Synthesis, crystal structures and properties of lead phosphite compounds

•A new lead phosphite, Pb2(HPO3)2 is reported.•Pb2(HPO3)2 features a unique 3D framework structure.•NLO property of Pb2(HPO3)(NO3)2 is investigated.•Pb2(HPO3)(NO3)2 produces a moderate SHG response of ∼1.8×KDP (KH2PO4).

Here, we report the preparation and characterization of two lead(II) phosphites, namely, Pb2(HPO3)2 and Pb2(HPO3)(NO3)2 through hydrothermal reaction or simple solution synthesis, respectively. A new lead phosphite, namely, Pb2(HPO3)2, crystallizes in the noncentrosymmetric space group Cmc21 (no. 36), which features 3D framework formed by the interconnection of 2D layer of lead(II) phosphites and 1D chain of [Pb(HPO3)5]∞. The nonlinear optical properties of Pb2(HPO3)(NO3)2 have been studied for the first time. The synergistic effect of the stereo-active lone-pairs on Pb2+ cations and π-conjugated NO3 units in Pb2(HPO3)(NO3)2 produces a moderate second harmonic generation (SHG) response of ∼1.8×KDP (KH2PO4), which is phase matchable (type I). IR, UV–vis spectra and thermogravimetric analysis (TGA) for the two compounds were also measured.

Graphical abstractTwo lead phosphites Pb2(HPO3)2 and Pb2(HPO3)(NO3)2 are studied. A new lead phosphite Pb2(HPO3)2 features a unique 3D framework structure and Pb2(HPO3)(NO3)2 shows a moderate SHG response of ∼1.8×KDP (KH2PO4).Figure optionsDownload full-size imageDownload as PowerPoint slide