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The present investigation involves the synthesis of a series of novel green ethylene oxide-linked diester-functionalized cationic gemini surfactants 2,2′-[(oxybis(ethane-1,2-diyl))bis(oxy)]bis(N-alkyl-N,N-dimethyl-2-oxoethanaminium) dichloride (Cm-DEG-Cm; m = 12, 14, 16). These compounds were characterized by 1H-NMR, MS-ESI (+), FT-IR spectroscopy and elemental analysis; their solution properties were evaluated by surface tension and rheology measurements. The dimeric surfactant, Cm-DEG-Cm, possesses improved physicochemical properties as compared to its monomeric counterpart. Much lower critical micelle concentration (cmc) makes the cationic gemini surfactants more useful for the biomedical, pharmaceutical, industrial and academic sectors. Longer the alkyl chain of surfactants lower are the cmc values, the order is C16-DEG-C16 < C14-DEG-C14 < C12-DEG-C12. For all the three synthesized gemini surfactants no cloud point was noticed in between the temperatures 0 °C to 100 °C at the concentrations 0.002 mM, 0.02 mM and 0.2 mM of the aqueous surfactant solutions which is a beneficial factor for the use of these amphiphiles in various areas of application. [ABSTRACT FROM AUTHOR]

The surface tensions of cationic geminis, alkanediyl-α,ω-bis(dimethylalkylammonium bromide) (mGs-m = 14,16 and s = 5,6) + triblock polymers (TBPs-F68, F127, L64) mixtures, over the entire mole fraction range were determined. Cationic conventional surfactants, alkyltrimethylammonium bromides (TTAB, CTAB) + TBP systems, were also studied for comparison. Analysis of the data by means of regular solution theory revealed that the adsorbed monolayer at the air/water interface was much richer in surfactants than the micelles and the intermicellar solution. The interaction between surfactants and TBP molecules at the air/water interface was strong in most of the cases. The participation of monomeric surfactants was lower than of gemini surfactants. The critical micelle concentration (cmc) was studied by the regular solution theory and the interaction parameter; the activity coefficient and the activity of components in mixed micelles were determined. The micelle composition at the cmc was also computed, and it was found that the mixed micelles were systematically richer in TBPs. Participation of surfactants in mixed micelles is lower than their contribution at interface. [ABSTRACT FROM AUTHOR]

We have assessed the biological properties such as cytotoxicity and antimicrobial activity of a series of biocompatible ester-linked cationic gemini surfactants, ethane-1,2-diyl bis( N , N -dimethyl- N -alkylammoniumacetoxy) dichlorides (m-E2-m, m = 12, 14, 16). The effect of alkyl chain length (12, 14 and 16 carbon atoms) on their antimicrobial activity and cytotoxicity was examined. Antimicrobial activity of m-E2-m, against various prokaryotic and eukaryotic microorganisms, was studied by measuring the diameter of inhibition zone whereas cytotoxicity was evaluated using 3T3-L1 fibroblast cells. Toxic effect against these cells depends upon the type of the target microorganisms, nature of the cells, and hydrophobicity of the molecules. Antimicrobial activity of the gemini surfactant 16-E2-16 is lower than that of its corresponding single-chain counterpart. The gemini surfactants used for the present study (m-E2-m) which have excellent surface properties and much lower cmc values show low toxicity and significant antimicrobial activity. [ABSTRACT FROM AUTHOR]

Three homologues of a novel biodegradable diester-linked cationic gemini surfactant series, C m H 2m+1 (CH 3 ) 2 N + (CH 2 COOCH 2 ) 2 N + (CH 3 ) 2 C m H 2m+1 .2Cl − (m-E2-m; m = 12, 14, 16), were used for investigation of the solubilization of polycyclic aromatic hydrocarbons (PAHs) such as naphthalene, anthracene and pyrene in single as well as binary surfactant solutions. Physicochemical parameters of the pure/mixed systems were derived by conductivity and surface tension measurements. Dissolution capacity of the equimolar binary surfactant solutions towards the PAHs was studied from the molar solubilization ratio ( MSR ), micelle–water partition coefficient (K m ) and free energy of solubilization (Δ G s 0 ) of the solubilizates. Influence of hydrophobic chain length of the dimeric surfactants on solubilization was characterized. Aqueous solubility of the PAHs was enhanced linearly with concentration of the surfactant in all the pure and mixed gemini–gemini surfactant systems. [ABSTRACT FROM AUTHOR]

The micellization and interfacial properties of three homologous dicationic ester-bonded cleavable and biodegradable gemini surfactants, ethane-1,2-diyl bis( N , N -dimethyl- N -alkylammoniumacetoxy) dichlorides, referred as m-E2-m (m = 12, 14, 16), and their binary mixtures were investigated in aqueous solution by performing conductivity and surface tension measurements. The decrease in critical micelle concentration (CMC) indicates nonideality of the mixed systems of different compositions. The unequal hydrophobic chain length might be playing a significant role in the reduction of CMC values. Several theoretical treatments were used to analyze and compare the mutual interaction parameters, counter ion binding, surface parameters, excess free energy of micellization and standard free energies for the mixed surfactant systems as well. The negative values of interaction parameters show an overall attractive force, i.e., synergistic effect in the mixed state. The excess free energy of mixing has negative values for all the systems. [ABSTRACT FROM AUTHOR]

This paper deals with a comprehensive study of the biodegradability, cleavability, hemolytic activity, and physicochemical properties of an ester-linked gemini surfactant, ethane-1,2-diyl bis( N , N -dimethyl- N -tetradecylammoniumacetoxy) dichloride (14-E2-14), along with the gemini-conventional mixed surfactant systems at different mole fractions of 14-E2-14. Some typical conventional surfactants of different polarities were used in the investigation at 303.15 K in aqueous medium by performing conductometric and tensiometric measurements. The data from both the techniques were used to obtain the critical micelle concentration ( cmc ) of mixed surfactant systems at different mole fractions. The decrease in cmc values indicates nonideality of the binary systems, and also occurrence of mixed micellization. Interaction parameters ( β m and β σ ) along with energetics of mixed micellization were evaluated by using theoretical models suggested by Clint, Rubingh, Rosen, Motomura and Maeda for mixed surfactant systems. Negative values of β indicate an overall attractive force in the mixed state. Also, the excess free energy of mixing has negative values for all the systems. The hydrophilic spacer of the gemini surfactant 14-E2-14 shows strong interaction with the conventional surfactants used as well as with the biological membranes such as human erythrocytes (RBC). [ABSTRACT FROM AUTHOR]

In this study, the solubilization of anthracene and pyrene was investigated in micellar solutions of ethane-1,2-diyl bis( N , N -dimethyl- N -dodecylammoniumacetoxy) dichloride (C 12 H 25 (CH 3 ) 2 N + (CH 2 COOCH 2 ) 2 N + (CH 3 ) 2 C 12 H 25 ·2Cl − , 12-E2-12) and its equimolar binary mixtures of conventional cationic, anionic and nonionic surfactants in water. Critical micelle concentration ( cmc ) and other physicochemical parameters were determined by the surface tension and conductivity measurements at 30 °C. Much lower cmc value was obtained for 12-E2-12 than the corresponding monomeric surfactant dodecyltrimethylammonium chloride (DTAC). Lower experimental cmc than the ideal cmc and the negative interaction parameters imply synergistic interaction between the surfactants in the binary solutions. Order of solubilization capacity of the pure/mixed surfactant micelles, for anthracene and pyrene, are not the same. Among the pure surfactants, Brij 58 has highest and SDBS has least efficiency for dissolution of the solutes. The mixed systems 12-E2-12 + SDS and 12-E2-12 + Brij 58 have highest dissolution power for anthracene and pyrene, respectively. Solubility enhancement was observed for both the solutes in the equivalent binary mixtures of the dicationic gemini 12-E2-12 with the anionic conventional surfactants SDS and SDBS. To determine the toxicity of 12-E2-12 and to quantify its interaction with erythrocytes, we have performed the hemolytic assessment. As regards the hemolytic activity and biodegradability test, 12-E2-12 is less toxic and readily biodegradable. [ABSTRACT FROM AUTHOR]

This study is an approach to especially investigate (i) the micellization behaviour of a cationic gemini surfactant 16-E2-16 (ethane-1,2-diylbis(N,N-dimethyl-N-hexadecylammoniumacetoxy) dichloride) and its equimolar binary mixtures with conventional cationic (CTAC), anionic (SDS), non-ionic (Brij 58) surfactants, and (ii) the solubilization capacity of the pure/mixed surfactant systems towards polycyclic aromatic hydrocarbons (PAHs) by 1H NMR spectroscopy. Proton chemical shifts (δ , ppm) of the binary or ternary surfactant/solute systems have been compared with the pure surfactant solutions. The results (δ values) indicate favoured micellization for all the surfactant solutions and the extent of solubilization depends on the nature of surfactants as well as solutes. Location of the PAHs in different parts, such as palisade layer, inner palisade layer and core of micelles alter the δ values. More pronounced changes in δ value of various protons of CTAC and Brij 58 indicate higher solubilization of pyrene. Among all the three surfactant combinations, 16-E2-16 + SDS is the most compact system as compared to the 16-E2-16 + CTAC and 16-E2-16 + Brij 58 systems. Image 1 • Study of equimolar gemini-conventional surfactant mixtures by 1H NMR spectroscopy. • Chemical shift (δ) data imply attractive interaction among surfactant components. • Pure Brij 58 and CTAC micelles show maximum dissolution capacity towards pyrene. • PAH−solubility in anionic surfactant micelles is lower than the cationic micelles. • Change in δ values suggest distinct location sites of solutes in micellar solutions. [ABSTRACT FROM AUTHOR]