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1.
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
2.
《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
3.
《无机化学与普通化学杂志》2018,644(5):293-300
Three dinuclear lanthanide complexes [Ln2(H2L)2(NO3)4] [Ln = Dy ( 1 ), Tb ( 2 ), and Gd ( 3 )] [H3L = 2‐hydroxyimino‐N′‐[(2‐hydroxy‐3‐methoxyphenyl)methylidene]‐propanohydrazone] were solvothermally synthesized by varying differently anisotropic rare earth ions. Single‐crystal structural analyses demonstrate that all the three complexes are crystallographically isostructural with two centrosymmetric LnIII ions aggregated by a pair of monodeprotonated H2L– anions. Weak intramolecular antiferromagnetic interactions with different strength were mediated by a pair of phenoxo bridges due to superexchange and/or single‐ion anisotropy. Additionally, the DyIII‐based entity shows the strongest anisotropy exhibits field‐induced single‐molecule magnetic behavior with two thermally activated relaxation processes. In contrast, 3 with isotropic GdIII ion has a significant cryogenic magnetocaloric effect with the maximum entropy change of 25.7 J · kg–1 · K–1 at 2.0 K and 70.0 kOe. 相似文献
4.
Trinuclear [CoIII2–LnIII] (Ln=Tb,Dy) Single‐Ion Magnets with Mixed 6‐Chloro‐2‐Hydroxypyridine and Schiff Base Ligands 下载免费PDF全文
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
5.
Large Hexadecametallic {MnIII–LnIII} Wheels: Synthesis,Structural, Magnetic,and Theoretical Characterization 下载免费PDF全文
Kuduva R. Vignesh Dr. Stuart K. Langley Dr. Boujemaa Moubaraki Prof. Keith S. Murray Prof. Gopalan Rajaraman 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(46):16364-16369
The synthesis, gas sorption studies, magnetic properties, and theoretical studies of new molecular wheels of core type {MnIII8LnIII8} (Ln=Dy, Ho, Er, Y and Yb), using the ligand mdeaH2, in the presence of ortho‐toluic or benzoic acid are reported. From the seven wheels studied the {Mn8Dy8} and {Mn8Y8} analogues exhibit SMM behavior as determined from ac susceptibility experiments in a zero static magnetic field. From DFT calculations a S=16 ground state was determined for the {Mn8Y8} complex due to weak ferromagnetic MnIII–MnIII interactions. Ab initio CASSCF+RASSI‐SO calculations on the {Mn8Dy8} wheel estimated the MnIII–DyIII exchange interaction as ?0.1 cm?1. This weak exchange along with unfavorable single‐ion anisotropy of DyIII/MnIII ions, however, led to the observation of SMM behavior with fast magnetic relaxation. The orientation of the g‐anisotropy of the DyIII ions is found to be perpendicular to the plane of the wheel and this suggests the possibility of toroidal magnetic moments in the cluster. The {Mn8Ln8} clusters reported here are the largest heterometallic MnIIILnIII wheels and the largest {3d–4f} wheels to exhibit SMM behavior reported to date. 相似文献
6.
Hetero‐tri‐spin [2p‐3d‐4f] Chain Compounds Based on Nitronyl Nitroxide Lanthanide Metallo‐Ligands: Synthesis,Structure, and Magnetic Properties 下载免费PDF全文
Mei Zhu Peng Hu Yungai Li Xiufeng Wang Prof. Licun Li Prof. Daizheng Liao V. M. L. Durga Prasad Goli Prof. S. Ramasesha Dr. Jean‐Pascal Sutter 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(41):13356-13365
Employing nitronyl nitroxide lanthanide(III) complexes as metallo‐ligands allowed the efficient and highly selective preparation of three series of unprecedented hetero‐tri‐spin (Cu?Ln‐radical) one‐dimensional compounds. These 2p–3d–4f spin systems, namely [Ln3Cu(hfac)11(NitPhOAll)4] (LnIII=Gd 1Gd , Tb 1Tb , Dy 1Dy ; NitPhOAll=2‐(4′‐allyloxyphenyl)‐4,4,5,5‐tetramethylimidazoline‐1‐oxyl‐3‐oxide), [Ln3Cu(hfac)11(NitPhOPr)4] (LnIII=Gd 2Gd , Tb 2Tb , Dy 2Dy , Ho 2Ho , Yb 2Yb ; NitPhOPr=2‐(4′‐propoxyphenyl)‐4,4,5,5‐tetramethyl‐imidazoline‐1‐oxyl‐3‐oxide) and [Ln3Cu(hfac)11(NitPhOBz)4] (LnIII=Gd 3Gd , Tb 3Tb , Dy 3Dy ; NitPhOBz=2‐(4′‐benzyloxyphenyl)‐4,4,5,5‐tetramethyl‐imidazoline‐1‐oxyl‐3‐oxide) involve O‐bound nitronyl nitroxide radicals as bridging ligands in chain structures with a [Cu‐Nit‐Ln‐Nit‐Ln‐Nit‐Ln‐Nit] repeating unit. The dc magnetic studies show that ferromagnetic metal–radical interactions take place in these hetero‐tri‐spin chain complexes, these and the next‐neighbor interactions have been quantified for the Gd derivatives. Complexes 1Tb and 2Tb exhibit frequency dependence of ac magnetic susceptibilities, indicating single‐chain magnet behavior. 相似文献
7.
Nickel(II)–Lanthanide(III) Magnetic Exchange Coupling Influencing Single‐Molecule Magnetic Features in {Ni2Ln2} Complexes 下载免费PDF全文
Naushad Ahmed Chinmoy Das Shefali Vaidya Dr. Stuart K. Langley Prof. Dr. Keith S. Murray Prof. Dr. Maheswaran Shanmugam 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(44):14235-14239
Four isostructural [Ni2Ln2(CH3CO2)3(HL)4(H2O)2]3+(Ln3+=Dy ( 1 ), Tb ( 2 ), Ho ( 3 ) or Lu ( 4 )) complexes and a dinuclear [NiGd(HL)2(NO3)3] ( 5 ) complex are reported (where HL=2‐methoxy‐6‐[(E)‐2′‐hydroxymethyl‐phenyliminomethyl]‐phenolate). For compounds 1 – 3 and 5 , the Ni2+ ions are ferromagnetically coupled to the respective lanthanide ions. The ferromagnetic coupling in 1 suppresses the quantum tunnelling of magnetisation (QTM), resulting in a rare zero dc field Ni–Dy single‐molecule magnet, with an anisotropy barrier Ueff of 19 K. 相似文献
8.
Two Oxime‐Based {LnIII3NiII3} Clusters with Triangular {Ln3(μ3‐Ο2)}7+ Core: Solvothermal Syntheses,Crystal Structures,and Magnetic Properties 下载免费PDF全文
Xiao‐Ting Wang Hui‐Ming Dong Xiu‐Guang Wang En‐Cui Yang Xiao‐Jun Zhao 《无机化学与普通化学杂志》2016,642(20):1166-1172
Two isostructural heterometallic complexes, {[Dy3Ni3(H2O)3(mpko)9(O2)(NO3)3](ClO4) · 3CH3OH · 3CH3CN} ( 1 ) and {[Gd3Ni3(H2O)3(mpko)9(O2)(NO3)3](NO3) · 10.75CH3OH} ( 2 ) [mpkoH = 1‐(pyrazin‐2‐yl)ethanone oxime], were solvothermally synthesized by varying lanthanide ions with different magnetic anisotropy. Structural analyses revealed that both complexes contain a peroxide anion‐aggregated triangular {Ln3(μ3‐Ο2)}7+ core, which is surrounded by three NiII octahedra through threefold oxime linkages into a heterometallic hexanuclear cluster. Apparent antiferromagnetic interactions are observed between the adjacent spin carriers of 1 and 2 with the coupling constant JLn ··· Ni ≈ 12JLn ··· Ln. Additionally, 1 with highly anisotropic DyIII site shows slow magnetization relaxation under zero dc field and 2 constructed from isotropic GdIII ion displays significant cryogenic magnetocaloric effect with a maximum entropy change of 24.8 J · kg–1 · K–1 at 3.0 K and 70 kOe. 相似文献
9.
Heterotrimetallic Coordination Polymers: {CuIILnIIIFeIII} Chains and {NiIILnIIIFeIII} Layers: Synthesis,Crystal Structures,and Magnetic Properties 下载免费PDF全文
Dr. Maria‐Gabriela Alexandru Dr. Diana Visinescu Prof. Marius Andruh Dr. Nadia Marino Dr. Donatella Armentano Dr. Joan Cano Prof. Francesc Lloret Prof. Miguel Julve 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(14):5429-5446
The use of the [FeIII(AA)(CN)4]? complex anion as metalloligand towards the preformed [CuII(valpn)LnIII]3+ or [NiII(valpn)LnIII]3+ heterometallic complex cations (AA=2,2′‐bipyridine (bipy) and 1,10‐phenathroline (phen); H2valpn=1,3‐propanediyl‐bis(2‐iminomethylene‐6‐methoxyphenol)) allowed the preparation of two families of heterotrimetallic complexes: three isostructural 1D coordination polymers of general formula {[CuII(valpn)LnIII(H2O)3(μ‐NC)2FeIII(phen)(CN)2 {(μ‐NC)FeIII(phen)(CN)3}]NO3 ? 7 H2O}n (Ln=Gd ( 1 ), Tb ( 2 ), and Dy ( 3 )) and the trinuclear complex [CuII(valpn)LaIII(OH2)3(O2NO)(μ‐NC)FeIII(phen)(CN)3] ? NO3 ? H2O ? CH3CN ( 4 ) were obtained with the [CuII(valpn)LnIII]3+ assembling unit, whereas three isostructural heterotrimetallic 2D networks, {[NiII(valpn)LnIII(ONO2)2(H2O)(μ‐NC)3FeIII(bipy)(CN)] ? 2 H2O ? 2 CH3CN}n (Ln=Gd ( 5 ), Tb ( 6 ), and Dy ( 7 )) resulted with the related [NiII(valpn)LnIII]3+ precursor. The crystal structure of compound 4 consists of discrete heterotrimetallic complex cations, [CuII(valpn)LaIII(OH2)3(O2NO)(μ‐NC)FeIII(phen)(CN)3]+, nitrate counterions, and non‐coordinate water and acetonitrile molecules. The heteroleptic {FeIII(bipy)(CN)4} moiety in 5 – 7 acts as a tris‐monodentate ligand towards three {NiII(valpn)LnIII} binuclear nodes leading to heterotrimetallic 2D networks. The ferromagnetic interaction through the diphenoxo bridge in the CuII?LnIII ( 1 – 3 ) and NiII?LnIII ( 5 – 7 ) units, as well as through the single cyanide bridge between the FeIII and either NiII ( 5 – 7 ) or CuII ( 4 ) account for the overall ferromagnetic behavior observed in 1 – 7 . DFT‐type calculations were performed to substantiate the magnetic interactions in 1 , 4 , and 5 . Interestingly, compound 6 exhibits slow relaxation of the magnetization with maxima of the out‐of‐phase ac signals below 4.0 K in the lack of a dc field, the values of the pre‐exponential factor (τo) and energy barrier (Ea) through the Arrhenius equation being 2.0×10?12 s and 29.1 cm?1, respectively. In the case of 7 , the ferromagnetic interactions through the double phenoxo (NiII–DyIII) and single cyanide (FeIII–NiII) pathways are masked by the depopulation of the Stark levels of the DyIII ion, this feature most likely accounting for the continuous decrease of χM T upon cooling observed for this last compound. 相似文献
10.
The Building Block [FeIII(pzphen)(CN)4]– and its Lanthanide Complexes: Synthesis,Crystal Structure,and Magnetic Properties 下载免费PDF全文
Jian‐Qing Tao Wen‐Wen Ju Zhou Zhou Li‐Yong Jia Ning‐Ning Chen Yun‐Shan Xue Jun Wang Xing‐Cai Huang 《无机化学与普通化学杂志》2016,642(24):1466-1471
The cyanide building block [FeIII(pzphen)(CN)4]– and its four lanthanide complexes [{FeIII(pzphen)(CN)4}2LnIII(H2O)5(DMF)3] · (NO3) · 2(H2O) · (CH3CN) [Ln = Nd ( 1 ), Sm ( 2 ), DMF = dimethyl formamide] and [{FeIII(pzphen)(CN)4}2LnIII(NO3)(H2O)2(DMF)2](CH3CN) [Ln = Gd ( 3 ), Dy ( 4 )] were synthesized and structurally characterized by single‐crystal X‐ray diffraction. Compounds 1 and 2 are ionic salts with two [FeIII(pzphen)(CN)4]– cations and one LnIII ion, but compounds 3 and 4 are cyano‐bridged FeIII‐LnIII heterometallic 3d‐4f complexes exhibiting a trinuclear structure in the same conditions. Magnetic studies show that compound 3 is antiferromagnetic between the central FeIII and GdIII atoms. Furthermore, the trinuclear cyano‐bridged FeIII2DyIII compound 4 displays no single‐molecular magnets (SMMs) behavior by the alternating current magnetic susceptibility measurements. 相似文献
11.
Dr. Min‐Xia Yao Qi Zheng Kang Qian Prof. Dr. You Song Prof. Dr. Song Gao Prof. Dr. Jing‐Lin Zuo 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(1):294-303
By using the node‐and‐spacer approach in suitable solvents, four new heterotrimetallic 1D chain‐like compounds (that is, containing 3d–3d′–4f metal ions), {[Ni(L)Ln(NO3)2(H2O)Fe(Tp*)(CN)3] ? 2 CH3CN ? CH3OH}n (H2L=N,N′‐bis(3‐methoxysalicylidene)‐1,3‐diaminopropane, Tp*=hydridotris(3,5‐dimethylpyrazol‐1‐yl)borate; Ln=Gd ( 1 ), Dy ( 2 ), Tb ( 3 ), Nd ( 4 )), have been synthesized and structurally characterized. All of these compounds are made up of a neutral cyanide‐ and phenolate‐bridged heterotrimetallic chain, with a {? Fe? C?N? Ni(? O? Ln)? N?C? }n repeat unit. Within these chains, each [(Tp*)Fe(CN)3]? entity binds to the NiII ion of the [Ni(L)Ln(NO3)2(H2O)]+ motif through two of its three cyanide groups in a cis mode, whereas each [Ni(L)Ln(NO3)2(H2O)]+ unit is linked to two [(Tp*)Fe(CN)3]? ions through the NiII ion in a trans mode. In the [Ni(L)Ln(NO3)2(H2O)]+ unit, the NiII and LnIII ions are bridged to one other through two phenolic oxygen atoms of the ligand (L). Compounds 1 – 4 are rare examples of 1D cyanide‐ and phenolate‐bridged 3d–3d′–4f helical chain compounds. As expected, strong ferromagnetic interactions are observed between neighboring FeIII and NiII ions through a cyanide bridge and between neighboring NiII and LnIII (except for NdIII) ions through two phenolate bridges. Further magnetic studies show that all of these compounds exhibit single‐chain magnetic behavior. Compound 2 exhibits the highest effective energy barrier (58.2 K) for the reversal of magnetization in 3d/4d/5d–4f heterotrimetallic single‐chain magnets. 相似文献
12.
Role of Magnetic Exchange Interactions in the Magnetization Relaxation of {3d–4f} Single‐Molecule Magnets: A Theoretical Perspective 下载免费PDF全文
Dr. Saurabh Kumar Singh Mohammad Faizan Beg Prof. Dr. Gopalan Rajaraman 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(2):672-680
Combined density functional and ab initio calculations are performed on two isomorphous tetranuclear {Ni3IIILnIII} star‐type complexes [Ln=Gd ( 1 ), Dy ( 2 )] to shed light on the mechanism of magnetic exchange in 1 and the origin of the slow magnetization relaxation in complex 2 . DFT calculations correctly reproduce the sign and magnitude of the J values compared to the experiments for complex 1 . Acute ?Ni?O?Gd bond angles present in 1 instigate a significant interaction between the 4fxyz orbital of the GdIII ion and 3d orbital of the NiII ions, leading to rare and strong antiferromagnetic Ni???Gd interactions. Calculations reveal the presence of a strong next‐nearest‐neighbour Ni???Ni antiferromagnetic interaction in complex 1 leading to spin frustration behavior. CASSCF+RASSI‐SO calculations performed on complex 2 suggest that the octahedral environment around the DyIII ion is neither strong enough to stabilize the mJ |±15/2〉 as the ground state nor able to achieve a large ground‐state–first‐excited‐state gap. The ground‐state Kramers doublet for the DyIII ion is found to be the mJ |±13/2〉 state with a significant transverse anisotropy, leading to very strong quantum tunneling of magnetization (QTM). Using the POLY_ANISO program, we have extracted the JNiDy interaction as ?1.45 cm?1. The strong Ni???Dy and next‐nearest‐neighbour Ni???Ni interactions are found to quench the QTM to a certain extent, resulting in zero‐field SMM behavior for complex 2 . The absence of any ac signals at zero field for the structurally similar [Dy(AlMe4)3] highlights the importance of both the Ni???Dy and the Ni???Ni interactions in the magnetization relaxation of complex 2 . To the best of our knowledge, this is the first time that the roles of both the Ni???Dy and Ni???Ni interactions in magnetization relaxation of a {3d–4f} molecular magnet have been established. 相似文献
13.
Ln12‐Containing 60‐Tungstogermanates: Synthesis,Structure, Luminescence,and Magnetic Studies 下载免费PDF全文
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
14.
Yingying Wang Zhuangdong Yuan Yunjie Guo Xuxiao Ma Zitong Meng Jingquan Sha Haifeng Zhang 《无机化学与普通化学杂志》2020,646(20):1696-1701
Two dinuclear LnIII-based clusters, namely [Dy2L2(NO3)2(DME)4] ( 1 ) and [Gd2L2(NO3)2(DME)4] ( 2 ) [H2L = (E)-2-((2-hydroxybenzylidene)amino)phenol] were obtained under hydrothermal condition. Two LnIII ions are bridged by two phenolic hydroxyl oxygen atoms, and the distances of them are 3.829 Å (Dy1–Dy1A) and 3.860 Å (Gd1–Gd1A). Two Dy1–O–Dy1A and Gd1–O–Gd1A angles are 109.4° and 109.8°, respectively. Magnetic studies reveal a weak antiferromagnetic interaction between Gd ions in complex 2 , and single-molecule magnet behavior for 1 with Ueff = 49.9 K and τ0 = 1.54 × 10–6 s. 相似文献
15.
Lanthanide(III) (Eu,Gd, Tb,Dy) Complexes Derived from 4‐(Pyridin‐2‐yl)methyleneamino‐1,2,4‐triazole: Crystal Structure,Magnetic Properties,and Photoluminescence 下载免费PDF全文
Dr. Evgeniya S. Bazhina Anna A. Bovkunova Dr. Alexey V. Medved'ko Evgeniya A. Varaksina Dr. Ilya V. Taidakov Dr. Nikolay N. Efimov Prof. Dr. Mikhail A. Kiskin Prof. Dr. Igor L. Eremenko 《化学:亚洲杂志》2018,13(16):2060-2068
The reaction of lanthanide(III) nitrates with 4‐(pyridin‐2‐yl)methyleneamino‐1,2,4‐triazole (L) was studied. The compounds [Ln(NO3)3(H2O)3] ? 2 L, in which Ln=Eu ( 1 ), Gd ( 2 ), Tb ( 3 ), or Dy ( 4 ), obtained in a mixture of MeCN/EtOH have the same structure, as shown by XRD. In the crystals of these compounds, the mononuclear complex units [Ln(NO3)3(H2O)3] are linked to L molecules through intermolecular hydrogen‐bonding interactions to form a 2D polymeric supramolecular architecture. An investigation into the optical characteristics of the Eu3+‐, Tb3+‐, and Dy3+‐containing compounds ( 1 , 3 , and 4 ) showed that these complexes displayed metal‐centered luminescence. According to magnetic measurements, compound 4 exhibits single‐ion magnet behavior, with ΔEeff/kB=86 K in a field of 1500 Oe. 相似文献
16.
《化学:亚洲杂志》2017,12(5):507-514
Five hexanuclear lanthanide clusters of composition [Ln6(μ4‐O)2(HCOO)2L4(HL′)2(dmf)2] [Ln=Dy ( 1 ), Er ( 2 ), Ho ( 3 ), Tb ( 4 ), Gd ( 5 ); H2L=2‐{[2‐(hydroxymethyl)phenylimino]methyl}‐6‐methoxyphenol; H3L′=3‐{[2‐(hydroxymethyl)phenylimino]methyl}benzene‐1,2‐diol; H3L′ was derived in situ from the H2L ligand] were prepared under solvothermal conditions. The [Ln6] cores of 1 – 5 possess an unprecedented motif, namely, two tetrahedron Ln4 units sharing an edge and two vertices. The six LnIII ions of 1 – 5 are connected through two μ4‐O anions. Magnetic susceptibility studies reveal that complex 1 exhibits frequency dependence of the alternating current susceptibility typical of single‐molecule magnets. Complex 1 possesses a relatively large energy barrier of 85 K among all of the reported Dy6 single‐molecule magnets. 相似文献
17.
Synthesis,Crystal Structure,Fluorescent and Antioxidation Properties of Cerium(III) and Europium(III) Complexes with Bis(3‐methoxysalicylidene)‐3‐oxapentane‐1,5‐diamine 下载免费PDF全文
Two aliphatic ether Schiff base lanthanide complexes (Ln = Eu, Ce) with bis(3‐methoxysalicylidene)‐3‐oxapentane‐1,5‐diamine (Bod), were synthesized and characterized by physicochemical and spectroscopic methods. [Eu(Bod)(NO3)3] ( 1 ) is a discrete mononuclear species and [Ce(Bod)(NO3)3DMF]∞ ( 2 ) exhibits an inorganic coordination polymer. In the two complexes, the metal ions both are ten‐coordinated and the geometric structure around the LnIII atom can be described as distorted hexadecahedron. Under excitation at room temperature, the red shift in the fluorescence band of the ligand in the complexes compared with that of the free ligand can be attributed to coordination of the rare earth ions to the ligand. Moreover, the antioxidant activities of the two complexes were investigated. The results demonstrated that the complexes have better scavenging activity than both the ligand and the usual antioxidants on the hydroxyl and superoxide radicals. 相似文献
18.
Jun‐Liang Liu Wei‐Quan Lin Yan‐Cong Chen Silvia Gómez‐Coca Daniel Aravena Prof. Dr. Eliseo Ruiz Ji‐Dong Leng Prof. Dr. Ming‐Liang Tong 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(51):17567-17577
A series of heterometallic [LnIIIxCuIIy] complexes, [Gd2Cu2]n ( 1 ), [Gd4Cu8] ( 2 ), [Ln9Cu8] (Ln=Gd, 3?Gd ; Ln=Dy, 3?Dy ), were successfully synthesized by a one‐pot route at room temperature with three kinds of in situ carbonyl‐related reactions: Cannizzaro reaction, aldol reaction, and oxidation. This strategy led to dysprosium analogues that behaved as single‐molecule magnets (SMMs) and gadolinium analogues that showed significant magnetocaloric effect (MCE). In this study a numerical DFT approach is proposed by using pseudopotentials to calculate the exchange coupling constants in three polynuclear [GdxCuy] complexes; with these values exact diagonalization or quantum Monte Carlo simulations have been performed to calculate the variation of the magnetic entropy involved in the MCE. For the [Dy9Cu8] complexes, local magnetic properties of the DyIII centers have been determined by using the CASSCF+RASSI method. 相似文献
19.
《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
20.
White Light Emissive DyIII Single‐Molecule Magnets Sensitized by Diamagnetic [CoIII(CN)6]3− Linkers 下载免费PDF全文
Dr. Szymon Chorazy Dr. Michał Rams Dr. Koji Nakabayashi Prof. Dr. Barbara Sieklucka Prof. Dr. Shin‐ichi Ohkoshi 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(22):7371-7375
The self‐assembly of DyIII–3‐hydroxypyridine (3‐OHpy) complexes with hexacyanidocobaltate(III) anions in water produces cyanido‐bridged {[DyIII(3‐OHpy)2(H2O)4] [CoIII(CN)6]}?H2O ( 1 ) chains. They reveal a single‐molecule magnet (SMM) behavior with a large zero direct current (dc) field energy barrier, ΔE=266(12) cm?1 (≈385 K), originating from the single‐ion property of eight‐coordinated DyIII of an elongated dodecahedral geometry, which are embedded with diamagnetic [CoIII(CN)6]3? ions into zig‐zag coordination chains. The SMM character is enhanced by the external dc magnetic field, which results in the ΔE of 320(23) cm?1 (≈460 K) at Hdc=1 kOe, and the opening of a butterfly hysteresis loop below 6 K. Complex 1 exhibits white DyIII‐based emission realized by energy transfer from CoIII and 3‐OHpy to DyIII. Low temperature emission spectra were correlated with SMM property giving the estimation of the zero field ΔE. 1 is a unique example of bifunctional magneto‐luminescent material combining white emission and slow magnetic relaxation with a large energy barrier, both controlled by rich structural and electronic interplay between DyIII, 3‐OHpy, and [CoIII(CN)6]3?. 相似文献