A new double-Keggin-anion-templated organic–inorganic hybrid architecture: Synthesis, crystal structure and photoluminescence

A new double-Keggin-anion-templated host–guest hybrid compound, (H4pzdc)5[(H2pzdc)6(pzdc)2(H2O)2Na6][PW12O40]4·31H2O (1) (H2pzdc = 2,3-pyrazinedicarboxylic acid), has been synthesized and characterized by elemental analysis, IR spectroscopy, TG analysis, and single crystal X-ray diffraction. Compound 1 exhibits an intriguing double-Keggin-anion-templated 2D structure, made up of [PW12O40]3− Keggin-type polyoxoanions covalently linked with hexanuclear [Na6(H2pzdc)6(pzdc)2]2+ macrocations. To our best knowledge, it represents the first example of host–guest compounds with double-Keggin anions as coordinating template. Furthermore, compound 1 displays stronger photoluminescence properties than the H2pzdc ligand, due to the introduction of alkali metal cations.