Bifacial ladder polymers enabled by chirality-assisted synthesis that exhibit self-assembly and chirality-induced spin selectivity

Authors:
Open Access
Publisher website
Google Scholar
Abstract
The development of structural concepts in polymers has repeatedly enabled advances in molecular organization and emergent functions. Here we introduce “bifacial ladder polymers” —rigid double-stranded backbones bearing two deliberately differentiated molecular faces— realized through a chirality-assisted synthetic strategy. To implement this architecture, we designed a C 2 -chiral 2,8-dibromoindenofluorene monomer bearing two different substituents with syn stereochemistry across the sp 3 -carbon pair, such that only one ladderization geometry is accessible. Polymerization of the enantiopure monomers with a diboronate comonomer under Suzuki-Miyaura conditions affords precursor polymers, which undergo regioselective ladderization to yield well-defined bifacial ladder polymers with fully preserved facial differentiation. The homochiral bifacial ladder polymers display emergent chiroptical behaviour in the solid state: thin films form one-handed supramolecular helices with circular dichroism intensities over 100-fold stronger than those of their monomeric or non-ladder analogues. Strikingly, these films also exhibit robust chirality-induced spin selectivity, with spin-polarization values exceeding ±90% and opposite signs for the two enantiomers, far surpassing their precursor polymers. These results demonstrate that bifacial ladder polymers provide a versatile platform for emergent self-assemblies and functions in organic polymeric materials.
Funding Information
  • Precursory Research for Embryonic Science and Technology (JPMJPR21A2)
  • Exploratory Research for Advanced Technology (JPMJER2503)
  • Japan Science and Technology Agency (JPMJFR246J)
  • Japan Society for the Promotion of Science (JP25H01409)
  • Japan Society for the Promotion of Science (JP23KJ1508)
  • Japan Society for the Promotion of Science (JP20H05836)
  • Japan Society for the Promotion of Science (JP24H00484)
  • Yazaki Memorial Foundation for Science and Technology (N.A.)
  • Core Research for Evolutional Science and Technology (JPMJCR23O2)

This publication has 48 references indexed in Scilit: