Designing excellent UV birefringent materials through the synergistic interaction of two highly distorted functional groups

Abstract

Enhancing the optical anisotropy of compounds is a pivotal pursuit with significant implications. In this study, we employed effective strategies by combining two high polarizability groups containing stereochemically active lone pairs (SCALP), two novel ultraviolet (UV) birefringent materials: SbTeO₃Cl (STC) and SbTeO₃Br (STB) were synthesized successfully through hydrothermal reaction. Both compounds exhibit a honeycomb-like two-dimensional (2D) layer structure comprised of 6-membered rings (6-MRs) formed by [SbO₃X]⁴⁻ (where X = Cl, Br) seesaws and [TeO₃]²⁻ triangular pyramids. This superior 2D layered structure induces significant birefringence in both compounds, with values of 0.223@546 nm and 0.281@546 nm, respectively. Furthermore, the introduction of highly electronegative halogens (Cl⁻, Br⁻) succeeded in making the cutoff edges of both compounds fall in the UV region (325 nm and 340 nm, respectively). Detailed theoretical analyses elucidate that the substantial optical anisotropy arises from the synergistic interaction between the [SbO₃X]⁴⁻ (where X = Cl, Br) and [TeO₃]²⁻ groups. This study provides valuable insights into the discovery of function-driven, high-performance optical materials for future applications.