalocyanines and [methoxy]2-phthalocyanines showed higher phototoxicity and lower dark toxicity, indicating they are better photosensitizer candidates. Their IC50values in Hela cells are0.42and0.30μM, respectively. The fluorescence intensity in Hela cells are higher than that in Siha cells for these SiPcs. Besides, the fluorescence intensity in cells decay along with capture time, indicating these photosensitizers suffered photobleaching.