| The construction of high-nuclearity and functional polyoxometalates(POMs)is always the main aim of chemistry's research.A great challenge in this field is how to optimize the assembly of POM anionic building units and functional groups.In this dissertation,the selenotungstate/tellurotungstate reaction systems that contain lone-pair-electron effects are selected,and several series of novel multi-nuclear lanthanide(Ln)/heterometal-substituted selenotungstate/tellurotungstate aggregates are prepared by employing the one-pot self-assembly and auxiliary organic-ligand protection strategies as well as by the introduction of functional metal ions and organic ingredients.These compounds have been structurally characterized by X-ray single-crystal diffractions,IR spectra,TG analyses,X-ray photoelectron spectra,and so on.The luminescent,magnetic and anticancer properties of some compounds have been further studied in detail.The work not only provides valuable guides for the preparation of novel high-nuclear Ln/heterometal-substituted POM aggregates,but also promotes the developments of POM synthetic cnemistry to material chemistry.The dissertation can be divided into the following four sections:1.Two acetic acid-decorated,multi-nuclear Ln-W-Te metal-oxo cluster encapsulated tellurotungstate hexamers K4H2[(CH3)2NH2]20[(Ln4 W4O9)(CH3COO)(H2O)7(TeO3)(B-?-TeW8O30)(B-?-TeW8O31)2]2·82H2O(Ln=Pr3+,Nd3+)(1-2)have been obtained by introducing acetic acid ligands into the tellurotungstate/Ln system.Compounds 1-2 contain four tetra-vacant Keggin-type[B-?-TeW8O31]10-fragments,two tetra-vacant Keggin-type[B-?-TeW8O30]8-fragments and one hexadeca-nuclear{[(Ln4W4O9)(CH3COO)(H2O)7(TeO3)]2}30+ metal-oxo cluster,representing the rare Ln-substituted hybrids based on mixed ?-and ?-type tellurotungstate building units.In the structure,Te atoms not only serve as heteroatoms inducing the formation of multi-vacant tellurotungstate fragments,but also work as bridging units together with Ln ions for the construction of high-nuclear aggregates.The solid-state near-infrared photoluminescent measurements have been carried out and the results show that the emission spectra of 1-2 respectively exhibit the typical emission peaks of Pr3+ and Nd3+ions,and their biexponential lifetimes are ?1=0.78?s(54.77%)and ?2=9.17?s(54.77%),as well as ?1=1.64?s(27.49%)and ?2=11.27 ?s(72.51%),respectively.The time-resovled emission spectrum of 1 reveals the absence of energy transfer betweem tellurotungstate fragments and Pr3+ ions.2.By introducing transition metal(TM)Fe3+ ions and 2,5-pyridine-dicarboxylic acid(H2pdca)ligands possessing both multi-coordinate centers(O-and N-coordination sites),a series of mixed organic-ligand-connecting Fe?-Ln heterometal encapsulated tungstotellurate tetrameric units[H2N(CH3)2]8K2Na4[Ln2(Ac)2(H20)4Fe2(Hpdca)2(B-?-TeW9O33)2][Ln2(H2O)8Fe2(Hpdca)2(B-?-TeW9O33)2]·50H2O(Ln=Eu3+,Tb3+,Dy3+,Er3+)(3-6)have been successfully prepared,in which adjacent tetramers are further connected by H2pdca molecules into infinite one-dimension(1-D)chain.Compounds 3-6 are the first exampes of inorganic-organic hybrid TM-Ln heterometal inserted tungstotellurate derivatives thus far.The solid-state photoluminescence properties of 3 and 4 have been studied,and their correlated color temperatures and color purities are 1995 and 3278 K,and 95.09%and 57.27%,respectively.Moreover,the magnetic measurements of 5 indicate the Ueff/kB?0.83 K and ?0?6.06×10-6 s,as well as Ueff/kB?0.76 K and ?0?6.97×10-5 s at 0 Oe and 1500 Oe,respectively.3.Besides TM or Ln linkages,the bioactive organometal groups[(CH3)2Sn]2+sereving as cationic linkages are also applied into the tellurotungstate and Ln reaction system,leading to two giant and nano scale organometal-Ln heterometallic substituted tungstotellurate nanoclusters[H2N(CH3)2]22KsNa10H6 {[Sn(CH3)2]12[Sn(CH3)2O]4(TeW4Ln4O16)2(TeW8O31)8(LnW5O18)2}·ca.186H2O(Ln=Ce3+,Pr3+)(7-8).7-8 are composed of two symmetry-related pentamers{[Sn(CH3)2]4(TeW4Ln4O16)(TeW8O31)4(LnW5O18)}27-bridged by four self-polymerized {[Sn(CH3)2]2O}2+ groups,and the pentamer can be described as the multi-hierarchy assembly templated by TeO4-and TeO3-heteroanions,namely the innermost[TeW4O20]12-core,the middle Sn-Ce-bridging {[Sn(CH3)2]4(Ce4TeW8031)4}32-tetrameric unit as well as the outer[CeW5O18]3-fragment.7-8 represent the largest POM-based organometal-Ln heterometallic aggregates so far.The good inhibitory effect against HeLa cells have been confirmed by multiple measurements such as MTT assays,Western-Blot analysis,the change of mitochondrial membrane potential,and so on.Furthermore,the in vivo antitumor activities of 7-8 have been comprehensively studied,illustrating that 7and 8 are able to inhibit tumor proliferation mainly by inducing apoptosis.4.Two Agl-Ln heterometallic cluster stabilized selenotungstate hexamers Na4(HDMEA)4[H2N(CH3)2]6H]6[Ag6Ln4Se2(DMEA)2(H2O)8 W8028][B-?-SeW9033]6·40H2O(Ln=Eu3+,Gd3+)(9-10)and one Co?-Ln heterometallic substituted selenotungstate tetramer Na2H12[Co(H2O)6]2{[Co(H2O)3]2[Ce(H2O)4]8W16O40(H2tart)6(Htart)2(Se2W14O52)4}·72H2O(11)have been synthesized by using the simple materials as reactants and tuning the metal ions(3d and 4d).Compounds 9-10 are comprised of six tri-vacant Keggin-type[B-?-SeW9033]8-fragments bridged by one multi-nuclear DMEA-decorated[Ag6Eu4Se2(DMEA)2(H2O)8W8028]18+heterometallic cluster,and are the largest Ag-Ln heterometallic substituted POM derivatives reported to date.Compound 11 can be regared as the assembly of four Dawson-type[(Ce2W2O4)Se2W14O52]2-fragments linked by one tart-bridged {[Co(H2O)3]2W8032(H2tart)6(Htart)2} metal-oxo cluster,to be one member of the few selenotungstate heterometallic clusters.The temperature-dependent photoluminescent properties of 9 have been studied,in which the emission intensities and the decay lifetimes decline along with the increase of temperature,implying the potential application of luminescent thermometry. |
PDF Full Text Request