Location and Photoionization Studies of a Series of Alkylporphyrin Derivatives Solubilized in Dioctadecyldimethylammonium Chloride and Dihexadecyl Phosphate Vesicles

Article abstract of DOI:10.1021/j100177a100

Three alkylporphyrins were synthesized, 5-(1-nonylpyridinium-4-yl)-10,15,20-triphenylporphyrin bromide (H2PC9), 5-(1-dodecylpyridinium-4-yl)-10,15,20-triphenylporphyrin bromide (H2PC12), and 5-(1-hexadecylpyridinium-4-yl)-10,15,20-triphenylporphyrin bromide (H2PC16).The location of these 5-(1-alkylpyridinium-4-yl)-10,15,20-triphenylporphyrin bromides (H2PCn) solubilized in cationic dioctadecyldimethylammonium chloride (DODAC) and anionic dihexadecyl phosphate (DHP) vesicles solutions was investigated using optical absorption spectroscopy.Electron spin resonance (ESR) was applied to observe the yields of photoionization of H2PCn in rapidly frozen DODAC and DHP vesicle solutions versus alkyl chain length.A decrease in photoyield correlated with a increase in the porphyrin-to-vesicle interface distance.The photoionization of H2PCn in rapidly frozen DODAC and DHP vesicle solutions containin electron acceptors was also studied by ESR.Two different electron acceptors were used in this study, tetrabromobenzoquinone (TBBQ) and potassium ferricyanide (K3Fe(CN)6).Electron transfer within the vesicle itself was examined with TBBQ, which solubilizes inside the lipophilic region of the vesicle near the interface, whereas K3Fe(CN)6 involved electron transfer across the vesicle interface.The yields of photoionization of H2PCn have generally been found to decrease upon addition of either acceptor.The results are discussed in terms of alkyl chain length, position of the porphyrin group relative to the vesicle interface, and vesicle surface charge.