Tracking the Micro‐Heterogeneity and Hydrogen‐Bonding Interactions in Hydroxyl‐Functionalized Ionic Liquid Solutions: A Combined Experimental and Computational Study

Abstract

Ionic liquids (ILs) are an important class of media that are usually used in combination with polar solvents to reduce costs and tune their physicochemical properties. In this regard, it is essential to understand the influence of adding solvents on the properties of ILs. In this work, the micro-heterogeneity and Hbonding interactions between a hydroxyl-functionalized IL, [HOEmim][TFSI], and acetonitrile (ACN) were investigated by attenuated total reflection Fourier transform infrared spectroscopy and molecular simulations. All studied IL-ACN mixtures were found to deviate from the ideal mixtures. The degree of deviations reaches the maximum at about x(ACN) = 0.7 with the presence of both homogeneous clusters of pure IL/ACN and heterogeneous clusters of IL-ACN. With the addition of ACN to IL, the mixtures undergo the transformation from "ACN solvated in [HOEmim][TFSI]" to " [HOEmim][TFSI] solvated in ACN". It is found that the newly formed H-bonding interactions between the IL and ACN is the main factor that contributes to the red shifts of OÀ H, C 2 À H, C 4,5 À H, and C alkyl À H of [HOEmim] + cation, and the blue shifts of CÀ D, C�N of ACN, and CÀ F, S=O of [TFSI] À anion. These in-depth studies on the mixtures of hydroxylfunctionalized IL and acetonitrile would help to understand the micro-heterogeneity and H-bonding interactions of miscible solutions and shed light on exploring their applications.

Work function regulation of surface-engineered Ti2CT2MXenes for efficient electrochemical nitrogen reduction reaction

“…43,48 Grimme's DFT-D3 approach was used to account for the van der Waals (vdW) interactions. [49][50][51] The kinetic energy cut-off for the plane waves was set to 500 eV for all the calculations in the 3 × 3 × 1 Ti 2 CT 2 (T = O, F, H, OH) supercells, and the Brillouin zones were sampled with a (4 × 4 × 1) Monkhorst-Pack k-point mesh. A vacuum layer of 25 Å was set for Ti 2 CT 2 MXenes to ensure sufficient vacuum to avoid interactions between two periods.…”

Generalized Excess Spectroscopy

“…At present, we recommend to do the job with the assistance of quantum chemical calculations. 23,[26][27][28][30][31][32]34 ■ ASSOCIATED CONTENT * sı Supporting Information…”

“…Their assignments, however, are arguable to some extent and need further efforts. At present, we recommend to do the job with the assistance of quantum chemical calculations. ,− ,− , …”

“…Particularly for IR, this method is widely suitable, regardless of the near-infrared, mid-infrared, or far-infrared range. In recent years, abundant interesting results of solution structures and molecular interactions have been obtained by employing the excess IR spectroscopy approach. ,,− …”

Electron Density Learning of Z-Bonds in Ionic Liquids and Its Application

“…Different from the homogeneous bulk [BMIM]Cl with E Z‑bond falling in −7.51 to −2.70 kcal mol –1 (67% center on −3.5 to −2.9 kcal mol –1 , and only 4% E Z‑bond < −5.0 kcal mol –1 , Figure b), the Z-bonds of loaded [BMIM] + and Cl – tend to weakly bind: they change from −4.88 to −3.01 kcal mol –1 in layer-1 (48% falls in −4.25 kcal mol –1 ), −4.80 to −3.20 kcal mol –1 in layer-2 (45% falls in −3.80 kcal mol –1 ), and −5.00 to −2.91 kcal mol –1 in layer-3 (62% falls in −4.25 kcal mol –1 ). Moreover, the Z-bond of imidazole-based ILs can be reflected via the prolonged intramolecular C–H bonds and the red-shifted C–H stretching frequencies . Fourier transform infrared spectroscopy (FTIR, Figure d) shows that the 3161 and 3123 cm –1 bands are assigned to antisymmetric and symmetric stretching vibration modes of C 4/5 -H of [BMIM] + , respectively, and the peak at 3087 cm –1 is assigned to the stretching vibration of C 2 –H in the bulk, respectively.…”