Surface and Biological Activity of Some Novel Cationic Surfactants

In this study, steps were taken toward the development of bactericidal and fungicidal synthetic cationic surfactants by reacting decyl, dodecyl or tetradecyl amine with acetic or hydrochloric acid to produce a series of amine salts which consequently converted to copper or cobalt cationic complexes via complexing the first series compounds with copper (II) or cobalt (II) ions. Surface properties such as interfacial tension and emulsifying power of these surfactants were investigated. The surface parameters including critical micelle concentration (CMC), maximum surface excess (Γ_max) and minimum surface area (A _min) were studied. Free energy of micellization (ΔG°_mic) and adsorption (ΔG°_ads) were calculated. The antimicrobial activity was determined via the inhibition zone diameter of the prepared compounds, which measured against five strains of a representative group of microorganisms. FTIR spectra, elemental analysis and H¹ NMR spectrum were performed to confirm compound structure and purity.

Synthesis and Antibacterial Activity of Novel Amido-Amine-Based Cationic Gemini Surfactants

A series of novel cationic gemini surfactants were synthesized from corresponding amido-amines in a single step reaction. The amido-amines were obtained from long chain carboxylic acids and 3-N,N-dimethylamino-1-propyl-amine with excellent isolated yield (up to 95 %). All the synthesized quaternary ammonium compounds (QACs) were further investigated for surface active properties. The critical micelle concentration (CMC) and the effectiveness of surface tension reduction were determined. The surface tension measurements of newly synthesized gemini surfactants showed good water solubility, and low CMC values, had great efficiency in lowering the surface tension and a strong adsorption at the air/water interface than the corresponding monomeric surfactants. Further, the antibacterial activity of the synthesized QACs against both Gram-positive and Gram-negative bacteria was also investigated.     

Syntheses and Characterization of Some Cationic Surfactants

A series of novel cationic surfactants were synthesized from the quaternization of triethyl amine and various long chain alkyl halide. The chemical structure of the prepared compounds was confirmed using elemental analysis, FTIR and ¹H-NMR spectra. The physical properties of the synthesized surfactants including, electrical conductivity, critical micelle concentration, (CMC) and the degree of ionization of the micelle, (β) were studied. The thermodynamic parameters of micelle formation, standard free energy ΔG _m°, enthalpy ΔH _m°, and entropy ΔS _m° were calculated. The results of the surface parameter determination were correlated with their chemical structures. It was found that the hydrocarbon chain length is the main factor which has an effect on the value of the thermodynamic parameters.

Synthesis,Surface Property and Antimicrobial Activity of Cationic Gemini Surfactants Containing Adamantane and Amide Groups

A series of novel cationic gemini surfactants, namely 1,3-adamantanedicarboxylic acid bis(alkyldimethyl-3-ammoniopropyl amide) dibromide designated as [Ad-2(amC _n )] (n = 12, 14, 16), containing adamantane, two amide groups, and two hydrocarbon chains, were synthesized from 1,3-adamantanedicarboxylic acid. The surface-active properties of the surfactants were investigated through surface tension and electrical conductivity measurement. A series of thermodynamic parameters such as standard free energy \(\left( {\Delta G^\circ_{\text{m}} } \right)\) , enthalpy \(\left( {\Delta H^\circ_{\text{m}} } \right)\) , and entropy \(\left( {\Delta S^\circ_{\text{m}} } \right)\) of micellization were evaluated from electrical conductivity measurements in the temperature range from 288 to 308 K. The micellization for [Ad-2(amC _n )] is entropy-driven at low temperature and enthalpy-driven at high temperature. Further, the antimicrobial activity of the synthesized gemini surfactants against both Gram-positive and Gram-negative bacteria was also investigated, and this study showed that the compound [Ad-2(amC₁₂)] has excellent antibacterial activity against all studied bacteria.     

Synthesis and Characterization of Multifunctional Surfactants in Oil-Field Protection Applications

A series of cationic surfactants was prepared using economical raw materials. The chemical structures of the prepared compounds were confirmed using elemental analysis, FTIR and ¹H-NMR spectra, and melting point determination. The synthesized surfactants were evaluated as oil-field protective additives. In this regard, several surface properties of the synthesized surfactants were studied including surface tension, critical micelle concentration, effectiveness, efficiency, maximum surface excess and minimum surface area. The results obtained from the surface activity measurements were correlated to their chemical structures. The emulsification power measurements for solutions of these surfactants showed their low emulsifying tendency towards paraffin and crude oil. The synthesized surfactants also exhibited high biocidal activity towards gram-positive and gram-negative bacteria and fungi. This activity was increased by increasing the hydrophobic chain length. The corrosion inhibition measurement of these surfactants for mild steel alloys in acidic media using a weight loss technique showed good protection of mild steel alloys against acidic environments. These properties qualify the synthesized compounds as economical oil-field protective additives.

一种不对称阴离子Gemini表面活性剂的合成及表面活性研究

以α-溴代十四酸乙酯和4-癸基苯酚为原料,经Williamson醚化、磺化及皂化反应制备了一种不对称阴离子Gemini表面活性剂α-(4-癸基-2-磺基)-苯氧基十四酸钠,简写为C12CO2Na-p-C10SO3Na,考察了醚化反应条件,并用FTIR和1HNMR表征了中间体及目标产物结构。结果表明,醚化反应的最佳条件为:以N,N-二甲基甲酰胺(DMF)和甲苯作溶剂,无水K2CO3作缚酸剂,物料比n(α-溴代十四酸乙酯)∶n(4-癸基苯酚)=1.05∶1,回流反应3 h,醚化产物收率为77.2%(以4-癸基苯酚计)。采用吊片法测定了目标产物的表面活性,其表面张力最低可降至26 mN/m左右,临界胶束浓度(CMC)为3.28×10-6mol/L,比相应常规单链表面活性剂十四烷酸钠和间癸基苯磺酸钠的CMC低3个数量级,体现出Gemini表面活性剂优异的表面活性。     

Synthesis,Surface and Antimicrobial Activities of Novel Cationic Gemini Surfactants

A series of novel cationic gemini surfactants [C_nH_2n+1–O–CH₂–CH(OH)–CH₂–N⁺(CH₃)₂–(CH₂)₂]₂·2Br^? [ 3a (n = 12), 3b (n = 14) and 3c (n = 16)] having a 2‐hydroxy‐1,3‐oxypropylene group [?CH₂–CH(OH)–CH₂–O–] in the hydrophobic chain have been synthesized and characterized. Their water solubility, surface activity, foaming properties, and antibacterial activity have been examined. The critical micelle concentration (CMC) values of the novel cationic gemini surfactants are one to two orders of magnitude smaller than those of the corresponding monomeric surfactants. Furthermore, the novel cationic gemini surfactants have better water solubility and surface activity than the comparable [C_nH_2n+1–N⁺(CH₃)₂–(CH₂)₂]₂·2Br^? (n‐4‐n) geminis. The novel cationic gemini surfactants 3a and 3b also exhibit good foaming properties and show good antibacterial and antifungal activities.     

Surface and Biological Activity of Some Prepared Iminium Surfactants Based on Schiff Bases

A series of novel iminium surfactants were prepared through quaternization of different prepared fatty Schiff bases with benzyl chloride. The chemical structures were confirmed using FTIR, ¹H-NMR and mass spectroscopy. The surface properties and biological activity of these surfactants were investigated. The surface parameters including critical micelle concentration (CMC), maximum surface excess (Γ_max) and minimum surface area (A _min), Efficiency (PC₂₀) and Effectiveness (π_CMC) as well as the free energy of micellization ( $ \Updelta G_{\text{mic}}^{\text{o}} $ ) and adsorption ( $ \Updelta G_{\text{ads}}^{\text{o}} $ ) were calculated. It was found that the prepared compounds have good surface and biological activity.     

糖基硼酸酯表面活性剂的合成及表面活性的研究

以硼酸、葡萄糖和癸酸氯为原料合成了糖基硼酸酯(即硼酸双葡萄糖酯双癸酸酯,简称DGBR),并利用红外对其结构进行了表征和分析,结果显示其结构和设计产物结构相符合。并采用表面张力法确定了DGBR的临界胶束浓度(CMC)和临界胶束浓度下的表面张力(γCMC),其CMC、γCMC和文献值相接近;考察了不同Na Cl浓度对DGBR表面性能的影响,并计算了饱和吸附量(Γmax)和单分子饱和吸附面积(Аmin)等参数,随着Na Cl浓度的增加,其表面性能增强。     

Synthesis and Surface Properties of Anionic Gemini Surfactants having N-acylamide and Carboxylate Groups

A straightforward synthetic strategy to an anionic gemini surfactant having both N-acylamide and carboxylate groups in a molecule has been demonstrated. The surface properties of the anionic gemini surfactant, such as CMC (critical micelle concentration), C₂₀ (the concentration required to reduce the surface tension of the solvent by 20 mN/m), γ _CMC (the surface tension at the CMC), ∏ _CMC (the surface pressure at the CMC), Γ _max (the maximum surface excess concentration at the air/aqueous solution interface), A _min (the minimum area per surfactant molecule at the air/water interface), and the CMC/C₂₀ ratio (a measure of the tendency to form micelles relative to adsorbtion at the air/water interface), have been studied. The influence of the different concentrations of NaCl on the surface properties of the gemini surfactant has been discussed. The results have shown that the CMC values decreased with an increase in the concentration of NaCl indicating that the Na⁺ preferentially adsorbs onto the surface of the charged aggregate and facilitates the aggregate growth by suppressing the main impediment of electrostatic repulsion among head groups. Additionally, the values of Γ _max are always higher in salt solutions as compared to those in pure water due to their salting out effect. The larger pC₂₀ value indicates that the surfactant adsorbs more efficiently at the air/water interface and reduces surface tension more efficiently. In addition, the geminis in water show little or no break in their specific conductance versus surfactant molar concentration plots. This is attributable to protonation of the carboxylate group and strong Na⁺ release during micellization.     

Effects of Spacers on Surface Activities and Aggregation Properties of Anionic Gemini Surfactants

This present article employs four anionic Gemini surfactants with different spacer groups and investigates their physicochemical and aggregation properties. The critical micelle concentration (CMC), surface tension at CMC (γ_CMC) and C ₂₀ of these surfactants have been investigated using the du Nouy ring method. The aggregation number (N) was determined with intrinsic fluorescence quenching method using pyrene as a fluorescence probe and benzophenone as a quencher. Results show that these anionic Gemini surfactants have lower CMC and C ₂₀ values compared with those conventional ones and show higher surface activity. As expected, the spacer plays an important role in the aggregation properties of Gemini surfactants. Under experimental conditions, Gemini B–D with an alkoxylated group as spacer has a lower CMC and a higher aggregation number than Gemini A with methylene as spacer. For Gemini B–D, the CMC and aggregation number values decrease with the increasing flexible spacer length. The micropolarity also affects the aggregation of the present anionic Gemini surfactants. The micropolarity of micelle becomes low when the concentration of surfactants increases. Aggregation numbers of surfactants increase and fluorescence intensities decrease with the increasing concentration of NaCl. These results will help us to understand the relationship between the architectures of Gemini surfactants and their various properties in aqueous solution. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.

Preparation and Application of Fluorinated Cationic Surfactants

Four fluorinated cationic surfactants were prepared by condensing 2,2,3,3, tetrafluoro-1-propyl chloroacetate with stoichiometric amounts of pyridine, 2-hydroxypyridine, 8-hydroxyquinoline and 8-hydroxyquinaldine to produce four quaternary ammonium salts. The surface and biocidal properties of these surfactants were investigated. Surface properties of their solutions including surface tension, critical micelle concentration (CMC), effectiveness (Π_cmc), maximum surface excess (Γ_max) and minimum surface area (A _min) were investigated with respect to different concentrations at 25 °C. Standard free energies of micellization and adsorption of the prepared surfactants in the aqueous solution were studied. The biocidal activity was determined via the inhibition zone diameter of prepared compounds which tested against six strains as a representative group of microorganisms.

The Effects of Amide Bonds and Aromatic Rings on the Surface Properties and Antimicrobial Activity of Cationic Surfactants

The cationic surfactants containing aromatic rings and amide bonds, N,N-dimethyl-N-dodecyl-2-pyrimidinylcarbamoylmethyl ammonium chloride ( a ), N,N-dimethyl-N-dodecyl-2-thiazolylcarbamoylmethyl ammonium chloride ( b ), and N,N-dimethyl-N-dodecyl-phenylcarbamoylmethyl ammonium chloride ( c ), were synthesized and characterized. The surface tension and conductivity values were employed to investigate the absorption and micellization behavior of the three cationic surfactants. The results showed that the synthesized surfactants have shown a low critical micelle concentration (CMC) and a high adsorption efficiency (pC₂₀) compared with the traditional cationic surfactant of N,N-dimethyl-N-dodecyl-N-benzyl ammonium chloride ( BAC-12 ). The aromatic rings of the a , b , and c molecular structures were analyzed using the ¹H NMR spectra for electrostatic repulsion effects between hydrophilic headgroups. The size distribution of the micelles was derived using dynamic light scattering (DLS) techniques. In addition, the foaming ability of a , b , c , and BAC-12 was investigated and the antimicrobial activity of a , b , c , and BAC-12 against Escherichia coli, Staphylococcus aureus, and Bacillus subtilis was examined. The effects of amide bonds and aromatic rings on the surface properties and antimicrobial activity of a , b , and c were analyzed and compared with BAC-12 of the same alkyl chain length. The synthesized surfactants exhibited a high surface ability and better antibacterial activity compared with BAC-12 .     

Aggregation and Thermodynamic Properties of Some Cationic Gemini Surfactants

In this study, the gemini surfactants of the alkanediyl-α-ω-bis(alkyl dimethyl ammonium) dibromide type, on the one hand, with different alkyl groups containing m carbon atoms and an ethanediyl spacer, referred to as “m-2-m” (m = 10, 12 and 16) and, on the other hand, with n-C₁₆ alkyl groups and different spacers containing s carbon atoms, referred to as “16-s-16” (s = 2, 6, 10 and Ar (8)) have been synthesized, purified and characterized. The critical micelle concentration (CMC), micelle ionization degree (α) and Gibbs free energy of micellization (∆G _mic) of these surfactants and the monomeric cationic surfactants DTAB and CTAB have been determined by means of electric conductivity measurements. In addition, the temperature dependence of the CMC was determined for the 10-2-10 gemini surfactant. The CMCs of the gemini surfactants are found to be much lower than those of the corresponding monomeric surfactants and the effect of the hydrophobic alkyl chain length is more important than that of the spacer. The CMC of 16-s-16 passes through a maximum of (or around) s = 6 and then decreases for s = 10. The presence of a maximum CMC is explained by the contribution of a change of conformation of the surfactant with increasing spacer chain length. The changes of α with s and m are found qualitatively similar to those found for CMC values. The values of ∆G _mic are more negative for the dimers than for the monomers and also change with an increasing spacer carbon number, as CMC values do. The thermodynamic parameters of micellization indicate that the micellization of 10-2-10 is enthalpy driven.     

Synthesis,Surface Activity,and Biological Activities of Phosphonium and Metronidazole Salts

A series of phosphonium amphiphilic compounds was synthesized. Cationic parts of molecules contain triphenylphosphonium moieties. Lipophilic parts of compounds are represented by straight alkyl chain or the alkyl chains which are ornamented by benzyl or metronidazole. The physicochemical properties of phosphonium amphiphilic compounds were investigated by the measurements of surface tension and conductivity. The critical micelle concentration (cmc), the surface tension value at the cmc (γ_cmc), the surface area at the surface saturation per head group (A_cmc) were determined. The lowest cmc value was determined for phosphonium salts with straight dodecyl alkyl chain. Its value was 1.5 × 10⁻³ mol dm⁻³. Surface tension at the cmc decreases with the addition of bulky moieties (benzyl, radical from metronidazol) at the end of alkyl chains. Biological activities of compounds were studied on human erythrocytes and strains of Acanthamoeba lugdunensis and Acanthamoeba quina. Dodecyltriphenylphosphonium bromide showed the highest activity against Acanthamoeba. To the best of our knowledge, it is the first compound of the group of phosphonium amphiphiles, which exhibited high activity against Acanthamoeba. The determined structure–activity relationship indicated nonspecific trophocidal and hemolytic activity that depends on physicochemical properties of the studied compounds.     

Salt Effect on the Solution Properties of Cationic Gemini/Conventional Surfactants in the Presence of the Nonionic Polymer Hydroxypropylmethyl Cellulose

In this article, we report the salt effect on interaction of a water-soluble polymer hydroxypropylmethyl cellulose (HPMC) with the cationic Gemini surfactant (ethane-1, 2-diyl bis(N,N-dimethyl-N-hexadecylammoniumacetoxy) dichloride, 16-E2-16), and also its monomeric counterpart cetyltrimethylammonium chloride (CTAC) using the tensiometric method. Surface tension of the amphiphiles diminished in the presence of the polymer as well as salts; eventually, the polymer gets saturated with the surfactant and there is no further change of surface tension of the solution. Interaction between the polymer and surfactant starts at the critical aggregation concentration (CAC) that is stronger for 16-E2-16 than CTAC. CAC and critical micelle concentration (CMC) values of the surfactant-polymer binary mixtures at various concentrations of the polymer were determined. CAC as well as CMC of 16-E2-16 are considerably lower than CTAC. The inorganic salts (KCl and KBr) have a considerable influence on the polymer–surfactant interaction.     

Biological Behaviors of Guanidine-Based Cationic Surfactants

The biological properties of novel guanidine‐based cationic surfactant including mono‐alkylguanidine (CnG), N,N,N′‐dimethyl alkylguanidine (CnMG), dicephalic guanidine surfactant (CnGQ), heterogemini guanidine surfactant (diCnGQ) were investigated. Antimicrobial activity was determined via the inhibition of cell viability of the prepared compounds, which was measured against three strains of a representative group of microorganisms. The inhibitions of cell viability were basically about 90 % at the concentration of 25 mg L^?1 to alkyl guanidium salts (CnG, CnMG), and higher than 95 % at a concentration of 10 mg L^?1 to dicephalic guanidine surfactants (CnGQ) and heterogemini guanidine surfactants (diCnGQ). The interactions of bovine serum albumin (BSA) with guanidine surfactants were investigated by fluorescence technology and the effect on BSA conformation follow the order: diC12GQ > C12GQ > C12G > C12MG. At any particular concentration, the biological activity depends on the alkyl chain length to any series of guanidine‐based cationic surfactants.     

Interactions of Glycols with Dodecyl Isothiouronium Cationic Surfactant on the Surface Active Parameters

Surface properties of the dodecyl isothiouronium cationic surfactant in a mixed solvent of water and polyethylene glycol of different molecular weights varied from ethylene glycol to polyethylene glycol-600 were determined using surface tension and conductivity measurements. The results showed an increase in the surface properties including critical micelle concentration, effectiveness and efficiency, compared to the surfactant in pure water as the solvent. The interaction between the cationic surfactant and the glycols was described and the molecular weight of the different glycols was rationalized.     

Modulation in Aggregation Behavior of Cationic Surfactant in Presence of Fluoroquinolone Drug: A Physicochemical Approach

Measurements of density, speed of sound, conductivity, and fluorescence spectroscopy have been carried out to study the interactions between cationic surfactant cetyltrimethylammonium bromide in an aqueous solution of the fluoroquinolone drug at different concentrations and temperatures. Volumetric and compressibility parameters, such as apparent molar volumes ( V _φ ), isentropic compressibility ( κ _s ), and apparent molar isentropic compressibility (κ _{φ, s}) , have been obtained from density and speed of sound. The critical micelle concentration (CMC) of cetyltrimethylammonium bromide (CTAB) is found to decrease with an increase in [antibiotic drug] and increase with an increase in temperature, accounting for the fact that hydrophilic dehydration plays a decisive role for micellization to take place. The various thermodynamic parameters indicate the spontaneity of micellization in the presence of drug moiety. The CMC values have been calculated using pyrene as a fluorescent probe at room temperature, and a good qualitative correlation is found to exist well with the CMC values determined using speed of sound and conductivity measurements.     

Surface activity of quaternary ammonium salts derived from jojoba oil

A number ofcis andtrans quatenary ammonium salts were synthesized from jojoba oil. All derivatives were found to be surface active agents, i.e., they reduced the surface tension to 35 dynes/cm⁻¹, at very low concentrations. The relationship between the surface activity and the molecular structure is discussed.