Two van der Waals Layered Antimony(III) Phosphites as UV Optical Materials.

Herein, two new Sb 3+ -based phosphites, Sb 2 O 2 (HPO 3 ) ( I ) and Sb 2 O(HPO 3 ) 2 ( II ), were successfully obtained by ingeniously combining Sb 3+ -based polyhedra containing stereochemically active lone pair (SCALP) and HPO 3 polar groups. Both reported compounds exhibit unique 2D van der Waals layered structures, [Sb 4 O 4 (HPO 3 ) 2 ] ∞ and [Sb 2 O(HPO 3 ) 2 ] ∞ , respectively, which favors compounds with large optical anisotropy. Interestingly, the different curvatures of the two layers resulted in the two title compounds showing significantly different birefringences (0.079@546 and 0.046@546 nm, respectively). Both compounds endow wide optical band gaps (4.32 and 4.54 eV, respectively), which indicates their potential as promising ultraviolet (UV) birefringent crystals. The synthesis of the two title compounds enriched Sb 3+ -based phosphites in the UV region and provided guidance for the subsequent synthesis of superior optical materials.