Approach to inherently chiralionic liquids

Ionic Liquids (ILs) constitute a class of solvents which got an increasing importance in the last ten years on account of some peculiar properties (low vapor pressure, chemical and thermal stability, solvating ability, non-flammability). Chiral ionic liquids (CILs) are used as solvents in asymmetric synthesis and in stereoselective polymerization, as chiral phases for gas chromatography, as chiral shift reagents in NMR spectroscopy and, in some cases, as promoters of cholesteric liquid crystals. Most of known CILs, are onium salts bearing chiral substituents characterized by one or several stereocenters. The research is focused to the design, synthesis, characterizetion and test in electrochemical oxo-reduction processes of a new family of CILs in which the stereogenic element (a stereogenic axis) coincides with the function responsible for the IL properties. Using the successful strategy recently employed for designing “inherently chiral” oligotiophenes,1 some “inherently chiral” CILs have been prepared based on bis-imidazolium and bi-piridinium atropisomeric scaffolds. The general structures and some specific examples are reported in the following scheme. The synthetic accessibility, the chromatographic behaviour of the precursors and the configurational stability of the new compounds is discussed. This work is supported by Fondazione Cariplo (reg. No 2011-1851) and C.N.R. (PM.P03.002.002). 1 Sannicolò, F.; Arnaboldi, S.; Benincori, T.; Bonometti, V.; Cirilli, R.; Dunsch, L.; Kutner, W.; Longhi, G.; Mussini, P.R.; Panigati, M.; Pierini, M.; Rizzo, S. Angew. Chem. Int. Ed. 2014, 53, 2623.