Sui Generis Helicene-Based Supramolecular Chirogenic System: Enantioselective Sensing, Solvent Control, and Application in Chiral Group Transfer Reaction.

A novel dioxa[6]helicene-based supramolecular chirogenic system () as a specific chiral recognition host for enantiopure -1,2-cyclohexanediamine () is reported. Host with an inherent free phenolic group and a (1)-camphanate chiral handle on the opposite terminal rings of the helicene chromophore acted as an efficient turn on fluorescent sensor for ,- with an excellent enantioselective factor, α = / = 6.3 in benzene. This specific host-guest interaction phenomenon is found to be solvent-dependent, which leads to an enantioselective chiral (camphanate) group transfer to the diamine guest molecule. In the case of ,-, the de value is up to 68% even at room temperature. Intriguingly, the induced helicity in dioxa[6]helicene diol , upon supramolecular hydrogen-bonding interactions, is of opposite sense with positive helicity for ,- and negative helicity for ,-, as shown by circular dichroism spectroscopy and in combination with theoretical calculations. This chiral supramolecular system is found to be an excellent host-guest pair for enantiomeric recognition of , based on their electronic and steric factors.