Catalytic role of 16‐s‐16 micelles on condensation reaction of ninhydrin and metal‐dipeptide complex

Physicochemical Studies on the Interaction between Sodium Dodecyl Sulfate and Methylene Blue in Methanol-Water Mixed Solvent Media

The surface activity and the process of micellization of sodium dodecyl sulfate (SDS) with methylene blue (MB) in a methanol-water mixed solvent system were investigated by tensiometry and conductometry at 298.15 K. The measurements of surface tension and conductivity of SDS-MB complex were carried up to 0.3 volume fractions of methanol because the resulting complex appeared turbid above 0.3 volume fractions of methanol. The critical micelle concentration (CMC) of the SDS was determined from both tensiometry and conductometry. The CMC of SDS increased with the increasing volume fraction of methanol due to the inclusion of methanol in the micelles and decreased in the presence of methylene blue due to the reduction of electrostatic repulsion within the anionic moiety of SDS by the positive charge of the added dye. Different properties like surface excess concentration $\left({\mathrm{\Gamma }}_{\max }\right)$ , minimum surface area $\left(A_{\text{min}}\right)$ , Gibbs free energy of micellization $\left(\mathrm{\Delta }{G}_{\mathrm{m}}^o\right)$ , surface pressure ( ${\pi }_{\text{CMC}}$ ), efficiency of a surfactant ( $\text{p}{C}_{20}$ ), packing parameter $\left(P\right)$ , and standard free energy interfacial adsorption $\left(\mathrm{\Delta }{G}_{\text{ads}}^o\right)$ of SDS in the absence/presence of MB were calculated. On the basis of $\mathrm{\Delta }{G}_{\mathrm{m}}^o$ values, it was noticed that the increasing volume fraction of methanol disfavors the micellization of SDS, while the presence of MB increased the efficiency of SDS making the micellization process more spontaneous.

Investigation of micellar and interfacial phenomenon of amitriptyline hydrochloride with cationic ester-bonded gemini surfactant mixture in different solvent media

Herein, the interaction among the antidepressant drug amitriptyline hydrochloride (AMT) and a green gemini surfactant, ethane-1, 2-diyl bis(N,N-dimethyl-N-tetradecylammoniumacetoxy) dichloride (14-E2-14), via numerous techniques such as tensiometry, fluorimetry, FT-IR and UV-visible spectroscopy in three different media (aqueous 0.050 mol·kg^-1 NaCl, 0.50 and 1.0 mol·kg^-1 urea) were investigated. AMT is used to treat mental illness or mood problems, such as depression. The aggregation of biologically active ingredients can enhance the bioavailability of hydrophobic drugs. A significant interaction between AMT and 14-E2-14 was detected by tensiometric study as the critical micelle concentration (cmc) of AMT+14-E2-14 is reduced upon an increase of mole fraction (α₁) of 14-E2-14. The decrease in cmc indicates the nonideality of studied mixtures of different compositions. Although, employed drug AMT is freely soluble in the aqueous and non-aqueous system but is not hydrophobic enough to act as its carrier. Instead, gemini surfactant formed spherical micelles in an aqueous system and their high solubilization capability, as well as their relatively lower cmc value, makes them highly stable in vivo. The cmc values of AMT+14-E-14 mixtures in all cases were further decreased and increased in NaCl and urea solutions respectively as compared with the aqueous system. Numerous micellar, interfacial, and thermodynamic parameters have been measured by applying various theoretical models. The obtained changes in the physicochemical assets of AMT upon adding of 14-E2-14 are likely to enhance the industrial and pharmaceutical applications of gemini surfactants. The negative interaction parameters (β^m and β^σ), indicate synergistic attraction is occurring in the mixed systems. The aggregation number (N_agg), Stern–Volmer constant (K_sv), etc. are attained through the fluorescence method, also supporting the attractive interaction behavior of AMT+14-E2-14 mixtures in all solvents. The N_agg was found to increase in the salt solution and decrease in the urea system compared with the aqueous solution. FT-IR and UV-visible analysis also depict the interaction between the constituent alike tensiometry and fluorimetry methods. The results suggested that gemini surfactants may serve as a capable drug delivery agent for antidepressants, improving their bioavailability.

Synthesis and characterization of geminis and implications of their micellar solution on ninhydrin and metal amino acid complex

In our study, three gemini dicationic surfactants with different methylene group spacer (16-6-16, 16-5-16 and 16-4-16) have been synthesized and characterized in solution by 1H NMR spectroscopic technique. The implications of gemini micellar solution on ninhydrin and metal amino acid complex ([Cu(II)-Trp]+) were performed by the means of single-beam UV-visible spectroscopy. The absorbance was noted at regular time intervals and values of rate constant (kψ ) were determined by using a computer-based program. Synthesized surfactants proved as an efficient catalyst on the interaction of ninhydrin with metal amino acid complex as compared with conventional surfactant and aqueous systems. The required description regarding the implications of gemini dicationic surfactants are provided in the text in detail. The conductivity technique was applied in order to get critical micelle concentration (cmc) of geminis in the presence and absence of reactants. Catalytic results developed in gemini dicationic surfactant system were explained effectively by pseudo-phase model. Various thermodynamic quantities, viz., activation energy, E a, activation enthalpy, ΔH #, and activation entropy, ΔS #, were obtained on interaction of ninhydrin with [Cu(II)-Trp]+ in gemini systems by applying Eyring equation. A detailed explanation about these evaluated parameters was also made.

Effects of temperature and polyols on the ciprofloxacin hydrochloride-mediated micellization of sodium dodecyl sulfate

Herein, a conductivity method was engaged to explore the effects of a fluoroquinolone drug, namely ciprofloxacin hydrochloride (CFH)/CFH + polyols (organic compounds with multiple hydroxyl groups (glucose and fructose)), on the aggregation phenomenon of sodium dodecyl sulfate (SDS) at different temperatures (298.15–318.15 K) while maintaining a gap of 5 K. In this study, the critical micelle concentration (cmc) of the SDS/SDS + CFH mixture in water and polyols media was determined from plots of the specific conductivity versus the concentration of SDS to gain knowledge of the effects of CFH/CFH + polyols on the micelle formation behavior of SDS. The cmc value of the surfactant decreases in the presence of CFH in an aqueous medium; thus, CFH favors the micellization of SDS. The cmc values of SDS and the SDS + CFH mixture were enhanced in polyols media. The cmc values of SDS/SDS + CFH show a U-shaped behavior with temperature. The counterion dissociation (α) of the pure surfactant is higher in the presence of the drug and is further enhanced through an increase in the CFH concentration in water/polyols media. Different thermodynamic parameters, such as the Gibbs free energy of micellization , standard enthalpy , entropy , different transfer energies and enthalpy–entropy compensation parameters of micellization were determined and illustrated in detail to compare these parameters between the pure SDS and SDS + CFH mixture in polyols media. The negative values of for the SDS/SDS + CFH mixture in all cases indicate spontaneous micelle formation. The and values indicate the presence of both hydrophobic and electrostatic interactions amongst the studied components.

A conductivity method was used to see effects of a ciprofloxacin hydrochloride (CFH)/CFH + polyols (organic compounds with multiple hydroxyl groups (glucose and fructose)) on aggregation phenomenon of sodium dodecyl sulfate (SDS) at 298.15–318.15 K.

Catalytic influence of 16-s-16 gemini surfactants on the rate constant of histidine and ninhydrin

The present paper reports the catalytic influence of 16-s-16 (spacer (s) = 4, 5, 6) gemini surfactants on the rate constant of histidine and ninhydrin at 343 K and pH 5.0 using the spectrophotometric technique. The effect of varying amounts of geminis was made on the rate constant of histidine and ninhydrin keeping other constituents constant. Characteristics of the rate constant (kψ ) versus [gemini] depict the effect of surfactants on the rate constant. A systematic explanation about the effect of surfactants is revealed and discussed in the text. The influence of different parameters that includes [reactants], temperature and pH has also been performed on the study. In order to determine the critical micelle concentration (cmc) of pure surfactants and their solution mixtures, conductivity measurement was employed. By using the Eyring equation, activation parameters at different temperatures have been obtained. The resultant data of kψ versus [gemini] plot were rationalized with the pseudo-phase model of micelles.

Study of the reaction of ninhydrin with tyrosine in gemini micellar media

This paper reports the study of the ninhydrin and l-tyrosine (Tyr) reaction in gemini micellar media. The aim of the study was to see the influence of different parameters on the reaction rate, including the influence of reactant concentration, temperature and pH. Spectrophotometric and conductometric techniques were employed to record the absorption of the product formed and cmc values as a function of the surfactants, respectively. The effect of varied surfactant concentrations on the reaction rate was also investigated. The quantitative treatment of the rate constant (k_ψ) vs. surfactant concentration was carried out on the basis of the pseudo-phase model suggested by Martinek et al., Menger and Portnoy, and established by Bunton. Micellar binding parameters and thermodynamic parameters have been calculated and are discussed in detail. A plausible reaction mechanism that is consistent with observed kinetic data has been proposed.

The importance of the study increased due to the use of a very small quantity of gemini surfactant required to perform the reaction.