Assembly of multinuclear Ag complexes and Keggin polyoxometalates adjusted by organic ligands: syntheses, structures and luminescence

Two unusual alpha-Keggin-based compounds with multinuclear silver clusters, {[Ag-7(H(2)biim)(5)][PW11O39]}center dot Cl center dot H3O (1) and {[Ag-2(H(2)biim)(2)][Ag(phnz)](PW12O40)}center dot H2O (2) (H(2)biim = 2,2'-biimidazole, phnz = phenazine), have been hydrothermally synthesized and structurally characterized by elemental analyses, IR spectra, thermogravimetric analysis and X-ray crystallography. Compound 1 displays a 2D network featuring dimerized monolacunary Keggin anions {PW11O39}(2) which are connected together through pentanuclear silver clusters. Interestingly, besides {Ag-5}(5+) clusters, there are another kinds of argentophilic {Ag-4}(4+) clusters coexisting in compound 1. Compound 2 consists of four subunits: 1D cationic chains [Ag(phnz)](+), dinuclear silver-H(2)biim units [Ag-2(H(2)biim)(2)](2+), discrete polyanions {PW12O40}(3-) and water molecules, which are further joined by hydrogen bonds to form a 3D supramolecular structure. The differences in the structures of compounds 1 and 2 indicate that the introduction of the secondary organic ligand plays a key role in determining the final structure. The electrochemical, electrocatalytic behaviors and luminescent properties of compounds 1 and 2 have also been investigated.