CH3)2 Research Articles

Surface Activities, Antibacterial Activity and Corrosion Inhibition Properties of Gemini Quaternary Ammonium Surfactants with Amido Group and Carboxylic Counterions.

A series of gemini quaternary ammonium surfactants containing carboxylate counterion with the formula C17H35CONH(CH2)2N+(CH3)2(CH2)2N+(CH3)2(CH2)2 NHCO C17H35·2Y (Y=HCOO-, CH3COO-, CH3CHOHCOO-) have been synthesized by a counterion conversion process and characterized by Fourier transform infrared spectroscopy and mass spectroscopy. It is found that these surfactants reduce the surface tension of water to a minimum value of 26.78 mN·m-1 at a concentration of 1.21 ×10-5 mol·L-1. TEM images reveal that aggregates with vesicles or tubular structure are spontaneously formed in these surfactants aqueous solution with the concentration of 1×10-3 mol·L-1. It is also found that they are effective corrosion inhibitors for A3 steel in acid solution and have superior antibacterial activity at a concentration of 0.1g·L-1.

The surface adsorption, aggregate structure and antibacterial activity of Gemini quaternary ammonium surfactants with carboxylic counterions.

A group of Gemini quaternary ammonium surfactants with the formula CnH2n+1CONH(CH2)2N+(CH3)2(CH2)2N+(CH3)2(CH2)2 NHCOCnH2n+1 · 2Y (n = 11, 13 and 15, Y = HCOO−, CH3COO− and CH3CHOHCOO−) have been synthesized by a counterion conversion process and characterized by Fourier transform infrared spectroscopy and mass spectroscopy. Their adsorption and self-aggregation properties are investigated by surface tension, conductivity, dynamic light scattering and transmission electron microscopy (TEM) measurements. The results show that these surfactants reduce the surface tension of water to a minimum value of 26.51 mN m−1 at a concentration of 5.72 × 10−2 mmol l−1. Furthermore, the increased alkyl chain length of the carboxylic counterions leads to the increased critical micelle concentration, the decreased degree of counterion binding (β) and the decreased self-assembly tendency, but the minimum area per surfactant molecule (Amin) adsorbed at the air–aqueous solution are similar. TEM images reveal that these surfactants self-assemble spontaneously into aggregates with vesicle or bilayer structures. It is also found that they have superior antibacterial activity at a concentration of 0.1 g l−1. The high surface activity and high antibacterial activity of the Gemini quaternary ammonium salt surfactants containing different carboxylic counterions bring more possibilities for the application in the field of biomedicine.

Reversed Micelles Formed by Polyfluorinated Surfactant II; the Properties of Core Water Phase in Reversed Micelle

Abstract The properties of water phase in reversed micelle formed by (CF3CONH(CH2)2N+(CH3)2(CH2)15CH3 Br− (C1F)) were investigated. The polarity and pH of water phase in reversed micelle were studied by dye probe method using porphyrin derivatives and alizarin red S. The mobility of water phase was studied by 1H NMR spectroscopy measuring the longitudinal relaxation time (T1) of water in the reversed micelle, and by near infrared (NIR) spectroscopy measuring absorption due to OH vibration. The effects of the w value (w = [water]/[C1F]) change on the polarity, pH, and mobility of water were examined. These measurements supported the biphase structure model of water in the reversed micelle. According to the analysis of polarity, the free water phase was estimated to be less polar than boundary water phase. The pH of water around the probe molecule in the reversed micelle was acidic and was not affected by the change of the w value. NIR spectroscopy of the reversed micelle indicated that OH vibration was much affected by the size of the water pool in the reversed micelle. The shift of absorption λmax due to OH vibration can be explained by the strong interaction between water and the ammonium group of the surfactant molecule.

Novel fluorinated quaternary ammonium salts and their in vitro activity as trypanocidal agents

As the impact of aromatic rings and fluorine substituents in commercial drugs is attributed to their electronic distribution and structure rigidity that determine metabolic stability and toxicity, 30 quaternary ammonium salts (QAS) of the form [X-CH2N(CH3)2(CH2)nCH = C(Ar2)]+I− (where X=H, Cl or I, n = 2 or 3, and Ar = m-C6H4CF3, p-C6H4CF3, m-C6H4F, p-C6H4F or C6H5) were tested as potential trypanocidal agents and assessed their cytotoxicity on U-937 cells. CF3-substituted QASs exhibited LC50 values in the range of 0.5 to 6.4 μg/mL and trypanocidal EC50 values between 0.6 and 7.0 μg/mL, while the LC50 values for F-substituted analogs are between 7.0 and 207 μg/mL and EC50 values range from 3.8 to 40.9 μg/mL. As a general trend, the more effective are those bearing an N-iodomethyl moiety or having a longer tether, and para-substituted ones. Few drugs therapies are in use for Chagas disease, so this study becomes a promising contribution.

Enhanced Aggregation of Stimuli Responsive Surfactants by Esterolytic Reactions.

Thioester surfactants, [C12H25N(CH3)2(CH2)mSCOCH3] Br (C12mSAc, m = 4, 11, 12), yielded thiol surfactants via thiol-thioester exchange upon addition of dithiothreitol in aqueous solution. The thiolthioester exchange reaction was enhanced in a micellar system owing to the concentration effect. The enhanced aggregation upon deprotection of the thioacetate group was observed by dynamic light scattering measurements. The thiol surfactants yielded disulfide-linked gemini surfactants upon air oxidation and incubation with hydrogen peroxide. In contrast, the thiol surfactants yielded thioester double-tailed products by esterolytic reactions with p-nitrophenyl hexanoate. The introduction of an alkyl chain to the second side chain significantly decreased the critical micelle concentration and induced the micellar growth.

Green Synthesis, Surface Activity, Micellar Aggregation, and Corrosion Inhibition Properties of New Gemini Quaternary Ammonium Surfactants

A new series of gemini quaternary ammonium surfactants containing amide groups with the formula CnH2n+1CONH(CH2)2N+(CH3)2(CH2)2 N+(CH3)2(CH2)2NHCOCnH2n+1·2CH3CO3– (n = 11, 13, 15, 17) have been synthesized by the using green reagent dimethyl carbonate. The structures of these surfactants were confirmed by Fourier transform infrared spectroscopy, 1H NMR, 13C NMR, and mass spectra. Their surface activities and aggregation properties were investigated by surface tension, conductivity, steady-state fluorescence, dynamic light scattering, and transmission electron microscope measurements. The results show that these synthesized gemini quaternary ammonium surfactants reduce the surface tension of water to a minimum value of 28.21 mN·m–1 at a concentration of 0.256 mmol·kg–1 and self-assemble spontaneously into double layer aggregates which are mostly single-room vesicles and multilamellar vesicles. Furthermore, with increasing alkyl chain length, their critical micelle concentration values and the degree of cou...

Aggregation Behavior and Thiol-Thioester Exchange for Cationic Surfactants with Propylthioacetate Side Chain.

A series of cationic surfactants containing the thioacetate group, [CnH2n+1N(CH3)2(CH2)3SCOCH3] Cl (Cn3SAc, n = 12, 14, 16), were prepared and their properties in aqueous solution were investigated by conductivity, fluorescence, and dynamic light scattering measurements. The critical micelle concentrations (CMCs) of Cn3SAc decreased to about half the value of the corresponding alkyltrimethylammonium chloride. Thioacetate was eliminated with the addition of dithiothreitol (DTT) as well as NaOH. HPLC (high performance liquid chromatography) analysis and NMR (nuclear magnetic resonance) spectroscopy showed that thiol surfactants, [CnH2n+1N(CH3)2(CH2)3SH]Cl (Cn3SH), were generated upon the addition of DTT in aqueous solution via thiol-thioester exchange, whereas gemini surfactants, [CnH2n+1N(CH3)2(CH2)3SS(CH2)3N(CH3)2CnH2n+1]2Cl (2Cn3SS), were generated upon incubation in alkaline solution via hydrolysis and air oxidation.

Aggregation and pH Responsive Behavior of Thioester Surfactants and Formation of Disulfide Linkages in Aqueous Solutions.

pH responsive surfactants, [C12H25N(CH3)2(CH2)nSCOCH3]Br (C12nSAc, n = 4, 11, 12), were prepared, and their properties in aqueous solution were examined. The critical micelle concentration (cmc) and critical vesicle concentration (cvc) were determined based on changes in conductivity, as well as by fluorescence measurements, and light scattering methods. A significant increase in the light scattering intensities of the C12nSAc (n=11, 12) systems suggested that the growth of aggregates was accompanied by considerable counterion binding with increasing surfactant concentration. The diameter of C1211SAc, recorded by the dynamic light scattering measurements, was about 9.6 ±1.0 nm, which was slightly smaller than that for didodecyldimethylammonium bromide (DDAB) vesicles. The thioester group was easily hydrolyzed upon the addition of NaOH, while it was hardly hydrolyzed with the addition of HCl. The time course of alkaline hydrolysis was examined by the conductivity measurements and high-performance liquid chromatography analysis. [C12H25N(CH3)2(CH2)11SS(CH2)11N(CH3)2C12H25]2Br (2C1211SS) was generated in the C1211SAc alkaline solution because of air oxidation. The C1211SAc alkaline solution gradually became an opaque blue color with increasing light scattering at 346 nm, indicating the remarkable growth of vesicles. The chemical structure of 2C1211SS was consistent with that of a disulfide linked double tailed surfactant, similar to DDAB. The disulfide linkage between the double tailed surfactants will contribute to the stabilization and growth of vesicles.

Aggregation Behavior of Disulfide Linked Gemini Surfactants Compared to that of Double Tailed Surfactants.

Disulfide linked gemini surfactant having a long spacer chain, [C10H21N(CH3)2(CH2)11SS(CH2)11N(CH3)2C10H21]2Br (2C1011SS), was prepared by the hydrolysis and oxidation process of thioester group for [C10H21N(CH3)2(CH2)11SCOCH3]Br. The critical vesicle concentrations of double tailed surfactants such as dialkyldimethylammonium bromide were observed by the conductivity and light scattering methods. The disulfide bonds of gemini surfactant, [C12H25N(CH3)2CH2CH2SSCH2CH2N(CH3)2C12H25]2Br (2C12SS), were rapidly cleaved by the addition of water-soluble dithiothreitol. However, it took long time to cleave the disulfide bonds of so-called double tailed surfactants 2C1011SS due to vesicle formation. The dynamic light scattering method showed that the diameters of 2C12SS micelles were increased with the cleavage of disulfide bonds, whereas those of 2C1011SS aggregates remained almost constant at 17.6 ±1.3 nm in similar size with dialkyldimethylammonium bromide vesicles. The time course of disulfide cleavage was examined by the conductivity and HPLC analysis. The produced thiol surfactants were returned to their original gemini surfactants by the addition of H2O2.

Kinetic Influence of Siliceous Reactions on Structure Formation of Mesoporous Silica Formed via the Co-Structure Directing Agent Route

We investigate the mechanism responsible for the formation of mesoporous silica formed with the so-called costructure directing agent (CSDA) route. The synthesis relies on the interaction between silica source (tetraethylorthosilicate), cationic surfactant (C18H37N+(CH3)2(CH2)3N+(CH3)3Br2), and CSDA (carboxyethylsilanetriol), which results in a material functionalized with carboxylic groups. Depending on the concentration of HCl in the synthesis, the structure is defined by Fm3m (at high pH) and by Fd3m (at low pH), with a gradual transition in the intermediate pH range. Here, we aim at finding the origin for the structural change triggered by pH and investigate the effects of the hydrolysis of the silica source on the overall kinetics of the synthesis. A fast process results in Fm3m, regardless of pH, and a slow process results in Fd3m. The hydrolysis step is the important structural control parameter. We studied the cross-linking of silica and CSDA using 29Si NMR. The cross-linking is similar for th...

Ionic binuclear ferrocenyl compounds containing 1,1,3,3-tetracyanopropenide anions – synthesis, structural characterization and catalytic effects on thermal decomposition of main components of solid propellants

Abstract Alkyl-substituted ferrocenes are typical burning-rate catalysts in composite solid propellants, but their high migration tendency and volatility has impeded their extensive applications. By introducing the concept of ionic energetic compounds, eight new ionic binuclear ferrocenyl compounds, [FcCH2N(CH3)2(CH2) n N(CH3)2CH2Fc]2+ (X– 2) (Fc = ferrocenyl; X– = 1,1,3,3-tetracyano propenide; n = 3–10; the compounds being numbered consecutively 1–8), were prepared and characterized. The molecular structures of 1, 2, and 4 were determined by single-crystal X-ray diffraction, and their cations were studied by density functional theory calculations (DFT). Compounds 1–5 show high thermal stability but 6–8 are slightly volatile. The results of cyclic voltammetry studies suggest that each salt exhibits a quasireversible redox system. Catalytic effects of the new salts on thermal degradation of ammonium perchlorate (AP), 1,3,5-trinitro-1,3,5-triaza-cyclo-hexane (RDX), and 1,2,5,7-tetranitro-1,3,5,7-tetraazacyclooctane (HMX), have been investigated by DSC and/or TG methods. The results show that the new compounds can bring the peak temperatures of both AP and RDX down significantly and enhance their heat release dramatically, indicating that the ferrocenyl salts possess high catalytic efficiency for the thermal decomposition of AP and RDX. Their catalytic activities are nearly equal to or higher than that of the corresponding nitrates and picrates, as well as their mononuclear counterparts. Compound 6 also efficiently catalyzes the thermal decomposition of hydroxyl-terminated polybutadiene (HTPB) and 1:1 mixtures of HTPB and AP.

Microstructure and the Mobility of Fluorinated Carbon Chain of Reversed Micelles Formed by Cationic Polyfluorinated Surfactant

Abstract Cationic polyfluorinated surfactants (CnF2n+1CONH(CH2)2N+(CH3)2(CH2)15CH3Br−; CnF (n = 1–3)) form reversed micelles in organic solvents such as toluene. The reversed micelle formation and their properties were studied by 1H NMR and 19F NMR measurements. The cmc (critical reversed micelle concentration) and the aggregation numbers of reversed micelles formed by fluorinated surfactants were determined. The aggregation numbers of reversed micelles formed by fluorinated surfactant were calculated to be 9–12 in toluene. According to the analysis of NMR longitudinal relaxation time T1, the polyfluorinated reversed micelles were shown to have a very unique microstructure, in which the perfluoroalkyl chains orientate at the interface between organic and water phase, and the mobility of perfluoroalkyl chains in reversed micelles was relatively larger than that of micelles and vesicles. The 19F-T1 values of fluorine nuclei in the terminal trifluoromethyl group of were 750 ± 23, 740 ± 29, and 855 ± 93 ms for C1F, C2F and C3F, respectively.

Investigations on reverse cationic flotation of iron ore by using a Gemini surfactant: Ethane-1,2-bis(dimethyl-dodecyl-ammonium bromide)

In this paper, a Gemini surfactant, ethane-1,2-bis(dimethyl-dodecyl-ammonium bromide) (EBAB), was introduced as a collector for reverse cationic flotation separation of quartz from magnetite, and its adsorption mechanisms on the two minerals and air/water interface were also investigated by FTIR spectra, zeta potential, density functional theory (DFT) calculation and surface tension. The flotation results showed that EBAB presented stronger collecting power than the conventional monomeric surfactant dodecylammonium chloride (DAC) and superior selectivity for quartz against magnetite. The results of FTIR spectra and zeta potential measurements demonstrated that the interaction of EBAB with quartz and magnetite was mainly through electrostatic attraction, which was further confirmed by DFT calculation. EBAB was preferred to adsorb on the negatively charged surface of quartz, increasing its zeta potentials and improving its hydrophobicity. Adsorption of EBAB at the quartz/water interface could be divided into four stages as the concentration of EBAB was increased in solution. At low concentrations, adsorption was controlled primarily by electrostatic interactions, but when the zeta potential of quartz was reversed from negative to positive, hydrophobic chain interactions controlled the adsorption process. EBAB’s unique properties, such as high positive grouping Mulliken charge of –CH2N+(CH3)2(CH2)2(CH3)2N+CH2–, and strong “surface activity” at the air–water interface, made it be a superior cationic collector for reverse flotation desilication from iron ores.

Ordered hexagonal mesoporous aluminosilicates with low Si/Al ratio: synthesis, characterization, and catalytic application.

Ordered hexagonal mesoporous aluminosilicates with lower Si/Al ratio below 5 have been successfully synthesized via the co-assembly of preformed aluminosilicate precursors with Gemini surfactant [C12H25N+(CH3)2(CH2)6N+(CH3)2C12H25] x 2Br(-) as the template. Powder X-ray diffraction, transmission electron microscopy, scanning electron microscopy, N2 adsorption-desorption isotherm measurements, Fourier transform infrared spectroscopy, 27Al nuclear magnetic resonance, thermogravimetric analysis, and temperature-programmed desorption of cyclohexylamine are employed to characterize the resulting samples. The phenol alkylation reaction is carried out to evaluate their catalytic performances. These studies indicate that the sample with a low Si/Al ratio of 3 still retains a highly ordered hexagonal mesoporous structure. And it also possesses the highest acidity of 0.96 mmol among the samples with lower Si/Al ratios below 5 due to its higher specific surface area together with more content of tetrahedrally coordinated Al in the framework. The catalytic tests confirm that the acidity of the samples plays a key role in determining their catalytic performances.

Interaction of nitrogen and hydrocarbon vapors with mesoporous silicas modified with perfluorohexylsilane

Using the static method and gas chromatography, the adsorption of nitrogen and hydrocarbons by SBA-15 silicas and commercially available silica gel (SG), as well as changes in the surface properties of these samples as a result of chemical modification with multifunctional perfluorohexylsilane ClSi(CH3)2(CH2)2(n-C6F13), are studied. The main factor that causes the high values of thermodynamic characteristics of adsorption on SBA-15 and its modified form is a relatively small pore size. The differences in the polarities of the samples testify to a high concentration of silanol groups on the initial and modified SG.

Silicon Phthalocyanine 4 Phototoxicity in Trichophyton rubrum

Trichophyton rubrum is the leading pathogen that causes long-lasting skin and nail dermatophyte infections. Currently, topical treatment consists of terbinafine for the skin and ciclopirox for the nails, whereas systemic agents, such as oral terbinafine and itraconazole, are also prescribed. These systemic drugs have severe side effects, including liver toxicity. Topical therapies, however, are sometimes ineffective. This led us to investigate alternative treatment options, such as photodynamic therapy (PDT). Although PDT is traditionally recognized as a therapeutic option for treating a wide range of medical conditions, including age-related macular degeneration and malignant cancers, its antimicrobial properties have also received considerable attention. However, the mechanism(s) underlying the susceptibility of dermatophytic fungi to PDT is relatively unknown. As a noninvasive treatment, PDT uses a photosensitizing drug and light, which, in the presence of oxygen, results in cellular destruction. In this study, we investigated the mechanism of cytotoxicity of PDT in vitro using the silicon phthalocyanine (Pc) 4 [SiPc(OSi(CH3)2(CH2)3N(CH3)2)(OH)] in T. rubrum. Confocal microscopy revealed that Pc 4 binds to cytoplasmic organelles, and upon irradiation, reactive oxygen species (ROS) are generated. The impairment of fungal metabolic activities as measured by an XTT (2,3-bis[2-methoxy-4-nitro-5-sulfophenyl]-2H-tetrazolium-5-carboxyanilide inner salt) assay indicated that 1.0 μM Pc 4 followed by 670 to 675 nm light at 2.0 J/cm(2) reduced the overall cell survival rate, which was substantiated by a dry weight assay. In addition, we found that this therapeutic approach is effective against terbinafine-sensitive (24602) and terbinafine-resistant (MRL666) strains. These data suggest that Pc 4-PDT may have utility as a treatment for dermatophytosis.

Synthesis and Characterization of a Quaternized Glucosamide‐Based Trisiloxane Surfactant

AbstractThe synthesis of quaternized glucosamide‐based trisiloxane surfactant (QGS) of the general formula Me3SiOSiMeR1OSiMe3(R1= (CH2)3N+(CH3)2(CH2)2R2, R2= glucosamide group) was described, and the surface activity properties of the surfactant were studied. TheN‐[2‐(dimethylamino)ethyl]‐d‐gluconamide was synthesized by amidation of the ethylenediamine withd‐gluconolactone. The 3‐(3‐chloropropyl)‐1,1,1,3,5,5,5‐heptamethyltrisiloxane was prepared by the acid‐catalyzed reaction of a silane monomer. The QGS was prepared by quaternization of the precursor halogenated hydrocarbon with a tertiary amine. They were structurally characterized by IR,1H NMR and MS. And it reduced the surface tension of water to approximately 21 mN m−1at concentration levels of 10−3mol L−1.

Gemini trisiloxane surfactant: Synthesis and flotation of aluminosilicate minerals

In this paper, an amino-trisiloxane Gemini cationic surfactant, butane-1,4-bis(dimethyl-(3-(3-aminopropyl trisiloxane-3-yl)-propyl)-ammonium bromide) (BBAB) was prepared, and its flotation potential was assessed on kaolinite, pyrophyllite and illite minerals. The flotation results showed that changes to the pulp pH did not significantly influence BBAB’s collecting power in floating three aluminosilicate minerals. In addition, BBAB was a stronger collector than the conventional monomeric surfactant dedecyl trimethylammonium bromide (DTAB) or dodecylamine (DDA). The results of FTIR spectra, zeta potential measurements and density functional theory (DFT) calculations indicated that the interaction of BBAB with the three aluminosilicates was mainly through electrostatic attraction. BBAB’s unique properties, such as high positive grouping Mulliken charge of –CH2N+(CH3)2(CH2)4(CH3)2N+CH2–, and “parachute” shape structure of [(CH3)3SiO]2SiCH3, resulted in superior collecting powers for the aluminosilicate minerals.

Investigation of structure–surface properties relationship of semi-fluorinated polymerizable cationic surfactants

Novel hybrid hydrocarbon/fluorocarbon ammonium type surfactant monomers (surfmers) of the general formula RF (CH2)l N(CH3)2(CH2)mOCOCH=CH2 with (RF=C4F9, C6F13, C8F17, l=4, 6, 11, and m=2–11) were synthesized and characterized. They exhibit very low surface tension as well as low critical micellar concentrations down to 1.39×10−5mol/L. Special attention was focused on theeffect of the polymerizable moiety, the length of the hydrocarbon spacers, and the fluorinated chains on surface activities of the reactive surfactants as compared to hydrocarbon surfmer analogs. Results indicate that the acrylic function has a pronounced effect on increasing the hydrophobic micelle character. This was confirmed by surface tensions and average surfaces occupied by these molecules at the water–gas interface. The micellar sizes were investigated by dynamic light scattering.

Kinetic study on effect of novel cationic dimeric surfactants for the cleavage of carboxylate ester

Kinetic study has been performed to understand the reactivity of novel cationic gemini surfactants viz. alkanediyl‐α,ω‐bis(hydroxyethylmethylhexadecylammonium bromide) C16‐s‐C16 MEA, 2Br− (where s = 4, 6) in the cleavage of p‐nitrophenyl benzoate (PNPB). Novel cationic gemini C16‐s‐C16 MEA, 2Br− surfactants are efficient in promoting PNPB cleavage in presence of butane 2,3‐dione monoximate and N‐phenylbenzohydroxamate ions. Model calculation revealed that the higher catalytic effect of ethanol moiety of gemini surfactants (C16H33N+ C2H4OH CH3 (CH2)S N+ C2H4OH CH3C16H33, 2Br−, s = 4, 6) is due to their higher binding capacity toward substrate. This is in line with finding that binding constants for novel series of cationic gemini surfactants are higher than conventional cationic gemini (C16H33N+(CH3)2(CH2)SN+(CH3)2C16H33, 2Br−, s = 10, 12), cetyldimethylethanolammonium bromide and zwitterionic surfactants, i.e. CnH2n+1N+Me2 (CH2)3 SO3− (n = 10; SB3‐10). The fitting of kinetic data was analyzed by the pseudophase model. Copyright © 2013 John Wiley & Sons, Ltd.