| In this paper, by using three kinds of pendent organic ligands, (4-butyl-1H-pyrazole (Hbpz),1-benzyl-1H-(1,2,4)triazole (2-btz) and 1-benzyl-1H-(1,3,4)triazole (3-btz)), nineteen polyoxometalate (POM)-based compounds were hydrothermally synthesized and structurally characterized by single crystal X-ray diffraction. By tuning the pH of reaction system, the location of the coordination sites, varieties of POMs, we have constructed a series of novel POM-based compounds. Furthermore, we also explored the electrochemical and photocatalytic properties of these new compounds.1. By utilizing simple pendant 4-butyl-1H-pyrazole (Hbpz) with an alkyl "tail"-(CH2)3CH3, four Keggin-based compounds containing different transition metal multi-nuclear clusters and an infinite chain were hydrothermally synthesized and structurally characterized:[CuⅠ4(bpz)4(pz)2(H6PW11CuⅡO39)2]·10H2O (1)[CuⅡ2(bpz)2(H2O)2(H3PCu0.5Mo11.5O40)]·3H2O(2)[Ag3(bpz)2(pz)(H4SiW12O40)]·4H2O (3)[Ag5(bpz)4(H5/2PMo12O40)2]·6H2O (4) (pz=pyrazole, bpz= 4-butyl-1H-pyrazole)Compound 1 contains a tetra-nuclear cluster [CuⅠ4(bpz)4(pz)2]2- linked by Keggin anion dimers to form a 2D layer. In compound 2, the ptz ligands fuse the CuⅡ ions and an infinite 1D metal-organic chain is constructed with the Keggin anions hanging up and down covalently. The 3D compound 3 has a planar triangle tri-nuclear cycle [Ag3(bpz)2(pz)]. In compound 4, there exist discrete [Ag5(bpz)4]+ clusters, which are linked by Keggin anions alternately to form a 1D chain and further a 2D layer is constructed. The bpz ligand is firstly introduced into the POM field and its successive two N donors are essential for the construction of multi-nuclear clusters and an infinite chain of 1-4.2. Hydrothermal technique has been proven an effective method to construct POM-based compounds. However, highly efficient usage of the technique to obtain two or more types of crystals in one pot has rarely been reported. By utilizing two kinds of pendent organic ligands (4-butyl-lH-pyrazole (Hbpz) and 1-benzyl-1H-(1,2,4)triazole (2-btz)), we have synthesized two pairs of new Keggin-based compounds:[AgⅠ3(bpz)2(pz)(H2O)(H3PMo12O40)2](5)[AgⅠ2(bpz)2(H3PMo12O40)]·2H2O (6) (pz=pyrazole, bpz= 4-butyl-1H-pyrazole)[AgⅠ3(2-btz)4(PMo12O40)] (7)[AgⅠ3(2-btz)3(PMo12O40)]·H2O (8) (2-btz=1-benzyl-1H-(1,2,4)triazole)Firstly, we introduced bpz in the POM-Ag system by tuning the pH range of 1.8-2.3 and mixed compounds 5 and 6 were obtained in one pot. In compound 5, bpz losing-(CH2)3CH3 to become pz, while only bpz was captured by 6. Secondly, we tuned the pH range of the POM-Ag-2-btz system to 1.7-2.4, and compounds 7 and 8 co-existed in one pot. Compound 7 exist [AgⅠ3(2-btz)4]3+ subunits, which are alternately connected by anions to form a 1D chain, while 8 is a 3D framework. Owing to the distinct color and shape, compounds 5 and 6, and 7 and 8 can be separated mechanically by using a microscope.3. By using two kinds of structural isomers organic ligands (1-benzyl-1H-(1,2,4)triazole (2-btz) and 1-benzyl-1H-(1,3,4)triazole (3-btz)), eleven polyoxometalate (POM)-based compounds were hydrothermally synthesized and structurally characterized:[CuⅡ(2-btz)4(HPMo12O40)]·2-btz-2H20(9)[CuⅡ(2-btz)4(HPW12O40)]·2-btz·H2O (10)[Cu4(2-btz)16(Mo8O26)2] (11)[Ag4(2-btz)5K(SiWⅤW11ⅥO40)]·13H2O (12)[Ag4(2-btz)4(HPMo2ⅤMo10ⅥO40)](13)[Ag4(2-btz)4(SiW12O40)] (14)[AgⅠ4(2-btz)4(SiMo12O40)] (15)[AgⅠ4(2-btz)4(HPWⅤ2WⅥ10O40)] (16)[CdⅡ3(3-btz)8(H2O)4]·(HSiMo12O40)2·2H2O(17)[Cu3(3-btz)8(H2O)4](PMo12O40)2·4H2O (18) (3-btz 1-benzyl-1H-(1,3,4)triazole)[Cu7(3-btz)16(OH)2(H2O)4(P2W18O62)2]·16H2O (19)The N sites in benzyl-1H-triazole ligands own obvious effect on structures. The two potential N donors in 2-btz are not successive, which is beneficial to form mono-nuclear clusters. Through using one N donor of 2-btz formed mono-nuclear subunits in compounds 9-11. In 12-16,2-btz only as a structural linker fromed chain-like AgⅠ subunits by using its two non-successive N donors. In compound 12, the anion dimers are linked by Ag5-O9 bonds to form 1D chains, which are further built a 3D framework. Compounds 13-16 are isostructural with two sets of Ag-(2-btz) chains linked by Keggin anions to construct a "ladder". These "ladders" are further build a 3D framework. Then, we change the strategy conduce to construct multi-nuclear clusters and the 3-btz was chosen. Compound 17 is a supermolecular structures including a tri-nuclear [CdⅡ3(3-btz)8(H2O)4]6+ cluster. Similarly, we obtained a linear tri-nuclear cluster [Cu3(3-btz)8(H2O)4]6+ in compound 18. Compound 19 is a discrete anion dimer containing a cycle tri-nuclear cluster-supporting anion [Cu3(3-btz)6(OH)(H2O)2(P2W18O62)]-... |
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