Silver‐Mediated Growth of Chiral Ag/Au‐Cysteine Hybrid Nanospheres with Giant Chiroptical Response

Abstract

AbstractThe chiral Ag/Au‐cysteine hybrid nanospheres (HNSs) have been prepared by using cysteine (Cys) as an inductive agent via wet chemistry methods. Unlike the case of the dipole approximation, the circular dichroism spectra can be divided into two components: 1) one region associated with the interband absorption enhanced optical activity of structural arrangement of Cys molecules at 200–320 nm; 2) another region corresponding to a ligand‐to‐metal charge transfer mixed with ligand‐to‐metal‐metal charge transfer excitation due to the synergetic interplay of the electrostatic interaction between Cys side chains and the Au(I)⋅⋅⋅Au(I) aurophilic attraction in the Au(I)‐Cys complexes, located at 350–400 nm. The chiroptical response increases dramatically with increasing the concentration of Au from 0.1 to 1.56 × 10−3 m, and subsequently decreases with further increasing the concentration of Au from 3.12 to 12.5 × 10−3 m, which is similar to the sergeants and soldiers effect of chiral polymer materials. Furthermore, the circinate‐like morphology of the alloyed nanospheres is strongly dependent on the presence of Ag and the chiral bimetal HNSs present excellent enantioselective recognition for amino acids in catalytic electrochemical reactions due to the specific activity and chiral active spots.