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1.
Dr. Sui‐Jun Liu Chen‐Chao Xie Ji‐Min Jia Jiong‐Peng Zhao Song‐De Han Yu Cui Yue Li Prof. Dr. Xian‐He Bu 《化学:亚洲杂志》2014,9(4):1116-1122
Four carboxylate‐bridged GdIII complexes ( 1 – 4 ) with 1D/2D structures have been synthesized by using the hydrothermal reaction of Gd2O3 with various carboxylate ligands. Compounds 1 and 2 contained the same [2n] GdIII? OH ladders, but with different crystallographically independent GdIII ions, whilst the structures of compounds 3 and 4 were composed of [Gd4(μ3‐OH)2(piv)8(H2O)2]2+ units and 1D ladder GdIII chains, respectively. Antiferromagnetic interactions occurred in compounds 1 – 3 , owing to their small Gd? O? Gd angles, whereas ferromagnetic coupling occurred in compound 4 , in which the Gd? O? Gd angles were larger. These complexes exhibited a distinct magnetocaloric effect (MCE), which was affected by their different magnetic densities and exchange interactions. Among these compounds, complex 4 presented the largest MCE (?ΔSmmax=43.6 J kg?1 K?1), the lowest Mw/NGd ratio (the highest magnetic density), and weak ferromagnetic coupling. Therefore, a lower Mw/NGd ratio and weaker exchange interactions (a smaller absolute value of θ) between GdIII ions resulted in a larger MCE for the GdIII complexes. 相似文献
2.
Seda Kartal Dr. Guillaume Rogez Dr. Jérôme Robert Dr. Benoît Heinrich Dr. Athanassios K. Boudalis 《Chemphyschem》2022,23(12):e202200213
[Gd5(L)16(H2O)8](Tf2N)15 was obtained from reaction of Gd2O3 with 1-carboxymethyl-3-ethylimidazolium chloride (LHCl). The material was found to be an ionic liquid that freezes to glassy state on cooling to −30 °C. Variable-temperature magnetic studies reveal the presence of weak magnetic intramolecular interactions in the glass. Isothermal variable-field magnetization demonstrates a magnetocaloric effect (MCE), which is the first finding of such an effect in a molecular glass. This MCE is explainable by an uncoupled representation, with a magnetic entropy change of −11.36 J K−1 kg−1 at 1.8 K for a 0–7 T magnetic field change, and with a refrigerant capacity of 125.9 J kg−1, in the 1.8-50 K interval. 相似文献
3.
Multimetal‐Substituted Epsilon‐Iron Oxide ϵ‐Ga0.31Ti0.05Co0.05Fe1.59O3 for Next‐Generation Magnetic Recording Tape in the Big‐Data Era
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Prof. Shin‐ichi Ohkoshi Dr. Asuka Namai Marie Yoshikiyo Dr. Kenta Imoto Kazunori Tamazaki Koji Matsuno Osamu Inoue Tsutomu Ide Kenji Masada Masahiro Goto Takashi Goto Takayuki Yoshida Tatsuro Miyazaki 《Angewandte Chemie (International ed. in English)》2016,55(38):11403-11406
From the viewpoints of large capacity, long‐term guarantee, and low cost, interest in magnetic recording tapes has undergone a revival as an archive storage media for big data. Herein, we prepared a new series of metal‐substituted ?‐Fe2O3, ?‐GaIII0.31TiIV0.05CoII0.05FeIII1.59O3, nanoparticles with an average size of 18 nm. Ga, Ti, and Co cations tune the magnetic properties of ?‐Fe2O3 to the specifications demanded for a magnetic recording tape. The coercive field was tuned to 2.7 kOe by introduction of single‐ion anisotropy on CoII (S=3/2) along the c‐axis. The saturation magnetization was increased by 44 % with GaIII (S=0) and TiIV (S=0) substitution through the enhancement of positive sublattice magnetizations. The magnetic tape media was fabricated using an actual production line and showed a very sharp signal response and a remarkably high signal‐to‐noise ratio compared to the currently used magnetic tape. 相似文献
4.
Xiaoling Wang Panpan Xu Xia Bao Fengwu Wang Yonghong Chen Yijun Wei 《无机化学与普通化学杂志》2013,639(1):176-180
Abstract. Two radical–LnIII–radical complexes, [Ln(hfac)3(NITPh‐Ph)2] [Ln = Gd ( 1 ) and Ho ( 2 ), hfac = hexafluoroacetylacetonate; and NITPh‐Ph = 4′‐biphenyl‐4, 4, 5, 5‐tetramethylimidazoline‐1‐oxyl‐3‐oxide] were synthesized and characterized by X‐ray diffraction, elemental analysis, magnetic measurements, as well as IR and UV/Vis spectroscopy. X‐ray crystal structure analysis revealed that the structures of both complexes are isomorphous, the central LnIII ions are coordinated by six oxygen atoms from three hfac ligand molecules and two oxygen atoms from nitronyl radicals. The temperature dependencies of the magnetic susceptibilities were studied. They showed that in the GdIII complex, ferromagnetic interactions between GdIII and the radicals and antiferromagnetic interactions between the radicals coexist in this system (with JRad–Gd = 0.1 cm–1, JRad–Rad = –0.309 cm–1). 相似文献
5.
Ju‐Wen Zhang Yi Man Yu‐Ning Ren Wen‐Hua Liu Bin‐Qiu Liu Yan‐Ping Dong 《无机化学与普通化学杂志》2019,645(6-7):580-587
The syntheses and crystal structures of eight lanthanide complexes with formula [Ln(2,5‐DCB)x(phen)y] are reported, which are characterized via single‐crystal, powder X‐ray diffraction, elemental analysis, IR spectroscopy, thermogravimetric analysis, photoluminescence measurement, and DC/AC magnetic measurement. These eight complexes are isostructural, and possess a discrete dinuclear structure. The adjacent dinuclear molecules are linked by the hydrogen bonding interactions into a one‐dimensional (1D) supramolecular chain. The neighboring 1D chains are further extended into a two‐dimensional (2D) supramolecular layer by the π–π stacking interactions. The photoluminescent properties of complexes 1 (NdIII), 2 (SmIII), 3 (EuIII), 5 (TbIII), 6 (DyIII), and 8 (YbIII) were investigated. Magnetic investigations also reveal the presence of ferromagnetic interactions in complexes 4 (GdIII), 6 (DyIII), and 7 (ErIII). Additionally, complex 6 (DyIII) demonstrates field‐induced slow magnetic relaxation behavior. 相似文献
6.
Kasper S. Pedersen Giulia Lorusso Juan Jos Morales Thomas Weyhermüller Stergios Piligkos Saurabh Kumar Singh Dennis Larsen Magnus Schau‐Magnussen Gopalan Rajaraman Marco Evangelisti Jesper Bendix 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2014,126(9):2426-2429
The reaction of fac‐[MIIIF3(Me3tacn)]⋅x H2O with Gd(NO3)3⋅5H2O affords a series of fluoride‐bridged, trigonal bipyramidal {GdIII3MIII2} (M=Cr ( 1 ), Fe ( 2 ), Ga ( 3 )) complexes without signs of concomitant GdF3 formation, thereby demonstrating the applicability even of labile fluoride‐complexes as precursors for 3d–4f systems. Molecular geometry enforces weak exchange interactions, which is rationalized computationally. This, in conjunction with a lightweight ligand sphere, gives rise to large magnetic entropy changes of 38.3 J kg−1 K−1 ( 1 ) and 33.1 J kg−1 K−1 ( 2 ) for the field change 7 T→0 T. Interestingly, the entropy change, and the magnetocaloric effect, are smaller in 2 than in 1 despite the larger spin ground state of the former secured by intramolecular Fe–Gd ferromagnetic interactions. This observation underlines the necessity of controlling not only the ground state but also close‐lying excited states for successful design of molecular refrigerants. 相似文献
7.
《应用有机金属化学》2017,31(12)
Reactions of manganese benzoate dihydrate and lanthanide nitrate hexahydrate with 2‐(hydroxymethyl)pyridine (hmpH) as ligand in the mixture solutions of acetonitrile and ethanol according to different molar ratios of NEt3 generated two kinds of Mn‐Ln compounds [MnIII4LaIII2(O)2(hmp)7(PhCO2)2(NO3)5] ·5H2O ( 1 ) and [MnIII2GdIII2(hmp)6(PhCO2)4(NO3)2] ·3CH3CN·3C2H5OH·2H2O ( 2 ). By comparison of the two compounds, there exist considerable effects of reaction alkalinity on the structures and magnetic properties of products. Compound 1 possesses a core of [MnIII4LaIII2(μ 4‐O)(μ 3‐O)(μ 3‐OR)(μ 2‐O)7]2−, which comprises three face‐sharing defected cubane units. The core topology represents a new core type of Mn‐Ln clusters. Compound 2 has a planar‐butterfly structure. The solid‐state dc magnetic susceptibility analyses indicate the antiferromagnetic interactions within compound 1 and ferromagnetic interactions within compound 2 . Compound 1 has an S = 0 ground state, while compound 2 possesses an S = 11 ground state, fitting of the dc data for the tetranuclear Mn2Gd2 with the Magpack program gives parameters of J Mn‐Mn = 3.11 cm−1, J Mn‐Gd = 0.02 cm—1 and g = 1.96. 相似文献
8.
Dr. Martín Regueiro‐Figueroa Dr. Aline Nonat Dr. Gabriele A. Rolla Dr. David Esteban‐Gómez Dr. Andrés de Blas Dr. Teresa Rodríguez‐Blas Dr. Loïc J. Charbonnière Prof. Mauro Botta Dr. Carlos Platas‐Iglesias 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(35):11696-11706
Homodinuclear lanthanide complexes (Ln=La, Eu, Gd, Tb, Yb and Lu) derived from a bis‐macrocyclic ligand featuring two 2,2′,2′′‐(1,4,7,10‐tetraazacyclododecane‐1,4,7‐triyl)triacetic acid chelating sites linked by a 2,6‐bis(pyrazol‐1‐yl)pyridine spacer (H2L3) were prepared and characterized. Luminescence lifetime measurements recorded on solutions of the EuIII and TbIII complexes indicate the presence of one inner‐sphere water molecule coordinated to each metal ion in these complexes. The overall luminescence quantum yields were determined (?=0.01 for [Eu2(L3)] and 0.50 for [Tb2(L3)] in 0.01 M TRIS/HCl, pH 7.4; TRIS=tris(hydroxymethyl)aminomethane), pointing to an effective sensitization of the metal ion by the bispyrazolylpyridyl unit of the ligand, especially with Tb. The nuclear magnetic relaxation dispersion (NMRD) profiles recorded for [Gd2(L3)] are characteristic of slowly tumbling systems, showing a low‐field plateau and a broad maximum around 30 MHz. This suggests the occurrence of aggregation of the complexes giving rise to slowly rotating species. A similar behavior is observed for the analogous GdIII complex containing a 4,4′‐dimethyl‐2,2′‐bipyridyl spacer ([Gd2(L1)]). The relaxivity of [Gd2(L3)] recorded at 0.5 T and 298 K (pH 6.9) amounts to 13.7 mM ?1 s?1. The formation of aggregates has been confirmed by dynamic light scattering (DLS) experiments, which provided mean particle sizes of 114 and 38 nm for [Gd2(L1)] and [Gd2(L3)], respectively. TEM images of [Gd2(L3)] indicate the formation of nearly spherical nanosized aggregates with a mean diameter of about 41 nm, together with some nonspherical particles with larger size. 相似文献
9.
Dr. Fabrice Pointillart Dr. Thomas Cauchy Dr. Olivier Maury Yann Le Gal Dr. Stéphane Golhen Dr. Olivier Cador Dr. Lahcène Ouahab 《Chemistry (Weinheim an der Bergstrasse, Germany)》2010,16(39):11926-11941
The tetrathiafulvalene‐amido‐2‐pyridine‐N‐oxide ( L ) ligand has been employed to coordinate 4f elements. The architecture of the complexes mainly depends on the ionic radii of the lanthanides. Thus, the reaction of L in the same experimental protocol leads to three different molecular structure series. Binuclear [Ln2(hfac)5(O2CPhCl)( L )3] ? 2 H2O (hfac?=1,1,1,5,5,5‐hexafluoroacetylacetonate anion, O2CPhCl?=3‐chlorobenzoate anion) and mononuclear [Ln(hfac)3( L )2] complexes were obtained by using rare‐earth ions with either large (LnIII=Pr, Gd) or small (LnIII=Y, Yb) ionic radius, respectively, whereas the use of TbIII that possesses an intermediate ionic radius led to the formation of a binuclear complex of formula [Tb2(hfac)4(O2CPhCl)2( L )2]. Antiferromagnetic interactions have been observed in the three dinuclear compounds by using an extended empirical method. Photophysical properties of the coordination complexes have been studied by solid‐state absorption spectroscopy, whereas time‐dependent density functional theory (TD‐DFT) calculations have been carried out on the diamagnetic YIII derivative to build a molecular orbital diagram and to reproduce the absorption spectrum. For the [Yb(hfac)3( L )2] complex, the excitation at 19 600 cm?1 of the HOMO→LUMO+1/LUMO+2 charge‐transfer transition induces both line‐shape emissions in the near‐IR spectral range assigned to the 2F5/2→2F7/2 (9860 cm?1) ytterbium‐centered transition and a residual charge‐transfer emission around 13 150 cm?1. An efficient antenna effect that proceeds through energy transfer from the singlet excited state of the tetrathiafulvalene‐amido‐2‐pyridine‐N‐oxide chromophore is evidence of the YbIII sensitization. 相似文献
10.
《无机化学与普通化学杂志》2018,644(8-9):443-448
A salen‐type Dy2 complex [Dy2(L)(MeOH)2(CH3COO)4] · 2(MeOH) was isolated and magnetically characterized, in which one hexadentate ligand H2L [H2L = N,N‐bis(2‐oxy‐3‐methoxybenzylidene)‐1,2‐phenylenediamine] chelated two DyIII ions, one is located on the apical position of the inner N2O2 site, leaving the outer O2O2 cavity for another DyIII ion. There are two distinct local coordination environments presented as square antiprism (D4d) for Dy1 and biaugmented trigonal prism (C2v) for Dy2. Magnetic measurements reveal that the ferromagnetic interaction between two DyIII ions occurred within low temperature range and accompanied with significant slow magnetic relaxation behavior with energy barriers to the reversal of magnetization Ueff/KB = 40 K under zero dc field. 相似文献
11.
Tong‐Hen Pan Kun‐Shan Huang Chong‐En Huang Fu‐Long Lai Chang‐Cang Huang 《Acta Crystallographica. Section C, Structural Chemistry》2011,67(2):m46-m49
The asymmetric unit of the title coordination polymer, [Gd2(C7H4O5S)2(C2O4)(H2O)6]n or [Gd(2‐SB)(ox)0.5(H2O)3]2n (2‐SB is 2‐sulfonatobenzoate and ox is oxalate), (I), consists of one GdIII ion, one 2‐SB anion, three coordinated water molecules and one half of an ox ligand. The ox ligand is located on a crystallographic inversion centre. The GdIII centre shows a distorted tricapped trigonal–prismatic coordination formed by nine O atoms from two 2‐SB anions, one ox ligand and three coordinated water molecules. The carboxylate and sulfonate groups of the 2‐SB anions adopt μ2‐η1:η2 and μ1‐η0:η0:η1 coordination modes to link two GdIII ions, generating a centrosymmetric binuclear [Gd2(2‐SB)2(H2O)6]2− subunit. The ox ligand acts as a bridge, linking the binuclear [Gd2(2‐SB)2(H2O)6]2− subunits into a one‐dimensional chain structure parallel to the b axis. Furthermore, extensive O—H...O hydrogen bonds connect the chains into a three‐dimensional supramolecular architecture. 相似文献
12.
Kasper S. Pedersen Dr. Giulia Lorusso Juan José Morales Dr. Thomas Weyhermüller Dr. Stergios Piligkos Saurabh Kumar Singh Dennis Larsen Magnus Schau‐Magnussen Dr. Gopalan Rajaraman Dr. Marco Evangelisti Prof. Dr. Jesper Bendix 《Angewandte Chemie (International ed. in English)》2014,53(9):2394-2397
The reaction of fac‐[MIIIF3(Me3tacn)]?x H2O with Gd(NO3)3?5H2O affords a series of fluoride‐bridged, trigonal bipyramidal {GdIII3MIII2} (M=Cr ( 1 ), Fe ( 2 ), Ga ( 3 )) complexes without signs of concomitant GdF3 formation, thereby demonstrating the applicability even of labile fluoride‐complexes as precursors for 3d–4f systems. Molecular geometry enforces weak exchange interactions, which is rationalized computationally. This, in conjunction with a lightweight ligand sphere, gives rise to large magnetic entropy changes of 38.3 J kg?1 K?1 ( 1 ) and 33.1 J kg?1 K?1 ( 2 ) for the field change 7 T→0 T. Interestingly, the entropy change, and the magnetocaloric effect, are smaller in 2 than in 1 despite the larger spin ground state of the former secured by intramolecular Fe–Gd ferromagnetic interactions. This observation underlines the necessity of controlling not only the ground state but also close‐lying excited states for successful design of molecular refrigerants. 相似文献
13.
Trinuclear [CoIII2–LnIII] (Ln=Tb,Dy) Single‐Ion Magnets with Mixed 6‐Chloro‐2‐Hydroxypyridine and Schiff Base Ligands
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Prof. Dr. Cai‐Ming Liu Prof. Dr. De‐Qing Zhang Prof. Dr. Xiang Hao Prof. Dao‐Ben Zhu 《化学:亚洲杂志》2014,9(7):1847-1853
The Schiff base ligand N1,N3‐bis(3‐methoxysalicylidene)diethylenetriamine (H2valdien) and the co‐ligand 6‐chloro‐2‐hydroxypyridine (Hchp) were used to construct two 3d–4f heterometallic single‐ion magnets [Co2Dy(valdien)2(OCH3)2(chp)2] ? ClO4 ? 5 H2O ( 1 ) and [Co2Tb(valdien)2(OCH3)2(chp)2] ? ClO4 ? 2 H2O ? CH3OH ( 2 ). The two trinuclear [CoIII2LnIII] complexes behave as a mononuclear LnIII magnetic system because of the presence of two diamagnetic cobalt(III) ions. Complex 1 has a molecular symmetry center, and it crystallizes in the C2/c space group, whereas complex 2 shows a lower molecular symmetry and crystallizes in the P21/c space group. Magnetic investigations indicated that both complexes are field‐induced single‐ion magnets, and the CoIII2–DyIII complex possesses a larger energy barrier [74.1(4.2) K] than the CoIII2–TbIII complex [32.3(2.6) K]. 相似文献
14.
《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2017,129(34):10237-10241
Assembly of the triangular, organic radical‐bridged complexes Cp*6Ln3(μ3‐HAN) (Cp*=pentamethylcyclopentadienyl; Ln=Gd, Tb, Dy; HAN=hexaazatrinaphthylene) proceeds through the reaction of Cp*2Ln(BPh4) with HAN under strongly reducing conditions. Significantly, magnetic susceptibility measurements of these complexes support effective magnetic coupling of all three LnIII centers through the HAN3−. radical ligand. Thorough investigation of the DyIII congener through both ac susceptibility and dc magnetic relaxation measurements reveals slow relaxation of the magnetization, with an effective thermal relaxation barrier of Ueff=51 cm−1. Magnetic coupling in the DyIII complex enables a large remnant magnetization at temperatures up to 3.0 K in the magnetic hysteresis measurements and hysteresis loops that are open at zero‐field up to 3.5 K. 相似文献
15.
Gadolinium(III)‐Hydroxy Ladders Trapped in Succinate Frameworks with Optimized Magnetocaloric Effect
Yan‐Cong Chen Fu‐Sheng Guo Prof. Dr. Yan‐Zhen Zheng Jun‐Liang Liu Ji‐Dong Leng Róbert Tarasenko Prof. Dr. Martin Orendáč Dr. Jan Prokleška Prof. Dr. Vladimír Sechovský Prof. Dr. Ming‐Liang Tong 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(40):13504-13510
Two kinds of inorganic gadolinium(III)‐hydroxy “ladders”, [2×n] and [3×n], were successfully trapped in succinate (suc) coordination polymers, [Gd2(OH)2(suc)2(H2O)]n ? 2n H2O ( 1 ) and [Gd6(OH)8(suc)5(H2O)2]n ? 4n H2O ( 2 ), respectively. Such coordination polymers could be regarded as alternating inorganic–organic hybrid materials with relatively high density. Magnetic and heat capacity studies reveal a large cryogenic magnetocaloric effect (MCE) in both compounds, namely (ΔH=70 kG) 42.8 J kg?1 K?1 for complex 1 and 48.0 J kg?1 K?1 for complex 2 . The effect of the high density is evident, which gives very large volumetric MCEs up to 120 and 144 mJ cm?3 K?1 for complexes 1 and 2 , respectively. 相似文献
16.
《Chemistry (Weinheim an der Bergstrasse, Germany)》2006,12(1):187-203
Heteronuclear cationic complexes, [LCuLn]3+ and [(LCu)2Ln]3+, were employed as nodes in designing high‐nuclearity complexes and coordination polymers with a rich variety of network topologies (L is the dianion of the Schiff base resulting from the 2:1 condensation of 3‐methoxysalycilaldehyde with 1,3‐propanediamine). Two families of linkers have been chosen: the first consists of exo‐dentate ligands bearing nitrogen‐donor atoms (bipyridine (bipy), dicyanamido (dca)), whereas the second consists of exo‐dentate ligands with oxygen‐donor atoms (anions derived from the acetylenedicarboxylic (H2acdca), fumaric (H2fum), trimesic (H3trim), and oxalic (H2ox) acids). The ligands belonging to the first family prefer copper(II ) ions, whereas the ligands from the second family interact preferentially with oxophilic rare‐earth cations. The following complexes have been obtained and crystallographically characterized: [LCuII(OH2)GdIII(NO3)3] ( 1 ), [{LCuIIGdIII(NO3)3}2(μ‐4,4′‐bipy)] ( 2 ), [LCuIIGdIII(acdca)1.5(H2O)2] ? 13 H2O ( 3 ), [LCuIIGdIII(fum)1.5(H2O)2] ? 4 H2O ? C2H5OH ( 4 ), [LCuIISmIII(H2O)(Hfum)(fum)] ( 5 ), [LCuIIErIII(H2O)2(fum)]NO3 ? 3 H2O ( 6 ), [LCuIISmIII(fum)1.5(H2O)2] ? 4 H2O ? C2H5OH ( 7 ), [{(LCuII)2SmIII}2fum2](OH)2 ( 8 ), [LCuIIGdIII(trim)(H2O)2] ? H2O ( 9 ), [{(LCuII)2PrIII}(C2O4)0.5(dca)]dca ? 2 H2O ( 10 ), [LCuIIGdIII(ox)(H2O)3][CrIII(2,2′‐bipy)(ox)2] ? 9 H2O ( 11 ), and [LCuGd(H2O)4{Cr(CN)6}] ? 3 H2O ( 12 ). Compound 1 is representative of the whole family of binuclear CuII–LnIII complexes which have been used as precursors in constructing heteropolymetallic complexes. The rich variety of the resulting structures is due to several factors: 1) the nature of the donor atoms of the linkers, 2) the preference of the copper(II ) ion for nitrogen atoms, 3) the oxophilicity of the lanthanides, 4) the degree of deprotonation of the polycarboxylic acids, 5) the various connectivity modes exhibited by the carboxylato groups, and 6) the stoichiometry of the final products, that is, the CuII/LnIII/linker molar ratio. A unique cluster formed by 24 water molecules was found in crystal 11 . In compounds 2 , 3 , 4 , 9 , and 11 the CuII–GdIII exchange interaction was found to be ferromagnetic, with J values in the range of 3.53–8.96 cm?1. Compound 12 represents a new example of a polynuclear complex containing three different paramagnetic ions. The intranode CuII–GdIII ferromagnetic interaction is overwhelmed by the antiferromagnetic interactions occurring between the cyanobridged GdIII and CrIII ions. 相似文献
17.
Two C3‐Symmetric Dy3III Complexes with Triple Di‐μ‐methoxo‐μ‐phenoxo Bridges,Magnetic Ground State,and Single‐Molecule Magnetic Behavior
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Dr. Mikko M. Hänninen Prof. Dr. Antonio J. Mota Dr. Daniel Aravena Prof. Dr. Eliseo Ruiz Prof. Dr. Reijo Sillanpää Dr. Agustín Camón Dr. Marco Evangelisti Prof. Dr. Enrique Colacio 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(27):8410-8420
Two series of isostructural C3‐symmetric Ln3 complexes Ln3 ? [BPh4] and Ln3 ? 0.33[Ln(NO3)6] (in which LnIII=Gd and Dy) have been prepared from an amino‐bis(phenol) ligand. X‐ray studies reveal that LnIII ions are connected by one μ2‐phenoxo and two μ3‐methoxo bridges, thus leading to a hexagonal bipyramidal Ln3O5 bridging core in which LnIII ions exhibit a biaugmented trigonal‐prismatic geometry. Magnetic susceptibility studies and ab initio complete active space self‐consistent field (CASSCF) calculations indicate that the magnetic coupling between the DyIII ions, which possess a high axial anisotropy in the ground state, is very weakly antiferromagnetic and mainly dipolar in nature. To reduce the electronic repulsion from the coordinating oxygen atom with the shortest Dy?O distance, the local magnetic moments are oriented almost perpendicular to the Dy3 plane, thus leading to a paramagnetic ground state. CASSCF plus restricted active space state interaction (RASSI) calculations also show that the ground and first excited state of the DyIII ions are separated by approximately 150 and 177 cm?1, for Dy3 ? [BPh4] and Dy3 ? 0.33[Dy(NO3)6], respectively. As expected for these large energy gaps, Dy3 ? [BPh4] and Dy3 ? 0.33[Dy(NO3)6] exhibit, under zero direct‐current (dc) field, thermally activated slow relaxation of the magnetization, which overlap with a quantum tunneling relaxation process. Under an applied Hdc field of 1000 Oe, Dy3 ? [BPh4] exhibits two thermally activated processes with Ueff values of 34.7 and 19.5 cm?1, whereas Dy3 ? 0.33[Dy(NO3)6] shows only one activated process with Ueff=19.5 cm?1. 相似文献
18.
Laura Cañadillas‐Delgado Dr. Tomás Martín Dr. Oscar Fabelo Dr. Jorge Pasán Dr. Fernando S. Delgado Dr. Francesc Lloret Prof. Dr. Miguel Julve Prof. Dr. Catalina Ruiz‐Pérez Prof. Dr. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2010,16(13):4037-4047
The preparation, X‐ray crystallography and magnetic investigation of the first examples of methanetriacetate (mta)‐containing lanthanide(III) complexes of formulae [Gd(mta)(H2O)3]n ? 4 n H2O ( 1 ) [Gd(mta)(H2O)3]n ? 2 n H2O ( 2 ) and [Gd2(mta)2(H2O)2]n ? 2 n H2O ( 3 ) are described herein. This tripodal ligand promotes the formation of 63 networks; thus 1 consists of a honeycomb structure, whereas in 2 two of these layers are condensed to form a rare five‐connected two‐dimensional (4862) network. Compound 3 can be seen as an aggregation of 63 layers leading to a three‐dimensional (6,6)‐connected binodal (41263)(4966)‐ nia net, in which the gadolinium(III) ions and the mta ligands act as octahedral and as trigonal prismatic nodes, respectively. The magnetic properties of 1 – 3 were investigated in the temperature range 1.9–300 K. A close fit to the Curie law ( 1 ) and weak either antiferro‐ [J=?0.0063(1) cm?1 ( 2 )] or ferromagnetic [J=+0.0264(6) cm?1 ( 3 )] interactions between the GdIII ions are observed; the different exchange pathways involved [extended tris‐bidentate mta ( 1 ) and μ‐O(1);κ2O(1),O(2) ( 2 and 3 ) plus single syn–syn carboxylate‐mta ( 3 )] accounting for these magnetic features. The nature and magnitude of the magnetic interactions, between the GdIII ions in 1 – 3 , agree with the small amount of data existing in the literature for these kind of bridges. 相似文献
19.
Ln12‐Containing 60‐Tungstogermanates: Synthesis,Structure, Luminescence,and Magnetic Studies
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Kai‐Yao Wang Dr. Bassem S. Bassil Dr. Zhengguo Lin Isabella Römer Stef Vanhaecht Prof. Tatjana N. Parac‐Vogt Dr. Cristina Sáenz de Pipaón Prof. José Ramón Galán‐Mascarós Linyuan Fan Prof. Jie Cao Prof. Ulrich Kortz 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(50):18168-18176
A new class of hexameric Ln12‐containing 60‐tungstogermanates, [Na(H2O)6?Eu12(OH)12(H2O)18Ge2(GeW10O38)6]39? ( Eu12 ), [Na(H2O)6?Gd12(OH)6(H2O)24Ge(GeW10O38)6]37? ( Gd12 ), and [(H2O)6?Dy12(H2O)24(GeW10O38)6]36? ( Dy12 ), comprising six di‐Ln‐embedded {β(4,11)‐GeW10} subunits was prepared by reaction of [α‐GeW9O34]10? with LnIII ions in weakly acidic (pH 5) aqueous medium. Depending on the size of the LnIII ion, the assemblies feature selective capture of two (for Eu12 ), one (for Gd12 ), or zero (for Dy12 ) extra GeIV ions. The selective encapsulation of a cationic sodium hexaaqua complex [Na(H2O)6]+ was observed for Eu12 and Gd12 , whereas Dy12 incorporates a neutral, distorted‐octahedral (H2O)6 cluster. The three compounds were characterized by single‐crystal XRD, ESI‐MS, photoluminescence, and magnetic studies. Dy12 was shown to be a single‐molecule magnet. 相似文献
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《无机化学与普通化学杂志》2018,644(15):827-832
The 1:1:2 mixture of Ln(hfac)3, Zn(hfac)2, and NIT‐Pyrim (hfac = hexafluoroacetylacetonate, NIT‐Pyrim = 2‐pyrimidine‐4,4,5,5‐tetramethylimidazoline‐1‐oxyl‐3‐oxide) afforded a series of 2p‐3d‐4f magnetic chains [Ln(hfac)3Zn(hfac)2(NIT‐Pyrim)2] [LnIII = Gd ( 1 ), Ho ( 2 ), Yb ( 3 )], in which Zn(hfac)2 and Ln(hfac)3 units are bridged by pyrimidine substituted nitronyl nitroxides through their NO moieties and pyrimidine nitrogen atoms. These complexes represent the first examples of 2p‐3d‐4f complexes with ZnII ions. Magnetic studies show that there exist ferromagnetic exchange couplings between the coordinated NO groups of radical ligands and the GdIII ions. 相似文献