Zn(C6H4NO2)2·4H2O: A Solar-Blind Birefringent Crystal

The present study reports an organic–inorganic hybrid birefringent crystal material, Zn(C6H4NO2)2·4H2O, exhibiting a short cutoff edge (274 nm) in the solar-blind ultraviolet region. This material exhibits large optical anisotropy with a birefringence of 0.37@550 nm. Furthermore, we indentified the (C6H4NO2)− anionic group as a good birefringence-active gene for the first time and compared it comprehensively with other six-membered ring compounds to showcase its excellent optical performance. Moreover, our findings have further advanced the upper limit of birefringence for zinc-based six-membered ring compounds in the solar-blind ultraviolet region.