Synthesis, photodynamic activity and supramolecular chemistry of unsymmetrical and side-strapped phthalocyanines

This thesis reports our studies on several novel series of phthalocyanines including a series of "3+1" unsymmetrical phthalocyanines formed by a one-pot cyclization-transesterification procedure, and several side-strapped phthalocyanines having an amphiphilic character or containing crown ether units. The applications of these compounds in photodynamic therapy and supramolecular chemistry have also been explored.;Chapter 2 reports the synthesis of a series of unsymmetrical "3+1" zinc(II) phthalocyanines via a one-pot cyclization-transesterification procedure in different alcoholic solvents. Their photophysical properties and in vitro photodynamic activities toward HT29 human colorectal adenocarcinoma cells and HepG2 human hepatocarcinoma cells are also reported. One of the compounds, a zinc(II) phthalocyanine substituted with two polyethylene glycol chains, can form surfactant-free nanoparticles in water and in the culture media. These phthalocyanine-containing nanoparticles exhibit a high photocytotoxicity toward HepG2 cells showing that the polymeric substituents may serve as an effective carrier system.;The synthesis, spectroscopic characterization, photophysical properties, aggregation properties, and in vitro photodynamic activities of several side-strapped phthalocyanines are described in Chapter 3. Pentaerythritol, having four hydroxyl groups, has been used as the linker to connect hydrophilic oligoethylene glycol chains or hydrophobic alkyl chains to the phthalocyanine core. The aggregation tendency of these compounds, which depends on their amphiphility, has been studied by absorption spectroscopy. The relationship of this property with the in vitro photocytotoxicity has also been revealed.;Chapter 4 reports the synthesis and spectroscopic properties of a side-strapped bis(17-crown-5)-containing zinc(II) phthalocyanine. In contrast to the previously reported benzo-fused crown ether-appended phthalocyanines, the ether rings of this molecule are orthogonal to the phthalocyanine plane. As a result, this compound forms J-aggregate in chloroform. Upon addition of alkali metal ions, these aggregates are disrupted forming a linear supramolecular structure, which has been inferred by absorption and fluorescence spectroscopic methods.;Chapter 1 presents an overview of the synthetic methods and properties of phthalocyanines, focusing on the unsymmetrical analogues, side-strapped derivatives, and crown ether-containing phthalocyanines. The use of these compounds in photodynamic therapy and their supramolecular chemistry are also reviewed.;Chapter 5 describes the synthesis and spectroscopic properties of two side-strapped zinc(II) phthalocyanines, which have one and two benzo-25-crown-8 moieties, respectively. The bis(crown ether) analogue favors the formation of J-aggregate in non-coordinating solvents. In CHCl 3, the aggregation of these compounds is promoted by the addition of 1,2-bis(pyridinium)ethane bis(hexfluorophosphate). The aggregation of these compounds can also be induced by the oxonium ions generated by the addition of organic acids such as trifluoroacetic acid and acetic acid. After neutralization with Et3N, the aggregate is disrupted and the phthalocyanines are converted back to their original nonaggregated state. For the symmetrically substituted compound, this acid-base switched aggregation-disaggregation process can be recycled for more than 8 times.