1155-74-4Relevant academic research and scientific papers
The Salt-Induced Sphere-Rod Transition of Micelles of 1-Tetradecylpyridinium Bromide in Aqueous NaBr Solutions
Fujio, Katsuhiko
, p. 83 - 89 (1998)
Static light scattering from aqueous NaBr solutions of 1-tetradecylpyridinium bromide (TPB) has been measured over the range of NaBr concentrations from 0 to 0.50 mol dm-3 at 25 °C, and the micelle molecular weight has been estimated. For 0 - 0.20 mol dm-3 NaBr, the reduced intensity of scattered light does not show any angular dependence, and the molecular weight of the spherical micelle of TPB slightly increases from 27.6×103 to 41.4×103 with increasing NaBr concentration. Beyond 0,20 mol dm-3 NaBr, the angular dissymmetry of the reduced scattering intensity and a steep increase in the micelle molecular weight from 41.4×103 to 177.8×103 are observed. Therefore, TPB has been considered to form rodlike micelles. The linear double logarithmic relationship between molecular weight and ionic strength holds for spherical and rodlike micelles, respectively. From the intersection of these two lines, the threshold NaBr concentration for the sphere-rod trainsition of TPB micelle is estimated to be 0.19 mol dm-3 where the micelle has a molecular weight of 41.3×103.
Effect of Alcohols and Oils on the Kinetics of Micelle Formation-Breakdown in Aqueous Solutions of Ionic Surfactants
Lang, Jacques,Zana, Raoul
, p. 5258 - 5265 (1986)
The temperature-jump method has been used for an extensive study of the dependence of the relaxation time τ2 characterizing the process of micelle formation-breakdown on the surfactant concentration C and upon additions of alcohols and oils to moderately concentrated surfactant solutions.The 1/τ2 vs.C curves have been found to be V-shaped, as in previous studies.For the four surfactants investigated, the increase of 1/τ2 at high C has been interpreted in terms of rapid coagulation-fragmentation processes postulated by Kahlweit (Kahlweit, M.Pure Appl.Chem. 1981, 53, 2060.J.Colloid Interface Sci. 1982, 90, 92).The changes of τ2 have been found to be very sensitive to the nature, chain length, and concentration of both the added alcohol and oil.Additions of medium chain length alcohols (up to 1-hexanol) increase dramatically 1/τ2 by up to a factor of 104.Additions of oils to mixed surfactant + alcohol micellar solutions result in the opposite effect.Longer chain alcohols behave like medium chain length alcohols at low alcohol concentration and like oils at high alcohol concentration, when they become solubilized in the micelle core.Additional measurements by means of time-resolved fluorescence probing and quasi-elastic light scattering have been performed in order to obtain information on the micelle aggregation number and the micelle size and polydispersity of some of the investigated systems.The observed changes of 1/τ2 upon addition of alcohols and oils have been interpreted in terms of variations of the concentration of the species around the minimum of the size distribution curve and, in turn, in terms of the polydispersity of the systems and its effect on the micelle breakdown-formation, in agreement with the quasi-elastic light-scattering results.The relationship between the present chemical relaxation results on micellar kinetics and those obtained recently by time-resolved fluorescence probing is discussed.
Micelle Size in Ethylammonium Nitrate As Determined by Classical and Quasi-Elastic Light Scattering
Evans, D. Fennell,Yamauchi, A.,Wei. G. Jason,Bloomfield, Victor A.
, p. 3537 - 3541 (1983)
Aggregation of surfactants to form micelles in ethylammonium nitrate, a low melting fused salt, was investigated by classical and quasi-elastic light scattering.For tetradecylpyridinium bromide and hexadecylpyridinium bromide the following data were obtained: critical micelle concentrations, 8.0E-2 and 2.0E-2 mol kg-1; micellar aggregation numbers, 17 and 26; second virial coefficients, 1.64E-3 and 1.30E-3 mol cm3 g-2; and hydrodynamic radii, 14 and 22 Angstroem, respectively.The results are consistent with either a small classical spherical micelle containing only surfactant or a spherical mixed micelle containing surfactant and ethylammonium ions as a cosurfactant.The measured second virial coefficients are almost equal to those calculated for hard spheres and reflect highly screened electrostatic interactions in the totally ionized solvent.
Importance of solution equilibria in the directed assembly of metal chalcogenide mesostructures
Bag, Santanu,Kanatzidis, Mercouri G.
, p. 8366 - 8376 (2008)
We describe the new nanostructured Pt/Ge/Se materials prepared from the molecular units [Ge2Se6]4- and [GeSe 4]4- and linking Pt2+ ions in the presence of surfactant micelles. X-ray diffraction coupled with transmission electron microscopy images reveals hexagonal pore symmetry. The solvent dependence and solution speciation of these building blocks were investigated by means of multinuclear NMR spectroscopy and by fast atom bombardment (FAB) mass spectroscopy and it is shown that rapid exchange equilibrium is reached between species like [Ge4Se10]4-, [Ge 2Se6]4-, and [GeSe4]4- in both water and formamide. This results in multiple Ge/Se anions being incorporated in the mesostructured materials which is supported by Raman and IR spectroscopic data. It is likely that the presence of multiple building units both in water and formamide solutions favors the assembly of mesostructured metal chalcogenides with good pore order. Systematic variation of both surfactant headgroup and chain length modulates the optoelectronic properties of the mesostructures. The Pt/Ge/Se materials show sharp band gap transitions in the range of 1.24-1.97 eV. Finally, the materials exhibit reversible ion-exchange properties and a marked inorganic framework flexibility that enables a contraction-expansion process in response to the exchange. The Pt/Ge/Se framework possesses a very high surface area as estimated by small-angle X-ray scattering techniques.
Structure-activity relationship modeling and experimental validation of the imidazolium and pyridinium based ionic liquids as potential antibacterials of mdr acinetobacter baumannii and staphylococcus aureus
Semenyuta, Ivan V.,Trush, Maria M.,Kovalishyn, Vasyl V.,Rogalsky, Sergiy P.,Hodyna, Diana M.,Karpov, Pavel,Xia, Zhonghua,Tetko, Igor V.,Metelytsia, Larisa O.
, p. 1 - 15 (2021/01/14)
Online Chemical Modeling Environment (OCHEM) was used for QSAR analysis of a set of ionic liquids (ILs) tested against multi-drug resistant (MDR) clinical isolate Acinetobacter baumannii and Staphylococcus aureus strains. The predictive accuracy of regression models has coefficient of determination q2 = 0.66 ? 0.79 with cross-validation and independent test sets. The models were used to screen a virtual chemical library of ILs, which was designed with targeted activity against MDR Acinetobacter baumannii and Staphylococcus aureus strains. Seven most promising ILs were selected, synthesized, and tested. Three ILs showed high activity against both these MDR clinical isolates.
Micelle formation as a factor influencing the mode(s) of metal ion partitioning into: N -alkylpyridinium-based ionic liquids (ILs): Implications for the design of IL-based extraction systems
Wankowski, James L.,Kaul, Michael J.,Dietz, Mark L.
supporting information, p. 5674 - 5682 (2017/12/06)
Prior studies of metal ion partitioning between an acidic aqueous phase and an ionic liquid in the presence of a macrocyclic polyether have demonstrated that the overall partitioning is a composite of three distinct pathways: neutral complex/ion-pair extraction, exchange of a cationic metal-crown ether (CE) complex for the cationic constituent of the IL, and exchange of the metal ion for a hydronium ion in a CE-H3O+ complex formed during acid preconditioning of the IL. The obvious undesirability of the ion-exchange pathways, which can lead to substantial loss of the IL cation to the aqueous phase, has led to efforts to identify means by which these processes can be suppressed or eliminated. Prior work with N,N′-dialkylimidazolium and quaternary ammonium bis [(trifluoromethyl)sulfonyl]imides has shown that increasing the hydrophobicity of the IL cation can be an effective means of diminishing the contribution of ion-exchange. Work with the corresponding N-alkylpyridinium ILs, however, indicates that in certain instances, an increase in the hydrophobicity of the IL cation is accompanied by a marked increase in its propensity to self-associate, leading to the formation of micelles in the aqueous phase. The net effect is to diminish or even negate the expected beneficial effect of IL cation hydrophobicity in reducing the contribution of ion exchange to the overall metal ion partitioning process, adversely impacting the "greenness" of extraction processes employing these ILs.
Synthesis, characterization and conductivity of quaternary nitrogen surfactants modified by the addition of a hydroxymethyl substructure on the head group
Jordan, Deborah,Tan, Eng,Hegh, Dylan
, p. 587 - 592 (2012/10/29)
Two novel series of hydroxymethyl group-appended quaternary nitrogen surfactants (QNSs) based on the aliphatic N-alkyl-trimethylammonium and aromatic N-alkylpyridinium head groups were synthesized from the appropriate nitrogen head group precursor and 1-bromoalkane. The QNSs were characterized using 1H and 13C nuclear magnetic resonance and infrared spectroscopy, and their purity confirmed using elemental analysis. The solution behavior of the QNSs was investigated by conductivity, assessing both the aggregation concentration as well as the amount of counter-ion dissociation. The results showed a general decrease in the aggregation concentration for the compounds with the hydroxymethyl addition, where the pyridinium compounds were more affected than the ammonium QNSs. In contrast, the extent of counter-ion dissociation (α) from the aggregate was slightly increased for the ammonium compounds but that of the pyridinium compounds was not generally affected by the structural modification.
Preparation of the pyridinium salts differing in the length of the N-alkyl substituent
Marek, Jan,Stodulka, Petr,Cabal, Jiri,Soukup, Ondrej,Pohanka, Miroslav,Korabecny, Jan,Musilek, Kamil,Kuca, Kamil
experimental part, p. 1967 - 1972 (2010/09/08)
Quaternary pyridinium salts with chains ranging from C8 to C20 belong in the large group of cationic surfactants. In this paper, the preparation of such cationic surface active agents based on the pyridinium moiety and differing in the length of the N-alkyl chain is described. Additionally, HPLC technique was established to distinguish each prepared pyridinium analogue. This study represents universal method for preparation and identification of quaternary pyridinium detergents.
Binding of N-Alkylpyridinium Chlorides to Nonionic Micelles
Shirahama, Keishiro,Nishiyama, Yoshinori,Takisawa, Noboru
, p. 5928 - 5930 (2007/10/02)
Binding of N-alkylpyridinium chlorides (C10, C12, and C14) to dodecyl oxyethylene ether (C12E6 and C12E8) micelles is determined in the presence of 5 mol m-3 NaCl at various temperatures by potentiometry which employs an electrode responsive to the surfactants.Binding affinity is expressed in terms of a distribution coefficient, Kx, of a cationic surfactant between the aqueous bulk phase and the nonionic micellar phase, and is larger for an alkylpyridinium cation with a longer hydrocarbon chain.The values of Kx are divided into three regions depending on the mole fraction of bound cationic surfactant in a micelle, X.At X x remains constant, while for 0.02 0.2.The constant Kx values reflect an intrinsic binding affinity (K0).With increase in X, electrostatic repulsion among bound cationic surfactants causes decreased Kx values, which may be analyzed by a simple electrostatic theory to estimate the position of bound cationic head groups.From the temperature dependence of K0, it is found that the binding process is nearly athermal for C12E8 micelles but exothermic for C12E6 micelles, the latter associated with the growth of micellar size with temperature.
