Inside Cover: Ultrawide Bandgap and Outstanding Second‐Harmonic Generation Response by a Fluorine‐Enrichment Strategy at a Transition‐Metal Oxyfluoride Nonlinear Optical Material (Angew. Chem. Int. Ed. 26/2022)

Oxyfluorides are widely studied functional solids that show great potential as nonlinear optical materials, while only few examples with a wide bandgap exist. In their Communication (e202203104), Chao Wu, Chi Zhang, and co-workers report the synthesis of a fluorine-rich oxyfluoride K5(NbOF4)(NbF7)2 by a fluorine-enrichment strategy. The crystalline oxyfluoride exhibits a wide bandgap and large second-harmonic generation response. The key role of the fluorine content in affecting the optical activity is disclosed.