Polycyclic aromatic hydrocarbons as model solutes for carbon nanomaterials in ionic liquids

Abstract

The aim of this work is to understand the details of the interactions of ionic liquids with carbon nanomaterials (graphene and nanotubes) using polyaromatic compounds as model solutes. We have combined the measurements of thermodynamic quantities of solvation with molecular dynamics simulations to provide a microscopic view. The solubility of five polycyclic aromatic hydrocarbons (naphthalene, anthracene, phenanthrene, pyrene and coronene) was determined in seven ionic liquids ([CCim][C(CN)], [CCpyrr][Ntf], [CCim][Ntf], [CCim][C(CN)], [CCim][Ntf], [CCpyrr][N(CN)] and [CCim][N(CN)]) at 298 K. The enthalpies of the dissolution of naphthalene, anthracene and pyrene were measured in four of the ionic liquids. Free energies were estimated from those measurements in order to analyse the entropic or enthalpic contributions to the dissolution process. Molecular dynamics simulations provided solvation free energies that were compared to experimental and structural information. Spatial distributions of solvent ions around the solutes when combined with IR measurements elucidate the structure of solvation environments. Interactions between the imidazolium rings of cations and the π system of the solutes have been identified. However, ionic liquids with pyrrolidinium cations appeared as better solvents due to favourable enthalpic contributions compared to imidazolium cations. Long alkyl side chains on cations lead to higher solubility and lower enthalpy of dissolution by creating a "softer" solvation environment. Considering the effect of anions, small and planar anions lead to higher solubilities and lower enthalpies of dissolution of polyaromatic hydrocarbons. These findings provide the design principles based on molecular interactions and the structure of solvation environments to choose or formulate ionic liquids in view of their affinity for carbon nanomaterials.

Ionic columnar clustomesogens: associations between anionic hexanuclear rhenium clusters and liquid crystalline triphenylene tethered imidazoliums

“…Usually TP derivatives show a monoexponential behavior in diluted solutions. The presence of a second component, beside the presence of an emitting impurity, might be interpreted as the result of interactions between the imidazolium head and the TP units, 89 but more preferably, by analogy with already reported intramolecular excimer forming polycyclic systems, [90][91][92] to the existence of a weakly emissive excimer. In this last case, the shorter decay (2.5 ns -3.4 ns) is attributed to the emission of the locally excited TP (monomer emission) while the longest one (5.6 ns -7.6 ns) is due to the excimer.…”

First Evidence of Cyclodextrin Inclusion Complexes in a Deep Eutectic Solvent

“…The experimental procedure described previously was followed but special care was taken when filling the glass ampule with dried samples of β-CD in order to avoid contamination with atmospheric water. 20,21 The glass ampule was flame-sealed before introduction in the calorimeter.…”

“…The experimental data obtained during the dissolution of β-CD in the DES was adjusted, as explained before to the equation. 20,21…”

Developing metal‐organic framework‐based composite for innovative fuel cell application: An overview

“…Besides, Jiang et al 54,55 stated that functional sites, including OMS, fluorine groups, and Lewis basic nitrogen sites explain enhanced affinity to increase polarizable molecules through thermodynamic selectivity. In the previous study, Bordes et al 56 also stated that coordinated unsaturated (open) metal sites in MOFs are provided by removing coordinated solvent molecules. Although polymeric structures and versatile molecular are altered and rearranged or merged to stop reactive sites, OMS are ready for foreign material to enter because MOF has been ensured to be rigid.…”

“…C atoms are shown in gray, O atoms in red, 6‐coordinate Mg atoms and terminal ligands in pink, and 5‐coordinate Mg atoms in blue. H atoms and terminal ligands on the fragment at the top right are unclear 56 …”