“Bottom-up” transmission of chirality between
different
length scales in hierarchically structured materials, which display
intricate interplay between inorganic compounds and chiral organic
ligands, is a complex phenomenon that requires insight into the origin
and evolution of chiroptical activity (optical asymmetry), an understanding
of chiral bias, and real-time visualization of atomic-level helicity.
In this study, we employ a comprehensive study on chiral antipodal
hierarchical CuO nanostructures as an archetype of a comprehensive
approach to reveal the origin of broadband chiroptical activity in
a stepwise manner and real-time demonstration of atomic-scale chirality/helicity
and the transfer of chirality from organics to inorganics followed
by their primary building block to their hierarchically assembled
structures. We report atomic-scale chirality in hierarchically organized d/l-CuO nanoflowers manifested through primary building
blocks of putative Boerdijk–Coxeter–Bernal (BCB)-like
tetrahelical fragments, with corresponding handedness, prepared through
a simple one-pot, template-less method. The atomic-scale chirality
in the as-prepared d/l-CuO nanoflowers has been
preserved on calcination (at 600 °C) through screw dislocation-driven
helicity on transformation into toroid-like nanostructures. We also
explore the intriguing presence of the BCB helix in polycrystalline
CuO and its connection to the nanocrystallite size of the nanoflowers.
Additionally, the phenomenon of cooperative chirality in d/l-CuO nanostructures, emerging from chiral synergism between
the crystallographic and geometric morphologies, could be corroborated
through microscopic and spectroscopic studies. This comprehensive
approach not only unveils the intricate details of chiral inorganic
materials but also opens avenues for tailoring chiral transfer pathways,
offering promising technological advancements. Our findings have implications
for understanding the translation of chirality and asymmetry across
structural motifs and length scales, which play a fundamental role
in nature, enabling unique functionalities in contexts ranging from
biological systems to synthetic materials.
