RbSb(SO4)(H2PO2)F: A Short-Wave UV Antimony(III) Oxysalt with Mixed-Anions Demonstrating Enhanced Birefringence

A short-wave UV antimony(III) oxysalt, RbSb(SO4)(H2PO2)F, by incorporating three different anions (SO42-, H2PO2-, F-) with trivalent antimony cations that possess stereochemically active lone-pair electrons (SCALP), has been successfully synthesized. Significantly, the mixed anions and Sb3+ cations combine to form a low-dimensional 1D infinite anionic chain, denoted as [Sb(SO4)(H2PO2)F]∞-, where synergistic interactions among these units contribute to a substantial birefringence of 0.192 at 546 nm and achieve a short cutoff edge down to 276 nm. This research expands the family of UV birefringent optical materials and provides guidance for the further exploration of novel structural-functional materials.