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

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)Cu2Br4 (MPZ = 2-methylpiperazinediium), which crystallize in the noncentrosymmetric space group P212121 and feature distinctive one-dimensional zigzag chains constructed from three-coordinate trigonal-planar CuBr3 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)Cu2Br4 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.