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Sutter JP, Béreau V, Jubault V, Bretosh K, Pichon C, Duhayon C. Magnetic anisotropy of transition metal and lanthanide ions in pentagonal bipyramidal geometry. Chem Soc Rev 2022; 51:3280-3313. [PMID: 35353106 DOI: 10.1039/d2cs00028h] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The magnetic anisotropy associated with a pentagonal bipyramidal (PBP) coordination sphere is examined on the basis of experimental and theoretical investigations. The origin and the characteristics of this anisotropy are discussed in relation to the electronic configuration of the metal ions. The effects of crystal field, structural distortion, and a second-coordination sphere on the observed anisotropies for transition meal and lanthanide ions are outlined. For the Ln derivatives, we focus on compounds showing SMM-like behavior (i.e. slow relaxation of their magnetization) in order to highlight the essential chemical and structural parameters for achieving strong axial anisotropy. The use of PBP complexes to impart controlled magnetic anisotropy in polynuclear species such as SMMs or SCMs is also addressed. This review of the magnetic anisotropies associated with a pentagonal bipyramidal coordination sphere for transition metal and lanthanide ions is intended to highlight some general trends that can guide chemists towards designing a compound with specific properties.
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Affiliation(s)
- Jean-Pascal Sutter
- Laboratoire de Chimie de Coordination du CNRS (LCC-CNRS), Université de Toulouse, CNRS, Toulouse, France.
| | - Virginie Béreau
- Laboratoire de Chimie de Coordination du CNRS (LCC-CNRS), Université de Toulouse, CNRS, Toulouse, France. .,Université de Toulouse, Institut Universitaire de Technologie Paul Sabatier-Département de Chimie, Av. Georges Pompidou, F-81104 Castres, France
| | - Valentin Jubault
- Laboratoire de Chimie de Coordination du CNRS (LCC-CNRS), Université de Toulouse, CNRS, Toulouse, France.
| | - Kateryna Bretosh
- Laboratoire de Chimie de Coordination du CNRS (LCC-CNRS), Université de Toulouse, CNRS, Toulouse, France.
| | - Céline Pichon
- Laboratoire de Chimie de Coordination du CNRS (LCC-CNRS), Université de Toulouse, CNRS, Toulouse, France.
| | - Carine Duhayon
- Laboratoire de Chimie de Coordination du CNRS (LCC-CNRS), Université de Toulouse, CNRS, Toulouse, France.
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2
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Zahradníková E, Císařová I, Drahoš B. Syntheses and crystal structures of Ni(II) complexes with pyridine-based macrocyclic ligands. Polyhedron 2022. [DOI: 10.1016/j.poly.2021.115552] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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3
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Zahradníková E, Císařová I, Drahoš B. Triple M as Manganese: Medicine, magnetism and macrocycles. Seven-coordinate Mn(II) complexes with pyridine-based macrocyclic ligands. Polyhedron 2021. [DOI: 10.1016/j.poly.2021.115231] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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4
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Anbu S, Hoffmann SHL, Carniato F, Kenning L, Price TW, Prior TJ, Botta M, Martins AF, Stasiuk GJ. A Single-Pot Template Reaction Towards a Manganese-Based T 1 Contrast Agent. Angew Chem Int Ed Engl 2021; 60:10736-10744. [PMID: 33624910 PMCID: PMC8252504 DOI: 10.1002/anie.202100885] [Citation(s) in RCA: 32] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2021] [Indexed: 12/23/2022]
Abstract
Manganese-based contrast agents (MnCAs) have emerged as suitable alternatives to gadolinium-based contrast agents (GdCAs). However, due to their kinetic lability and laborious synthetic procedures, only a few MnCAs have found clinical MRI application. In this work, we have employed a highly innovative single-pot template synthetic strategy to develop a MnCA, MnLMe , and studied the most important physicochemical properties in vitro. MnLMe displays optimized r1 relaxivities at both medium (20 and 64 MHz) and high magnetic fields (300 and 400 MHz) and an enhanced r1b =21.1 mM-1 s-1 (20 MHz, 298 K, pH 7.4) upon binding to BSA (Ka =4.2×103 M-1 ). In vivo studies show that MnLMe is cleared intact into the bladder through renal excretion and has a prolonged blood half-life compared to the commercial GdCA Magnevist. MnLMe shows great promise as a novel MRI contrast agent.
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Affiliation(s)
- Sellamuthu Anbu
- Department of Biomedical SciencesUniversity of HullCottingham RoadHullHU6 7RXUK
- Department of ChemistryUniversity of HullCottingham RoadHullHU6 7RXUK
| | - Sabrina H. L. Hoffmann
- Werner Siemens Imaging CenterDepartment of Preclinical Imaging and RadiopharmacyEberhard Karls University Tübingen, Röntgenweg 13/172076TübingenGermany
| | - Fabio Carniato
- Dipartimento di Scienze e InnovazioneTecnologicaUniversità del Piemonte Orientale “A. Avogadro”Viale Teresa Michel 1115121AlessandriaItaly
| | - Lawrence Kenning
- MRI centreHull Royal Infirmary Hospital NHS TrustAnlaby RoadHullHU3 2JZUK
| | - Thomas W. Price
- Department of Imaging Chemistry and BiologySchool of Biomedical Engineering and Imaging SciencesKing's College LondonFourth Floor Lambeth WingSt Thomas' HospitalLondonSE1 7EHUK
| | - Timothy J. Prior
- Department of ChemistryUniversity of HullCottingham RoadHullHU6 7RXUK
| | - Mauro Botta
- Dipartimento di Scienze e InnovazioneTecnologicaUniversità del Piemonte Orientale “A. Avogadro”Viale Teresa Michel 1115121AlessandriaItaly
| | - Andre F. Martins
- Werner Siemens Imaging CenterDepartment of Preclinical Imaging and RadiopharmacyEberhard Karls University Tübingen, Röntgenweg 13/172076TübingenGermany
- Cluster of Excellence iFIT (EXC 2180) “Image-Guided and Functionally Instructed Tumor Therapies”University of TuebingenGermany
| | - Graeme J. Stasiuk
- Department of Imaging Chemistry and BiologySchool of Biomedical Engineering and Imaging SciencesKing's College LondonFourth Floor Lambeth WingSt Thomas' HospitalLondonSE1 7EHUK
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5
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Anbu S, Hoffmann SHL, Carniato F, Kenning L, Price TW, Prior TJ, Botta M, Martins AF, Stasiuk GJ. A Single-Pot Template Reaction Towards a Manganese-Based T1 Contrast Agent. ANGEWANDTE CHEMIE (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2021; 133:10831-10839. [PMID: 38505690 PMCID: PMC10947048 DOI: 10.1002/ange.202100885] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/19/2021] [Indexed: 12/20/2022]
Abstract
Manganese-based contrast agents (MnCAs) have emerged as suitable alternatives to gadolinium-based contrast agents (GdCAs). However, due to their kinetic lability and laborious synthetic procedures, only a few MnCAs have found clinical MRI application. In this work, we have employed a highly innovative single-pot template synthetic strategy to develop a MnCA, MnLMe, and studied the most important physicochemical properties in vitro. MnLMe displays optimized r 1 relaxivities at both medium (20 and 64 MHz) and high magnetic fields (300 and 400 MHz) and an enhanced r 1 b=21.1 mM-1 s-1 (20 MHz, 298 K, pH 7.4) upon binding to BSA (K a=4.2×103 M-1). In vivo studies show that MnLMe is cleared intact into the bladder through renal excretion and has a prolonged blood half-life compared to the commercial GdCA Magnevist. MnLMe shows great promise as a novel MRI contrast agent.
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Affiliation(s)
- Sellamuthu Anbu
- Department of Biomedical SciencesUniversity of HullCottingham RoadHullHU6 7RXUK
- Department of ChemistryUniversity of HullCottingham RoadHullHU6 7RXUK
| | - Sabrina H. L. Hoffmann
- Werner Siemens Imaging CenterDepartment of Preclinical Imaging and RadiopharmacyEberhard Karls University Tübingen, Röntgenweg 13/172076TübingenGermany
| | - Fabio Carniato
- Dipartimento di Scienze e InnovazioneTecnologicaUniversità del Piemonte Orientale “A. Avogadro”Viale Teresa Michel 1115121AlessandriaItaly
| | - Lawrence Kenning
- MRI centreHull Royal Infirmary Hospital NHS TrustAnlaby RoadHullHU3 2JZUK
| | - Thomas W. Price
- Department of Imaging Chemistry and BiologySchool of Biomedical Engineering and Imaging SciencesKing's College LondonFourth Floor Lambeth WingSt Thomas' HospitalLondonSE1 7EHUK
| | - Timothy J. Prior
- Department of ChemistryUniversity of HullCottingham RoadHullHU6 7RXUK
| | - Mauro Botta
- Dipartimento di Scienze e InnovazioneTecnologicaUniversità del Piemonte Orientale “A. Avogadro”Viale Teresa Michel 1115121AlessandriaItaly
| | - Andre F. Martins
- Werner Siemens Imaging CenterDepartment of Preclinical Imaging and RadiopharmacyEberhard Karls University Tübingen, Röntgenweg 13/172076TübingenGermany
- Cluster of Excellence iFIT (EXC 2180) “Image-Guided and Functionally Instructed Tumor Therapies”University of TuebingenGermany
| | - Graeme J. Stasiuk
- Department of Imaging Chemistry and BiologySchool of Biomedical Engineering and Imaging SciencesKing's College LondonFourth Floor Lambeth WingSt Thomas' HospitalLondonSE1 7EHUK
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6
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Chirayil S, Jordan VC, Martins AF, Paranawithana N, Ratnakar SJ, Sherry AD. Manganese(II)-Based Responsive Contrast Agent Detects Glucose-Stimulated Zinc Secretion from the Mouse Pancreas and Prostate by MRI. Inorg Chem 2021; 60:2168-2177. [PMID: 33507742 PMCID: PMC8112388 DOI: 10.1021/acs.inorgchem.0c02688] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
A Mn(II)-based zinc-sensitive MRI contrast agent, MnPyC3A-BPEN, was prepared, characterized, and applied in imaging experiments to detect glucose-stimulated zinc secretion (GSZS) from the mouse pancreas and prostate in vivo. Thermodynamic and kinetic stability tests showed that MnPyC3A-BPEN has superior kinetic inertness compared to GdDTPA, is less susceptible to transmetalation in the presence of excess Zn2+ ions, and less susceptible to transchelation by albumin. In comparison with other gadolinium-based zinc sensors bearing a single zinc binding moiety, MnPyC3A-BPEN appears to be a reliable alternative for imaging β-cell function in the pancreas and glucose-stimulated zinc secretion from the prostate.
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Affiliation(s)
- Sara Chirayil
- Advanced Imaging Research Center, University of Texas Southwestern Medical Center, Dallas, Texas 75390, United States
| | - Veronica Clavijo Jordan
- Advanced Imaging Research Center, University of Texas Southwestern Medical Center, Dallas, Texas 75390, United States
- Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Harvard Medical School, Charlestown, Massachusetts 02129, United States
| | - André F Martins
- Advanced Imaging Research Center, University of Texas Southwestern Medical Center, Dallas, Texas 75390, United States
- Werner Siemens Imaging Center, Eberhard Karls University Tübingen, Tübingen 72076, Germany
- Cluster of Excellence iFIT (EXC 2180) "Image-Guided and Functionally Instructed Tumor Therapies", University of Tübingen, Tübingen 72076, Germany
- Department of Chemistry, University of Texas at Dallas, Richardson, Texas 75080, United States
| | - Namini Paranawithana
- Department of Chemistry, University of Texas at Dallas, Richardson, Texas 75080, United States
| | - S James Ratnakar
- Advanced Imaging Research Center, University of Texas Southwestern Medical Center, Dallas, Texas 75390, United States
| | - A Dean Sherry
- Advanced Imaging Research Center, University of Texas Southwestern Medical Center, Dallas, Texas 75390, United States
- Department of Chemistry, University of Texas at Dallas, Richardson, Texas 75080, United States
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7
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Chu JF. The crystal structure of bis(isothiocyanato-κ 1
N)-(methanol-κ 1
O)-[2-morpholine-4-yl-4,6-di(pyrazol-1-yl)-1,3,5-triazine-κ 3
N, N′, N′′] manganese(II), C 16H 18MnN 10O 2S 2. Z KRIST-NEW CRYST ST 2020. [DOI: 10.1515/ncrs-2020-0161] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Abstract
C16H18MnN10O2S2, triclinic, P1̄ (no. 2), a = 7.8738(7) Å, b = 12.012(2) Å, c = 12.182(2) Å, α = 85.635(16)°, β = 81.077(14)°, γ = 74.540(14)°, V = 1096.3(3) Å3, Z = 2, R
gt(F) = 0.0353, wR
ref(F
2) = 0.0896, T = 96.5 K.
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Affiliation(s)
- Jin-Feng Chu
- State Key Laboratory of Chemical Resource Engineering, Beijing University of Chemical Technology , Beijing 100029, P.R. China
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8
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Zahradníková E, Herchel R, Šalitroš I, Císařová I, Drahoš B. Late first-row transition metal complexes of a 17-membered piperazine-based macrocyclic ligand: structures and magnetism. Dalton Trans 2020; 49:9057-9069. [PMID: 32568334 DOI: 10.1039/d0dt01392g] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
A 17-membered piperazine-based macrocyclic ligand LdiProp (1,5,13,17,22-pentaazatricyclo[15.2.2.17,11]docosa-7,9,11(22)-triene) was resynthesized in high yield by using a linear pump. Its Mn(ii), Fe(ii), Co(ii) and Ni(ii) complexes of the general formula [MnLdiProp(ClO4)2] (1), [FeLdiProp(CH3CN)](ClO4)2 (2), [CoLdiProp(CH3CN)](ClO4)2 (3), [NiLdiProp](ClO4)2 (4) were prepared and thoroughly characterized. X-ray diffraction analysis confirmed that Mn(ii) complex 1 has capped trigonal prismatic geometry with a coordination number of seven, Fe(ii) and Co(ii) complexes 2 and 3 are trigonal prismatic with a coordination number of six and Ni(ii) complex 4 has square pyramidal geometry with a coordination number of five. The decrease of the coordination number is accompanied by a shortening of M-N distances and an increase of torsion of the piperazine ring from the equatorial plane. Magnetic measurement reveals moderate anisotropy for 4 and rather large magnetic anisotropy for 2 and 3 (axial zero-field splitting parameter D(Ni) = 9.0 cm-1, D(Fe) = -14.4 cm-1, D(Co) = -25.8 cm-1, together with rather high rhombicity). Co(ii) complex 3 behaves as a field-induced SMM with a combination of Raman and direct or Orbach and direct relaxation mechanisms. Obtained magnetic data were extensively supported by theoretical CASSCF calculations. The flexibility and rather large 17-membered macrocyclic cavity of ligand LdiProp could be responsible for the variation of coordination numbers and geometries for the investigated late-first row transition metals.
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Affiliation(s)
- Eva Zahradníková
- Department of Inorganic Chemistry, Faculty of Science, Palacký University, 17. listopadu 12, CZ-771 46 Olomouc, Czech Republic.
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9
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Drahoš B, Císařová I, Laguta O, Santana VT, Neugebauer P, Herchel R. Structural, magnetic, redox and theoretical characterization of seven-coordinate first-row transition metal complexes with a macrocyclic ligand containing two benzimidazolyl N-pendant arms. Dalton Trans 2020; 49:4425-4440. [PMID: 32176762 DOI: 10.1039/d0dt00166j] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A structurally new heptadentate derivative of a 15-membered pyridine-based macrocycle containing two benzimidazol-2-yl-methyl N-pendant arms (L = 3,12-bis((1H-benzimidazol-2-yl)methyl)-6,9-dioxa-3,12,18-triazabicyclo[12.3.1]octadeca-1(18),14,16-triene) was synthesized and its complexes with the general formula [M(L)](ClO4)2·1.5CH3NO2 (M = MnII (1), FeII (2), CoII (3) and NiII (4)) were thoroughly investigated. X-ray crystal structures confirmed that all complexes are seven-coordinate with axially compressed pentagonal bipyramidal geometry having the largest distortion for NiII complex 4. FeII, CoII and NiII complexes 2, 3 and 4 show rather large magnetic anisotropy manifested by moderate to high obtained values of the axial zero-field splitting parameter D (7.9, 40.3, and -17.2 cm-1, respectively). Magneto-structural correlation of the FeII, CoII and NiII complexes with L and with previously studied structurally similar ligands revealed a significant impact of the functional group in pendant arms on the magnetic anisotropy especially that of the CoII and NiII complexes and some recommendations concerning the ligand-field design important for anisotropy tuning in future. Furthermore, complex 3 showed field-induced single-molecule magnet behavior described with the Raman (C = 507 K-n s-1 for n = 2.58) relaxation process. The magnetic properties of the studied complexes were supported by theoretical calculations, which very well correspond with the experimental data of magnetic anisotropy. Electrochemical measurements revealed high positive redox potentials for M3+/2+ couples and high negative redox potentials for M2+/+ couples, which indicate the stabilization of the oxidation state +ii expected for the σ-donor/π-acceptor ability of benzimidazole functional groups.
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Affiliation(s)
- Bohuslav Drahoš
- Department of Inorganic Chemistry, Faculty of Science, Palacký University, 17. listopadu 12, 771 46, Olomouc, Czech Republic.
| | - Ivana Císařová
- Department of Inorganic Chemistry, Faculty of Science, Charles University, Hlavova 2030, 128 00, Prague, Czech Republic
| | - Oleksii Laguta
- Central European Institute of Technology, CEITEC BUT, Purkyňova 656/123, 61200, Brno, Czech Republic
| | - Vinicius T Santana
- Central European Institute of Technology, CEITEC BUT, Purkyňova 656/123, 61200, Brno, Czech Republic
| | - Petr Neugebauer
- Central European Institute of Technology, CEITEC BUT, Purkyňova 656/123, 61200, Brno, Czech Republic
| | - Radovan Herchel
- Department of Inorganic Chemistry, Faculty of Science, Palacký University, 17. listopadu 12, 771 46, Olomouc, Czech Republic.
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10
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Recent developments in penta-, hexa- and heptadentate Schiff base ligands and their metal complexes. Coord Chem Rev 2019. [DOI: 10.1016/j.ccr.2019.03.010] [Citation(s) in RCA: 189] [Impact Index Per Article: 37.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
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11
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Ternary pentagonal-bipyramidal oxovanadium(V) complexes containing five- and six-membered chelate rings: Syntheses, structures and properties. Inorganica Chim Acta 2018. [DOI: 10.1016/j.ica.2018.08.036] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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12
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Antal P, Drahoš B, Herchel R, Trávníček Z. Structure and Magnetism of Seven‐Coordinate Fe
III
, Fe
II
, Co
II
and Ni
II
Complexes Containing a Heptadentate 15‐Membered Pyridine‐Based Macrocyclic Ligand. Eur J Inorg Chem 2018. [DOI: 10.1002/ejic.201800769] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Affiliation(s)
- Peter Antal
- Division of Biologically Active Complexes and Molecular Magnets Regional Centre of Advanced Technologies and Materials Faculty of Science Palacký University Šlechtitelů 27 78371 Olomouc, Czech Republic
| | - Bohuslav Drahoš
- Division of Biologically Active Complexes and Molecular Magnets Regional Centre of Advanced Technologies and Materials Faculty of Science Palacký University Šlechtitelů 27 78371 Olomouc, Czech Republic
| | - Radovan Herchel
- Division of Biologically Active Complexes and Molecular Magnets Regional Centre of Advanced Technologies and Materials Faculty of Science Palacký University Šlechtitelů 27 78371 Olomouc, Czech Republic
| | - Zdeněk Trávníček
- Division of Biologically Active Complexes and Molecular Magnets Regional Centre of Advanced Technologies and Materials Faculty of Science Palacký University Šlechtitelů 27 78371 Olomouc, Czech Republic
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13
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Drahoš B, Herchel R, Trávníček Z. Single-Chain Magnet Based on 1D Polymeric Azido-Bridged Seven-Coordinate Fe(II) Complex with a Pyridine-Based Macrocyclic Ligand. Inorg Chem 2018; 57:12718-12726. [DOI: 10.1021/acs.inorgchem.8b01798] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Bohuslav Drahoš
- Division of Biologically Active Complexes and Molecular Magnets, Regional Centre of Advanced Technologies and Materials, Faculty of Science, Palacký University, Šlechtitelů 27, CZ-783 71 Olomouc, Czech Republic
| | - Radovan Herchel
- Division of Biologically Active Complexes and Molecular Magnets, Regional Centre of Advanced Technologies and Materials, Faculty of Science, Palacký University, Šlechtitelů 27, CZ-783 71 Olomouc, Czech Republic
| | - Zdeněk Trávníček
- Division of Biologically Active Complexes and Molecular Magnets, Regional Centre of Advanced Technologies and Materials, Faculty of Science, Palacký University, Šlechtitelů 27, CZ-783 71 Olomouc, Czech Republic
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14
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Haque A, Ilmi R, Al-Busaidi IJ, Khan MS. Coordination chemistry and application of mono- and oligopyridine-based macrocycles. Coord Chem Rev 2017. [DOI: 10.1016/j.ccr.2017.07.008] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
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15
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Drahoš B, Herchel R, Trávníček Z. Impact of Halogenido Coligands on Magnetic Anisotropy in Seven-Coordinate Co(II) Complexes. Inorg Chem 2017; 56:5076-5088. [PMID: 28406642 DOI: 10.1021/acs.inorgchem.7b00235] [Citation(s) in RCA: 51] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The structural and magnetic features of a series of mononuclear seven-coordinate CoII complexes with the general formula [Co(L)X2], where L is a 15-membered pyridine-based macrocyclic ligand (3,12,18-triaza-6,9-dioxabicyclo[12.3.1]octadeca-1(18),14,16-triene) and X = Cl- (1), Br- (2), or I- (3), were investigated experimentally and theoretically in order to reveal how the corresponding halogenido coligands in the apical positions of a distorted pentagonal-bipyramidal coordination polyhedron may affect the magnetic properties of the prepared compounds. The thorough analyses of the magnetic data revealed a large easy-plane type of the magnetic anisotropy (D > 0) for all three compounds, with the D-values increasing in the order 35 cm-1 for 3 (I-), 38 cm-1 for 1 (Cl-), and 41 cm-1 for 2 (Br-). Various theoretical methods like the Angular Overlap Model, density functional theory, CASSCF/CASPT2, CASSCF/NEVPT2 were utilized in order to understand the observed trend in magnetic anisotropy. The D-values correlated well with the Mayer bond order (decreasing in order Co-I > Co-Cl > Co-Br), which could be a consequence of two competing factors: (a) the ligand field splitting and (b) the covalence of the Co-X bond. All the complexes also behave as field-induced single-molecule magnets with the spin reversal barrier Ueff increasing in order 1 (Cl-) < 2 (Br-) < 3 (I-); however, taking into account the easy-plane type of the magnetic anisotropy, the Raman relaxation process is most likely responsible for slow relaxation of the magnetization. The results of the work revealed that the previously suggested and fully accepted strategy employing heavier halogenido ligands in order to increase the magnetic anisotropy has some limitations in the case of pentagonal-bipyramidal CoII complexes.
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Affiliation(s)
- Bohuslav Drahoš
- Department of Inorganic Chemistry, Regional Centre of Advanced Technologies and Materials, Faculty of Science, Palacký University , 17. listopadu 12, CZ-771 46 Olomouc, Czech Republic
| | - Radovan Herchel
- Department of Inorganic Chemistry, Regional Centre of Advanced Technologies and Materials, Faculty of Science, Palacký University , 17. listopadu 12, CZ-771 46 Olomouc, Czech Republic
| | - Zdeněk Trávníček
- Department of Inorganic Chemistry, Regional Centre of Advanced Technologies and Materials, Faculty of Science, Palacký University , 17. listopadu 12, CZ-771 46 Olomouc, Czech Republic
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16
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Antal P, Drahoš B, Herchel R, Trávníček Z. Late First-Row Transition-Metal Complexes Containing a 2-Pyridylmethyl Pendant-Armed 15-Membered Macrocyclic Ligand. Field-Induced Slow Magnetic Relaxation in a Seven-Coordinate Cobalt(II) Compound. Inorg Chem 2016; 55:5957-72. [DOI: 10.1021/acs.inorgchem.6b00415] [Citation(s) in RCA: 52] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Peter Antal
- Department of Inorganic Chemistry, Regional Centre of
Advanced Technologies and Materials, Faculty of Science, Palacký University, 17. listopadu 12, CZ-771 46 Olomouc, Czech Republic
| | - Bohuslav Drahoš
- Department of Inorganic Chemistry, Regional Centre of
Advanced Technologies and Materials, Faculty of Science, Palacký University, 17. listopadu 12, CZ-771 46 Olomouc, Czech Republic
| | - Radovan Herchel
- Department of Inorganic Chemistry, Regional Centre of
Advanced Technologies and Materials, Faculty of Science, Palacký University, 17. listopadu 12, CZ-771 46 Olomouc, Czech Republic
| | - Zdeněk Trávníček
- Department of Inorganic Chemistry, Regional Centre of
Advanced Technologies and Materials, Faculty of Science, Palacký University, 17. listopadu 12, CZ-771 46 Olomouc, Czech Republic
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