2024 journal article
Influence of cationic dimeric and trimeric-type surfactants on the aggregation behavior of water-soluble phthalocyanine: A combined experimental and computational study
JOURNAL OF MOLECULAR LIQUIDS, 400.
author keywords: Phthalocyanine; Aggregation behavior; Cationic dimeric and trimeric surfactants; Fluorescence; Density functional theory
UN Sustainable Development Goal Categories
6. Clean Water and Sanitation
(OpenAlex)
Source: Web Of Science
Added: August 19, 2024
The aggregation behavior of the water-soluble phthalocyanine, namely zinc 2,9,16,23–tetra(tert–butyl)–29H,31H–phthalocyanine tetrasulphonic acids (ZnPcS4), has been examined in the presence of dimeric and trimeric-type cationic surfactants and their conventional counterpart cetyltrimethylammonium bromide (CTAB). The absorption and fluorescence studies of ZnPcS4 in water showed a different feature than that in methanol suggesting the formation of aggregated ZnPcS4 in an aqueous medium. The fluorescence studies of ZnPcS4 in the presence of examined dimeric-type cationic surfactants showed lower critical aggregation concentration (CAC = 0.62–13.6 µM) compared to that of CTAB (CAC = 16 µM). It was found that the position of the substituents affected the critical micelle concentration (CMC) value, and the ortho-dimeric surfactant had a lower CMC value compared to those surfactants with meta, and para-dimeric surfactant. It was interesting to see that the CMC for the dimeric surfactant with two groups at the para position (13.6 µM) decreased significantly (0.04 µM) by removing the (O-CH2) protons attached to the benzene group which can be explained by structural parameters determined by theoretical calculations. By changing the surfactants from dimers to cationic trimers surfactants, a significant decrease in the CAC values was observed (0.04 µM for Trimer-12 with two dodecyl groups and 0.39 µM for Trimer-8 with two octyl groups). This finding indicates that the increase in tail length by four methylene groups of Trimer-12 compared to Trimer-8 results in a decrease in CAC by about one order of magnitude. These new findings suggest that the trimeric-type cationic surfactants are remarkably superior to conventional and dimeric-type surfactants, which could have a profound impact on many applications of ZnPCS4 including, but not limited to, medical, organic electronics, light harvesting, photonics, and optical sensors.