Sophie Fourmentin

The absorption performance of fatty acid‐based deep eutectic solvents (DESs) for volatile organic compounds (VOCs) of varying hydrophobicity was investigated through a combination of experiments and molecular simulations. Partition coefficient experiments demonstrated the DES composed of tetrabutylammonium bromide (TBAB) and octanoic acid (OCA) in a molar ratio of 1:2 exhibits dual‐functional absorption performance, effectively absorbing both weakly hydrophobic VOCs (e.g., dichloromethane and chloroform) and strongly hydrophobic VOCs (e.g., limonene and octamethylcyclotetrasiloxane). Fatty acid‐based DESs retained both absorption performance and structural stability in five absorption–desorption cycles. Both VOC and solvent hydrophobicity are likely to positively affect absorption performance, with higher hydrophobicity leading to stronger absorption ability. Molecular simulations uncover that VOC absorption in TBAB:OCA can be attributed to three mechanisms: (1) large free volume of TBAB:OCA, (2) electrostatic interactions between TBAB and weakly hydrophobic VOCs that promote solubilization, and (3) Van der Waals interactions between OCA and strongly hydrophobic VOC that enhance absorption.

Type II porous ionic liquids could be prepared at room temperature by dissolving up to 5 wt% of anti-cryptophane-A derivatives functionalized with alkyl or fluorinated alkyl chains in phosphonium- and pyrrolidinium-based ionic liquids. In this study, we provide the first direct experimental evidence that these molecular cages retain their internal free volume when dissolved in ionic liquids. At 303 K and 1 bar, the porous ionic liquids prepared as solutions of anti-cryptophane-A grafted with a ten-carbon alkyl chain in the ionic liquids [P6,6,6,14][NTf2] (1:36), [P6,6,6,14][DCA] (1:52) and [C1C3pyrr][NTf2] (1:50) absorb 1 3.0, 3.5 and 11 times more methane than the pure ionic liquid, respectively. The solution of anti-cryptophane-A grafted with a fluorinated alkyl chain in [P6,6,6,14][NTf2] (1:73) absorbs in turn 1.8 times more methane than the pure ionic liquid. We show that 97(2)% of the cryptophane dissolved in [P6,6,6,14][NTf2] can encapsulate one molecule of methane, whereas only 60(1)% of the cavities in solid cryptophane are available for gas encapsulation. The presence of permanent porosity in the liquid solution is further supported by controlled atmosphere 1H NMR spectroscopy that allows to distinguish between free and caged methane thus providing molecular-level evidence that the gas is encapsulated in the free cryptophane cavities.

Biocompatible cyclodextrin-based metal–organic frameworks (CD-MOFs) form porous suspensions when dispersed in ionic liquids.