Planar Chiral p,p-Terphenyl-Based Cyclophanes with Remarkable Enantiomer Stability: Synthesis, Theoretical Investigations, and Complexation Studies

Design of conformationally stable compounds with planar chirality is a topic of great interest mainly because of their potential applications as enantioselective ligands or other functional materials. Herein, we present the design and synthesis of novel planar chiral cyclophanes, obtained by ortho, ortho '' anchoring of the p,p '-terphenyl unit, with bridges of different lengths and rigidities, along with their nuclear magnetic resonance, mass spectrometry, and X-ray characterizations. We investigated the influence of the structural particularities of the bridges over the stability of the enantiomers, by means of nuclear magnetic resonance and chiral high-performance liquid chromatography as well as by density functional theory calculations. We also demonstrated the ability of one of the cyclophanes to preferentially bind arginine with Ka > 110 M-1 (Delta G > -11 kJ mol(-1)) in acetonitrile solutions containig 10 % water, in the presence of other amino acids.