Kundawlet Alimaje

Keggin POM-based 3D framework tuned by silver polymeric motifs: structural influences of tetrazolate functional groups

By altering the functional groups of tetrazolate ligands in the same Ag–POM reaction system, two novel inorganic–organic hybrids: [Ag7(L1)4(H2O)(PMo12O40)] (1) and [Ag5(L2)2(PMo12O40)]·H2O (2) (HL1 = 5-(4-imidazol-1-yl-phenyl)-2H-tetrazole, HL2 = 5-(4-triazol-1-ylmethyl-phenyl)-2H-tetrazole), have been synthesized under hydrothermal conditions, which are characterized by single crystal X-ray diffraction, IR spectra and elemental analyses. Compounds 1 and 2 both display POM-based 3D frameworks modified by different Ag–tetrazolate motifs. In compound 1, a beautiful POM-inserted 2D network is formed by {Ag6(L1)4}n chains and POM polyoxoanions, which are linked to each other through covalent bonds into a (6,6,10)-connected 3D framework. The 3D framework of compound 2 is constructed from chains of circle-connecting-circle and dimeric polyoxoanions. The different structural features of the two compounds suggest that the functional groups of tetrazolate ligands should play a key role in the process of assembly. The luminescent properties for compounds 1 and 2 are investigated.

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

Two unusual α-Keggin-based compounds with multinuclear silver clusters, {[Ag7(H2biim)5][PW11O39]}·Cl·H3O (1) and {[Ag2(H2biim)2][Ag(phnz)](PW12O40)}·H2O (2) (H2biim = 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 {Ag5}5+ clusters, there are another kinds of argentophilic {Ag4}4+ clusters coexisting in compound 1. Compound 2 consists of four subunits: 1D cationic chains [Ag(phnz)]+, dinuclear silver-H2biim units [Ag2(H2biim)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.

Keggin-Type Polyoxometalate Cluster Functionalized with Dinuclear M-H 2 biim (M = Cu, Ag) Metal–Organic Segments

Three inorganic–organic hybrid complexes, [Cu2(H2biim)2(OH)2]2(SiW12O40)·2H2O (1), [Cu2(H2biim)2]2(SiW12O40)·2H2O (2) and [Ag2(H2biim)2]2(SiW12O40)·2H2O (3) (H2biimxa0=xa02, 2′-biimidazole), have been synthesized under hydrothermal conditions, and characterized by elemental analysis, IR, PXRD, TG and single-crystal X-ray diffraction. The crystallographic analysis reveals that in compounds 1–3, the Keggin polyanions [α-SiW12O40]4− act as inorganic building blocks, which are linked with the dinuclear metal–organic units via Cu–O bonds in compound 1, or through supramolecular interactions in compounds 2 and 3. Compound 1 shows a 3D supramolecular structure constructed by net-like layers. Compounds 2 and 3 display 2D layer structures which were composed of wave-like chains. In addition, these compounds show electrochemical activities, and photoluminescence properties are measured in the solid state.

Two Bisupporting Keggin-Type POM-Based Hybrids Decorated by [Zn(phen)2]2+ Fragments

Two bisupporting Keggin-type polyoxoanion-based hybrids decorated by [Zn(phen)2]2+ complexes, [Zn(phen)2]2(PW11VIWVO40) (1) and K[Zn(phen)2(H2O)]2(OH) (SiW12O40)·H2O (2) (phenxa0=xa01,10′-phenanthroline), have been hydrothermally synthesized, and characterized by elemental analysis, IR spectra, UV–Vis spectrum, X-ray photoelectron spectroscopy (XPS), thermogravimetric analysis, and single-crystal X-ray diffraction. The structural analyses reveal that compound 1 consists of a 0D bisupporting Keggin-type heteropoly blue cluster obtained by using reductant glucose, which is grafted by two [Zn(phen)2]2+ fragments; compound 2 presents a 1D infinite chain, which is constructed from bisupporting [SiW12O40]4− polyoxoanions decorated by [Zn(phen)2(H2O)]2+ fragments and K+ ions. Additionally, the electrochemical behaviors of two compounds were studied.