Zn(C 2 H 4 NO 2 ) 2 (SO 2 CH 3 NH 2 ) 2 and Zn(C 2 H 4 NO 2 ) 2 SO 2 (NH 2 ) 2 : Regulation of Unique ZnO(C 2 H 4 NO 2 ) 2 Units by Polar Tetrahedrons for Balanced UV Nonlinear Optical Performance

ABSTRACT Short‐wave ultraviolet (200–280 nm) nonlinear optical (NLO) crystals are scarce. Herein, by mixing two types of hetero‐coordinate substituted groups, we synthesized two new crystals, Zn(C 2 H 4 NO 2 ) 2 (SO 2 CH 3 NH 2 ) 2 (ZGlyM) and Zn(C 2 H 4 NO 2 ) 2 SO 2 (NH 2 ) 2 (ZGlyS), featuring a unique ZnO(C 2 H 4 NO 2 ) 2 secondary functional building unit which tends to assemble into a polar chain. Interestingly, disorder in ZGlyM results in a centrosymmetric structure, whereas in ZGlyS, the replacement of the polar tetrahedral group eliminates disorder and preserves a non‐centrosymmetric structure. Notably, the ZGlyS exhibits a rare balance between a short UV cutoff edge of 209 nm, a large second harmonic generation effect of 1.36 × KH 2 PO 4 , and a large birefringence of 0.126@546 nm. Remarkably, its phase‐matching range covers the entire transparent wavelength range, namely, the shortest phase‐matching wavelength is 209 nm. This work provides a potential short‐wave UV NLO crystal and offers new insights for the design of such crystals.