A novel heteropolyoxometalate, Nb-substituted hexatungstate compound; (C 9 H 8 N) 3 [NbW 5 O 19 ]Á3H 2 O triquinolinium l 6 -oxido-dodeca-l 2 -oxidohexaoxido[niobium(V)pentatungsten(VI)]ate trihydrate (QNbW5) has been grown by slow evaporation method and characterized by powder X-ray and single-crystal XRD methods, NMR, IR, UV-Vis and photoluminescence spectroscopy measurements, elemental analysis and thermogravimetric analysis. Single-crystal XRD analyses show that QNbW5 crystallizes in the triclinic space group P1 and its crystal structure consists of 3D grid-like network of components in a close connection through N-HÁÁÁO, C-HÁÁÁO and offset pÁÁÁp stacking interactions between neighboring rings of quinolinium moieties. Moreover, the spectroscopic and electronic properties of QNbW5 have also been investigated showing a considerable important gap energy well confirming the semiconductor behavior and the blue photoluminescent property of reported material. In addition, the complex shows promising antimicrobial activity against four pathogenic microbes in comparison with its components alone.Electronic supplementary material The online version of this article (

In the title hydrated salt, [Co(C12H8N2)3]2[PVW11O40]·2H2O, the complete Kegggin ion is generated by crystallographic inversion symmetry, which imposes statistical disorder on the O atoms of its central PO4 group. The V atom is statistically disordered over all the metal sites of the anion. In the cation, the Co2+ ion is coordinated by three bidentate 1,10-phenanthroline (phen) ligands, generating a distorted CoN6 octa­hedron. Possible very weak intra­molecular C—H⋯π inter­actions occur in the cation. In the crystal, the components are linked by O—H⋯O and C—H⋯O inter­actions, building a three-dimensional network featuring one-dimensional voids along the c-axis direction.