Synthesis and investigation of new type silicon phthalocyanines for photodynamic therapy

Phthalocyanines (Pcs) are important dyes used in the medicinal field as photosensitizers for photodynamic therapy (PDT) of cancer treatment because of their properties that exhibit high absorption coefficients in the visible region of the spectrum, mainly in the phototherapeutic window (600–800 nm), a long lifetime of triplet excited state to produce efficiently singlet molecular oxygen, O2(1∆g) and the reactive oxygen species lead to necrosis of selected tissues. Applications of phthalocyanines are restricted owing to their insolubility in common solvents and water. But the solubility of phthalocyanines can be improved by introducing different kinds of bulky substituents, such as crown ethers, alkyl, alkoxy and alkylthio and the donor atoms such as N and O within the substituents at the periphery of the phthalocyanines. Besides, for PDT applications, the drug is injcted into the patient's blood stream, and since the blood itself is a hydrophilic system, water solubility becomes crucial for a potential photosensitizer for PDT. The photophysical properties of metallophthalocyanines (MPcs) are strongly influenced by the nature of the central metal ion. Diamagnetic ions, for example Zn2+, Ga3+ and Si4+, give phthalocyanine complexes excellent properties such as high triplet yields and long triplet lifetimes. In this thesis, it is desired to combine the above mentioned features to create a more effective photodynamic agent. Thus, axially substitued o-carborane-monool, 2-quinolinethiol, 8-hydroxyquinoline and 5-(trifluoromethyl)-2-thiopyridine silicon phthalocyanines and their quaternized derivatives have been synthesized and examined for their photochemical and photophysical properties in different solvents. The structures of the synthesized compounds were characterized by UV-Vis, FT-IR, 1 H-NMR and Mass spectrophotometry. Keywords: Phthalocyanines, silicon phthalocyanine, photodaynamic therapy (PDT), photophysic, photochemistry