Chiral Inversion and Recovery of Supramolecular Luminescent Copper Nanocluster Hydrogels Triggered by Polyethyleneimine and Polyoxometalates

Construction of controllable chiroptical supramolecular luminescence systems is of great significance for developing intelligent chiral luminescence materials with precise and effective regulation and understanding chirality-switching phenomena in biological systems, which has attracted extensive attention. Because chiral metal nanoclusters (NCs) can provide facilities for the study of nanoscale chiral effects, in this study, we select chiral glutathione-stabilized copper NCs (G-SH-Cu NCs) to construct a supramolecular luminescent hydrogel with achiral branched polyethyleneimine (PEI) and polyoxometalates [Na-9(EuW10O36)center dot 32H(2)O, denoted as EuW10]. Thus, a chiral property precise controlled system was constructed by self-assembly. Interestingly, the addition of PEI to G-SH-Cu NC solution induced the formation of luminescent hydrogels with chiral inversion, while further addition of EuW10 not only enhanced the luminescence of the hydrogel but also recovered the chiroptical properties. The chiral inversion behavior is possibly ascribed to the hydrogen bond interaction/electrostatic interaction between G-SH-Cu NCs and PEI in the chiral inversion process, while the competition of hydrogen bonding interaction (between G-SH-Cu NCs and PEI) and electrostatic interaction (between PEI and EuW10) was accountable for the chiral recovery process. Manipulation of chirality inversion in the metal NC-containing coassemblies is rare, while this work establishes a feasible strategy to modulate the chiral inversion behavior of Cu NCs, which not only produces new physicochemical properties of metal NCs through synergistic behavior but also offers a feasible way to realize the potential application of chiroptical materials.

Automated summary

The construction of controllable chiroptical supramolecular luminescence systems using chiral metal nanoclusters (NCs) is important for developing intelligent chiral luminescence materials and understanding chirality-switching phenomena. In this study, a supramolecular luminescent hydrogel was constructed using chiral glutathione-stabilized copper NCs (G-SH-Cu NCs), achiral branched polyethyleneimine (PEI), and polyoxometalates (EuW10). The addition of PEI induced chiral inversion in the hydrogel, while further addition of EuW10 enhanced the luminescence and recovered the chiroptical properties. The mechanisms behind the chiral inversion and recovery were attributed to hydrogen bonding and electrostatic interactions. This work provides a feasible strategy for modulating the chiral inversion behavior of metal NCs and offers potential applications for chiroptical materials.