Dissymmetry enhancement in enantioselective synthesis of helical polydiacetylene by application of superchiral light

Chenlu He,Gang Zou,Lin Yang,Sizhen Shan,Yan Kuai,Guang Yang,Jingang Hu,Qijin Zhang,Douguo Zhang

doi:10.1038/s41467-018-07533-y

Abstract

Superchiral light, generated by the interference of two counter-propagating circularly polarized light (CPL) with same frequency, opposite handedness and different intensity, exhibits enhanced dissymmetry in its interaction with chiral molecules, and has the potential for ultrasensitive detection and characterization of chiral molecules. It is anticipated that the enhanced optical dissymmetry in superchiral light (SCL) field may be utilized to promote asymmetric photochemical reactions efficiency. Herein we reported SCL impart greater chiral bias to trigger asymmetric photo-polymerization reaction from initially achiral diacetylene (DA) monomer, and the enhanced optical dissymmetry for whole polydiacetylene (PDA) films could be achieved. An explanation based on the chiral transfer and amplification of chiral bias from SCL during the polymerization process has been proposed. Moreover, thus formed chiral PDA films polymerized by SCL exhibited enhanced enantioselective recognition ability, and can serve as a direct visual probe for the discrimination of some specific enantiomers.

Highlights

When above films were subjected to the characterization of circular dichroism (CD), it was interesting to note that the samples polymerized with superchiral light (SCL) exhibited stronger CD signals than those polymerized with conventional circularly polarized light (CPL), while the samples polymerized with linearly polarized light (LPL) exhibited CD silence
Based on the chiral transfer and amplification during polymerization process, the small chiral perturbation induced by SCL could be further amplified and had been utilized to synthesis macroscopic chiral PDA films with enhanced optical activity and enantioselective discrimination ability
The present study experimentally demonstrates that symmetry breaking in photo-polymerization from initially achiral DA monomer could be further enhanced by application of SCL field, generated by the interference of two counterpropagating CPL beams

Summary

Results

Four-fold enhancement in DCE values for the PDA films polymerized by application of SCL over CPL could be observed, indicating that SCL could impart greater chiral bias into asymmetric photo-polymerization reactions, eventually promoted the enantioselective synthesis of helical PDA chains. As for the samples prepared by traditional CPL technique, only low CR values (10% for S-type, and 6% for R-type PPA enantiomers, respectively) could be detected, owing to their weaker enantioselective discrimination ability (Supplementary Fig. 13)

10 L-PDA R-PDA

Discussion

Methods