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Enantioselective Self‐Assembly of Triangular Dy3 Clusters with Single‐Molecule Magnet Behavior 下载免费PDF全文
Three pairs of enantiopure chiral triangular Ln3 clusters, [Ln3LRRRRRR/SSSSSS(μ3‐OH)2(H2O)2(SCN)4]?xCH3OH?yH2O ( R ‐Dy3 , Ln=Dy, x=6, y=0; S ‐Dy3 , Ln=Dy, x=6, y=1; R ‐Ho3 , Ln=Ho, x=6, y=1; S ‐Ho3 , Ln=Ho, x=6, y=1; R ‐Er3 , Ln=Er, x=6, y=0; S ‐Er3 , Ln=Er, x=6, y=1), have been successfully synthesized by a rational enantioselective synthetic strategy. The core of triangular Ln3 is bound in the central N6O3 of the macrocyclic ligand, and the coordination spheres of Ln ions are completed by four SCN? anions and two H2O molecules in axial positions of the macrocycle. The circular dichroism (CD) and vibrational circular dichroism (VCD) spectra of the enantiomers demonstrate that the chirality is successfully transferred from the ligands to the resulting Ln3 clusters. Ac susceptibility measurements reveal that single‐molecule magnet behavior occurs for both enantiopure clusters of R ‐Dy3 and S ‐Dy3 . This work is one of the few examples of the successful design of a pair of triangular Dy3 clusters showing simultaneously slow magnetic relaxation and optical activity, and this might open up new opportunities to develop novel multifunctional materials. 相似文献
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A High‐Temperature Molecular Ferroelectric Zn/Dy Complex Exhibiting Single‐Ion‐Magnet Behavior and Lanthanide Luminescence 下载免费PDF全文
Dr. Jérôme Long Dr. Jérôme Rouquette Jean‐Marc Thibaud Dr. Rute A. S. Ferreira Prof. Dr. Luís D. Carlos Bruno Donnadieu Veaceslav Vieru Prof. Dr. Liviu F. Chibotaru Dr. Leszek Konczewicz Dr. Julien Haines Dr. Yannick Guari Prof. Dr. Joulia Larionova 《Angewandte Chemie (International ed. in English)》2015,54(7):2236-2240
Multifunctional molecular ferroelectrics are exciting materials synthesized using molecular chemistry concepts, which may combine a spontaneous electrical polarization, switched upon applying an electric field, with another physical property. A high‐temperature ferroelectric material is presented that is based on a chiral Zn2+/Dy3+ complex exhibiting Dy3+ luminescence, optical activity, and magnetism. We investigate the correlations between the electric polarization and the crystal structure as well as between the low‐temperature magnetic slow relaxation and the optical properties. 相似文献
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A linear tetranuclear 3d–4f Co2Dy2 cluster assembled from a polydentate Schiff base exhibits single‐molecule magnet (SMM) behavior with an anisotropic barrier of 33.8 K. Due to the presence of diamagnetic cobalt(III) ions, the tetranuclear cluster of 1 behaves magnetically like a dinuclear Dy2 system. However, the diamagnetic segment might efficiently minimize undesirable intermolecular magnetic interactions, thereby improving the performance of the SMM behavior of 1 . This discrete complex presents us with a unique opportunity to study the magnetic properties and to probe the dynamics of magnetization in a magnetically isolated Dy2 system. 相似文献
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Rinta Sato Dr. Kosuke Suzuki Midori Sugawa Prof. Dr. Noritaka Mizuno 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(39):12982-12990
Polyoxometalates (POMs) with heterodinuclear lanthanoid cores, TBA8H4[{Ln(μ2‐OH)2Ln′}(γ‐SiW10O36)2] ( LnLn′ ; Ln=Gd, Dy; Ln′=Eu, Yb, Lu; TBA=tetra‐n‐butylammonium), were successfully synthesized through the stepwise incorporation of two types of lanthanoid cations into the vacant sites of lacunary [γ‐SiW10O36]8? units without the use of templating cations. The incorporation of a Ln3+ ion into the vacant site between two [γ‐SiW10O36]8? units afforded mononuclear Ln3+‐containing sandwich‐type POMs with vacant sites ( Ln1 ; TBA8H5[{Ln(H2O)4}(γ‐SiW10O36)2]; Ln=Dy, Gd, La). The vacant sites in Ln1 were surrounded by coordinating W? O and Ln? O oxygen atoms. On the addition of one equivalent of [Ln′(acac)3] to solutions of Dy1 or Gd1 in 1,2‐dichloroethane (DCE), heterodinuclear lanthanoid cores with bis(μ2‐OH) bridging ligands, [Dy(μ2‐OH)2Ln′]4+, were selectively synthesized ( LnLn′ ; Ln=Dy, Gd; Ln′=Eu, Yb, Lu). On the other hand, La1 , which contained the largest lanthanoid cation, could not accommodate a second Ln′3+ ion. DyLn′ showed single‐molecule magnet behavior and their energy barriers for magnetization reversal (ΔE/kB) could be manipulated by adjusting the coordination geometry and anisotropy of the Dy3+ ion by tuning the adjacent Ln′3+ ion in the heterodinuclear [Dy(μ2‐OH)2Ln′]4+ cores. The energy barriers increased in the order: DyLu (ΔE/kB=48 K)< DyYb (53 K)< DyDy (66 K)< DyEu (73 K), with an increase in the ionic radii of Ln′3+; DyEu showed the highest energy barrier. 相似文献
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Jun‐Liang Liu Jie‐Yi Wu Yan‐Cong Chen Dr. Valeriu Mereacre Prof. Dr. Annie K. Powell Dr. Liviu Ungur Prof. Dr. Liviu F. Chibotaru Prof. Dr. Xiao‐Ming Chen Prof. Dr. Ming‐Liang Tong 《Angewandte Chemie (International ed. in English)》2014,53(47):12966-12970
A record anisotropy barrier (319 cm?1) for all d‐f complexes was observed for a unique FeII‐DyIII‐FeII single‐molecule magnet (SMM), which possesses two asymmetric and distorted FeII ions and one quasi‐D5h DyIII ion. The frozen magnetization of the DyIII ion leads to the decreased FeII relaxation rates evident in the Mössbauer spectrum. Ab initio calculations suggest that tunneling is interrupted effectively thanks to the exchange doublets. 相似文献
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Andrew J. Brown Dr. Dawid Pinkowicz Dr. Mohamed R. Saber Prof. Kim R. Dunbar 《Angewandte Chemie (International ed. in English)》2015,54(20):5864-5868
Given the recent advent of mononuclear single‐molecule magnets (SMMs), a rational approach based on lanthanides with axially elongated f‐electron charge cloud (prolate) has only recently received attention. We report herein a new SMM, [Li(THF)4[Er{N(SiMe3)2}3Cl]?2 THF, which exhibits slow relaxation of the magnetization under zero dc field with an effective barrier to the reversal of magnetization (ΔEeff/kB=63.3 K) and magnetic hysteresis up to 3 K at a magnetic field sweep rate of 34.6 Oe s?1. This work questions the theory that oblate or prolate lanthanides must be stabilized with the appropriate ligand framework in order for SMM behavior to be favored. 相似文献
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Control of the Single‐Molecule Magnet Behavior of Lanthanide‐Diarylethene Photochromic Assemblies by Irradiation with Light 下载免费PDF全文
Dr. Dawid Pinkowicz Min Ren Prof. Li‐Min Zheng Saki Sato Prof. Miki Hasegawa Dr. Masakazu Morimoto Prof. Masahiro Irie Prof. Brian K. Breedlove Dr. Goulven Cosquer Dr. Keiichi Katoh Prof. Masahiro Yamashita 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(39):12502-12513
Lanthanide‐based extended coordination frameworks showing photocontrolled single‐molecule magnet (SMM) behavior were prepared by combining highly anisotropic DyIII and HoIII ions with the carboxylato‐functionalized photochromic molecule 1,2‐bis(5‐carboxyl‐2‐methyl‐3‐thienyl)perfluorocyclopentene (H2dae), which acts as a bridging ligand. As a result, two new compounds of the general formula [{LnIII2(dae)3(DMSO)3(MeOH)} ? 10 M eOH]n (M=Dy for 1 a and Ho for 2 ) and two additional pseudo‐polymorphs [{DyIII2(dae)3(DMSO)3(H2O)} ? x MeOH]n ( 1 b ) and [{DyIII2(dae)3(DMSO)3(DMSO)} ? x MeOH]n ( 1 c ) were obtained. All four compounds have 2D coordination‐layer topologies, in which carboxylate‐bridged Ln2 units are linked together by dae2? anions into grid‐like frameworks. All four compounds exhibited a strong reversible photochromic response to UV/Vis light. Moreover, both 1 a and 2 show field‐induced SMM behavior. The slow magnetic relaxation of 1 a is influenced by the photoisomerization reaction leading to the observation of the cross‐effect: photocontrolled SMM behavior. 相似文献
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Min Ren Dr. Song‐Song Bao Dr. Norihisa Hoshino Prof. Dr. Tomoyuki Akutagawa Prof. Dr. Bingwu Wang Yu‐Chen Ding Prof. Dr. Shiqiang Wei Prof. Dr. Li‐Min Zheng 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(29):9619-9628
A new dysprosium(III) phosphonate dimer {Dy(notpH4)(NO3)(H2O)}2 ? 8 H2O ( 1 ) [notpH6=1,4,7‐triazacyclononane‐1,4,7‐triyl‐tris(methylenephosphonic acid)] that contains two equivalent DyIII ions with a three‐capped trigonal prism environment is reported. Complex 1 can be transformed into {Dy(notpH4)(NO3)(H2O)}2 ( 2 ) in a reversible manner by desorption and absorption of solvent water at ambient temperature. This process is accompanied by a large dielectric response. Magnetic studies reveal that both 1 and 2 show thermally activated magnetization relaxation as expected for single‐molecule magnets. Moreover, the magnetic dynamics of the two compounds can be manipulated by controlling the number of solvent molecules at room temperature. 相似文献
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Rational Electrostatic Design of Easy‐Axis Magnetic Anisotropy in a ZnII–DyIII–ZnII Single‐Molecule Magnet with a High Energy Barrier 下载免费PDF全文
Itziar Oyarzabal Prof. Dr. José Ruiz Prof. Dr. José Manuel Seco Dr. Marco Evangelisti Dr. Agustín Camón Prof. Dr. Eliseo Ruiz Dr. Daniel Aravena Prof. Dr. Enrique Colacio 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(44):14262-14269
Two novel trinuclear complexes [ZnCl(μ‐L)Ln(μ‐L)ClZn][ZnCl3(CH3OH)]?3 CH3OH (LnIII=Dy ( 1 ) and Er ( 2 )) have been prepared from the compartmental ligand N,N′‐dimethyl‐N,N′‐bis(2‐hydroxy‐3‐formyl‐5‐bromo‐benzyl)ethylenediamine (H2L). X‐ray studies reveal that LnIII ions are coordinated by two [ZnCl(L)]? units through the phenoxo and aldehyde groups, giving rise to a LnO8 coordination sphere with square‐antiprism geometry and strong easy‐axis anisotropy of the ground state. Ab initio CASSCF+RASSI calculations carried out on 1 confirm that the ground state is an almost pure MJ=±15/2 Kramers doublet with a marked axial anisotropy, the magnetic moment is roughly collinear with the shortest Dy?O distances. This orientation of the local magnetic moment of the DyIII ion in 1 is adopted to reduce the electronic repulsion between the oblate electron shape of the MJ=±15/2 Kramers doublet and the phenoxo‐oxygen donor atoms involved in the shortest Dy?O bonds. CASSCF+RASSI calculations also show that the ground and first excited states of the DyIII ion are separated by 129 cm?1. As expected for this large energy gap, compound 1 exhibits, in a zero direct‐current field, thermally activated slow relaxation of the magnetization with a large Ueff=140 K. The isostructural Zn–Er–Zn species does not present significant SMM behavior as expected for the prolate electron‐density distribution of the ErIII ion leading to an easy‐plane anisotropy of the ground doublet state. 相似文献
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Frontispiece: Rational Electrostatic Design of Easy‐Axis Magnetic Anisotropy in a ZnII–DyIII–ZnII Single‐Molecule Magnet with a High Energy Barrier 下载免费PDF全文
Itziar Oyarzabal Prof. Dr. José Ruiz Prof. Dr. José Manuel Seco Dr. Marco Evangelisti Dr. Agustín Camón Prof. Dr. Eliseo Ruiz Dr. Daniel Aravena Prof. Dr. Enrique Colacio 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(44)
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Lighting one by one: The electroluminescence (EL) from single molecules of a red phosphorescent iridium complex dispersed in a hole‐transporting polymer matrix is studied. The single‐molecule EL dynamics is determined by local structural inhomogeneities in the matrix polymer (see picture).
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Reversible SC‐SC Transformation involving [4+4] Cycloaddition of Anthracene: A Single‐Ion to Single‐Molecule Magnet and Yellow‐Green to Blue‐White Emission 下载免费PDF全文
Xin‐Da Huang Yan Xu Kun Fan Prof. Dr. Song‐Song Bao Prof. Dr. Mohamedally Kurmoo Prof. Dr. Li‐Min Zheng 《Angewandte Chemie (International ed. in English)》2018,57(28):8577-8581
In search of magneto‐optic materials, the mononuclear compounds LnIII(depma)(NO3)3(hmpa)2 (Ln=Dy, Gd) were synthesized. The anthracene moieties undergo [4+4] dimerization when irradiated at 365 nm without loss of crystallinity. The Dy compound switches from a single‐ion to a single‐molecule magnet with doubling of the spin reversal barrier energy and from yellow‐green to blue‐white emission. The dimerization is reversed by heating at 100 °C or partially on light irradiating at 254 nm. The results suggest that lanthanide phosphonates with anthracene are promising smart materials displaying synergistic magneto‐optic property. 相似文献
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Self‐Assembly of a Giant Tetrahedral 3 d–4 f Single‐Molecule Magnet within a Polyoxometalate System 下载免费PDF全文
Dr. Masooma Ibrahim Dr. Valeriu Mereacre Dr. Nicolas Leblanc Prof. Wolfgang Wernsdorfer Dr. Christopher E. Anson Prof. Annie K. Powell 《Angewandte Chemie (International ed. in English)》2015,54(51):15574-15578
A giant tetrahedral heterometallic polyoxometalate (POM) [Dy30Co8Ge12W108O408(OH)42(OH2)30]56?, which shows single‐molecule magnet (SMM) behavior, is described. This hybrid contains the largest number of 4f ions of any polyoxometalate (POM) reported to date and is the first to incorporate two different 3d–4f and 4f coordination cluster assemblies within same POM framework. 相似文献