0000000001299589
AUTHOR
J. Krzystek
showing 36 related works from this author
Cytosine Nucleobase Ligand: A Suitable Choice for Modulating Magnetic Anisotropy in Tetrahedrally Coordinated Mononuclear CoII Compounds
2017
A family of tetrahedral mononuclear CoII complexes with the cytosine nucleobase ligand is used as the playground for an in-depth study of the effects that the nature of the ligand, as well as their noninnocent distortions on the Co(II) environment, may have on the slow magnetic relaxation effects. Hence, those compounds with greater distortion from the ideal tetrahedral geometry showed a larger-magnitude axial magnetic anisotropy (D) together with a high rhombicity factor (E/D), and thus, slow magnetic relaxation effects also appear. In turn, the more symmetric compound possesses a much smaller value of the D parameter and, consequently, lacks single-ion magnet behavior.
Dinuclear manganese(iii) complexes with bioinspired coordination and variable linkers showing weak exchange effects: a synthetic, structural, spectro…
2019
Three dimanganese(iii) complexes have been synthesised and fully characterised by standard spectroscopic methods and spectroelectrochemistry. Each MnIII ion is chelated by a salen type ligand (H2L), but there is variation in the bridging group: LMn(OOCCH[double bond, length as m-dash]CHCOO)MnL, LMn(OOCC6H4COO)MnL, and LMn(OOCC6H4C6H4COO)MnL. X-ray diffraction revealed an axial compression of each six-coordinate high-spin d4 MnIII ion, which is a Jahn-Teller-active ion. Temperature dependent magnetic susceptibility and variable temperature-variable field (VTVH) magnetisation measurements, as well as high-frequency and -field EPR (HFEPR) spectroscopy were used to accurately describe the magne…
Coligand Effects on the Field-Induced Double Slow Magnetic Relaxation in Six-Coordinate Cobalt(II) Single-Ion Magnets (SIMs) with Positive Magnetic A…
2019
Two mononuclear cobalt(II) compounds of formula [Co(dmphen)2(OOCPh)]ClO4·1/2H2O·1/2CH3OH (1) and [Co(dmbipy)2(OOCPh)]ClO4 (2) (dmphen = 2,9-dimethyl-1,10-phenanthroline, dmbipy = 6,6'-dimethyl-2,2'-bipyridine and HOOCPh = benzoic acid) are prepared and magnetostructurally investigated. Each cobalt(II) ion is six-coordinate with a distorted octahedral CoN4O2 environment. The complex cations are interlinked leading to supramolecular chains (1) and pairs (2) that grow along the crystallographic c-axis with racemic mixtures of (Δ,Λ)-Co units. FIRMS allowed us to directly measure the zero-field splitting between the two lowest Kramers doublets, which led to axial anisotropy values of 58.3 cm-1 ≤…
Incorporation of CrIII into a Keggin Polyoxometalate as a Chemical Strategy to Stabilize a Labile {CrIIIO4} Tetrahedral Conformation and Promote Unat…
2020
Polyoxometalates (POMs) provide rigid and highly symmetric coordination sites and can be used as a strategy for the stabilization of magnetic ions. Herein, we report a new member of the Keggin archetype, the Cr-centered Keggin anion [α-CrW12O40]5– (CrW12), with the unusual tetrahedral coordination of CrIII reported for the first time in POMs conferring unattended magnetic properties. POM chemistry has recently presented excellent examples of single-molecule and single-ion magnets (SMMs and SIMs) as well as molecular spin qubits; however, the majority of POM-based SIMs reported to date contain lanthanoid ions. CrW12, as the first example of a chromium(III) SIM, exhibits slow relaxation of ma…
A five-coordinate manganese(iii) complex of a salen type ligand with a positive axial anisotropy parameter D.
2017
A new high-spin d4 roughly trigonal–bipyramidal (TBP) manganese(III) complex with a salen type ligand (H2L), namely MnL(NCS)·0.4H2O, has been synthesised and characterised by elemental analysis, ESI mass spectrometry, IR and UV-vis spectroscopy, and spectroelectrochemistry. X-ray diffraction analysis revealed an axial compression of the approximate TBP. Temperature dependent magnetic susceptibility and variable-temperature variable-field (VTVH) magnetisation measurements, as well as high-frequency and -field EPR (HFEPR) spectroscopy, were used to accurately describe the magnetic properties of this complex and, in particular, determine the spin Hamiltonian parameters: g-values and the zero-f…
Reversible solvatomagnetic switching in a single-ion magnet from an entatic state
2016
We have developed a new strategy for the design and synthesis of multifunctional molecular materials showing reversible magnetic and optical switching.
Field-Induced Hysteresis and Quantum Tunneling of the Magnetization in a Mononuclear Manganese(III) Complex
2013
International audience
Highly Anisotropic Rhenium(IV) Complexes: New Examples of Mononuclear Single-Molecule Magnets
2013
The rhenium(IV) complex (NBu4)2[ReBr4(ox)] (1) (ox = oxalate and NBu4(+) = tetra-n-butylammonium cation) has been prepared and its crystal structure determined by X-ray diffraction. The structure is made up of discrete [ReBr4(ox)](2-) anions and bulky NBu4(+) cations. Each [ReBr4(ox)](2-) anion is surrounded by six NBu4(+) cations, which preclude any significant intermolecular contact between the anionic entities, the shortest rhenium···rhenium distance being 9.373(1) Å. Variable temperature dc and ac magnetic susceptibility measurements and field-dependent magnetization experiments on polycrystalline samples of 1 reveal the occurrence of highly anisotropic magnetically isolated Re(IV) cent…
A unique single carboxylate-bridged spin-frustrated chiral Mn(II) metallatriangle.
2010
The reaction between Hmbpymca ligand (prepared in situ from the hydrolysis of 5-methyl-4-cyano-bispyrimidine with NaOH and further neutralization with 2 M HCl) and Mn(ClO(4))(2)·4H(2)O in 1:1 molar ratio afforded the triangulo-trimanganese(II) complex [Mn(3)(bpymca)(3)(H(2)O)(6)]Cl(3)·6H(2)O 1. The chloride anions in this complex come from the HCl used in the neutralization process. The molecular structure of 1 consists of cationic molecular triangles [Mn(3)(μ-mbpymca)(3)(H(2)O)(6)](3+) with C(3) symmetry, chloride anions and crystallization water molecules, all of them involved in an extensive network of hydrogen bonds, leading to a chiral network. Within the [Mn(3)(μ-mbpymca)(3)(H(2)O)(6)…
Field-Induced Slow Magnetic Relaxation in a Mononuclear Manganese(III)-Porphyrin Complex
2015
We report on a novel manganese(III)-porphyrin complex with the formula [Mn(III) (TPP)(3,5-Me2 pyNO)2 ]ClO4 ⋅CH3 CN (2; 3,5-Me2 pyNO=3,5-dimethylpyridine N-oxide, H2 TPP=5,10,15,20-tetraphenylporphyrin), in which the Mn(III) ion is six-coordinate with two monodentate 3,5-Me2 pyNO molecules and a tetradentate TPP ligand to build a tetragonally elongated octahedral geometry. The environment in 2 is responsible for the large and negative axial zero-field splitting (D=-3.8 cm(-1) ), low rhombicity (E/|D|=0.04) of the high-spin Mn(III) ion, and, ultimately, for the observation of slow magnetic-relaxation effects (Ea =15.5 cm(-1) at H=1000 G) in this rare example of a manganese-based single-ion ma…
Guest-dependent single-ion magnet behaviour in a cobalt(ii) metal-organic framework.
2015
Single-ion magnets (SIMs) are the smallest possible magnetic devices for potential applications in quantum computing and high-density information storage. Both, their addressing in surfaces and their organization in metal-organic frameworks (MOFs) are thus current challenges in molecular chemistry. Here we report a two-dimensional 2D MOF with a square grid topology built from cobalt(ii) SIMs as nodes and long rod-like aromatic bipyridine ligands as linkers, and exhibiting large square channels capable to host a large number of different guest molecules. The organization of the cobalt(ii) nodes in the square layers improves the magnetic properties by minimizing the intermolecular interaction…
.Single-Ion Magnetic Behaviour in an Iron(III) Porphyrin Complex: A Dichotomy Between High Spin and 5/2-3/2 Spin Admixture
2020
International audience; A mononuclear iron(III) porphyrin compound exhibiting unexpectedly slow magnetic relaxation, which is a characteristic of single-ion magnet behaviour, is reported. This behaviour originates from the close proximity (approximate to 550 cm(-1)) of the intermediate-spinS=3/2 excited states to the high-spinS=5/2 ground state. More quantitatively, although the ground state is mostlyS=5/2, a spin-admixture model evidences a sizable contribution (approximate to 15 %) ofS=3/2 to the ground state, which as a consequence experiences large and positive axial anisotropy (D=+19.2 cm(-1)). Frequency-domain EPR spectroscopy allowed them(S)= |+/- 1/2⟩->|+/- 3/2&Rig…
Slow Magnetic Relaxation in a Co (II)–Y (III) Single‐Ion Magnet with Positive Axial Zero‐Field Splitting
2013
This work was supported by the MINECO (Spain) (Project CTQ2011-24478), the Junta de Andalucía (FQM-195 and Project of excellence P08-FQM-03705), and the University of Granada. E.R. and E.Cr. thank MINECO grant No. CTQ2011-23862-C02-01 and Generalitat de Catalunya grant No. 2009SGR-1459, for financial support. We would like to thank Prof. Liviu Chibotaru for providing us the SINGLE_ANISO program and Dr. Andrew Ozarowski for the EPR simulation software. E.K.B. thanks the EPSRC and Leverhulme Trust for financial support. The NHMFL is funded by the NSF, DoE, and the state of Florida. J.C. acknowledges financial support by the Spanish Ministerio de Ciencia e Innovación through projects CTQ2010-1…
CCDC 1914220: Experimental Crystal Structure Determination
2019
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CCDC 1415919: Experimental Crystal Structure Determination
2016
Related Article: Julia Vallejo, Francisco R. Fortea-Pérez, Emilio Pardo, Samia Benmansour, Isabel Castro, J. Krzystek, Donatella Armentano, Joan Cano|2016|Chemical Science|7|2286|doi:10.1039/C5SC04461H
CSD 1913668: Experimental Crystal Structure Determination
2020
Related Article: Nadiia I. Gumerova, Alexander Roller, Gerald Giester, J. Krzystek, Joan Cano, Annette Rompel|2020|J.Am.Chem.Soc.|142|3336|doi:10.1021/jacs.9b12797
CCDC 1415917: Experimental Crystal Structure Determination
2016
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CCDC 934656: Experimental Crystal Structure Determination
2013
Related Article: E.Colacio,J.Ruiz,E.Ruiz,E.Cremades,J.Krzystek,S.Carretta,J.Cano,T.Guidi,W.Wernsdorfer,E.K.Brechin|2013|Angew.Chem.,Int.Ed.|52|9130|doi:10.1002/anie.201304386
CCDC 1474778: Experimental Crystal Structure Determination
2017
Related Article: Rosaria Bruno, Julia Vallejo, Nadia Marino, Giovanni De Munno, J. Krzystek, Joan Cano, Emilio Pardo, and Donatella Armentano|2017|Inorg.Chem.|56|1857|doi:10.1021/acs.inorgchem.6b02448
CCDC 952077: Experimental Crystal Structure Determination
2017
Related Article: J. Vallejo, E. Pardo, M. Viciano-Chumillas, I. Castro, P. Amorós, M. Déniz, C. Ruiz-Pérez, C. Yuste-Vivas, J. Krzystek, M. Julve, F. Lloret, J. Cano|2017|Chemical Science|8|3694|doi:10.1039/C6SC05188J
CCDC 938463: Experimental Crystal Structure Determination
2017
Related Article: J. Vallejo, E. Pardo, M. Viciano-Chumillas, I. Castro, P. Amorós, M. Déniz, C. Ruiz-Pérez, C. Yuste-Vivas, J. Krzystek, M. Julve, F. Lloret, J. Cano|2017|Chemical Science|8|3694|doi:10.1039/C6SC05188J
CCDC 1415920: Experimental Crystal Structure Determination
2016
Related Article: Julia Vallejo, Francisco R. Fortea-Pérez, Emilio Pardo, Samia Benmansour, Isabel Castro, J. Krzystek, Donatella Armentano, Joan Cano|2016|Chemical Science|7|2286|doi:10.1039/C5SC04461H
CCDC 1063253: Experimental Crystal Structure Determination
2016
Related Article: Alejandro Pascual-Álvarez, Julia Vallejo, Emilio Pardo, Miguel Julve, Francesc Lloret, J. Krzystek, Donatella Armentano, Wolfgang Wernsdorfer, Joan Cano|2015|Chem.-Eur.J.|21|17299|doi:10.1002/chem.201502637
CCDC 953476: Experimental Crystal Structure Determination
2013
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CCDC 1415918: Experimental Crystal Structure Determination
2016
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CCDC 1875357: Experimental Crystal Structure Determination
2019
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CCDC 1515780: Experimental Crystal Structure Determination
2017
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CCDC 1415921: Experimental Crystal Structure Determination
2016
Related Article: Julia Vallejo, Francisco R. Fortea-Pérez, Emilio Pardo, Samia Benmansour, Isabel Castro, J. Krzystek, Donatella Armentano, Joan Cano|2016|Chemical Science|7|2286|doi:10.1039/C5SC04461H
CCDC 1474777: Experimental Crystal Structure Determination
2017
Related Article: Rosaria Bruno, Julia Vallejo, Nadia Marino, Giovanni De Munno, J. Krzystek, Joan Cano, Emilio Pardo, and Donatella Armentano|2017|Inorg.Chem.|56|1857|doi:10.1021/acs.inorgchem.6b02448
CCDC 1415915: Experimental Crystal Structure Determination
2016
Related Article: Julia Vallejo, Francisco R. Fortea-Pérez, Emilio Pardo, Samia Benmansour, Isabel Castro, J. Krzystek, Donatella Armentano, Joan Cano|2016|Chemical Science|7|2286|doi:10.1039/C5SC04461H
CCDC 1914219: Experimental Crystal Structure Determination
2019
Related Article: Julia Vallejo, Marta Viciano-Chumillas, Francisco Lloret, Miguel Julve, Isabel Castro, J. Krzystek, Mykhaylo Ozerov, Donatella Armentano, Giovanni De Munno, Joan Cano|2019|Inorg.Chem.|58|15726|doi:10.1021/acs.inorgchem.9b01719
CCDC 1875359: Experimental Crystal Structure Determination
2019
Related Article: Sergiu Shova, Angelica Vlad, Maria Cazacu, J. Krzystek, Andrew Ozarowski, Michal Malček, Lukas Bucinsky, Peter Rapta, Joan Cano, Joshua Telser, Vladimir B. Arion|2019|Dalton Trans.|48|5909|doi:10.1039/C8DT04596H
CCDC 1875358: Experimental Crystal Structure Determination
2019
Related Article: Sergiu Shova, Angelica Vlad, Maria Cazacu, J. Krzystek, Andrew Ozarowski, Michal Malček, Lukas Bucinsky, Peter Rapta, Joan Cano, Joshua Telser, Vladimir B. Arion|2019|Dalton Trans.|48|5909|doi:10.1039/C8DT04596H
CCDC 1415916: Experimental Crystal Structure Determination
2016
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CCDC 779232: Experimental Crystal Structure Determination
2011
Related Article: J.E.Perea-Buceta, A.J.Mota, J.-P.Costes, R.Sillanpaa, J.Krzystek, E.Colacio|2010|Dalton Trans.|39|10286|doi:10.1039/c0dt00613k
CCDC 854108: Experimental Crystal Structure Determination
2014
Related Article: José Martínez-Lillo , Teresa F. Mastropietro , Elsa Lhotel , Carley Paulsen , Joan Cano , Giovanni De Munno , Juan Faus , Francesc Lloret , Miguel Julve , Saritha Nellutla , and J. Krzystek|2013|J.Am.Chem.Soc.|135|13737|doi:10.1021/ja403154z