Microscopic Structural and Dynamic Features in Triphilic Room Temperature Ionic Liquids

Abstract

Here we report a thorough investigation of the microscopic and mesoscopic structural organization in a series of triphilic fluorinated room temperature ionic liquids, namely [1-alkyl,3-methylimidazolium][(trifluoromethanesulfonyl)(nonafluorobutylsulfonyl)imide], with alkyl = ethyl, butyl, octyl ([C n mim][IM 14 ], n = 2, 4, 8), based on the synergic exploitation of X-ray and Neutron Scattering and Molecular Dynamics simulations. This study reveals the strong complementarity between X-ray/neutron scattering in detecting the complex segregated morphology in these systems at mesoscopic spatial scales. The use of MD simulations delivering a very good agreement with experimental data allows us to gain a robust understanding of the segregated morphology. The structural scenario is completed with determination of dynamic properties accessing the diffusive behavior and a relaxation map is provided for [C 2 mim][IM 14 ] and [C 8 mim][IM 14 ], highlighting their natures as fragile glass formers.

Structural features of selected protic ionic liquids based on a super-strong base

“…Although the presently considered anion is different from [TFSI] that was studied in reference 56 , we can determine that the occurrence of this HB interaction is quite rare with the present choice of cation and anion: the integrated number of neighbour anion nitrogen around the reference cation hydrogen is <0.1 for r<3 Å (corresponding to Recently, we undertook a series of investigations on a variety of AILs containing fluorous chains in their anions. 36,48,55,[57][58][59][60] Therein, we observed that, in agreement with other experimental 61 Figure 2), that typically would fingerprint the existence of segregated domains with mesoscopic spatial extent. 36,48,55,[57][58][59][60] Recently, we showed in a number of examples that while neutrons can successfully appreciate such a feature, due to contrast reasons, X-ray may fail to detect it.…”

“…36,48,55,[57][58][59][60] Therein, we observed that, in agreement with other experimental 61 Figure 2), that typically would fingerprint the existence of segregated domains with mesoscopic spatial extent. 36,48,55,[57][58][59][60] Recently, we showed in a number of examples that while neutrons can successfully appreciate such a feature, due to contrast reasons, X-ray may fail to detect it. 36,55,[57][58][59][60]66 Neutron diffraction measurements therefore might indicate the presence of a further low Q peak centred at ca.…”

“…36,48,55,[57][58][59][60] Recently, we showed in a number of examples that while neutrons can successfully appreciate such a feature, due to contrast reasons, X-ray may fail to detect it. 36,55,[57][58][59][60]66 Neutron diffraction measurements therefore might indicate the presence of a further low Q peak centred at ca. 0.4 Å -1 , fingerprinting the existence of fluorous domains.…”

A review on machine learning algorithms for the ionic liquid chemical space

“…172 MD simulations provided invaluable insight into how and when these domains form. [173][174][175][176][177][178][179][180] Even in cases where the liquid structure can be probed experimentally with scattering experiments, MD simulations are required to trace back the observed features to structural motifs on the molecular scale. 181,182 One of the crucial advantages here is that MD simulations based on classical force elds allow for targeted modications which are not possible experimentally.…”

Conformational design concepts for anions in ionic liquids

“…The structuring effect of uorinated side chains, such as lamellae formation as probed by small angle X-ray scattering, exceeds the structuring from extended alkyl side chains. [91][92][93][94] The stability of the cis conformer of [N(Ms) 2 ] À is signicantly decreased relative to [N(Tf) 2 ] À and is now 20 kJ mol À1 higher in Fluorination of anions is known to positively affect the properties of ILs, leading to lower viscosities, higher ionic conductivity, and higher diffusion, provided that the uorinated groups are not too big. 38,72,[87][88][89] It has been demonstrated here that uorination distinctively affects conformational exibility, and the properties of ILs with uorinated anions will also be a function of this exibility.…”