The kinetics of basic hydrolysis of tris(1,10-phenanthroline)iron(II)has been carried out in aqueous, N-cetyl-N,N,N-trimethyl ammonium bromide (CTAB) micellar, and CTAB reverse micellar media by UV-visible spectroscopy system. The reaction follows the overall second-order kinetics; first order in each Fe(II) complex and the base ( − OH). CTAB micelles catalyze the reaction rate through the adsorption of the Fe(II) complex and the hydroxyl ions on the micellar surface. In the reverse micellar medium, interesting physicochemical features are observed. Being ionic nature of reactants, both the reactants prefer to stay and react inside the water pool in place of the hydrophobic environment. The rate increases with w, that is, the size of the water pool, attains a maximum value at w = 8.33, and then decreases. But the rate increases as the concentration of surfactant increases at fixed w values. For a better explanation of the kinetic data, the activation parameters, standard enthalpy of activation ( ‡ H • ), standard entropy of activation ( ‡ S • ), and energy of activation (E a ) were determined.in surfactant-based organized assemblies, such as micelles, microemulsions, and vesicles, often achieve a greater degree of organization compared to their geometries in homogeneous continuous solution, can mimic reactions in biosystems, and also have potential for energy storage [1]. Micellar medium is a heterogeneous system where a given solvent is isolated from a continuous phase solvent by a surfactant or a pair of surfactants and a cosurfactant. It can catalyze many reactions due to the concentration effect in the micellar pseudophase [2] and can also change the reaction pathway [3]. Such organized media
The degradation of malachite green (MG) by an alkaline hydrolytic process has been explored spectrophotometrically. The kinetics of the reaction have been meticulously studied under the influence of cationic alkyltrimethylammonium bromide (DTAB, TTAB and CTAB) surfactants, a-, band gcyclodextrins (CDs) and surfactant-b-CD mixed systems applying pseudo-first order conditions at 298 K. The surfactants and cyclodextrins individually catalyze the hydrolytic rate, whereas surfactant-b-CD mixed systems exhibit both an inhibiting and catalytic influence depending on the surfactant concentrations. The kinetic results have been explained precisely based on the pseudo-phase ion exchange (PIE) model of micelles and CD-catalyzed model of CD systems. The surfactants exhibit micellar surface catalysis, while CDs accelerate the rate by forming MG-CD inclusion complexes, thereby facilitating nucleophilic attack of its ionized secondary hydroxyl group on the carbocation center of MG. The encapsulation of MG within the supramolecular host cavity of the CDs has been investigated diligently using a steady-state absorption spectroscopic technique. The result shows 1 : 1 host-guest complexation with different relative orientations of the guest (MG) inside the hosts. Studies employing density functional theory (DFT) as well as molecular docking analysis provide valuable insight on the insertion mechanism. The results reveal that quantitative analysis can be utilized to predict the optimum conditions for the fastest degradation of MG in ambient environments.Fig. 2 Plots of k obs versus [CD] 0 for the reaction of MG and À OH in aqueous medium at 298 K. [MG] 0 ¼ 1.25 Â 10 À5 M, [ À OH] 0 ¼ 1.875 mM. Inset: catalytic factor (k max obs /k w ) in different cyclodextrin systems at fixed [CD] ¼ 1.0 mM. Scheme 3 Hydrolysis of MG in aqueous solution of CD.This journal is
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