- Physico-chemical properties and nanoscale morphology in N-alkyl-N-methylmorpholinium dicyanamide room temperature ionic liquids
-
A series of new room temperature ionic liquids based on N-alkyl-N-methylmorpholinium cations (the alkyl chain ranging from ethyl to nonyl) and a hydrophilic anion (dicyanamide), a mostly unexplored class of room temperature ionic liquids (RTILs), has been synthesized and characterized. Selected physico-chemical properties (density, viscosity and ionic conductivity) have been measured and the salts' propensity to organize into ionic clusters has been explored. The inspection of their Walden plots and electrospray ionization spectra strongly prompts for the occurrence of clustering phenomena, especially for salts bearing long alkyl chains. This structural organization has been confirmed using X-ray scattering techniques and the existence of a high degree of intermediate range order has been detected, as fingerprinted by distinct diffraction features at low Q. These evidences are rationalized in terms of a structural model where, similarly to other RTILs, the alkyl chains tend to segregate from the charged moieties.
- Russina, Olga,Caminiti, Ruggero,Triolo, Alessandro,Rajamani, Sunita,Melai, Bernardo,Bertoli, Alessandra,Chiappe, Cinzia
-
-
Read Online
- Cation does matter: How cationic structure affects the dissolution of cellulose in ionic liquids
-
As a kind of promising solvents, ionic liquids (ILs) have been used to dissolve cellulose and great progress has been made in recent years. However, the dissolution mechanism, especially the role of cations of ILs in the dissolution of cellulose, is still in debate. In this work, 13 kinds of ILs with a fixed anion [CH3COO]- but varied cationic backbones and alkyl chains have been prepared and characterized. The solubilities of cellulose in these ILs were measured at different temperatures. This allowed us to systematically study the effect of cationic structures on the cellulose dissolution at a given temperature. In order to investigate the dissolution mechanism, Kamlet-Taft parameters of these ILs in the temperature range from 25 to 65 °C and 13C NMR spectra of 1-benzyl-3-methylimidazolium acetate ([phC1mim][CH3COO]) + cellulose systems at 90 °C were also determined. It was found that acidic protons on the heterocyclic rings of the cations are essential for the dissolution of cellulose in the ILs, but the van der Waals interaction of cation with cellulose is not important. These protons may form C-H...O hydrogen bonds with hydroxyl and ether oxygen of cellulose to increase cellulose solubility. Cations of the ILs may also decrease cellulose solubility by strong interaction with anions or steric hindrance effect of large size group in their alkyl chains. These interactions together with strong O-H...O hydrogen bonds between the anion and hydroxyl protons of cellulose resulted in the disruption of the inter- and intra-molecular hydrogen bonds and thus effective dissolution of cellulose.
- Lu, Benlian,Xu, Airong,Wang, Jianji
-
-
Read Online
- FCS study of the structural stability of lysozyme in the presence of morpholinium salts
-
Ability of the ionic liquids to alter the structural stability of proteins in aqueous solution is a topic of considerable interest in modern bioscientific research because of possible applications of these substances in protein purification and as refolding agents. A few early studies involving the imidazolium ionic liquids have demonstrated their role as both denaturants and refolding agents. As the influence of an ionic liquid on a given protein depends on the identity of both species, it is necessary to extend the studies to a wider number of ionic liquids and proteins to obtain insight into the mechanism of interaction between the two and to arrive at a comprehensive picture. It is in this context that we have studied the effect of two morpholinium salts, [Mor1,2][Br] and [Mor1,4][Br], differing in the alkyl chain length of cation, on chicken egg white lysozyme in its native and chemically denatured states employing primarily the fluorescence correlation spectroscopy (FCS) technique. Fluorescence signal of Alexa488-labeled lysozyme (A488-Lysz) has been used to determine the changes in hydrodynamic radius of protein in the presence of additives. The results reveal a conformational dynamics of lysozyme with a time constant of 56 ?± 10 ??s in its native state. It is observed, when in its native state, both the morpholinium salts induce structural changes of lysozyme. However, when in its unfolded state, [Mor1,4][Br] at low concentration compacts the protein, but at higher concentration, it stabilizes the unfolded state, unlike [Mor1,2][Br], which compacts lysozyme at both low and high concentrations. A comparison of the effect of these salts and arginine, a protein stabilizer, on lysozyme indicates that [Mor1,2][Br] is a superior compacting agent for the unfolded state of the protein compared to arginine. ? 2013 American Chemical Society.
- Pabbathi, Ashok,Ghosh, Shalini,Samanta, Anunay
-
-
Read Online
- Apparent molar volumes and expansivities of ionic liquids based on N -Alkyl- N -methylmorpholinium cations in acetonitrile
-
Densities of some acetonitrile solutions of ionic liquids based on N-alkyl-N-methyl-morpholinium cations, N-ethyl-N-methylmorpholinium bis(trifluoromethanesulfonyl)imide, N-butyl-N-methylmorpholinium bis(trifluoromethanesulfonyl)imide, N-methyl-N-octylmorpholinium bis(trifluoromethanesulfonyl)imide and N-decyl-N-methylmorpholinium bis(trifluoromethanesulfonyl)imide were measured at T = (298.15-318.15) K and at atmospheric pressure. From density data the apparent molar volumes and partial molar volumes of the ILs at infinite dilution as well as the limiting apparent molar expansibilities and the Hepler's constant values have been evaluated. The results have been discussed in terms of the effect that alkyl chain length of the ILs and experimental temperature have on the ionic liquid-acetonitrile interactions occurring in the studied solutions.
- Marcinkowski, Lukasz,Olszewska, Teresa,Kloskowski, Adam,Warminska, Dorota
-
p. 718 - 725
(2014/04/03)
-
- Photopolymerization of Poly(ethylene glycol) dimethacrylates: The influence of ionic liquids on the formulation and the properties of the resultant polymer materials
-
The photo-initiated polymerization of poly(ethylene glycol)dimethacrylates [PEGDM(n)] in the presence of various ionic liquids (ILs) is reported. The influence of ILs concentrations as well as of their nature upon the photopolymerization kinetics was studied in detail. It was found that according to reactive ability in bulk and in solution photopolymerization, the investigated monomers can be divided into two groups: PEGDM(1)-PEGDM(2)-PEGDM(3) and PEGDM(4)-PEGDM(7-8). ILs slightly influence the photopolymerization of monomers from the first group and greatly change kinetics of those from the second. Such behavior was explained by the theory of "kinetically favorable or unfavorable monomer associations." It was demonstrated that certain ILs accelerate the photopolymerization of the highest PEGDMs and offer access to the polymers derived from low reactive monomers. Relying on the obtained data, the attempt to predict the structu re of the "best" ionic additive for the given monomer photopolymerization was performed and proved. Finally, the influence of both residual and specially added ILs quantities upon the properties of obtained polymer materials was investigated. It was revealed that ILs can physically interact with polymer networks increasing their thermal stability, plasticizing films, and blocks, imparting ionic conductivity equal up to 3.62 × 10 -3 Sm/cm at 25 °C.
- Chesnokov, Sergey A.,Zakharina, Marya Yu.,Shaplov, Alexander S.,Lozinskaya, Elena I.,Malyshkina, Inna A.,Abakumov, Gleb A.,Vidal, Frederic,Vygodskii, Yakov S.
-
experimental part
p. 2388 - 2409
(2011/03/20)
-
- Ionic liquids based on N-alkyl-N-methylmorpholinium salts as potential electrolytes
-
Ionic liquids based on N-alkyl-N-methylmorpholinium salts have been synthesized and the physical and electrochemical characteristics of this family of ionic liquids have been investigated for use as electrolytes.
- Kim, Ki-Sub,Choi, Sukjeong,Demberelnyamba,Lee, Huen,Oh, Jaeseung,Lee, Byoung-Bae,Mun, Su-Jin
-
p. 828 - 829
(2007/10/03)
-