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51.
Georgios Velkos Denis S. Krylov Kyle Kirkpatrick Lukas Spree Vasilii Dubrovin Bernd Büchner Stanislav M. Avdoshenko Valeriy Bezmelnitsyn Sean Davis Paul Faust James Duchamp Harry C. Dorn Alexey A. Popov 《Angewandte Chemie (International ed. in English)》2019,58(18):5891-5896
The azafullerene Tb2@C79N is found to be a single‐molecule magnet with a high 100‐s blocking temperature of magnetization of 24 K and large coercivity. Tb magnetic moments with an easy‐axis single‐ion magnetic anisotropy are strongly coupled by the unpaired spin of the single‐electron Tb?Tb bond. Relaxation of magnetization in Tb2@C79N below 15 K proceeds via quantum tunneling of magnetization with the characteristic time τQTM=16 462±1230 s. At higher temperature, relaxation follows the Orbach mechanism with a barrier of 757±4 K, corresponding to the excited states, in which one of the Tb spins is flipped. 相似文献
52.
A Terbium Metal–Organic Framework for Highly Selective and Sensitive Luminescence Sensing of Hg2+ Ions in Aqueous Solution 下载免费PDF全文
Dr. Tifeng Xia Dr. Tao Song Gege Zhang Prof. Dr. Yuanjing Cui Dr. Yu Yang Prof. Dr. Zhiyu Wang Prof. Dr. Guodong Qian 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(51):18429-18434
A series of isomorphic lanthanide metal–organic frameworks (MOFs) Ln(TATAB)?(DMF)4(H2O)(MeOH)0.5 (LnTATAB, Ln=Eu, Tb, Sm, Dy, Gd; H3TATAB=4,4′,4′′‐s‐triazine‐1,3,5‐triyltri‐p‐aminobenzoic acid) have been solvothermally synthesized and structurally characterized. Among these MOFs, TbTATAB exhibits good water stability and a high fluorescence quantum yield. Because mercury ions (Hg2+) have a high affinity to nitrogen atoms, and the space between multiple nitrogen atoms from triazine and imino groups is suitable for interacting with Hg2+ ions, TbTATAB shows highly selective and sensitive detection of Hg2+ in aqueous solution with a detection limit of 4.4 nm . Furthermore, it was successfully applied to detect Hg2+ ions in natural water samples. 相似文献
53.
《Surface and interface analysis : SIA》2018,50(7):734-743
Metal oxides have only recently begun to be used as catalysts for the growth of carbon nanotubes. Here, we propose a new model for the growth of carbon nanotubes, based on the intra‐granular charge transfer transition and the lattice strain of the catalyst nanoparticles. This is supported by results obtained from the doped metal oxides like samarium doped zinc oxide (SmZnO) and terbium doped zinc oxide (TbZnO). The intragranular charge transfer transition is believed to be responsible for the dissociation of the hydrocarbon molecules. The lattice strain of the catalyst nanoparticles appears to be responsible for the diffusion of carbon atoms through the catalyst particles. 相似文献
54.
Dr. Chisato Kato Ryo Machida Rio Maruyama Dr. Ryo Tsunashima Prof. Dr. Xiao‐Ming Ren Prof. Dr. Mohamedally Kurmoo Prof. Dr. Katsuya Inoue Dr. Sadafumi Nishihara 《Angewandte Chemie (International ed. in English)》2018,57(41):13429-13432
Continual progress has been achieved in information technology through unrelenting miniaturisation of the single memory bit in integrated ferromagnetic, ferroelectric, optical, and related circuits. However, as miniaturisation approaches its theoretical limit, new memory materials are being sought. Herein, we report a unique material exhibiting single‐molecule electric polarisation switching that can operate above room temperature. The phenomenon occurs in a Preyssler‐type polyoxometalate (POM) cluster we call a single‐molecule electret (SME). It exhibits all the characteristics of ferroelectricity but without long‐range dipole ordering. The SME affords bi‐stability as a result of the two potential positions of localisation of a Tb3+ ion trapped in the POM, resulting in extremely slow relaxation of the polarisation and electric hysteresis with high spontaneous polarisation and coercive electric fields. Our findings suggest that SMEs can potentially be applied to ultrahigh‐density memory 1 and other molecular‐level electronic devices operating above room temperature. 2 相似文献
55.
Guang Yang Hui-An Chen Zhong-Yuan Zhou Xiao-Ming Chen 《Journal of chemical crystallography》1999,29(3):309-316
Three dimeric lanthanide(III) complexes, [Eu2(bet)8(H2O)4](CIO4)6
(1), [Tb2(bet)8(H2O)4](ClO4)6
(2), and [Eu2(bet)4(H2O)8] Cl6·6H2O (3) (bet = Me3N+CH2COO–, trimethyl-aminoacetate), have been prepared and structurally characterized by X-ray crystallography. Complex 1 crystallizes in the monoclinic space group P21/c, with a = 11.7807(8), b = 27.757(5), c = 11.7980(8) Å, = 99.500(4)°, V = 3805.1(8) Å3, and Z = 2. Complex 2 is isomorphous to complex 1, crystallizing in the monoclinic space group P21/c, with a = 11.7769(14), b = 27.725(3), c = 11.795(5) Å, = 99.668(14)°, V = 3797(2) Å3, and Z = 2. Complex 3 crystallizes in the orthorhombic space group Pbca, with a = 12.5664(8), b = 17.8645(9), c = 22.2573(8) Å, V = 4996.6(4) Å3 and Z = 4. Both complexes 1 and 2 comprise quadruply carboxylate-O,O-bridged [M2(bet)4]6+ dimeric cores (M = Eu, Tb), and each metal ion is further coordinated by two terminal aqua ligands and two monodentate bet carboxylates to form a distorted square-antiprismatic coordination geometry. Complex 3 also has a [Eu2(bet)4]6+ core, in which two bet ligands act in the 1:1:2 bridging fashion, and the other two bet ligands in the less common 2:1:2 bridging fashion, namely bridging-chelate mode. Each europium(III) ion in complex 3 is further coordinated by four water molecules to complete a monocapped square antiprism. 相似文献
56.
合成了两种双核铽配合物[Tb(4-BrBA)2(Phen)(NO3)]2 (1)和[Tb(4-BrBA)3(2,2′-bipy)(H2O)]2·2H2O (2)(4-BrBA=4-溴苯甲酸根,Phen=1,10-邻菲咯啉,2,2′-bipy=2,2′-联吡啶),并用X-射线单晶衍射结构分析方法测定了其晶体结构。这2种配合物均是具有反演中心的二聚体。在四元混配配合物1中,2个Tb3+离子被4个4-溴苯甲酸根以双齿桥联和三齿桥联两种方式联结;每个Tb3+离子与邻菲咯啉的2个氮原子、硝酸根的2个氧原子和4个桥联4-溴苯甲酸根的5个氧原子配位;Tb3+离子的配位数为9。在配合物2中,2个Tb3+离子被4个4-溴苯甲酸根以双齿桥联方式联结;每个Tb3+离子与2,2′-联吡啶的2个氮原子、水分子的1个氧原子、4个双齿桥联4-溴苯甲酸根的4个氧原子以及1个单齿配位4-溴苯甲酸根的1个氧原子配位;Tb3+离子的配位数为8。配合物2中游离水分子与配位水分子以及4-溴苯甲酸根之间形成了氢键,氢键将双核分子2连接成一维链状结构。配合物1和2在紫外灯照射下均发出强烈的绿光,它们的荧光光谱在490、545、585和621 nm处出现4条谱线,这是由Tb3+离子的 5D4 → 7Fj(j=6~3)跃迁产生的。 相似文献
57.
在水热条件下,利用硫代羟基二乙酸配体[thiodiglycolic acid=H2tda]和TbCl3·nH2O合成了新型稀土配合物[Tb2(tda)3(H2O)2]。单晶结构表明,配合物是以共边多面体[Tb2O16]为基本单元构筑的二维结构,并通过弱相互作用拓展为三维超分子体系。中心原子铽与氧原子的配位数是8和9,分别形成了单帽反四棱柱和三帽三角棱柱构型的空间配位多面体。配体H2tda在配合物中存在两种配位模式:(a) 双“顺-顺桥式双齿、螯合桥式三齿”模式和(b) 双“螯合双齿、顺-反桥式双齿”模式。荧光光谱研究表明:该配合物在室温下呈现较强的绿色荧光发射。配合物属三斜晶系,空间群P1。 相似文献
58.
Use of Lanthanide‐Containing Polyoxometalates to Sensitise the Emission of Fluorescent Labelled Serum Albumin 下载免费PDF全文
Dr. A. Sheila Holmes‐Smith Jacob Crisp Dr. Firasat Hussain Prof. Dr. Greta R. Patzke Dr. Graham Hungerford 《Chemphyschem》2016,17(3):418-424
Monitoring the interaction of biomolecules is important, and the use of energy transfer is a principal technique in elucidating nanoscale interactions. Lanthanide compounds are promising luminescent probes for biological samples as their emission is longer‐lived than any native autofluorescence. Polyoxometalates (POMs) are interesting structural motifs to incorporate lanthanides, offering low toxicity and a size pertinent for biological applications. Here, we employ iso‐structured POMs containing either terbium or europium and assess their interaction with serum albumin by sensitisation of a fluorescent tag on the protein via LRET (luminescence resonance energy transfer) by exciting the lanthanide. Time‐resolved measurements showed energy transfer with an efficiency of over 90 % for the POM–protein systems. The Tb–POM results were relatively straightforward, while those with the iso‐structured Eu–POM were complicated by the effect of protein shielding from the aqueous environment. 相似文献
59.
Charbonnière LJ Weibel N Retailleau P Ziessel R 《Chemistry (Weinheim an der Bergstrasse, Germany)》2007,13(1):346-358
A series of six new ligands (L(1)-L(6)) suitable for the formation of luminescent lanthanide complexes in water is described. Ligands L(1)-L(4) are constructed from two 6'-carboxy-6-methylene-2,2'-bipyridine chromophoric arms bonded to the amino function of a 2-aminomethylene-6-carboxy-pyridine (L(1)), an N,N-diacetate-ethylene diamine (L(2)), a serine (L(3)), or an aminomalonic acid (L(4)). For ligands L(5) and L(6), the linking amino function is provided by a glutamic acid, and the anionic functions at the 6'-position of the bipyridyl arms are made of the sodium salts of monoethylphosphonic ester (L(5)) and phosphonic acid (L(6)). The synthesis and characterisation of the ligands are described, together with the study of the formation of lanthanide complexes with europium and terbium. In the case of L(3), the europium complex obtained in acidic conditions was crystallised and the X-ray crystal structure is depicted. Photophysical properties of the complexes were studied by means of UV-visible absorption, and steady-state and time-resolved luminescence spectroscopy. Excited-state luminescence lifetimes of the complexes were determined in water and deuterated water to gain insight into the number of water molecules directly coordinated in the first coordination sphere of the complexes. The coordination behaviour of the series of ligands is questioned in the light of the spectroscopic data and discussed in terms of protection of the cation towards water molecules and their impact on the luminescence efficiency. 相似文献
60.
应用光谱技术研究铽及铕与水杨基羟肟酸所形成的配合物的发光性能,并探讨配合物的形成,以及溶剂、pH值及稀土含量对发光强度和能量传递的影响。 相似文献