| In this paper,under hydrothermal conditions,by using Tris,pyrazole derivatives 4-butyl-1H-pyrazole(bpz)and 1,1'—bis(3,5—dimethy1—1H—pyrazolate)methane(H2bdpm)and thiophene derivatives 2—(4,5—diphenyl—1H—imidazole)—4—thiophene(L1)and 4-(2-thiophene-2-ethyl)-4H-[1,2,4]triazole(L2)ligands and through tuning the varieties of POMs,the reaction temperature and pH in different reaction system,eleven compounds based on Keggin/Wells-Dawson/Lindqvist/Preyssler type polyoxometalates were synthesized.They were characterized by single X-ray crystal diffractometry.In addition,we have studied the electrochemical,photocatalytic and fluorescent properties of these new POM—based compounds.1.Two isomorphic compounds were synthesized under hydrothermal conditions using tris(Tris)ligand and Lindqvist POM anions:[Co(Tris)3(H20)3(H3V6019)]H20(1)[Zn(Tris)3(H2O)3(H3V6O19)]H20(2)Compounds 1 and 2 are isostructural,containing a mix-capped Lindqvist—type[V6O19]5-anion.One octahedron coordinative Co/Zn atom links with three bridging O atoms of anion,forming the "inorganic cap" Furthermore,three Tris organic ligands offer their nine O atoms to build a[V6O19]5-anion.These three Tris molecules become the "organic cap" of the anion,realizing the organic functionalization of[V6O19]5-.2.The pendent ligand 4—butyl—1H—pyrazole(bpz)and 1,1'—bis(3,5—dimethyl—1H—pyrazolate)metane(H2bdpm)were introduced into POM—Cu/Co system.Both ligands contain a five—membered ring of pyrazole,that is,they own two coordinating N atoms,which have strong coordination ability.This feature conduces to aggregate metal ions to form multi-nuclear clusters.By tuning the temperature,pH and other conditions,under the hydrothermal conditions,one Preyssler-based compound,one Wells—Dawson-based compoud and one[MO8O26]4-—based compound were synthesized:[Cu4(H2bdpm)4(H2O)10(H6KP5W30O110)]-2(H2bdpm).14H2O(3)[CO4(H2bdpm)4(H2P2W18062)](4)[Cu2(bpz)2H2(?-Mo8O26)0.5(0-Mo8O26)0.5].H2O(5)Compound 3 contains a rare K atom as a center of Preyssler type anion,which are further by a binuclear Cu2+ring to form a 1D double-stranded structure.Adjacent one-dimensional double chains form a two-dimensional supramolecular layer structure through abundant intermolecular forces.In compound 4,the polyanion does not participate in the coordination and each polyanion is dispersed around the sin sinusoidal chain constructed by Co atom and the ligand to constitute a 1D supramolecular chain.In compound 5,there are two different types of polyanions[?-Mo8O26]4-and[?-Mo8O26]4-,in which only[?-Mo8O26]4-participates in coordination and links transition metal and bpz ligands to build a 1D chain.3.Six isopolymolybdate-and Keggin—based compounds were synthesized under hydrothermal conditions through using different POM anions.This series of compounds were modified by S-containing rigid thiophene ligand 2—(4,5—diphenyl—lH—imidazole)-4—thiophene(L1)and S-containing flexible thiophene ligand 4—(2—thiophene—2—yl-et.hyl)—4H—[1,2,4]t.riazole(L2):[H4L14(Mo8O26)2H2O](6)[H6L18CPMo12)](7)[Cu3L23(PMo12O40)](8)[Cu4L26(SiW12O40)](9)[Cu4L26(SiMo12O40)](10)[Zn4L26(SiW12O40)](11)The compound 6 consists of one isopolymolybdate anion[Mo8O26]4-,four L1 ligands and two crystal water molecules.Between[Mo8O26]4-anions and ligands there are rich hydrogen bonding force,inducing a one-dimensional supramolecular chain of compound 6.In the compound 7,a large amount of hydrogen bonding force exist between the PMo12 polyanions and the organic ligands L1,and a supramolecular one-dimensional chain is formed.In compound 8 the coordination features of Cu+and L2 ligand induce a cyclic tri-nuclear Cu+cluster.Compounds 9,10 and 11 are isostructural,containing a 1D chain induced by[Cu4L26]4+subunits and POM anions.Furthermore,we have studied the sensor character of compounds 8-11.Their suspension has a good fluorescence recognition Hg2+.By using S-containing ligands,we are also working to further explore other POM-based Hg2+fluorescent probes. |
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