Three polar indium phosphites exhibiting diverse structural networks and SHG-activity

Abstract

Phosphites have attracted extensive attention for their abundant open-frameworks and special performances. Here, three inorganic indium phosphites, namely In2(HPO3)3(H2O) (1), In2(HPO3)3(H2O)3·(H2O) (2) and NH4[In(HPO3)2] (3), have been obtained via facile hydrothermal reactions. 1 and 2 crystallize in the same polar space group P21, and 3 crystalizes in the polar space group of P63mc. Isolated HPO3 tetrahedra connect to twisted InO6 octahedra via corner-sharing forming neutral 3D {In2(HPO3)3(H2O)}∞ and {In2(HPO3)3(H2O)3}∞ as well as 2D [In(HPO3)2]-∞ frameworks for 1–3, respectively. Second harmonic generation (SHG) effect measurements have shown that their phase-matched SHG signals are 0.17, 0.20 and 0.28 times of KDP. Thermal stability analyses, optical property measurements and theoretical studies of them were also performed.