Syntheses,Structures,Luminescent And Magnetic Properties Of Lanthanide-inserted Borotungstate/Tungstobismuthate Derivatives

In this dissertation,on the basis of the self-assembly strategy,twenty-three novel Ln-substituted borotungstates?BTs?and tungstobismuthates?TBs?have been successfully prepared by utilizing polyoxotungstate fragments containing electron-deficient B^III heteroatoms and lone-electron-pair active Bi^III heteroatoms to react with lanthanide?Ln?ions in the conventional aqueous solution,and further characterized by elemental analyses,single-crystal X-ray diffraction,IR spectroscopy.Furthermore,magnetic susceptibility measurements and solid-state photoluminescence properties of some derivatives have been conducted.This dissertation can be divided into four parts to introduce my work during the master study:Part ?.Three kinds of Ln^III-substituted BT derivatives KH₂[Ce?H₂O?₈][Ce?H₂O?₃][?-BW₁₁O₃₉]·14H₂O?1?,K₄Na₄H₄[Pr?H₂O?₃]₂[?-BW₁₁O₃₉]₂·30H₂O?2?,KH₃[Nd_0.5K_0.5?H₂O?₈][Nd?H₂O?₃][?-BW₁₁O₃₉]·14H₂O?3?and NaK₆H₅{[W₅O₁₈]Ln[BW₁₁O₃₉]}·22H₂O[Ln=Sm³⁺?4??Eu³⁺?5??Dy³⁺?6??Ho³⁺?7??Er³⁺?8??Yb³⁺?9?]have been successfully synthesized.1–3 were obtained from the mixture of K₈[?-BW₁₁O₃₉H]·13H₂O,NaAc·3H₂O and Ln?NO₃?₃·6H₂O in the acidic aqueous medium.The structural units of 1 and 2 contain a 1:1-type mono-Ln-substituted polyoxoanionfragment{[Ce?H₂O?₈][Ce?H₂O?₃][?-BW₁₁O₃₉]}^3–or[Nd_0.5K_0.5?H₂O?₈][Nd?H₂O?₃][?-BW₁₁O₃₉]^4–that is composed of a[?-BW₁₁O₃₉]^9–unit,a bridging[Ln?H₂O?₃]³⁺(Ln=Ce³⁺,Nd³⁺)cation and a decorated[Ce?H₂O?₈]³⁺or[Nd_0.5K_0.5?H₂O?₈]²⁺cation,in which adjacent{[Ce?H₂O?₈][Ce?H₂O?₃][?-BW₁₁O₃₉]}^3–or[Nd_0.5K_0.5?H₂O?₈][Nd?H₂O?₃][?-BW₁₁O₃₉]^4–units are linked together by Ln³⁺bridges forming a 1-D chain arrangement.Moreover,neighboring 1-D chains are further interconnected by K⁺ions into the 2-D extended architecture.2 consists of a dimeric unit[Pr?H₂O?₃]₂[?-BW₁₁O₃₉]₂^12–,and neighboring dimers are linked into the 1-D chain via Pr³⁺ions.The near-infrared photoluminescence properties of 3 have been studied and the luminescence emission spectrum exhibits the characteristic emission bands derived from Nd³⁺ions.The thermostability of 1 has been probed by variable-temperature power X-ray diffraction,variable-temperature IR spectra and TG analyses.The solution electrochemical and electrocatalytic properties of 1 have been measured.4–9 were prepared from the simple materials of Na₂WO₄·2H₂O?H₃BO₃ and Ln?NO₃?₃·6H₂O in the KCl aqueous medium,featuring that the mono-vacant[?-BW₁₁O₃₉]^9–fragment and one[W₅O₁₈]^6–fragment fused together by the assistance of Ln³⁺ion into a new dimer.The solid-state photoluminescent studies of 4 6 have been conducted at ambient temperature and all exhibit typical emissions of Ln³⁺ions,besides,all of them show the long luminescent decay lifetimes.Part ?.By introducing organic ligands into the BT–Ln system,a series of inorganic–organic hybrid Ln-substituted BT derivatives K₄Na₄H₄[Ln₂?gly?₄(?-BW₁₁O₃₉)₂]·23H₂O[Ln=Ce³⁺?10?,Pr³⁺?11?,Nd³⁺?12?,Sm³⁺?13?,Eu³⁺?14?and Tm³⁺?15?]have been successfully prepared.10–15 were obtained via the reaction of K₈[?-BW₁₁O₃₉H]·13H₂O,NaAc·3H₂O and Ln?NO₃?₃·6H₂O in the presence of gly ligands under the aqueous conditions.10–15 are isostructural and all consist of two mono-Ln-substituted Keggin[Ln(?-BW₁₁O₃₉)]^6-fragments linked by four gly ligands,representing the first inorganic–organic hybrid Ln-substituted BTs bridged by a quadruple-gly linker.The near-infrared photoluminescence properties of 12 as well as the visible photoluminescence properties of 13,14 and K₈[?-BW₁₁O₃₉H]·13H₂O have been investigated.By comparison of the luminescence decay profiles of 13 and 14 with K₈[?-BW₁₁O₃₉H]·13H₂O,it can be found that the luminescence behavior of 13 is accomplished by the combined actions of K₈[?-BW₁₁O₃₉H]·13H₂O and Sm³⁺ions whereas the luminescence behavior of 14 is mainly derived from the characteristic emission of Eu³⁺ions.Magnetic susceptibility measurements of 11,13 and 14 have been carried out.Part ?.An unprecedented Ce^IV-substituted nanosized TB Na₁₆?NH₄?₁₀H₅{(W₁₄Ce₆O₆₁)[W₃Bi₆Ce_2.5Na_0.5?H₂O?₃O₁₄(?-BiW₉O₃₃)₃]₂}·38H₂O?16?has been obtained from the one-pot self-assembly reaction.16 was synthesized by reaction of simple materials Na₂WO₄·2H₂O,NaAc·3H₂O,Bi?NO₃?₃·5H₂O and?NH₄?₂Ce?NO₃?₆ in the mild acidic aqueous.The prominent structural feature of 16 is that six trivacant Keggin building blocks,two trivacant Lindqvist and two W-capped trivacant Lindqvist building blocks are perfectly linked by a splendid?flying eagle?shaped cluster{[W₃Bi₆Ce_2.5Na_0.5?H₂O?₃O₁₄]₂[Ce₆O₈]}involving two{W₃Bi₆Ce_2.5Na_0.5?H₂O?₃O₁₄}?{Bi₆}?units and one{Ce₆O₈}?{Ce}?unit into a giant Ce^IV-substituted TB aggregate.Interestingly,six Ce⁴⁺ions in the{Ce₆O₈}unit constitute an octahedral configuration.16represents the first Ln-based TB aggregate incorporating three distinct trivacant Keggin,trivacant Lindqvist and W-capped trivacant Lindqvist building blocks connected by the{Bi₆}and{Ce₆}clusters.16 has been firstly dopped with Eu³⁺and Tb³⁺ions,which is further functionalized into nanoparticles by the cationic surfactant cetyltrimethylammonium bromide?CTAB?.The morphologies of the nanoparticles have been tuned by controlling the mass of CTAB,and their photoluminescence behaviors have been discussed.The proton-conducting measurements of 16 are employed over the temperature range of–40–30 ^oC and the result shows a high proton conductivity of 16.Besides,the thermal decomposition procedure of 16has been comprehensively studied by TG analyses,variable-temperature IR spectra and variable-temperature power X-ray diffraction.Part ?:Two types of HAc-bridged Ln-containing dimeric TBs Na₂Li₁₀[Pr?H₂O?₂?Ac?Bi₂W₂₁O₇₃]₂·36H₂O?17?and Na₂Li₁₀[Ln?H₂O??Ac?Bi₂W₂₁O₇₃]₂·54H₂O[Ln=Eu³⁺?18?,Gd³⁺?19?,Tb³⁺?20?,Dy³⁺?21?,Ho³⁺?22?,Er³⁺?23?]have been synthesized by the one-pot self-assembly reaction.17–23 were attained by reacting Na₂WO₄·2H₂O,Bi?NO₃?₃·5H₂O with Ln?NO₃?₃·6H₂O in LiAc aqueous solution,and represent the first examples of inorganic–organic hybrid HAc-bridged Ln-substituted TB derivatives,which all encompass two units[Bi₂W₂₁O₇₃]^8–linked by the metal-organic connectors forming a novel dimeric species.The difference between17 and 18–23 exists in the metal-organic connectors[Pr?H₂O?₂?Ac?]²⁺and[Ln?H₂O??Ac?]²⁺,in which the Pr³⁺ion has two coordination water molecules whereas other Ln³⁺ions have one coordination water molecule.The solid-state near-infrared photoluminescence behaviors of 17,22 and 23 as well as the solid-state visible photoluminescence behaviors of 17,18,20 23 have been examined under ambient temperature.Furthermore,the magnetic properties of 17,20,21and 23 have also been preliminarily studied,and the alternating-current susceptibility measurements suggest the slow magnetic relaxation and the possible single-molecule magnetic behavior in 21.