We report two chiral NCS compounds, (R)-Sb and (S)-Sb, featuring aligned Sb³⁺ lone pairs and hydrogen-bonded [SbOF₃] polyhedra with 4-hydroxyphenylglycine. These structures exhibit strong SHG (2.6 × KDP), a wide band gap (4.19 eV), and suitable birefringence (0.184@546.1 nm), highlighting the potential of Sb³⁺-based hybrids for NLO applications.

Abstract

Noncentrosymmetric (NCS) materials have garnered significant attention due to their unique second-harmonic generation (SHG) properties, which are crucial for nonlinear optical (NLO) applications. However, achieving optimal SHG efficiency and birefringence remains challenging for Sb³⁺-based hybrid materials, which are being actively explored as potential alternatives to toxic Pb²⁺-based systems. In this study, we successfully synthesized two novel chiral NCS compounds, (R)-SbF₃(C₈H₉NO₃) [(R)-Sb] and (S)-SbF₃(C₈H₉NO₃) [(S)-Sb], by incorporating the stereochemically active lone pair cation Sb³⁺, highly electronegative F⁻ anions, and the chiral zwitterionic 4-hydroxyphenylglycine. The compounds crystallize in the polar noncentrosymmetric space group, P2₁ (No. 4), featuring [SbOF₃] polyhedra that form hydrogen bonds with 4-hydroxyphenylglycine. Notably, the Sb³⁺ lone pairs align along the b-axis, resulting in enhanced polar characteristics. These structural features endow the compounds with outstanding NLO properties, including an SHG response 2.6 times greater than that of KH₂PO₄, a wide band gap of 4.19 eV, and suitable birefringence (0.184@546.1 nm). This work contributes to the expanding research on chiral hybrid materials and underscores the potential of Sb³⁺-based systems for advanced optical applications.