(3‐C 6 H 10 N 2 )ZnX 4 (X = Cl and Br): Two Excellent UV Nonlinear Optical Crystals Designed by Combination of π‐conjugated and [ZnX 4 ] 2− Tetrahedral Units

Abstract To design excellent UV nonlinear optical crystals, via a combination of the two excellent genes, planar π‐conjugated 3‐(aminomethyl)pyridinium ((3‐AMP) 2+ , (C 6 H 10 N 2 ) 2+ ) and d 10 metallic tetrahedral anion, two novel organic–inorganic hybrid (3‐C 6 H 10 N 2 )ZnX 4 (X = Cl and Br) bulk crystals are synthesized using a simple solution method. Remarkably, they exhibit excellent UV nonlinear optical performances, including in short UV absorption edge (229 and 235 nm), robust second harmonic generation (SHG) intensity (2.05 and 4.36 × KDP), suitable large birefringence (0.129–0.144@546 nm) and short phase‐matching wavelength (238 and 262 nm). First‐principles calculations elucidate that the excellent SHG performances of (3‐AMP)ZnCl 4 and (3‐AMP)ZnBr 4 are dominated by the synergetic contributions of planar π‐conjugated (C 6 H 10 N 2 ) 2+ and distorted [ZnX 4 ] 2− tetrahedral groups. This research not only provides two NLO‐active genes but also paves the way for efficient exploration and rational design of organic–inorganic hybrid new NLO materials with optimal balanced optical performances.