| In this paper,two quinoline–imidazole–monoamide ligands containing N-(quinoline-5-yl)-1H-imidazole-4-carboxamide(L1)and N-(quinolin-5-yl)-1H-pyrazole-3-carboxamide(L2),and three Bis-imidazole/pyridine-bisamide ligands containing 4-[(1H-imidazole-4-carboxamide)ethyl]phenyl-1H-imidazole-4-carboxamide(L3),bis[4-(1H-imidazole-4-carboxamide)phenyl]methanone(L4),and N-(4-(2-(pyridin-3-yl)acetyl)phenethyl)nicotinamide)(L5)were selected as organic ligands and combine with Keggin or octamolybdate anions with Co(II)/Ni(II)/Zn(II)/Cu(II)ions as the central metal ions.Fifteen complexes with various structures were prepared by hydrothermal or solvothermal synthesis.A series of technical methods including single-crystal X-ray diffraction,IR,PXRD and UV/Vis spectroscopy were used to analyse and characterize complexes 1-15.And the electrocatalytic and electrochemical sensing,dye photocatalytic and adsorption properties of part complexes have been investigated.1.By introducing quinoline-imidazole/pyrazole-monoamide ligands into the reaction system containing[Mo7O24]6-anions or[SiW12O40]4-anions with different metal ions,complexes1-8 have been segregated by adjusting these factors including the organic ligands,types of POMs,metal ions and solvent molecules in the reaction system.[Co(HL1)2(?-Mo8O26)](1)[Ni(HL1)2(?-Mo8O26)](2)[Zn(HL1)2(?-Mo8O26)](3)[Cu2(HL1)2(?2-OH)2(?-Mo8O26)](4)[Co(HL1)2][SiW12O40](5)[Co(HL1)2(H2O)2][SiW12O40](6)[Zn(HL2)2(?-Mo8O26)](7)[Co(HL2)2(?-Mo8O26)](8)L1=N-(quinoline-5-yl)-1H-imidazole-4-carboxamide L2=N-(quinolin-5-yl)-1H-pyrazole-3-carboxamideComplexes 1-4 have been hydrothermally synthesized by changing different metal ions and all are 2D supramolecular structures with 1D chains based on the[?-Mo8O26]4-polyoxoanion.Complexes 1–3 are isostructural with the same architectural feature of a mononuclear[M(HL1)2]4+unit,but a binuclear[Cu2(HL1)2(?2-OH)2]4+cation in complex 4,manifesting that the metal cation has a marked impact on the structures of 1–4.Meanwhile,the formation of the supramolecular structure also depends on the hydrogen bonding interactions between the protonated nitrogen atom in the quinoline ring and the surface oxygen atom of POMs.Solvent molecules also affect the formation of POMs-based metal-organic complexes.Under the same Co/L1/[SiW12O40]4-system,compolexes 5 and 6 have been synthesized by changing the solvent molecules of the reaction.Complexes 5 and 6 are 2D supramolecular structures with[SiW12O40]4-anion as template.The different differences are that a Co(HL1)24+metal-organic unit is existed in 5,but a similar metals-organic unit[Co(HL1)2(H2O)2]4+in 6.Two isostructural complexes 7 and 8 have been obtained under hydrothermal conditions by introducing L2and metal ions.Complexes 7 and 8 have the same metal-organic units[M(HL2)2]4+and 1D chains,which are similar to complexes 1-3.Complexes 1-5 and 7-8 have good electrochemical behaviors.Among them,complexes 1-4 show dual-functional electrocatalytic activities,and can not only reduce inorganic bromate,nitrite and hydrogen peroxide,but also oxidize AA.Meanwhile,complexes 1-4 can sense these substances with low detection limits and excellent anti-interference abilities.Complex 7-8 also can electrocatalytically reduce and sense bromate,nitrite and Cr(?)ions with low detection limits and excellent anti-interference abilities.The photocatalytic performance for organic dyes GV and MB of complexes 1-5 and 7-8 were aslo investigated in detail.Complex 1,2,4 and 5 have photocatalytic degradation effects on GV,as well as complexes 3,7 and 8 on MB.2.By introducing three bis-imidazole/pyridine-bis-amide ligands into the reaction system based on different metal ions and POMs,seven POMs-based metal organic complexes(9-15)have been prepared successfully by changing these fators in the reaction system including the organic ligands,types of POMs,metal ions and solvent molecules.[Co L3(?-Mo8O26)0.5](9)[Co2(HL3)2(H2O)][SiW12O40](10)[Ni(H2O)2L4(?-Mo8O26)0.5](11)[Co(H2O)2L4(?-Mo8O26)0.5](12)[(L4)2][SiW12O40](13)[Co2(HL4)2(H2O)][SiW12O40](14)[(HL5)2][SiW12O40](15)L3=4-[(1H-imidazole-4-carboxamide)ethyl]phenyl-1H-imidazole-4-carboxamide L4=bis[4-(1H-imidazole-4-carboxamide)phenyl]methanoneL5=N-(4-(2-(pyridin-3-yl)acetyl)phenethyl)nicotinamide)By changing the types of POMs and solvent moleculars,complex 9 based on[?-Mo8O26]4-anion and complex 10 based on[SiW12O40]4-anion have been formed under hydrothermal or solvothermal conditions.Complexes 9-10 show 2D supramolecular structures with similar 1D chain.The 1D chains were formed by using L3ligand,where the Co-L3metal-organic chain acted as the“sides”of the ladder and the polyoxoanion acts as the“middle rails”,indicating that the solvent molecules and types of POMs could be changed to build diversified POMs-based metal-organic complexes.By introducing L4ligand into the reaction based on different metal ions and POMs,two complexes(11 and 12)based on[?-Mo8O26]4-anion and two complexes(13and 14)based on[SiW12O40]4-anion were synthesized under hydrothermal or solvothermal conditions.Complexes 11 and 12 are isostructural 2D supramolecular structures with POMs anions as templates to form 1D wave-like metal-organic M-L4chain.Complexes 13 and 14were synthesized under hydrothermal and solvothermal conditions,respectively.Among them,complex 13 is 0D structure without metal ions.But complex 14 is 2D supramolecular structure and possess similar 1D chain with complex 10,which was formed by combining the adjacent metal-organic long chain with the[SiW12O40]4-anion.The different structures of complexes11-14 indicate that organic ligands,POMs anions and solvent molecules could be changed to build diversified POMs-based metal-organic complexes.Complex 15 has been synthesized with0D supramolecular structure by introducing L5ligand and combining with[SiW12O40]4-anion.The electrocatalytic,electrochemical sensing,dye adsorption and photocatalytic properties of complexes 9-12 and 14-15 were also studied.Complexes 9,11 and 12 can electrocatalytically reduce and sense bromate and nitrite with low detection limits and excellent anti-interference abilities.In addition,complex 9 and 15 aslo can sense Cr(?)and Fe(?)ions.Complex 11 has good photocatalytic properties on NR,as well as complexes 10,14 and 15 can absorb MB in the dark. |
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