Multidentate Chirality Inducers in the Synthesis of Intrinsically Chiral Gold Nanoparticles: Effects of Multiplicity and Spatial Distribution of Cysteine

Nanomaterials with chiral shapes have the potential to revolutionize medicine, communication technologies, and electronics. However, their syntheses usually rely on chirality inducers of natural origin, restricting the development of chiral nanomaterials. Here, multidentate hybrid organic compounds are introduced as a novel approach to effective symmetry breaking in the synthesis of chiral Au nanoparticles (NPs). Natural and synthetic chemical motifs within a single molecule are integrated by attaching cysteine (Cys) moieties to aromatic units. Au NPs synthesized using these chirality inducers exhibit fourfold rotational symmetry with varied spikiness as evidenced by transmission electron tomography. Optimized samples exhibit high dissymmetry values, g-factor of the order of 10^-2. This is notable given the small size of NPs, less than 130 nm in length and 90 nm in width. By varying the inducers' architecture, it is uncovered that the multiplicity of Cys units and the type of the central aromatic units are crucial to the effectiveness of chirality induction. The reproducibility of the synthetic procedure is also verified. These findings represent a substantial evolution from the classical chiral inducers of natural origin. They promise to advance enantioselective synthesis by uncovering molecular design principles of chirality inducers that affect chirality transfer between organic and inorganic materials.