Abstract
The increasing concern about chiral pharmaceutical pollutants is connected to environmental contamination causing both chronic and acute harmful effects on living organisms. The design and application of sustainable surfactants in the remediation of polluted sites require knowledge of partitioning between surfactants and potential pollutants. The interfacial and thermodynamic properties of two gemini surfactants, namely, alkanediyi-α,ω-bis(dimethylhexadecyl ammonium bromide) (16-s-16, where s = 10, 12), were studied in the presence of the inherently biodegradable oxime-functionalized ionic liquid (IL) 4-((hydroxyimino)methyl)-1-(2-(octylamino)-2-oxoethyl)pyridin-1-ium bromide (4-PyC8) in an aqueous solution using surface tension, conductivity, fluorescence, FTIR and 1H NMR spectroscopic techniques. The conductivity, surface tension and fluorescence measurements indicated that the presence of the IL 4-PyC8 resulted in decreasing CMC and facilitated the aggregation process. The various thermodynamic parameters, interfacial properties, aggregation number and Stern–Volmer constant were also evaluated. The IL 4-PyC8-gemini interactions were studied using DLS, FTIR and NMR spectroscopic techniques. The hydrodynamic diameter of the gemini aggregates in the presence of promethazine (PMZ) as a potential chiral pollutant and the IL 4-PyC8 underwent a transition when the drug was added, from large aggregates (270 nm) to small micelles, which supported the gemini:IL 4-PyC8:promethazine interaction. The structural transitions in the presence of promethazine may be used for designing systems that are responsive to changes in size and shape of the aggregates as an analytical signal for selective detection and binding pollutants.
Highlights
IntroductionThe increasing concern about chiral pharmaceutical pollutants is connected to environmental contamination causing both chronic and acute harmful effects on living organisms
(gemini surfactants/ionic liquid (IL) 4-PyC8) were evaluated (Table 1) from the ratio of the Conductivity post-micellar and pre-micellar concentration range slopes obtained from the plots of speWe investigated the aggregation properties of gemini surfactants in water in the cificpresence conductance of the surfactant solution at different concentrations
The of IL4-PyC8 to the gemini:PMZ system, the value of ξ slightly decreased (Table 6). This surface tension and conductometry results revealed a decrease in the Critical micelle concentration (CMC) of both the may have reflected the strong electrostatic interactions that took place between the oppogemini surfactants in the presence of the IL 4-PyC8, favoring the micelle formation sitely charged ions present within 0the micellar system [72]
Summary
The increasing concern about chiral pharmaceutical pollutants is connected to environmental contamination causing both chronic and acute harmful effects on living organisms. It is a problem of direct importance to detect chiral compounds [1], including chiral pollutants of different natures [2]. Using surfactants for increasing analytical signals and, reducing the detection concentration of the pollutants is one of the attractive strategies in chemical analysis [3,4] since it may ensure selective binding of one of the components, providing more reliable detection in the cases when the structurally similar compounds are present in the mixture. Dimeric (gemini) surfactants were reported to exhibit selectivity toward the binding of calixarenes modified with different
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