Three Cadmium Tartratoborates with Good Second Harmonic Generation (SHG) or Luminescence Performances

Three new cadmium(II) tartratoborates, namely, Cd₅[(C₄H₂O₆)₂B]₂(H₂O)₈·3H₂O (1), K₂Cd₄[(C₄H₂O₆)₂B]₂(H₂O)₂ (2), and Li_0.92K_1.08Cd_1.5[(C₄H₂O₆)₂B](H₂O)₂ (3), have been successfully synthesized by the hydrothermal method. Compounds 1-3 belong to centric C2/ c, acentric Pc, and the polar C2, respectively. Through based on the same hybrid borate-tartrate [(C₄H₂O₆)₂B]^5- anions, they exhibit different structures. The [(C₄H₂O₆)₂B]^5- anion is composed of two tartrate anions and a B(OH)₄^- unit. Compound 1 features a novel 3D network formed by 2D {Cd₃[(C₄H₂O₆)₂B]₂(H₂O)₂}^4- anionic layers and [Cd₂O₁₀] dimers, forming tunnels of large 14-MRs which are filled by the non-coordination water molecules. Compound 2 has a characteristic 3D network based on {Cd₂[(C₄H₂O₆)₂B]}^- units interlinked via carboxylate groups, forming tunnels of 11-MRs, half of which stuffed with the K⁺ ions. Compound 3 features 2D {Cd₄[(C₄H₂O₆)₄B]}³⁺ layers which are separated by K/Li ions. Luminescent studies suggest that they emit blue light. Compounds 2 and 3 display phase-matchable second harmonic generation signs of about 3.2× and 1.5× KH₂PO₄, respectively.