Sn 7 Br 10 S 2 : The First Ternary Halogen-Rich Chalcohalide Exhibiting a Chiral Structure and Pronounced Nonlinear Optical Properties.

Infrared nonlinear optical (IR NLO) materials are significant in laser technology for civil and military uses. Here, we report the synthesis, structural chemistry and NLO properties of a halogen-rich chalcohalide Sn 7 Br 10 S 2 . Its noncentrosymmetric (NCS, P6 3 ) structure can be considered as partially aliovalent anion substitution of SnBr 2 (P6 3 /m) induced centrosymmetric (CS) to NCS structural transformation. The 3D ∞ [Sn(1) 6 Sn(2) 6 Br 6 X 6 ] 6- (X=Br/S) channel framework consists of Sn(1)BrX 2 and Sn(2)X 3 trigonal pyramids. It exhibits excellent NLO performance, including a strong phase-matchable NLO response of 1.5 × AgGaS 2 and high laser-induced damage threshold of 6.3 × AgGaS 2 .Investigation of the structure-NLO performance relationship confirms that the effective arrangement of Sn(1)BrX 2 and Sn(2)X 3 units predominantly contributes to the large SHG response. These results indicate Sn 7 Br 10 S 2 is a potential IR NLO candidate and provides a new feasible system for promising NLO materials.