Chirality inversion via van der Waals interactions to π–π stacking in non-equilibrium assembly within a narrow temperature range

Understanding the dynamic control of supramolecular chirality is essential for the development of advanced chiral materials. This study presents a system where solvent-induced self-assembly of ortho-pyridine-azo-cholesterol (o-PAzPCC) and temperature-regulated co-assembly with Cu²⁺ exhibit dynamic supramolecular chirality inversion. Dimethylsulfoxide (DMSO) and alcohol solvents induce the reverse assembly of o-PAzPCC monomers, leading to circular dichroism (CD) signal inversion. Notably, the chloro-bridged Cu²⁺/o-PAzPCC co-assembly system demonstrates temperature-regulated chirality inversion within a narrow range (283 to 293 K). At 283 K, van der Waals forces drive the formation of non-equilibrium nanosheet structures (Agg I) with positive CD absorption at 390 nm. At 293 K, π−π stacking interactions promote equilibrium nanoribbon structures (Agg III) with negative CD absorption at 440 nm wavelength. Increasing the temperature from 283 K can induce a transformation of the nanosheet structures to nanoflower structures (Agg II), characterized by positive CD absorption at 440 nm. The chirality inversion can be finely tuned by adjusting the concentrations and ultrasonication time. This work enhances our understanding of chiral assembly processes and their chirality transmission mechanisms, advancing the development of chiral supramolecular materials for applications in biological systems.