Classical nexus between chiral inducers and achiral silver nanoparticles and integration of the digital XOR logic gate

Abstract

Chirality-induced metallic and metal–oxide nanoparticles (NPs) hold promising potential in chiroptical activity, asymmetric catalysis, chiral discrimination, and drug delivery. Herein, we report a simple but scalable method for the preparation of achiral, metallic colloidal Ag NPs in which chirality was imprinted using organic chiral inducers. Chirality can be imprinted into Ag NPs upon surface functionalization using L- and D-cysteine. The formation of nanostructure assemblies, morphology, and chemical compositions are ensured by electron microscopy (TEM, FE-SEM) and X-ray photoelectron spectroscopy (XPS). Amino acid-driven enhanced chiroptical activity, followed by anisotropy factors (g-factor) of the Ag core and thiolate adsorbates were investigated by CD spectroscopy. Strong chiroptical activity in cysteine-modified Ag NPs originates from metal-based interband electronic transitions (as transitions are highly energetic), which is absent in free chiral inducers. Considering the chiral ligands, individual or combined use for Ag NP surface modification as chemical inputs and CD signal as an output, an XOR logic gate was implemented. L-Cys@Ag and D-Cys@Ag NPs are integrated into electronic devices for DC-based electrical measurements (current–voltage, I–V) and AC-based electrical impedance spectroscopy (EIS) for deducing individual electrical components, followed by equivalent circuit modeling. The conductivity of the L-Cys driven-Ag NPs assembly decreases compared to the D-Cys Ag-NPs assemblies, thus ensuring a higher degree of Ag NPs surface modification than the former chiral inducer. The present work enriches the facile synthesis of chiral NPs and large-scale electrical devices that can be envisioned for chirality-driven photocatalysis, optoelectronic devices, bio-sensing, and molecular spintronics.