Active Regulation of Supramolecular Chirality through Integration of CdSe/CdS Nanorods for Strong and Tunable Circular Polarized Luminescence.

Abstract

Building the cooperativity in artificial self-assembling systems will synergistically reshape their properties and expand their application spectrum. Here, we show how the cooperativity between achiral CdSe/CdS nanorods (NRs) and chiral perylene diimide (PDI)-based molecules is built upon their coassembly. We demonstrate that chirality transfer from chiral molecular assemblies to CdSe/CdS NRs is enabled by the encapsulation of NRs into PDI suprascrolls through chain-chain van der Waals interactions, which in turn gives rise to markedly enhanced circularly polarized luminescence of the nanocomposites. Additionally, the circularly polarized emissive bands of the nanocomposites could be finely tuned by engineering the emissive bands of NRs. More importantly, these nanocomposites are able to invert their chirality when NRs are self-assembled into chiral superlattices under a larger amount of NRs. Detailed mechanistic studies unveil that these jammed NRs assemblies hamper the folding of two-dimensional (2D) chiral nanosheets, which consequently suppress the interlayer excitonic coupling and implement the nanocomposites with inverted chirality. Our finding exemplifies a way to invert the chirality switching from folding to unfolding of 2D supramolecular nanosheets, akin to the chirality inversion in the helix-to-superhelix transition in conventional one-dimensional (1D) supramolecular systems. We also show that the strong van der Waals interactions from aliphatic chains are crucial in achieving such chirality transfer and inversion. Overall, we demonstrate that these achiral CdS/CdSe NRs could serve as artificial molecular chaperones to aid the unfolding of supramolecular nanosheets with controlled chirality.