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Updated: Jan 17, 2026
From Molecules to Materials: Engineering New Ionic Liquid Crystals Through Halogen Bonding
Published on: March 24, 2018
KF·[SO2(NH2)2]: the First Deep-Ultraviolet Transparent Sulfonamide Fluoride Nonlinear Optical Crystal with Novel
Yuchen Yan1, Xin Wen2, Piao Tang1
1State Key Laboratory of Crystal Materials, Tianjin Key Laboratory of Functional Crystal Materials, Institute of Functional Crystal, College of Materials Science and Engineering, Tianjin University of Technology, Tianjin, 300384, China.
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The sulfonamide group (SO2(NH2)2) shows great potential for deep-ultraviolet nonlinear optical (NLO) crystals due to its strong hyperpolarizability and anisotropy, but its neutrality and poor protonation limit its application. Here, we propose a new design strategy that introduces an ionic framework via halide salts to both stabilize sulfonamide molecules and control their orientation, thereby enabling desirable second-harmonic generation (SHG) and birefringence. Following this concept, the first sulfonamide fluoride, KF·[SO2(NH2)2], was successfully synthesized, with SO2(NH2)2 units firmly anchored in the KF lattice by K─O ionic and N─H···F hydrogen bonds. Remarkably, this crystal exhibits a unique and compact Cairo pentagonal configuration. Benefiting from its well-ordered structure, the crystal exhibits a strong SHG response of 1.4 × KDP at 1064 nm, a large birefringence of 0.079@546 nm, and a short cutoff edge below 190 nm. This work opens new avenues for the design of advanced NLO crystals with a sulfonamide group.
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