01292nas a2200157 4500008004100000022001400041245011000055210006900165260007300234300001200307490000800319520064800327100001900975700001600994856012401010 2010 eng d a0009-261400aReversal from endothermic to exothermic behavior of imidazolium-based ionic liquids in molecular solvents0 aReversal from endothermic to exothermic behavior of imidazoliumb aPO BOX 211, 1000 AE AMSTERDAM, NETHERLANDSbELSEVIER SCIENCE BVcAUG a143-1470 v4963 a

In this communication, we present an interesting reversal in the enthalpic behavior from endothermic to exothermic on increasing the carbon chain length attached to the imidazolium ring in the imidazolium-based ionic liquids. A systematic investigation is presented on the excess partial molar enthalpy, H(IL)(E) directly measured using isothermal titration calorimeter at 298.15 K for the interactions operating between cation and anion of four imidazolium ionic liquids with aqueous and various non-aqueous solvents. This reversal behavior is analyzed in terms of hydrophobic and solvation effects. (C) 2010 Published by Elsevier B.V.

1 aRai, Gitanjali1 aKumar, Anil uhttps://library.ncl.res.in/content/reversal-endothermic-exothermic-behavior-imidazolium-based-ionic-liquids-molecular-001993nas a2200157 4500008004100000022001400041245012300055210006900178260011000247300001600357490000700373520129700380100001901677700001601696856012301712 2011 eng d a1463-907600aEnthalpic approach to delineate the interactions of cations of imidazolium-based ionic liquids with molecular solvents0 aEnthalpic approach to delineate the interactions of cations of i aTHOMAS GRAHAM HOUSE, SCIENCE PARK, MILTON RD, CAMBRIDGE CB4 0WF, CAMBS, ENGLANDbROYAL SOC CHEMISTRYcJUN a14715-147220 v133 a

We present a systematic investigation on the enthalpic assessment of the interactions operating between the cation and anion of four imidazolium ionic liquids with aqueous and various nonaqueous solvents. Accurate experimental information gathered with the help of an isothermal titration calorimeter at 298.15 K has been analyzed for excess partial molar enthalpy of the ionic liquid, H(IL)(E), in terms of hydrophobic and solvation effects. The variations in the limiting excess partial molar enthalpy of the ionic liquid, H(IL)(E infinity), have been correlated with solvent properties. We have quantified the enthalpic effects due to dissociation of ionic liquids in very dilute solutions and to clathrate formation with the increasing concentration of ionic liquid. A change in enthalpic behavior from endothermic to exothermic is observed on increasing the carbon chain length attached to the imidazolium ring. The solvent reorganization around the cationic species has been unraveled by employing the ionic liquid interaction parameters called as H(IL-IL)(E) deduced from the H(IL)(E) data. The apparent relative molar enthalpy, phi(L), derived from H(IL)(E) data has been examined in the light of the specific ion interaction theory as advanced by Pitzer with accurate results.

1 aRai, Gitanjali1 aKumar, Anil uhttps://library.ncl.res.in/content/enthalpic-approach-delineate-interactions-cations-imidazolium-based-ionic-liquids-001300nas a2200217 4500008004100000022001400041245007400055210006900129260007700198300001400275490000700289520055100296653001600847653002300863653001800886653002000904653002000924100001900944700001600963856010300979 2012 eng d a1439-423500aProbing thermal interactions of ionic liquids with dimethyl sulfoxide0 aProbing thermal interactions of ionic liquids with dimethyl sulf aBOSCHSTRASSE 12, D-69469 WEINHEIM, GERMANYbWILEY-V C H VERLAG GMBHcMAY a1927-19330 v133 a

Interactions between ionic liquids and dimethyl sulfoxide (DMSO) are probed by isothermal titration calorimetry. The excess partial molar enthalpies of ionic liquids H-IL(E) in DMSO are discussed in terms of solutesolvent interactions. The specific interaction theory originally developed by Pitzer is used to analyze the apparent molar enthalpy phi(L) of ionic liquids in DMSO with the help of ion-interaction parameters. Furthermore, quantitative information on solvent reorganization and clathrate formation is obtained and interpreted.

10acalorimetry10adimethyl sulfoxide10aionic liquids10asolvent effects10athermochemistry1 aRai, Gitanjali1 aKumar, Anil uhttps://library.ncl.res.in/content/probing-thermal-interactions-ionic-liquids-dimethyl-sulfoxide-001145nas a2200157 4500008004100000022001400041245010200055210006900157260011000226300001400336490000700350520047000357100001900827700001600846856012500862 2013 eng d a1463-907600aInteresting thermal variations owing to cationic ring structural features in protic ionic liquids0 aInteresting thermal variations owing to cationic ring structural aTHOMAS GRAHAM HOUSE, SCIENCE PARK, MILTON RD, CAMBRIDGE CB4 0WF, CAMBS, ENGLANDbROYAL SOC CHEMISTRYcAPR a8050-80530 v153 a

The present communication divulges interesting thermal behavior of different protic ionic liquids arising due to the hydrophobicity modifications in their parent cationic ring structures. This work assists us in differentiating between protic ionic liquids, their aprotic counterparts and common electrolytes in water. The thermal signatures produced by protic ionic liquids, aprotic ionic liquids and electrolytes emerge as individual fingerprints for them.

1 aRai, Gitanjali1 aKumar, Anil uhttps://library.ncl.res.in/content/interesting-thermal-variations-owing-cationic-ring-structural-features-protic-ionic-001806nas a2200205 4500008004100000022001400041245009400055210006900149260005700218300001400275490000700289520103500296653001701331653002301348653003401371653003501405100001901440700001601459856012501475 2014 eng d a1618-954X00aCalorimetric elucidation of ionic interactions in room temperature ionic liquid solutions0 aCalorimetric elucidation of ionic interactions in room temperatu a233 SPRING ST, NEW YORK, NY 10013 USAbSPRINGERcDEC a1529-15360 v163 a

Knowledge of thermal properties of room temperature ionic liquid (RTIL) solutions is essential in chemical process designing in addition to their application in understanding ionic interactions at molecular level. RTILs are considered to be substitutes for volatile organic compounds. While some experimental thermal data on these systems are available in a random manner, the modeling efforts to correlate enthalpy-concentration profiles of RTIL solutions are very scanty. In this review, an effort has been made to compare and discuss the experimental data of these RTIL solutions available in the literature. The readers are also made aware of the disappointing situation regarding the availability of any type of correlative models for the enthalpy-concentration data of the RTIL systems. An accurate knowledge of activity coefficients at infinite dilutions, Iyen (i) (a) acquired from thermal data will serve as inputs for the newer less polluting process designing and thus open opportunity for a cleaner environment.

10aCalorimeters10aCorrelative models10aExcess partial molar enthalpy10aRoom temperature ionic liquids1 aRai, Gitanjali1 aKumar, Anil uhttps://library.ncl.res.in/content/calorimetric-elucidation-ionic-interactions-room-temperature-ionic-liquid-solutions-002059nas a2200157 4500008004100000022001400041245011100055210006900166260007100235300001400306490000800320520141500328100001901743700001601762856012301778 2014 eng d a1520-610600aElucidation of ionic interactions in the protic ionic liquid solutions by isothermal titration calorimetry0 aElucidation of ionic interactions in the protic ionic liquid sol a1155 16TH ST, NW, WASHINGTON, DC 20036 USAbAMER CHEMICAL SOCcAPR a4160-41680 v1183 a

The strong hydrogen-bonded network noted in protic ionic liquids (PILs) may lead to stronger interactions of the ionic entities of PILs with solvents (water, methanol, ethylene glycol, climethylsulfoxide (DMSO), N,N'-dimethylformamide (DMF)) as compared with those of aprotic ionic liquids (APILs). The PILs used in this work are 1-methylimidazolium tetrafluoroborate, 2-methylpyridinium tetrafluoroborate, and N-methylpyrrolodinium tetrafluoroborate in comparison to 1-butyl-3-methylimidazolium tetrafluoroborate, which is classified as an APIL. In this work, the excess partial molar enthalpy, H-IL(E) obtained from isothermal calorimetric titrations at 298.15 K is used to probe the nature of interactions of the PIL cations with solvent molecules against those present in APIL solvent systems. This work also reports interesting flip-flopping in the thermal behavior of these PIL-solvent systems depending upon the structure of the cationic ring of a PIL. In some cases, these flip-flops are the specific fingerprints for specific PILs in a common solvent environment. The excess partial molar enthalpy at infinite dilution, H-IL(E,infinity), of these PILs bears a critical dependence on the solvent properties. An analysis of relative apparent molar enthalpies, phi(L), of the PIL solutions by the ion interaction model of Pitzer yields important information on ionic interactions of these systems.

1 aRai, Gitanjali1 aKumar, Anil uhttps://library.ncl.res.in/content/elucidation-ionic-interactions-protic-ionic-liquid-solutions-isothermal-titration-001602nas a2200241 4500008004100000022001400041245015300055210006900208260007500277300001200352490000700364520070200371653002301073653001801096653002201114653002001136653000901156653001401165100001601179700001901195700001601214856013001230 2015 eng d a0095-978200aInteresting viscosity changes in the aqueous urea-ionic liquid system: effect of alkyl chain length attached to the cationic ring of an ionic liquid0 aInteresting viscosity changes in the aqueous ureaionic liquid sy a233 SPRING ST, NEW YORK, NY 10013 USAbSPRINGER/PLENUM PUBLISHERScAPR a742-7530 v443 a

In the present article, we demonstrate the effect of urea on the structure of the ionic liquids in their aqueous solutions through viscometric methods. We unravel the structure altering effect of urea in its aqueous solutions of ionic liquids possessing higher alkyl chains. The finding is an attempt to discern the anomalous behavior of urea as shown in the past with the help of many techniques. Interestingly, in the aqueous solutions of the imidazolium based ionic liquids having substitution of -C4H9 and -C6H13 groups on the imidazolium ring, urea exhibits kosmotropic behavior. Further increase in the substituted alkyl group such as -C8H17 alters the urea behavior to be chaotropic.

10aAlkyl chain length10aionic liquids10aStructure-breaker10aStructure-maker10aUrea10aviscosity1 aNanda, Raju1 aRai, Gitanjali1 aKumar, Anil uhttps://library.ncl.res.in/content/interesting-viscosity-changes-aqueous-urea-ionic-liquid-system-effect-alkyl-chain-length-001655nas a2200169 4500008004100000245015300041210006900194260000800263300001600271490000700287520093700294653007301231100001901304700001701323700001601340856012901356 2016 eng d00aIsothermal titration calorimetric study of the ionic liquid solutions in alcohols in extreme dilutions: an investigation of ion-solvent interactions0 aIsothermal titration calorimetric study of the ionic liquid solu cAUG a1313–13310 v453 a

In this work an effort has been made to show the effect of an alcohol-rich environment on imidazolium-based ionic liquids at 298.15 K using an isothermal titration calorimeter. It is divulged from this study that the thermal behavior expressed in terms of excess partial molar enthalpy, \( H_{\text{IL}}^{\text{E}} \), of ionic liquids in various linear alcohols is governed by the increasing hydrophobicity of the residual alkyl group attached to the cation of an ionic liquid and to the alcohol molecules. An interesting observation about the systems consisting of ethylated residuals on both the cations of the ionic liquid and the alcohol molecules is that these systems do not follow the trend exhibited by other ionic liquid–alcohol systems. Interesting information on ionic interactions is obtained by using a simple methodology that gives the enthalpic interaction parameter \( H_{{I{\text{L - IL}}}}^{\text{E}} \).

10aIonic liquidsAlcoholsExcess enthalpyIsothermal titration calorimeter1 aRai, Gitanjali1 aJain, Preeti1 aKumar, Anil uhttps://library.ncl.res.in/content/isothermal-titration-calorimetric-study-ionic-liquid-solutions-alcohols-extreme-dilutions