Aqueous Brønsted-Lowry Chemistry of Ionic Liquid Ions

Visible-light-driven CO2 reduction to formate with a system of water-soluble zinc porphyrin and formate dehydrogenase in ionic liquid/aqueous media

Visible-light-driven CO₂ reduction to formate with a system consisting of water-soluble zinc tetraphenylporphyrin tetrasulfonate (ZnTPPS), formate dehydrogenase from Candida boidinii (CbFDH) and methylviologen (MV) in the presence of triethanolamine (TEOA) as an electron donor in an ionic liquid, 1-ethyl-3-methylimidazolium dimethyl phosphate ([EMlm][Me₂PO₄])/aqueous media was investigated. The catalytic activity of CbFDH for formate oxidation to CO₂ and CO₂ reduction to formate did not decrease significantly even in [EMlm][Me₂PO₄]/aqueous media, compared with that in aqueous media. The visible-light-driven MV reduction by the photosensitization of ZnTPPS in [EMlm][Me₂PO₄]/aqueous media proceeds more efficiently than in the aqueous media system. In the visible-light-driven CO₂ reduction to formate system of ZnTPPS, MV and CbFDH with [EMlm][Me₂PO₄]/aqueous media, moreover, the formate production concentration after 180 min decreased by only 20% as compared with the system in aqueous media.

Hydrogen-Bonding-Driven Ion-Pair Formation in Protic Ionic Liquid Aqueous Solution

Protic ionic liquids (PILs) in solution especially in water have attracted more and more attention due to their unique properties. The solvation of PILs in water is important to their properties and applications. To explore the solvation of bio-based PILs in water, acidity of 49 [AA]X amino acid ionic liquids (AAILs) consisting of 7 different cations and 7 different anions was studied as a favorable probe. The pK_a values for [AA]X PILs containing same cations were obtained and discussed. The acidity strength of the [AA]X PILs varies with both cation and anion which does not follow the conventional assumption that the acidity for PILs is independent of anions. The acidic discrepancy of [AA]X PILs aqueous solution is probably mediated by the formation of ion pairs according to a revised solvation model of PILs. Quantum-chemistry calculation was employed to unpuzzle anion's different effects on the acid balance of cations where cation-anion hydrogen bonds play an important role. Such difference in acidity allows us to understand the formation of solvated ion pairs. This work provides an insight into the fundamental solvation of PILs from acid perspective and their influence on acidity properties for the first time.

Sulphur dioxide cooperation in hydrolysis reactions of vanadium oxide and hydroxide cluster dianions

Gas-phase hydrolysis takes place due to the synergistic action of SO₂ and vanadium-containing dianions that succeeds in tightening hydrogen bonds.