Search results for "single-molecule"

Single-molecule magnet behavior and magnetocaloric effect in ferromagnetically coupled LnIII-NiII-NiII-LnIII (LnIII = DyIII and GdIII) linear complex…

2014

New types of linear tetranuclear LnIII-NiII-NiII-LnIII (LnIII = Dy (1), Gd (2)) complexes have been prepared using the multidentate ligand N,N′-bis(3-methoxysalicylidene)-1,3-diaminobenzene, which has two sets of NO and OO′ coordination pockets that are able to selectively accommodate NiII and LnIII ions, respectively. The X-ray structure analysis reveals that the NiII ions are bridged by phenylenediimine groups forming a 12-membered metallacycle in the central body of the complex, whereas the LnIII ions are located at both sides of the metallacycle and linked to the NiII ions by diphenoxo bridging groups. Phenylenediimine and diphenoxo bridging groups transmit ferromagnetic exchange intera…

Exploring the Role of Intramolecular Interactions in the Suppression of Quantum Tunneling of the Magnetization in a 3d-4f Single-Molecule Magnet.

2021

Hydroxide-bridged FeIII4LnIII2 clusters having the general formula [Fe4Ln2(μ3-OH)2(mdea)6(SCN)2(NO3)2(H2O)2]·4H2O·2MeCN {Ln = Y (1), Dy (2), mdea = N-methyldiethanolamine} were synthesized and magnetically characterized. The thermal relaxation of the magnetization for 2 and the diluted FeIII4DyIIIYIII complex 3 (with and without applied field) has been analyzed. The diluted sample shows a dominant QTM at low temperatures that can be removed with a 0.15 T dc field. Both 2 and 3 show moderately high Ueff barriers and exhibit hysteresis loops until 5 K.

Single Molecule Magnet Features in the Butterfly [Co III 2 Ln III 2 ] Pivalate Family with Alcohol‐Amine Ligands

2021

Field-induced single molecule magnet behavior of a dinuclear cobalt(II) complex: a combined experimental and theoretical study.

2020

Two dinuclear cobalt(ii) complexes, [(dmso)CoIIL1(μ-(m-NO2)C6H4COO)CoII(NCS)] (1) and [(dmso)CoIIL2(μ-(m-NO2)C6H4COO)CoII(NCS)] (2) [dmso = dimethylsulfoxide, H2L1 = (2,2-dimethyl-1,3-propanediyl)bis(iminomethylene)bis(6-methoxyphenol) and H2L2 = (2,2-dimethyl-1,3-propanediyl)bis(iminomethylene)bis(6-ethoxyphenol)] have been synthesized and structurally characterized by single-crystal X-ray diffraction, magnetic-susceptibility measurements and various spectroscopic techniques. Each complex contains a cobalt(ii) center with a slightly distorted octahedral geometry and a second cobalt(ii) center with a distorted trigonal prismatic one. To obtain insight into the physical nature of weak non-co…

From Paramagnetic to Single‐Molecule Magnet Behaviour in Heterobimetallic Compounds Containing the Tetrakis(thiocyanato‐ κN )cobaltate(II) Anion

2018

A Click‐Functionalized Single‐Molecule Magnet Based on Cobalt(II) and Its Analogous Manganese(II) and Zinc(II) Compounds

2014

A mononuclear CoII single-molecule magnet suitable for click chemistry was investigated. [M(oda)(aterpy)] complexes (oda2– = oxodiacetate, aterpy = 4′-azido-2,2′:6′,2″-terpyridine) with M = MnII, ZnII, and CoII were synthesized as azide-functionalized building blocks for the copper-catalyzed azide–alkyne cycloaddition reaction. The required structural integrity of the complexes in solution was proven in great detail by using ESI-MS and NMR spectroscopy. For the six-coordinate [Co(oda)(aterpy)] complex, single-molecule magnet behavior was confirmed with an effective energy barrier of 4.2 cm–1.

Protein Conformational Landscapes and Catalysis. Influence of Active Site Conformations in the Reaction Catalyzed by L-Lactate Dehydrogenase

2015

In the past decade, L-Lactate Dehydrogenase (LDH) has become an extremely useful marker in both clinical diagnosis and in monitoring the course of many human diseases. It has been assumed since the 1980s that the full catalytic process of LDH starts with the binding of the cofactor and the substrate followed by the enclosure of the active site by a mobile loop of the protein before the reaction takes place. In this paper, we show that the chemical step of the LDH-catalyzed reaction can proceed within the open loop conformation, and the different reactivity of the different protein conformations would be in agreement with the broad range of rate constants measured in single-molecule spectrom…

Electronic, Structural and Functional Versatility in Tetrathiafulvalene-Lanthanide Metal-Organic Frameworks

2019

<div>Tetrathiafulvalene-Lanthanide (TTF-Ln) Metal-Organic Frameworks (MOFs) are an interesting class of multifunctional materials in which porosity can be combined with electronic properties such as electrical conductivity, redox activity, luminescence and magnetism. Herein we report a new family of isostructural TTF-Ln MOFs, denoted as <b>MUV-5(Ln)</b> (Ln = Gd, Tb, Dy, Ho, Er), exhibiting semiconducting properties as a consequence of the short intermolecular S···S contacts established along the chain direction between partially oxidised TTF moieties. In addition, this family shows photoluminescence properties and single-molecule magnetic behaviour, finding near-infrared …

A Dysprosium Metallocene Single-Molecule Magnet Functioning at the Axial Limit

2017

Abstraction of a chloride ligand from the dysprosium metallocene [(Cpttt)2DyCl] (1Dy Cpttt=1,2,4‐tri(tert‐butyl)cyclopentadienide) by the triethylsilylium cation produces the first base‐free rare‐earth metallocenium cation [(Cpttt)2Dy]+ (2Dy) as a salt of the non‐coordinating [B(C6F5)4]− anion. Magnetic measurements reveal that [2Dy][B(C6F5)4] is an SMM with a record anisotropy barrier up to 1277 cm−1 (1837 K) in zero field and a record magnetic blocking temperature of 60 K, including hysteresis with coercivity. The exceptional magnetic axiality of 2Dy is further highlighted by computational studies, which reveal this system to be the first lanthanide SMM in which all low‐lying Kramers doub…

Role of Orbital Degeneracy in the Single Molecule Magnet Behavior of a Mononuclear High-Spin Fe(II) Complex

2010

To explain the single-molecule magnet behavior of the mononuclear complex [(tpaMes)Fe](-) we have developed a model that takes into account the trigonal ligand field splitting of the atomic (5)D term of the Fe(II) ion, and the spin-orbital splitting and mixing of the ligand field terms. The ground ligand field term is shown to be the orbital doublet (5)E possessing an unquenched orbital angular momentum. We demonstrate that the splitting of this term cannot be described by the conventional zero-field splitting Hamiltonian proving thus the irrelevance of the spin-Hamiltonian formalism in the present case. The first-order orbital angular momentum is shown to lead to the strong magnetic anisot…