Ultra-broadband Tunable Mid-infrared Metallic Plasmonic Antenna for Universal Chiral Recognition

Surface-enhanced infrared absorption (SEIRA) is a sensitive and orientation-selective technique that is theoretically suitable for in-depth chiral recognition studies related to molecular conformations. However, the aforementioned concept is challenging to realize because of the narrow bandwidth and weak near-field strength of plasmonic antennas (PAs). Herein, a seed-mediated growth method for synthesizing ultrabroadband (400-4000 cm^-1) submicrometer Au superparticles was proposed. In this work, the issue of uncontrolled particle growth due to secondary nucleation is thoroughly discussed, which is a common phenomenon during the synthesis of large-scale particles. Thus, tunable Au superparticles are acquired through precise kinetic regulation and a phase transfer strategy. Furthermore, the distinctly different SEIRA signal intensities of various chiral enantiomers demonstrate the reliability of this approach and the sensitivity of this PA. This work provides insights into the general issue of seed-mediated synthesis of large-scale particles while also expanding the materials and methods toolkit for advanced molecular chiral research.