Effect of side chain length on the aggregation of amphiphilic 5,10,15-tris (1-methylpyridinium-4-yl)-20-[4-(alkoxy) phenyl] 21H, 23H porphyrin tritosylates

Self-aggregation of cationic amphiphilic 5, 10, 15-tris-(1-methylpyridinium-4-yl)-20-[4-(alkoxy)phenyl]-21H, 23H porphyrin tritosylates (2a-e) with different alkoxy chain length in aqueous and binary solvent systems has been studied by UV-visible, fluorescence and (I)H NMR spectroscopy. Binary solvent, concentration, ionic strength, presence of surfactants, and temperature govern the aggregations of 2a-e. Porphyrins having side chain length more than ten carbon atoms (2c-e) form higher aggregates, such as vesicles by sonication of dimers formed initially, whereas porphyrins with lesser side chain length (2a & b) form lower aggregates only. Further, the size and the formation of vesicles have been confirmed by transmission electron microscopy (TEM) and dye entrapment experiments for 2e.