| The four series/ten novel polymolybdate crystal materials decorated by metal complexes have been designed and synthesized under hydrothermal conditions based on molecular design and engineering idea. The polymolybdate anion as the basic building unit, transition metal and nitrogen (N) ligand forming metal complexes to decorate polymolybdate anions (such as 1,10'-phenanthroline (1,10'-phen), 2,2'- bipyridine (2,2'-bpy), 4,4'-bipyridine (4,4'-bpy) and ethylenediamine (en)). Through orthogonal experiments, we summarized synthesis strategy and determine the optimum condition. The experimental condition is: pH = 4.0-6.5, L : M (mol) < 2:1, T = 140℃-160℃.Chemical formulas of the crystal materials were confirmed by elemental analysis, ICP and TG analysis as follows: (1) metal complexes decorated isopolymolybdates K2[{Cu(1,10′-phen)}4Mo6O22][Mo8O26]·2H3O(denoted Cu4Mo14), [Ni(2,2′-bpy)3]2[Mo8O26]·4H2O(denoted Ni2Mo8), [Zn2(4,4′-bpy)(MoO4)2]n?3nH2O (denoted Zn2Mo2); (2) metal complexes decorated Keggin-type polymolybdates [Cu4(1,10′-phen)4(HPO4)2(H2O)2(OH)2][HPMo12O40]?H2O(denoted Cu4PMo12), [4,4′-bpy][CuI(4,4′-bpy)]2[HPMoV2MoVI10O39](denoted Cu2PMo12), [Cd(1,10′-phen)3]2[H PMo12(VO)2O40](denoted Cd2PMo12V2); (3) metal complexes decorated reduced polymolybdates [Ni(2,2′-bpy)2(H2O)2]{[Ni(H2O)2][Ni0.5(MoO2)6(OH)3(PO4)(HPO4)3 [Ni(2,2′-bpy)2(H2O)]2][Ni0.5(MoO2)6(OH)3(PO4)(H2PO4)2(HPO4)]}·14H2O (denoted Ni5P4Mo6), (en)6{Cu(H2O)Na[(MoO2)6(OH)3(PO4)(H2PO4)(HPO4)2][(MoO2)6(OH)3 (H2PO4)2(HPO4)2]}·5H3O (denoted CuP4Mo6); (4) metal complexes decorated Standberg-type polymolybdates [Cu(en)2][Cu(en)2(H2O)1.5][Cu(en)2(H2O)2]0.5[{Cu (en)2}5{HP2Mo5O23}3]·6.5H2O (denoted Cu7.5P2Mo5), [Ni(en)(Hen)(HP2Mo5O23)] [H2en]?3H2O (denoted NiP2Mo5).The crystal materials were characterized with IR, XPS and X-ray single crystal diffractometer. Cu4Mo14 is firstly found with 1D chain structure formed copper-complex-substituted dilacunaryβ-octamolybdate fragments and [β-Mo8O26]4- cluster anions. Ni5P4Mo6 is an novel unusual one-dimensional chain formed Ni[P4Mo6]2 and transition metal complexes decorated polymolybdate clusters alternately connected by [Ni(H2O)2] subunit.The thermal stabilities were studied by TG-DTA. It was found that thermal stability is improved by hydrothermal process than conventionally synthesized, and Cu4Mo14 didn't lose water molecules until above 346℃because there exist many weak interactions in its structure. High thermal stability has great significance for its application.Magnetic measurements indicate that Cu4Mo14 exists ferromagnetic interaction, Cu4PMo12 and Cu7.5P2Mo5 exist antiferromagnetic interaction. Redox properties and electrocatalytic toward nitrite of Cu4PMo12 is better than CuP4Mo6. Carbon paste electrodes (CPE) of CuP4Mo6 and Cu4PMo12 show good stability. Fluorescent measurements indicate that Cd2PMo12V2, Ni5P4Mo6 and Cu2PMo12 exhibit strong emission in the solid state at room temperature. These crystal materials may be potential candidates for photoluminescence materials. |
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