High-Throughput Synthesis of Chiroptical Nanostructures from Synergistic Hydrogen-Bonded Coassemblies

ACS Nano. 2020 Feb 25;14(2):2522-2532. doi: 10.1021/acsnano.0c00352. Epub 2020 Feb 10.

Abstract

The emergence, amplification, and manipulation of chiroptical activity in self-assembled nanostructures, including circularly polarized absorbance and luminescence (CPL), remain considerable challenges. Here, we report the high-throughput synthesis of nanostructures with finely tailored chiroptical activities. Two fully π-conjugated benzimidazoles formed H-bonded complexes with natural hydroxyl acids (tartaric acid and mandelic acid), which self-assembled into diversified macroscopically chiral nanostructures. Synergistic coassembly allows for the emergence of Cotton effects and CPL with high dissymmetry g-factors (gabs up to 8 × 10-3, glum up to 3 × 10-3). The tartaric acid coassembled system exhibits enantiomer-independent left-handed CPL, which transforms into a cooperative ternary coassembly appended with enantiomer-resolved CPL with extended emission wavelength upon selective transition metal ion chelation. This H-boned coassembly system provides a vast number of chiral nanostructures with flexibly tuned Cotton effects and CPL, which also behaves as a selective chiroptical sensor to metal ions.

Keywords: chiral nanostructures; circularly polarized light; hydrogen bonding; self-assembly; supramolecular chirality.