Chiral Ligand-Induced Second-Harmonic Generation Response in Helical One-Dimensional Hybrid Lead Bromides

Chiral hybrid organic–inorganic metal halides have garnered broad attention due to their unique optoelectronic properties. Here, a pair of chiral helical lead halides, (d-/l-pro)PbBr3·H2O (pro = proline), with centimeter-size has been successfully synthesized via integrating three types of functional building units including chiral amino acid ligand, ns2 metal cations, and halide anion. Their structures are composed of one-dimensional helical {[Pb2Br6]2–}∞ chains formed by face-sharing distorted [PbBr6]4– octahedra, which are separated by chiral cations and crystallize into the space group P21. They present a phase-matchable second-harmonic-generation (SHG) response and moderate birefringence. First-principles calculations elucidate that the effective SHG performances originate from the synergetic contribution of chiral cations and distorted [PbBr6]4– octahedra. This work not only enriches the structural chemistry of lead-based hybrid halides but also provides an important reference for the development of chiral metal halides.