Linear and Nonlinear Optical Properties of Centrosymmetric SbOSO and Noncentrosymmetric SbO(SO)(OH) Induced by Lone Pair Stereoactivity.

Introducing stereochemically active lone-pair Sb cations into sulfates, two three-dimensional (3D) antimony-sulfates, SbOSO () and SbO(SO)(OH) (), were achieved under moderate hydrothermal conditions. Both structures are constructed by tetranuclear-{Sb}-clusters-based layers and SO tetrahedra. However, owing to the different packing patterns of the layers, they display different characteristics: exhibits a centrosymmetric structure while possesses a noncentrosymmetric structure. UV-vis spectra show that they possess wide band gaps. SbO(SO)(OH) is nonlinear optical (NLO) active with a second-harmonic generation (SHG) response of ∼1.2 times of KHPO, together with the phase-matchable capacity, endowing it a promising UV NLO material. The first-principle calculations were performed to elucidate the structure-property relationships. The results indicate that the lone pair stereoactivity of Sb provides the large contribution to the macroscopic SHG effect.