Regulable chiral amplification effects in copoly(phenylacetylene)s and bidirectional manipulation for helix preferences

Abstract

Regulable chiral communication mechanisms within two-chiral-component copolymers have great significance for manipulating the helicity of macromolecules and their practical applications. Herein, we report two nontraditional chiral amplification effects in copoly(phenylacetylene)s: the abnormal majority-rules and chiral-to-chiral sergeant-and-soldiers effects, both of which can be regulated ON and OFF to achieve bidirectional helix manipulation. The abnormal majority-rules effect is effectively activated in CHCl₃ for the enantiomeric copolymer series poly-[1(L)_r-co-1(D)_1−r], in which the minority enantiomer determines the helix preference of whole chain. On the other hand, the chiral-to-chiral sergeant-and-soldiers effect appears in the diastereomeric copolymer series poly-[1(L)_r-co-2(L)_1−r], and the “sergeant” (comonomer L-2) dominates the helix preference (M helix). In THF, the chiral conflict effect emerges in both copolymer series, resulting in a helix preference opposite to that under chiral amplification effects. We propose that this phenomenon may be related to the anti- or syn-conformation shift of the pendant groups and verified this with VCD. Based on the regulable chiral amplification effects in both the enantiomeric and diastereomeric copolymer series, Boolean logic operations were selected to demonstrate the applications of controllable helix manipulation. Uniquely, the reversible switching of left- and right-handed CPL can be realized via regulating the abnormal majority rules of the copolymers in the designed CPL system. This study opens up new possibilities for the development of controllable helical structure-based smart polymer materials.