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

Phosphites have attracted extensive attention for their abundant open-frameworks and special performances. Here, three inorganic indium phosphites, namely In 2 (HPO 3 ) 3 (H 2 O) (1), In 2 (HPO 3 ) 3 (H 2 O) 3 ·(H 2 O) (2) and NH 4 [In(HPO 3 ) 2 ] (3), have been obtained via facile hydrothermal reactions . 1 and 2 crystallize in the same polar space group P 2 1 , and 3 crystalizes in the polar space group of P 63 mc . Isolated HPO 3 tetrahedra connect to twisted InO 6 octahedra via corner-sharing forming neutral 3D {In 2 (HPO 3 ) 3 (H 2 O)} ∞ and {In 2 (HPO 3 ) 3 (H 2 O) 3 } ∞ as well as 2D [In(HPO 3 ) 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.