Hydrothermal synthesis, structures and optical properties of A2Zn3(SeO3)4·XH2O (A=Li, Na, K; X=2 or 0)

• Three new alkali zinc selenites, A2Zn3(SeO3)4·XH2O (A=Li, Na, K; X=2 or 0) have been successfully synthesized.
• The crystal structures of A2Zn3(SeO3)4·XH2O (A=Li, Na, K; X=2 or 0) are all composed of layered, two-dimensional [Zn3(SeO3)4]2− sheets.
• The alkali cations size has a dramatic effect on the resulting crystal layer structure.

New alkali metal zinc selenites, A2Zn3(SeO3)4·XH2O (A=Li, Na, K; X=2 or 0) were prepared through hydrothermal reactions. Li2Zn3(SeO3)4·2H2O (1) crystallizes in the monoclinic space group P21/c with lattice parameters a=8.123(4), b=9.139(4), c=7.938(3) Å, β=112.838(9)°. Na2Zn3(SeO3)4·2H2O (2) crystallizes in the monoclinic space group C2/c with lattice parameters a=15.7940(18), b=6.5744(8), c=14.6787(17) Å, β=107.396(3)°. K2Zn3(SeO3)4 (3) crystallizes in the monoclinic space group C2/c with lattice parameters a=11.3584(12), b=8.6091(9), c=13.6816(14) Å, β=93.456(2)°. The anionic structures are composed of [Zn3O12]18− sheets, chains, and “isolated” units in compound 1, 2, 3, respectively, and trigonal pyramids SeO32−. The compounds were characterized by the solid state UV–vis–NIR diffuse reflectance spectroscopy, infrared spectra and thermogravimetric analysis.

The crystal structures of A2Zn3(SeO3)4·XH2O (A=Li, Na, K; X=2 or 0) are all composed of layered, two-dimensional [Zn3(SeO3)4]2− sheets. These sheets are made up of two-dimensional [Zn3O12]18− layers, chains and “isolated” units, respectively, and trigonal pyramidal SeO32− ligands.Figure optionsDownload as PowerPoint slide