- Micellization, surface activities and thermodynamics study of pyridinium-based ionic liquid surfactants in aqueous solution
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The micellization and surface activity properties of long-chain pyridinium ionic liquids n-Alkyl-3-methylpyridinium bromide ([Cnmpy][Br], n: The carbon numbers of hydrophobic tails, n = 12, 14, 16) in aqueous solution were systematically investigated through electronic conductivity measurement, surface tension, and ultraviolet-Absorption spectra. The surface chemical parameters and thermodynamics parameters were obtained. The [Cnmpy][Br] ionic liquids exhibit higher surface activities than conventional surfactants with corresponding alkyl chain lengths. The effects of inorganic salts (LiBr, NaBr, MgBr2), organic alcohols (C2H5OH, C3H7OH, C4H9OH, C5H11OH) and temperature on the critical micelle concentration (CMC) values of [Cnmpy][Br] aqueous solutions were also investigated. The CMC values remarkably decreased with the addition of inorganic salts. The CMC values increased slightly in the presence of ethanol, but decreased gradually as the chain length of the alcohol increased. The CMC values assumed a trend of decreasing and then increasing with the increase of temperature. The calculation results of thermodynamic parameters show that both adsorption and micellization processes of [Cnmpy][Br] are spontaneous; the enthalpy of [C12mpy][Br] is negative at 293.15 K and becomes negative with temperature increasing. For [C14mpy][Br] and [C16mpy][Br] this transition occurs at 288.15 K and the micellization process is entropy-driven in the investigated temperature range.
- Fu, Dong,Gao, Xiaoru,Huang, Bo,Wang, Jue,Sun, Yao,Zhang, Weijun,Kan, Kan,Zhang, Xiaochen,Xie, Yang,Sui, Xin
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- Wide-Antimicrobial Spectrum of Picolinium Salts
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Nosocomial infections, which greatly increase morbidity among hospitalized patients, together with growing antibiotic resistance still encourage many researchers to search for novel antimicrobial compounds. Picolinium salts with different lengths of alkyl chains (C12, C14, C16) were prepared by Menshutkin-like reaction and evaluated with respect to their biological activity, i.e., lipophilicity and critical micellar concentration. Picolinium salts with C14 and C16 side chains achieved similar or even better results when in terms of antimicrobial efficacy than benzalkoniums; notably, their fungicidal efficiency was substantially more potent. The position of the methyl substituent on the aromatic ring does not seem to affect antimicrobial activity, in contrast to the effect of length of the N-alkyl chain. Concurrently, picolinium salts exhibited satisfactory low cytotoxicity against mammalian cells, i.e., lower than that of benzalkonium compounds, which are considered as safe.
- Benkova, Marketa,Dolezal, Rafael,Gunde-Cimerman, Nina,Kuca, Kamil,Malinak, David,Marek, Jan,Prchal, Lukas,Salajkova, Sarka,Sep?íc, Kristina,Sleha, Radek,Soukup, Ondrej
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- β-CD assisted aqueous dissolution of cetylpicolinium dichromates (CPDC)—Evolution of a class of green water compatible lipopathic Cr(VI) oxidants
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Water-insoluble lipopathic dichromates have been successfully solubilized in aqueous phase by the entrapment of their hydrophobic tails in β-cyclodextrin (β-CD) non-polar cavity. Aqueous solubility of α-, β-, and γ- cetylpicolinium dichromate (CPDC) molecules, synthesized in our lab, has been studied to find their suitability for Cr(VI) oxidation purposes in water medium. The analysis of phase solubility shows the existence of a Bs type curve and its significance has been fully deciphered through dynamic light scattering (DLS) analysis. The limiting concentration of β-CD up to which it can induce 1:1 host-guest complexation with the CPDC entities, has been determined and the stoichiometry has been confirmed from Job's plot. The binding constant and complexation efficiency of the β-CD-CPDC complexes have been determined and temperature effect on these parameters has been discussed through thermodynamic calculations. Analyses of viscosity variation of the aqueous solutions of the complexes have been done and correlated with the solubilization phenomenon.
- Priyadarshini, Supriya,Guru, Partha Sarathi,Dash, Sukalyan
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p. 122 - 128
(2017/05/15)
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