Strong Second‐Order Nonlinear Optical Activities in Chiral Hybrid Copper(I) Bromide Microplates

ABSTRACT Organic–inorganic chiral hybrid metal halides (HMHs) with efficient second‐order nonlinear optical responses are promising for various photonic applications. However, chiral HMHs that simultaneously deliver strong second‐harmonic generation (SHG) and pronounced nonlinear chiroptical responses remain limited. Herein, we report a pair of chiral hybrid copper(I) bromide microplates, ( R ‐ and S ‐MPZ)Cu 2 Br 4 (MPZ = 2‐methylpiperazinediium), which crystallize in the noncentrosymmetric space group P 2 1 2 1 2 1 and feature distinctive one‐dimensional zigzag chains constructed from three‐coordinate trigonal–planar CuBr 3 units. Benefiting from the highly distorted Cu─Br frameworks, the microplates exhibit an SHG intensity approximately 376 times that of Y‐cut quartz at 870 nm, together with a high laser damage threshold of up to 11.14 mJ cm −2 . More importantly, the ( R ‐ and S ‐MPZ)Cu 2 Br 4 microplates display effective SHG circular dichroism (SHG‐CD) and circularly polarized SHG responses, enabling a conceptual chirality‐encoded SHG tagging and decoding protocol. This work highlights chiral hybrid copper(I) halides as a versatile lead‐free platform for integrating efficient frequency conversion, nonlinear chiroptical functionality, and information encryption capabilities.