Assembly And Properties Of Inorganic-organic Hybrids Decorated By Polyoxometalates And Muti-topic N/O-containing Ligantls

In this paper, nine new inorganic-organic POM-based hybrids decorated bymuti-topic N/O-containing ligands have been synthesized under hydrothermalconditions, which also have been structurally characterized by single crystal X-raydiffractions, elemental analyses, IR, TG. And the electrochemical properties andphotocatalytic properties of these compounds have been studied. Additionally, theeffects of the POMs, the length (configurations) of the flexible ligands and the TMs onthe final structures have been explored.1. Four new CuII/Icomplexes based on Keggin-type [PMo12O40]3-andpolyoxomolybdate anions have been synthesized and characterized, through using2-pyrazinecarboxylic acid (pzca) as organic ligands:[H2en]2[Cu(pzca)2(Mo8O26)].4H2O (1)[Cu2(pzca)2(Mo8O26)0.5(H2O)4]·H2O (2)[CuI3CuII4(pzca)7(Mo8O26)(H2O)2]·4H2O (3)[CuII4CuI2(pzca)6(HPCuMo11O39)(H2O)6]·2H2O (4)Compounds1-3have been successfully synthesized under hydrothermal conditionsvia adding different kinds of amine and adjusting the pH values. In compound1, the[Cu(pzca)2] units bridge the [β-Mo8O26]4clusters to generate a1D chain, which isextended by hydrogen-bonding interactions to a3D supramolecular structure.Compound2exhibits a3D coordination framework based on the1D infinite[Cu2(pzca)2]n2n+zigzag chains and β-Mo8O264anions, and shows a trinodal3,3,4-connected {83}4{86} topology containing a dodecagonal channel with thedimension of13.496×19.6422. Compound3is a3D metal–organic network derivedfrom the“λ”-like [Cu5(pzca)4] subunits and [β-Mo8O26]4anions, which represents anovel{4·6·83·10}2{4·6·8}2{42·104}{42·83·10}{6·82}2{62·103·12}{62·82·102}{62·83·10}{63}4topology in octamolybdate-based MOCs. The structural diversities showthat the different amines and pH value of the reaction system play key roles in theconstruction of high dimensional architectures. Compound4shows a (2,3,4,7)-connected three-dimensional framework with{4·62·9·102}{4·92}{42·69·87·103}{6·9·10}2{9}2topology, which is constructed fromthe monosubstituted Keggin chains [HPCuMo11O39]n4n and metal–carboxylate chains[Cu6(pzca)6]n4n+.2. By tuning the length of the flexible bis-pyridyl-bis-amide ligands and the kinds ofPOMs, we synthesized three new POM-based coordination compounds:(L1)(H3PMo12O40)(5)(L1)2(H4Mo8O26)(6)(3-C5H6N2)(L2)(H3PMo12O40)(7)Compounds5-7are supramolecular structures composed of discretebis-pyridyl-bis-amide ligands and polyanions, which exhibit three differentsupramolecular frameworks directed by the different hydrogen bonding interactions.Compounds5and6show (5,5)-and (4,8)-connected3D supramolecular frameworks,respectively. In the (4,5)-connected3D supramolecular network of compound7, thefascinating structural feature is the existence of1D double helix chains and2D doublelayers. Compounds5-7represent the first example of POM-based supramolecularhybrids derived from the flexible bis-pyridyl-bis-amide ligands.3. Two new complexes based on Keggin-type [PMo12O40]4-and [Mo4O16]8-have beensynthesized, through using two different amines and transition metal Cu/Ag as organicligands and metal centers:[Cu(en)2](H4Mo4O16)0.5(8)Ag(3-C5N2H6) H2PMo12O40(9)In8, each (H4Mo4O16)0.52-cluster links four neighboring ones through four [Cu(en)]2+units to yield a2D (2,4)–connected network, which further extend to a3Dsupramolecular via the hydrogen bonding interactions. In9, the adjacent H2PMo12O40–clusters are bridged by two [Ag(3-C5H6N2)2]+units to generate a1D chain structure.The introduction of transition-metal and amine is the crucial factor for construction ofmetal-organic subunits, which further assemble with the POMs to give rise to differentstructures of inorganic-organic coordination polymers.In additional, we have also studied the electrochemical behavior, electrocatalytic and potocatalytic degradation MB performance of some title compounds. The resultssuggest that many compounds exhibit good properties and will become the potentialinorganic-organic hybrid materials.