Designing a 3-Hydroxypropane-1-Sulfonate Deep-Ultraviolet Nonlinear Optical Crystal

Although 3-hydroxypropane-1-sulfonates are discovered several decades ago, their nonlinear optical (NLO) properties have remained unexplored, mainly because most of them crystallize in centrosymmetric space groups. Herein, by incorporating polarizable rare-earth metal La³⁺ cations, a novel non-centrosymmetric 3-hydroxypropane-1-sulfonate, namely La[SO₃(CH₂)₃OH]₃ is designed and synthesized, whose crystal structure features 3D framework constructed by highly distorted [LaO₉] polyhedra and [SO₃(CH₂)₃OH]^- anions. Experimental results reveal that La[SO₃(CH₂)₃OH]₃ is NLO-active with a moderate second-harmonic generation response of 0.6 times that of the benchmark KH₂PO₄ and a wide absorption edge below 190 nm. Structural analyses and first-principles calculations reveal that the non-centrosymmetric nature and NLO properties are closely related to highly polarizable cationic [LaO₉] polyhedra. This work highlights 3-hydroxypropane-1-sulfonates as promising candidates for deep-ultraviolet NLO materials and provides some inspiration for designing non-centrosymmetric structures.