(C3N6H7)2SiF6·H2O: an ultraviolet birefringent crystal exceeding the intrinsic energy gap of an organic reagent

Abstract

Here, we report a new crystal, (C₃N₆H₇)₂SiF₆·H₂O, which exhibits a large birefringence (0.152@550 nm) resulting from the aligned [C₃N₆H₇]⁺ cations. Notably, its energy gap breaks the limit of the organic matrix under the regulation of a SiF₆ octahedron. Our findings provide a method to elevate the band gap of organics.