Chemosensors (Aug 2021)

2,12-Diaza[6]helicene: An Efficient Non-Conventional Stereogenic Scaffold for Enantioselective Electrochemical Interphases

  • Francesca Fontana,
  • Benedetta Bertolotti,
  • Sara Grecchi,
  • Patrizia Romana Mussini,
  • Laura Micheli,
  • Roberto Cirilli,
  • Matteo Tommasini,
  • Simona Rizzo

DOI
https://doi.org/10.3390/chemosensors9080216
Journal volume & issue
Vol. 9, no. 8
p. 216

Abstract

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The new configurationally stable, unsymmetrical 2,12-diaza[6]helicene was synthesized as a racemate and the enantiomers were separated in an enantiopure state by semi-preparative HPLC on chiral stationary phase. Under selected alkylation conditions it was possible to obtain both the enantiopure 2-N-mono- and di-N-ethyl quaternary iodides. Metathesis with bis(trifluoromethanesulfonyl)imide anion gave low-melting salts which were tested as inherently chiral additives to achiral ionic liquids for the electrochemical enantiodiscrimination of chiral organic probes in voltammetric experiments. Remarkable differences in the oxidation potentials of the enantiomers of two probes, a chiral ferrocenyl amine and an aminoacid, were achieved; the differences increase with increasing additive concentration and number of alkylated nitrogen atoms.

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