Keggin-based 3D frameworks tuned by silver polymeric motifs: effect of the bi(triazole) substituent group on the architectures†
Abstract
By using an uncommon bi(triazole) ligand and tuning the substituent group on the ligand in the Ag–polyoxometalate (POM) reaction system, three new three-dimensional (3D) Keggin-based metal–organic complexes (MOCs), [Ag4(L1)2(PWVI11VVO40)]·∼14H2O (1), Ag4(L1)2(HSiWVI11VVO40)]·∼25H2O (2) and [Ag4(L2)2(H2O)2(PWVI11VVO40)]·2H2O (3) (L1 = 4-(1H-1,2,4-triazol-3-yl)-2H-1,2,4-triazolyl and L2 = 3-(pyrid-2-yl)-5-(1H-1,2,4-triazol-3-yl)-1,2,4-triazolyl), have been hydrothermally synthesized and structurally characterized by single crystal X-ray diffraction, IR spectra and elemental analyses. In compounds 1–3, the Keggin-type POMs act as highly connected inorganic ligands and are modified by the Ag–triazole polymeric motifs. Compounds 1 and 2 exhibit similar (4,4,4,5,10)-connected 3D frameworks with {414·616·815}{44·62}3{46}{49·6}2 topologies, which are constructed from infinite one-dimensional (1D) [Ag4(L1)2]n chains and 10-connected polyoxoanions. Compounds 1 and 2 represent the first examples of coordination complexes using bi(triazole) as a ligand. In compound 3, there is a twisted 1D chain consisting of [Ag4(L2)2]4+ subunits, which are linked by 6-connected Keggin anions to generate a complicated 3D framework with a {4·6·8}{42·62·82}{42·6}{43·62·8}{43·63}{43·64·85·103}{44·62} topology. The substituent group on the bi(triazole) plays a key role in the assembly and structures of the title compounds. The photocatalytic activities and selectivities, and the electrochemical properties of compounds 2 and 3 have been investigated.