Two novel octamolybdate-based frameworks decorated by flexible bis-pyridyl-bis-amide ligands with different spacer lengths

Abstract

Two octamolybdate hybrid complexes based on flexible bis-pyridyl-bis-amide ligands with different spacer lengths, namely, {[Cu(L₁)(β-Mo₈O₂₆)_0.5(H₂O)₂]·H₂O}_n (1), [Cu(L₂)(β-Mo₈O₂₆)_0.5(H₂O)] (2) (L₁ = N,N′-bis(3-pyridinecarboxamide)-1,2-ethane, L₂ = N,N′-bis(3-pyridinecarboxamide)-1,6-hexane), have been successfully synthesized. Crystal structure analysis reveals that 1 is a two-dimensional (2D) network constructed from [Cu-L₁]_n²ⁿ⁺ chains and [β-Mo₈O₂₆]_n⁴ⁿ⁻ anions, displaying a 4-connected framework with 3²·6²·7² topology. Compound 2 consists of double one-dimensional (1D) meso-helical chains and 1D inorganic chains to generate a three-dimensional (3D) framework with a (4,4)-connected (4·6⁴·8)₂(4²·6²·8²) topology. The title compounds represent the first examples of introducing a flexible bis-pyridyl-bis-amide ligand into the isopolymolybdates system. In addition, the electrochemical behavior of 1, luminescent properties and photocatalytic activities of the title compounds have been investigated.