Herein, unprecedented NLO-brominated tin hypophosphites, namely [Sn(HPO)]Br, were discovered via a facile surfactant-induced method, which displayed a moderate powder SHG intensity (3.0 × KDP) in type - I phase matching behavior. This complex has high chemical and thermal stability at room temperature. DFT calculations and SHG coefficient analyses revealed that the alignment of the SHG-active-units SnO trigonal pyramids and Br anions in its structure mainly contribute to the macroscopical SHG behaviors.

Two interesting noncentrosymmetric metal chalcogenides, M 2 Ag 3 Sb 3 S 7 (M = Rb 1, Cs 2) were obtained by ionothermal synthesis. Crystals of compounds 1 and 2 are isostructural, consisting of two-dimensional (2D) anionic networks ¥[Ag3Sb3S7] 2with Rb + or Cs + cations located between the adjacent anionic layers. The optical band gaps of 1 and 2 are 2.11 and 2.02 eV, respectively. Second-harmonic generation (SHG) measurements revealed that 1 affords a phase-matching powder SHG response of ~0.5 × AgGaS2, while 2 exhibits a stronger SHG response of ~0.6 × AgGaS2 with type-I phase matchability. Both 1 and 2 possess wide transparency ranges (~0.6-20 μm), suggesting their potential as infrared (IR) nonlinear optical (NLO) materials. The laser damage thresholds (LDTs) of both 1 and 2 are about 2.3 times larger than that of AgGaS 2. The calculated birefringence indexes Δn are 0.1885 and 0.1944 at 1.064 μm, respectively, which are sufficiently large to achieve phase matching. Theoretical studies using density functional theory have been carried out to further understanding of the relationship between their NLO properties and band structures.