Application of the "Inherent Chirality" Concept to Ionic Liquids Design: Effective Chiral Electroanalysis on Achiral Electrodes

In "inherently chiral" materials the coincidence of the stereogenic element responsible for - :- "3 ity with the molecular portion responsible for their specific properties results in : .... tstanding chiroptical and enantiorecognition properties. We successfully experimented this ::-:ept in designing chiral organic semiconductors employed as highly stereoselective ,: sctrode surfaces.' This strategy is now applied to the preparation of "inherently chiral" ionic :;Jids (IC1Ls) and transport electrolytes: atropisomeric l,l'-biimidazolium 1 or 3,3'¬ : cvridiniurn 2 scaffolds (in particular l,l'-bibenzimidazolium and 3,3'-bicollidinium) :-o"acterize these unconventional organic salts (Scheme 1). Several members of both the ':"Tiles have been obtained by alkylation of 2,2'-dialkyl-1,l'-benzimidazoles and 3,3'¬ : cctlidine, prepared through easy syntheses from inexpensive reagents. The racemates of -EJtral scaffolds have been resolved by semi-preparative HPLC on CSP in the former case" and - : crystallization of the diastereomeric salts with chiral acids in the latter. The long-chained ::: a.kvl salts 2 display melting points below room T and are, therefore, the first atropisomeric :ILs. The new dionium salts, employed as low concentration additives in commercial achiral ILs, afford outstanding enantiodiscrimination of structurally different chiral probes on achiral electrodes. This work was supported by Fondazione Cariplo (reg. No 2011-1851) and CNR.