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1.
Tian H Zhao L Guo YN Guo Y Tang J Liu Z 《Chemical communications (Cambridge, England)》2012,48(5):708-710
A novel octanuclear dysprosium(III) compound, templated by quadruple μ(4)-CO(3)(2-) introduced via spontaneous fixation of atmospheric carbon dioxide, shows single-molecule-magnet behaviour with an obvious hysteresis loop detected by a traditional SQUID magnetometer. 相似文献
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Milios CJ Vinslava A Whittaker AG Parsons S Wernsdorfer W Christou G Perlepes SP Brechin EK 《Inorganic chemistry》2006,45(14):5272-5274
The use of microwave heating has improved the reaction rate, enhanced the yield of an inorganic cluster complex, and allowed for the high-temperature/high-pressure synthesis of a Mn(III) single-molecule magnet. 相似文献
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Chen GJ Gao CY Tian JL Tang J Gu W Liu X Yan SP Liao DZ Cheng P 《Dalton transactions (Cambridge, England : 2003)》2011,40(20):5579-5583
By changing the ratio of reactants, two mononuclear Dy complexes, [Dy(phen)(acac)(3)] (1) and [Dy(phen)(2)(NO(3))(2)(acac)]·H(2)O (2) have been synthesized and structurally characterized. In 1, a Dy atom bearing square-antiprism coordination geometry exhibits SMM behaviour, while compound 2 with a bicapped-square-antiprism geometry does not show such SMM properties. The different magnetic behaviours seen in 1 and 2 are probably due to a different coordination environment and ligand field around the Dy(III) ions. The results proved the important influence of the structural environment of a SMM on its magnetic behaviour. 相似文献
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Godbole MD Roubeau O Clérac R Kooijman H Spek AL Bouwman E 《Chemical communications (Cambridge, England)》2005,(29):3715-3717
The novel octanuclear cluster [Mn8O2(OH)2(OMe)12(OAc)2(Mesalim)4] (1) presents SMM behaviour with a relatively high experimental energy barrier (eff/kB= 36.0 K) as shown by its dc and ac magnetic properties. 相似文献
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Zhu YY Guo X Cui C Wang BW Wang ZM Gao S 《Chemical communications (Cambridge, England)》2011,47(28):8049-8051
A pair of enantiopure star-shaped Fe(III)(4) clusters were constructed from simple chiral ligands. AC field frequency dependence and a hysteresis loop, which are very important features of SMMs, were observed. Circular dichroism (CD) spectra demonstrated that the chirality was successfully transferred from the ligand to the coordination environment of Fe(3+) ions. 相似文献
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Long J Habib F Lin PH Korobkov I Enright G Ungur L Wernsdorfer W Chibotaru LF Murugesu M 《Journal of the American Chemical Society》2011,133(14):5319-5328
A family of five dinuclear lanthanide complexes has been synthesized with general formula [Ln(III)(2)(valdien)(2)(NO(3))(2)] where (H(2)valdien = N1,N3-bis(3-methoxysalicylidene)diethylenetriamine) and Ln(III) = Eu(III)1, Gd(III)2, Tb(III)3, Dy(III)4, and Ho(III)5. The magnetic investigations reveal that 4 exhibits single-molecule magnet (SMM) behavior with an anisotropic barrier U(eff) = 76 K. The step-like features in the hysteresis loops observed for 4 reveal an antiferromagnetic exchange coupling between the two dysprosium ions. Ab initio calculations confirm the weak antiferromagnetic interaction with an exchange constant J(Dy-Dy) = -0.21 cm(-1). The observed steps in the hysteresis loops correspond to a weakly coupled system similar to exchange-biased SMMs. The Dy(2) complex is an ideal candidate for the elucidation of slow relaxation of the magnetization mechanism seen in lanthanide systems. 相似文献
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Chesman AS Turner DR Moubaraki B Murray KS Deacon GB Batten SR 《Dalton transactions (Cambridge, England : 2003)》2012,41(13):3751-3757
The nucleophilic addition of methanol and water to the dicyanonitrosomethanide anion, resulting in the formation of cyano(imino(methoxy)methyl)nitrosomethanide (cmnm) and carbamoylcyanonitrosomethanide (ccnm), respectively, is used as a means of in situ ligand synthesis during the formation of [Dy(8)(OH)(6)(OMe)(6)(cmnm)(10)(ccnm)(2)(H(2)O)(2)(MeOH)(2)] (1). This is the first time these reactions have been observed to be promoted by the presence of a lanthanoid ion. The core of the octanuclear cluster consists of two cubane moieties ([Dy(4)(OH)(3)(OMe)]), bridged by four methoxide ligands to form a central [Dy(8)(OH)(6)(OMe)(6)] moiety. The complex displays magnetic properties that are indicative of probable single molecule magnet features. 相似文献
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The synthesis, X-ray crystallography, magnetic properties, and high-field electron paramagnetic resonance (HFEPR) of a new heptanuclear manganese complex [Mn(7)(heamp)(6)](ClO(4))(2)·4CH(2)Cl(2)·H(2)O (complex 2), in which heampH(3) is 2-[N,N-di(2-hydroxyethyl)aminomethyl]phenol (compound 1), is reported. Complex 2 has a hexagonal, disk-shaped topology and contains six Mn(III) ions and a central Mn(II) ion. It crystallizes in the monoclinic space group P2(1)/c with two molecular orientations. Consideration of the cluster topology, together with variable-temperature and variable-field DC magnetic susceptibility data, suggest that complex 2 exists in a half-integer, S = (19)/(2) ± 1 spin ground state, with appreciable uniaxial zero-field splitting (D = -0.16 cm(-1)). AC magnetic susceptibility measurements clearly show out-of-phase signals, which are frequency- and temperature-dependent, indicating slow magnetization relaxation behavior. An analysis of the relaxation data employing the Arrhenius formula yielded an effective relaxation barrier of 12.9 cm(-1). Simulations of HFEPR studies agree with the assignment of an S ≈ (19)/(2) spin ground state, with g = 1.96, D = -4.71 GHz (-0.16 cm(-1)), and a longitudinal fourth-order zero-field splitting parameter B(4)(0) = -2.7 × 10(-4) GHz (-9.0 × 10(-6) cm(-1)). 相似文献
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Pointillart F Le Gal Y Golhen S Cador O Ouahab L 《Chemistry (Weinheim an der Bergstrasse, Germany)》2011,17(37):10397-10404
The reactions between the [Ln(tta)(3)]·2H(2)O precursors (tta(-)=2-thenoyltrifluoroacetonate anion) and the tetrathiafulvalene-3-pyridine-N-oxide ligands (L(1)) lead to dinuclear complexes of formula [{Ln(tta)(3)(L(1))}(2)]·xCH(2)Cl(2) (x=0.5 for Ln=Dy(III) (1) and x=0 for Ln=Gd(III) (2)). The crystal structure reveals that two {Ln(tta)(3)} moieties are bridged by two donors through the nitroxide groups. The Dy(III) centre adopts a distorted square antiprismatic oxygenated polyhedron structure. The antiferromagnetic nature of the exchange interaction between the two Dy(III) ions has been determined by two methods: 1) an empirical method using the [Dy(hfac)(3)(L(2))(2)] mononuclear complex as a model (3) (hfac(-)=1,1,1,5,5,5-hexafluoroacetylacetonate anion, L(2)=tetrathiafulvaleneamido-2-pyridine-N-oxide ligand), and 2) assuming an Ising model for the Dy(III) ion giving an exchange energy of -2.30 cm(-1), g=19.2 in the temperature range of 2-10 K. The antiferromagnetic interactions have been confirmed by a quantitative determination of J for the isotropic Gd(III) derivative (J=-0.031 cm(-1), g=2.003). Compound 1 displays a slow magnetisation relaxation without applied external magnetic fields. Alternating current susceptibility shows a thermally activated behaviour with pre-exponential factors of 5.48(4)×10(-7) s and an energy barrier of 87(1) K. The application of an external field of 1.6 kOe compensates the antiferromagnetic interactions and opens a new quantum tunnelling path. 相似文献
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Canaj AB Tzimopoulos DI Philippidis A Kostakis GE Milios CJ 《Inorganic chemistry》2012,51(14):7451-7453
The employment of 2-(β-naphthalideneamino)-2-(hydroxymethyl)-1-propanol and 2-aminoisobutyric acid in dysprosium chemistry has led to the isolation of a novel heptanuclear [Dy(III)(7)] cluster displaying single-molecule-magnetism behavior and blue-emitting properties. 相似文献
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Cho KJ Ryu DW Kwak HY Lee JW Lee WR Lim KS Koh EK Kwon YW Hong CS 《Chemical communications (Cambridge, England)》2012,48(59):7404-7406
A tetranuclear Fe(III)(2)Mn(III)(2) compound was prepared using highly blocked precursors. The well-isolated molecular entity associated with appropriate magnetic anisotropy allows for single-molecule magnet behavior. 相似文献
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Treatment of [NEt4][(pzTp)Fe(III)(CN)3] (1) with Ni(II)(OTf)2 (OTf = trifluoromethanesulfonate) and 1,5,8,12-tetraazadodecane (L) affords {[(pzTp)Fe(III)(CN)3]2[Ni(II)L]} x 1/2MeOH (2), while 2,2'-bipyridine (bipy) affords {[(pzTp)Fe(III)(CN)3]2[Ni(II)(bipy)2]} x 2 H2O (3). Magnetic measurements indicate that 2 and 3 have S = 2 ground states and that 3 exhibits slow relaxation of the magnetization above 2 K. 相似文献
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Galloway KW Whyte AM Wernsdorfer W Sanchez-Benitez J Kamenev KV Parkin A Peacock RD Murrie M 《Inorganic chemistry》2008,47(16):7438-7442
An investigation of the magnetic properties of the cobalt(II) citrate cubane [C(NH 2) 3] 8{Co 4(cit) 4}.4H 2O reveals that the cluster is a new cobalt(II) single-molecule magnet, with an energy barrier to reorientation of the magnetization, Delta E/ k B = 21 K, and tau 0 = 8 x 10 (-7) s. The compound displays distinct, frequency-dependent peaks in the out-of-phase (chi') component of the ac magnetic susceptibility and magnetization versus field hysteresis loops that are temperature and sweep rate dependent. The hysteresis loops collapse at zero field due to very fast quantum tunneling of the magnetization (QTM). 相似文献
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Waters M Moro F Krivokapic I McMaster J van Slageren J 《Dalton transactions (Cambridge, England : 2003)》2012,41(4):1128-1130
Bis(octacyanophthalocyanine)dysprosium(III) (1) has been synthesised, characterised and magnetically studied. By the incorporation of cyano substituents on the phthalocyanine (Pc) rings, a starting point has been created for the chemical modification of double deckers for the purpose of surface self-assembly. The modification of the rings leaves the magnetic properties of the double decker largely unaffected. 相似文献