Thermodynamically Stable Cationic Dimers in Carboxyl-Functionalized Ionic Liquids: The Paradoxical Case of "Anti-Electrostatic" Hydrogen Bonding.

ABSTRACT: We show that carboxyl-functionalized ionic liquids (ILs) form doubly hydrogen-bonded cationic dimers (c+=c+) despite the repulsive forces between ions of like charge and competing hydrogen bonds between cation and anion (c+-a-). This structural motif as known for formic acid, the archetype of double hydrogen bridges, is present in the solid state of the IL 1-(carboxymethyl)pyridinium bis(trifluoromethylsulfonyl)imide [HOOC-CH2-py][NTf2]. By means of quantum chemical calculations, we explored different hydrogen-bonded isomers of neutral (HOOC-(CH2)n-py+)2(NTf2-)2, single-charged (HOOC-(CH2)n-py+)2(NTf2-), and double-charged (HOOC- (CH2)n-py+)2 complexes for demonstrating the paradoxical case of "anti-electrostatic" hydrogen bonding (AEHB) between ions of like charge. For the pure doubly hyd

SUBMITTER: Al-Sheakh L 

PROVIDER: S-EPMC8778807 | biostudies-literature | 2022 Jan

REPOSITORIES: biostudies-literature