Amplification of Chirality in Monodisperse, Enantiopure Alleno-Acetylenic Oligomers

Novel enantiopure alleno-acetylenic oligomers exhibit chiroptical properties that are among the most intense ever reported. The nonlinear enhancement of these chiroptical responses suggests the existence of a conformational preference preserved along the backbone of all oligomers. From quantum mech. calcns., probably the oligomers bearing (P)-DEAs exist predominantly as an ensemble of right-handed helical conformers, with the torsion angle across the butadiyne axes ranging from 0° to + 45°. Such stabilization is expected to further enhance the chiroptical properties.