Work

Engineering Multiple Hydrogen‐Bond Sites With D‐π‐A Motifs for Strong Optical Nonlinearity and Giant Birefringence in Organic‐Inorganic Halides

Year: 2026

Type: article

Abstract: ABSTRACT Organic‐inorganic metal halides (OIMHs) have emerged as promising nonlinear optical (NLO) materials, but simultaneously achieving large birefringence (Δ n ) and strong second‐harmonic generation (SHG) remains challenging owing to the propensity of π‐conjugated organic motifs to favor centrosymmetric packing. Herein, we develop a molecular design strategy by constructing a donor‐π‐acceptor (D‐π‐A) long‐chain cation, [DA7ClQ] 2+ , featuring multiple hydrogen‐bonding sites. Hybridization with inorganic [Sb 2 Cl 9 ] 3− anions yields the non‐centrosymmetric crystal (DA7ClQ)SbCl 5 , which exhibits a record birefringence of 0.46 at 550 nm among OIMHs‐based NLO crystals, coupled with a robust SHG response of 0.4 × KTP at 1550 nm and exceptional thermal and environmental stability. Theoretical calculations reveal that the D‐π‐A motif possesses superior first‐order hyperpolarizability (12.1 × 10 −29 esu) and polarizability anisotropy (739 a.u.), while a robust hydrogen‐bond network locks the acentric alignment. This work establishes that engineering extended π‐conjugated systems with augmented asymmetry and precise orientational control provides a versatile pathway toward advanced hybrid NLO materials.

Source: Angewandte Chemie International Edition

DOI: 10.1002/anie.2193506