The Experts below are selected from a list of 303 Experts worldwide ranked by ideXlab platform
Thomas A. Jung - One of the best experts on this subject based on the ideXlab platform.
-
Emergence of On-Surface Magnetochemistry
The Journal of Physical Chemistry Letters, 2013Co-Authors: Nirmalya Ballav, Christian Wackerlin, Dorota Siewert, Peter M. Oppeneer, Thomas A. JungAbstract:The control of exchange coupling across the molecule–substrate interface is a key feature in molecular spintronics. This Perspective reviews the emerging field of on-surface Magnetochemistry, where coordination chemistry is applied to surface-supported metal porphyrins and metal phthalocyanines to control their magnetic properties. The particularities of the surface as a multiatomic ligand or “surface ligand” are introduced. The asymmetry involved in the action of a chemical ligand and a surface ligand on the same planar complexes modifies the well-established “trans effect” to the notion of the “surface-trans effect”. As ad-complexes on ferromagnetic substrates are usually exchange-coupled, the magnetochemical implications of the surface-trans effect are of particular interest. The combined action of the different ligands allows for the reproducible control of spin states in on-surface supramolecular architectures and opens up new ways toward building and operating spin systems at interfaces. Notably, spin-switching has been demonstrated to be controlled collectively via the interaction with a ligand (chemical selectivity) and individually via local addressing at the interface
-
emergence of on surface Magnetochemistry
Journal of Physical Chemistry Letters, 2013Co-Authors: Nirmalya Ballav, Christian Wackerlin, Dorota Siewert, Peter M. Oppeneer, Thomas A. JungAbstract:The control of exchange coupling across the molecule–substrate interface is a key feature in molecular spintronics. This Perspective reviews the emerging field of on-surface Magnetochemistry, where coordination chemistry is applied to surface-supported metal porphyrins and metal phthalocyanines to control their magnetic properties. The particularities of the surface as a multiatomic ligand or “surface ligand” are introduced. The asymmetry involved in the action of a chemical ligand and a surface ligand on the same planar complexes modifies the well-established “trans effect” to the notion of the “surface-trans effect”. As ad-complexes on ferromagnetic substrates are usually exchange-coupled, the magnetochemical implications of the surface-trans effect are of particular interest. The combined action of the different ligands allows for the reproducible control of spin states in on-surface supramolecular architectures and opens up new ways toward building and operating spin systems at interfaces. Notably, sp...
Karl Wieghardt - One of the best experts on this subject based on the ideXlab platform.
-
Synthesis and Electronic Structure of Cationic, Neutral, and Anionic Bis(imino)pyridine Iron Alkyl Complexes: Evaluation of Redox Activity in Single-Component Ethylene Polymerization Catalysts
Journal of the American Chemical Society, 2010Co-Authors: Aaron M. Tondreau, Karl Wieghardt, Carsten Milsmann, Andrew D. Patrick, Helen M. Hoyt, Emil B. Lobkovsky, Paul J. ChirikAbstract:A family of cationic, neutral, and anionic bis(imino)pyridine iron alkyl complexes has been prepared, and their electronic and molecular structures have been established by a combination of X-ray diffraction, Mossbauer spectroscopy, Magnetochemistry, and open-shell density functional theory. For the cationic complexes, [(iPrPDI)Fe-R][BPh4] (iPrPDI = 2,6-(2,6-iPr2-C6H3N═CMe)2C5H3N; R = CH2SiMe3, CH2CMe3, or CH3), which are known single-component ethylene polymerization catalysts, the data establish high spin ferrous compounds (SFe = 2) with neutral, redox-innocent bis(imino)pyridine chelates. One-electron reduction to the corresponding neutral alkyls, (iPrPDI)Fe(CH2SiMe3) or (iPrPDI)Fe(CH2CMe3), is chelate-based, resulting in a bis(imino)pyridine radical anion (SPDI = 1/2) antiferromagnetically coupled to a high spin ferrous ion (SFe = 2). The neutral neopentyl derivative was reduced by an additional electron and furnished the corresponding anion, [Li(Et2O)3][(iPrPDI)Fe(CH2CMe3)N2], with concomitant coordi...
-
mono and dinuclear o thioetherphenolato copper ii complexes structural models for galactose oxidase
Inorganica Chimica Acta, 2002Co-Authors: Tobias Kruse, Thomas Weyhermuller, Karl WieghardtAbstract:Three new o -thioetherphenol ligands have been synthesized: 1,2-bis(3,5-di- tert -butyl-2-hydroxyphenylsulfanyl)ethane (H 2 bse), 1,2-bis(3,5-di- tert -butyl-2-hydroxyphenylsulfanyl)benzene (H 2 bsb), and 4,6-di- tert -butyl-2-phenylsulfanylphenol (Hpsp). Their complexes with copper(II) were prepared and investigated by UV–Vis-, EPR-spectroscopy; their electro- and Magnetochemistry have also been studied: [Cu II (psp) 2 ] ( 1 ), [Cu II 2 (bse) 2 ] ( 2 ), [Cu II 2 (bsb) 2 ] ( 3 ), [Cu II (bsb)(py) 2 ] ( 4 ). The crystal structures of the ligands H 2 bse, H 2 bsb, Hpsp and of the complexes 1 , 2 , 3 , 4 have been determined by X-ray crystallography.
-
Mono- and dinuclear (o-thioetherphenolato)-copper(II) complexes. Structural models for galactose oxidase
Inorganica Chimica Acta, 2002Co-Authors: Tobias Kruse, Thomas Weyhermuller, Karl WieghardtAbstract:Three new o-thioetherphenol ligands have been synthesized: 1,2- bis(3,5-di-tert-butyl-2-hydroxyphenylsulfanyl)ethane (H(2)bse), 1,2-bis (3,5-di-tert-butyl-2-hydroxyphenylsulfanyl)benzene (H(2)bsb), and 4,6-di-tert-butyl-2-phenylsulfanylphenol (Hpsp). Their complexes with copper(II) were prepared and investigated by UV-Vis-, EPR-spectroscopy, their electro- and Magnetochemistry have also been studied: [Cu-II(psp)(2)] (1). [Cu-2(II)(bse)(2)] (2), [Cu-2(II)(bsb)(2)] (3), [Cu- II(bsb)(py)(2)] (4). The crystal structures of the ligands H(2)bse, H(2)bsb, Hpsp and of the complexes 1, 2, 3, 4 have been determined by X-ray crystallography. (C) 2002 Elsevier Science B.V. All rights reserved
Christian Wackerlin - One of the best experts on this subject based on the ideXlab platform.
-
emergence of on surface Magnetochemistry
Journal of Physical Chemistry Letters, 2013Co-Authors: Nirmalya Ballav, Christian Wackerlin, Dorota Siewert, Peter M. Oppeneer, Thomas A. JungAbstract:The control of exchange coupling across the molecule–substrate interface is a key feature in molecular spintronics. This Perspective reviews the emerging field of on-surface Magnetochemistry, where coordination chemistry is applied to surface-supported metal porphyrins and metal phthalocyanines to control their magnetic properties. The particularities of the surface as a multiatomic ligand or “surface ligand” are introduced. The asymmetry involved in the action of a chemical ligand and a surface ligand on the same planar complexes modifies the well-established “trans effect” to the notion of the “surface-trans effect”. As ad-complexes on ferromagnetic substrates are usually exchange-coupled, the magnetochemical implications of the surface-trans effect are of particular interest. The combined action of the different ligands allows for the reproducible control of spin states in on-surface supramolecular architectures and opens up new ways toward building and operating spin systems at interfaces. Notably, sp...
-
Emergence of On-Surface Magnetochemistry
The Journal of Physical Chemistry Letters, 2013Co-Authors: Nirmalya Ballav, Christian Wackerlin, Dorota Siewert, Peter M. Oppeneer, Thomas A. JungAbstract:The control of exchange coupling across the molecule–substrate interface is a key feature in molecular spintronics. This Perspective reviews the emerging field of on-surface Magnetochemistry, where coordination chemistry is applied to surface-supported metal porphyrins and metal phthalocyanines to control their magnetic properties. The particularities of the surface as a multiatomic ligand or “surface ligand” are introduced. The asymmetry involved in the action of a chemical ligand and a surface ligand on the same planar complexes modifies the well-established “trans effect” to the notion of the “surface-trans effect”. As ad-complexes on ferromagnetic substrates are usually exchange-coupled, the magnetochemical implications of the surface-trans effect are of particular interest. The combined action of the different ligands allows for the reproducible control of spin states in on-surface supramolecular architectures and opens up new ways toward building and operating spin systems at interfaces. Notably, spin-switching has been demonstrated to be controlled collectively via the interaction with a ligand (chemical selectivity) and individually via local addressing at the interface
-
on surface Magnetochemistry
2013Co-Authors: Christian WackerlinAbstract:This thesis reports on the on-surface Magnetochemistry of square-planar transition-metal complexes adsorbed on ferromagnetic substrates. Specifically, the Magnetochemistry of the transition-metal ions (Mn / Fe / Co / Ni) coordinated in square-planar porphyrin / phthalocyanine ligands arranged on native and oxygen-reconstructed ferromagnetic Ni(001) / Co(001) thin-films is studied. The metal-centers in the surface-adsorbed complexes are five-fold coordinated: four coordination-bonds with the square-planar ligand and one bond with the “surface-ligand”. This arrangement leaves the sixth site on-top of the complex open for an additional ligand to bind with the transition-metal center and give the possibility to control the magnetic properties of the on-surface complex. Specifically, nitric oxide (NO) or ammonia (NH3) gas is used to serve as the sixth ligand. The experiments were performed in ultra-high vacuum and the samples were studied by X-ray absorption spectroscopy (XAS), X-ray magnetic circular dichroism (XMCD), X-ray photoemission spectroscopy (XPS) and scanning tunneling microscopy (STM). This work is based on the induced magnetic ordering in a monolayer of transition-metal porphyrins adsorbed on ferromagnetic substrates. The effect allows to study the Magnetochemistry at ambient / near-ambient temperature in the remanent magnetization of the substrate. The experimental results are complemented by density functional theory with additional Hubbard interactions taken into account (DFT+U) conducted by Kartick Tarafder and Peter Oppeneer from Uppsala (Sweden). Within the scope of this thesis, mechanisms for switching off, tuning and switching on the magnetic moments in the adsorbed complexes are demonstrated and explained. Furthermore, we show that apart from controlling the magnetic moment, the axial-ligand can also be used to control the exchange-interaction with the ferromagnetic substrate. Specifically, we observe that the strength and sign of the exchange-interaction can be controlled. These results clearly illustrate that the coordination-chemistry and Magnetochemistry on-surface extends the framework of classical coordination-chemistry, since the interaction with the “surface-ligand” has to be included into the considerations. Furthermore, we show that highly-ordered two-dimensional arrays of molecular spin-systems can be fabricated by chemically directed self-assembly. Specifically, we produce chessboard-like Fe - Mn - Fe spin-arrays by mere co-evaporation of the functionalized molecular building-blocks. In a second step, the magnetic properties of this spin-array can be controlled by ammonia exposure and one half of the chessboard-like spin-array can be selectively and reversibly switched. Also, the on-surface charge-transfer between the strong electron-acceptor TCNQ and alkali-halides (e.g. Na+Cl-) is discussed. The experiments show that the 2D metal-organic layers can be produced by the on-surface reaction of alkali-halides (instead of alkali-metals) and sufficiently strong electron acceptors.
Nirmalya Ballav - One of the best experts on this subject based on the ideXlab platform.
-
Emergence of On-Surface Magnetochemistry
The Journal of Physical Chemistry Letters, 2013Co-Authors: Nirmalya Ballav, Christian Wackerlin, Dorota Siewert, Peter M. Oppeneer, Thomas A. JungAbstract:The control of exchange coupling across the molecule–substrate interface is a key feature in molecular spintronics. This Perspective reviews the emerging field of on-surface Magnetochemistry, where coordination chemistry is applied to surface-supported metal porphyrins and metal phthalocyanines to control their magnetic properties. The particularities of the surface as a multiatomic ligand or “surface ligand” are introduced. The asymmetry involved in the action of a chemical ligand and a surface ligand on the same planar complexes modifies the well-established “trans effect” to the notion of the “surface-trans effect”. As ad-complexes on ferromagnetic substrates are usually exchange-coupled, the magnetochemical implications of the surface-trans effect are of particular interest. The combined action of the different ligands allows for the reproducible control of spin states in on-surface supramolecular architectures and opens up new ways toward building and operating spin systems at interfaces. Notably, spin-switching has been demonstrated to be controlled collectively via the interaction with a ligand (chemical selectivity) and individually via local addressing at the interface
-
emergence of on surface Magnetochemistry
Journal of Physical Chemistry Letters, 2013Co-Authors: Nirmalya Ballav, Christian Wackerlin, Dorota Siewert, Peter M. Oppeneer, Thomas A. JungAbstract:The control of exchange coupling across the molecule–substrate interface is a key feature in molecular spintronics. This Perspective reviews the emerging field of on-surface Magnetochemistry, where coordination chemistry is applied to surface-supported metal porphyrins and metal phthalocyanines to control their magnetic properties. The particularities of the surface as a multiatomic ligand or “surface ligand” are introduced. The asymmetry involved in the action of a chemical ligand and a surface ligand on the same planar complexes modifies the well-established “trans effect” to the notion of the “surface-trans effect”. As ad-complexes on ferromagnetic substrates are usually exchange-coupled, the magnetochemical implications of the surface-trans effect are of particular interest. The combined action of the different ligands allows for the reproducible control of spin states in on-surface supramolecular architectures and opens up new ways toward building and operating spin systems at interfaces. Notably, sp...
Leonid D. Popov - One of the best experts on this subject based on the ideXlab platform.
-
Synthesis, Structure, and Spectral Properties of 3,5-Di-tert-butyl-1,2-benzoquinone 3-Hydroxynaphthoyl Hydrazone and Its Complexes with Zn(II), Cd(II), Ni(II), and Co(II)
Russian Journal of General Chemistry, 2019Co-Authors: A S Burlov, Igor S. Vasilchenko, Valery G. Vlasenko, Nadezhda I. Makarova, S. B. Zaichenko, Leonid D. Popov, Gennadii S. Borodkin, E. V. Korshunova, K. A. Lysenko, Sergey I. LevchenkovAbstract:Novel complexes of Zn(II), Cd(II), Ni(II), and Co(II) with 3,5-di-tert-butyl-1,2-benzoquinone 3-hyd-roxynaphthoyl hydrazone have been synthesized. Composition, structure, magnetic and spectral properties of the obtained compounds have been studied by means of elemental analysis, IR, 1H NMR, and UV spectroscopy, X-ray diffraction analysis, quantum-chemical simulations, and Magnetochemistry.
-
Copper(II), nickel(II), and zinc(II) complexes with o -tozylaminobenzaldehyde 4,6-dimethylpyrimidyl hydrazone
Russian Journal of Inorganic Chemistry, 2017Co-Authors: Leonid D. Popov, A S Burlov, Yu. P. Tupolova, S. A. Borodkin, Valery V. Tkachev, Gennady V. Shilov, Elena A. Ugolkova, O. I. Askalepova, Vladimir V. Lukov, Igor N. ShcherbakovAbstract:o-Tosylaminobenzaldehyde dimethylpyrimidyl hydrazone and its copper(II), nickel(II), and zinc(II) complexesare synthesized and studied. According to the X-ray diffraction data, the zinc(II) complex has the structure of a tetragonal pyramid with the N3O donor ligand environment. According to EPR and Magnetochemistry data, the copper(II) complex has a similar structure of the chelate core. In the nickel(II) complex, the solvent molecule completes the coordination core to an octahedron.
-
Salicylic aldehyde and 2-N-tosylaminobenzaldehyde tetrazolyl hydrazones and their complexes
Russian Journal of General Chemistry, 2016Co-Authors: Sergey I. Levchenkov, A S Burlov, Leonid D. Popov, E. A. Raspopova, I. N. Scherbakov, A. N. Morozov, V. A. KoganAbstract:Tetrazolyl hydrazones of salicylic aldehyde and 2-N-tosylaminobenzaldehyde as well as zinc(II) and copper(II) complexes on their base have been prepared. Quantum-chemical simulation of tautomerism of the hydrazones in vacuum and in the solutions has been performed. IR and NMR spectroscopy and Magnetochemistry studies have revealed that the complexes are mononuclear; however, weak intermolecular exchange interaction of the antiferromagnetic type has been detected in the copper(II) complexes.
-
New copper(II), nickel(II), and cobalt(II) chelates derived from 2-methyl-3-{[3-methyl-5-oxo-1-phenylpyrazol-4- ylidene)methyl]amino}-quinazolin-4-one
Russian Journal of Inorganic Chemistry, 2016Co-Authors: Leonid D. Popov, Yu. P. Tupolova, E. V. Korshunova, Sergey I. Levchenkov, G. I. Bondarenko, S. A. Borodkin, Valery V. Tkachev, Gennady V. Shilov, Igor N. Shcherbakov, E. A. RaspopovaAbstract:Ligand system derived from pyrazolone-5 and N-aminoquinazolinone was prepared, its structure was studied. Metal chelates ML2 were prepared by reaction of the obtained ligand with copper(II), nickel(II), and cobalt(II) acetates. The complexes were studied by IR, electronic, and ESR spectroscopy, Magnetochemistry, X-ray diffraction. Copper(II) complex was shown to have pseudo-tetrahedral structure, nickel(II) and cobalt(II) complexes are octahedral.
-
Structural, EPR spectroscopic, and magnetochemical study of hydrogen-bonded dimeric copper(II) complexes with hetaryl hydrazones
Russian Journal of Inorganic Chemistry, 2015Co-Authors: Sergey I. Levchenkov, Leonid D. Popov, Nikolay N Efimov, Vadim V Minin, Igor N. Shcherbakov, Elena A. Ugolkova, G. G. Aleksandrov, Zoya A. Starikova, A. M. Ionov, V. A. KoganAbstract:The copper(II) complexes [CuL1(NO3)] · CH3OH and [CuL2Cl] · CH3OH (L1 is 3,5-di-tert-butylsalicylal 1′-phthalazinyl hydrazone, and L2 is 2-N-tosylaminobenzal 2-imidazolinyl hydrazone) forming hydrogen-bonded dimers in a crystal were synthesized. A weak antiferromagnetic exchange interaction transmitted through extensive linkers incorporating the N–H···O hydrogen bond (2J is–3.0 and–2.6 cm–1, respectively) was recognized by EPR spectroscopy and low-temperature Magnetochemistry.