RESUMEN
An exceptional efficiency of pyrazine-annelated porphyrin as a general photocatalyst for the oxidation of organic sulfides is demonstrated. It is shown that phosphonate-substituted pyrazinoporphyrin 2H-1 brings together sufficient photostability and high efficiency in the aerobic photooxidation of a series of various sulfides. The influence of the reaction conditions onto the efficiency of homogeneous sulfide photooxidation in the presence of the PS was investigated and strong dependence on the solvent system was observed. The use of methanol is required for the photocatalytic sulfoxidation and the ratio of the alcohol/other solvent can significantly affect the conversion and selectivity of the reaction. The application of the prepared photosensitizer (PS) in 0.001 mol% loading allowed achieving complete conversion (97-100%, turnover number up to 100000, turnover frequency up to 6250 h-1) of substrates bearing substituents of different nature, namely aromatic and aliphatic sulfides with donor or acceptor substituents and substituents prone to oxidation, as well as cyclic sulfides. The selectivity of the of the corresponding sulfoxides formation of 96-100% was revealed. Finally, a gram-scale synthesis of several sulfoxides was successfully performed with the PS under investigation, providing desired products in 66-96% yield with over 98% purity.
RESUMEN
The scope and limitations of the condensation of labile 2,3-diaminoporphyrin derivatives with aromatic aldehydes to provide functionalized imidazole- and pyrazine-appended porphyrins were investigated in detail. The presence of an acidic catalyst in the reaction was found to be a tool that allows the reaction path to be switched. The influence of the electronic origin of the substituents in the carbonyl components of the condensation on the yields and selectivity of the reaction was revealed. Metal-promoted cross-coupling transformations were found to be convenient for the further targeted construction of functional derivatives based on the prepared bromo-substituted pyrazinoporphyrins. Overall, these strategies provide a versatile technique for the elaboration of a variety of functionalized heterocycle-appended porphyrins for further application in the development of hybrid materials.
RESUMEN
Photosensitizers (PSs) represent a group of molecules capable of generating reactive oxygen species (ROS), such as singlet oxygen (SO); thus, they are considered to be promising agents for anti-cancer therapy. The enhancement of the photodynamic efficiency of these compounds requires increasing the PS activity in the cancer cell milieu and exactly at the target cells. In the present work, we report the synthesis, lipid membrane binding and photodynamic activity of three novel cationic PSs based on ß-imidazolyl-substituted porphyrin and its Zn(II) and In(III) complexes (1H2, 1Zn and 1In). Comparison of the behavior of the investigated porphyrins at the bilayer lipid membrane (BLM) demonstrated the highest adsorption for the 1In complex and the lowest one for 1Zn. The photodynamic efficiency of these porphyrins was evaluated by determining the oxidation rate of the styryl dye, di-4-ANEPPS, incorporated into the lipid membrane. These rates were proportional to the surface density (SD) of the porphyrin molecules at the BLM and were roughly the same for all three porphyrins. This indicates that the adsorption of these porphyrins at the BLM determines their photodynamic efficiency rather than the extinction or quantum yield of singlet oxygen.