A Helically‐twisted Stereodynamic Probe for Chiroptical Sensing of Chiral Amines through Point‐to‐helical Chirality Transmission

Chiral amines and amino alcohols form an important category of molecules employed in the designing of new drugs and catalyst. Herein, we present a helically‐twisted stereodynamic dialdehyde probe 1 for the determining of absolute configuration, and enantiomeric excess of chiral amine and amino alcohols. Probe 1 is based on the pyridine‐2,6‐dicarboxamide (PDC) core and undergoes rapid interconversion between the P‐ and M‐ conformers. However, upon imine formation with chiral amines, probe 1 gets locked it in a single conformer majorly. This induces a strong CD signal in addition to changes in the UV‐vis and fluorescence signals. The CD spectral change allowed for quantitative enantiomeric excess determination of chiral amines. Circular polarized luminescence (CPL) spectra having the glum of 1×10−3 was obtained upon imine formation between probe 1 and diamine 2. Single crystal X‐ray diffraction studies (SCXRD) confirmed the twisted conformation in 1@(R)‐4 and 1@(S)‐4, stabilized by intramolecular hydrogen bonding between bound imine nitrogen and proximate amide group.