Single-ion magnet behaviour of heptacoordinated Fe(<scp>ii</scp>) complexes: on the importance of supramolecular organization

Bar, Arun Kumar; Pichon, Céline; Gogoi, Nayanmoni; Duhayon, Carine; Ramasesha, S.; Sutter, Jean‐Pascal

doi:10.1039/c4cc10182k

Cited by 99 publications

(73 citation statements)

References 23 publications

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“…The neutral ligand H 4 L binds at the five equatorial positions, leaving the two axial positions free for the two dicyanamide anions, which balanced the charge of the metal center (Figure ). The Fe−N and Fe−O bond lengths (Table S2) are very close to those in other reported heptacoordinated Fe II complexes, further indicating the presence of an Fe II center in all of the studied complexes. The structure of complex 3 resembles those of 1 and 2 , but the axial coordination is somewhat different [axial bond angle 173.3° (N8−Fe−N9), as compared to 179.46° in 1 and 178.2° in 2 ] due to the larger size of the dicyanamide anion (Tables S2 and S3).…”

Section: Resultssupporting

confidence: 83%

“…As a consequence, the easy axis of magnetization of the magnetic centers is not parallel to a given direction (Figure S24). The non‐colinear dipolar interaction probably generates a transverse field, which opens the more efficient QTM relaxation pathway, and this may be responsible for the rapid magnetization relaxation in complex 3 …”

Section: Resultsmentioning

confidence: 99%

“…For example, Bar et al. reported the importance of supramolecular organization for the relaxation dynamics of heptacoordinated Fe II complexes . In addition, single‐chain magnets based on Fe II PBP units with aligned axial anisotropy have been reported by Sutter and co‐workers .…”

Section: Introductionmentioning

confidence: 99%

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Effect of Axial Ligands on Easy‐Axis Anisotropy and Field‐Induced Slow Magnetic Relaxation in Heptacoordinated Fe^II Complexes

Mondal

Sato

et al. 2020

Chemistry A European J

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A rational approach to modulating easy‐axis magnetic anisotropy by varying the axial donor ligand in heptacoordinated FeII complexes has been explored. In this series of complexes with formulae of [Fe(H4L)(NCS)2]⋅3 DMF⋅0.5 H2O (1), [Fe(H4L)(NCSe)2]⋅3 DMF⋅0.5 H2O (2), and [Fe(H4L)(NCNCN)2]⋅DMF⋅H2O (3) [H4L=2,2′‐{pyridine‐2,6‐diylbis(ethan‐1‐yl‐1‐ylidene)}bis(N‐phenylhydrazinecarboxamide)], the axial positions are successively occupied by different nitrogen‐based π‐donor ligands. Detailed dc and ac magnetic susceptibility measurements reveal the existence of easy‐axis magnetic anisotropy for all of the complexes, with 1 [Ueff=21 K, τ0=1.72×10−6 s] and 2 [Ueff=25 K, τ0=2.25×10−6 s] showing field‐induced slow magnetic relaxation behavior. However, both experimental studies and theoretical calculations indicate the magnitude of the D value of complex 3 to be larger than those of complexes 1 and 2 due to the axial bond angle being smaller than that for an ideal geometry. Detailed analysis of the field and temperature dependences of relaxation time for 1 and 2 has revealed that multiple relaxation processes (quantum tunneling of magnetization, direct, and Raman) are involved in slow magnetic relaxation for both of these complexes. Magnetic dilution experiments support the role of intermolecular short contacts.

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Section: Resultssupporting

confidence: 83%

Section: Resultsmentioning

confidence: 99%

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Effect of Axial Ligands on Easy‐Axis Anisotropy and Field‐Induced Slow Magnetic Relaxation in Heptacoordinated Fe^II Complexes

Mondal

Sato

et al. 2020

Chemistry A European J

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“…The obtained values of the interatomic distances do not differ from those found in the complex diaqua-(2',2'''-(2,6-pyridinediyldiethylidyne)dioxamohydrazide)-iron(III) perchlorate hydrate [27,28]. In the Cambridge Structural Database 47 hits on structures of compounds of transition metals with ligands of this class are reported [29], mainly manganese or cobalt compounds, only 6 of them being iron compounds [27][28][29][30][31][32][33].…”

Section: Chemistrymentioning

confidence: 99%

Structure and Some Biological Properties of Fe(III) Complexes with Nitrogen-Containing Ligands

Bulhac¹,

Deseatnic-Ciloci²,

Боурош³

et al. 2016

ChemJMold

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Abstract. Four coordination compounds of iron(III) with ligands based on hydrazine and sulfadiazine: [Fe(dig) 2 -2,6-diacetylpyridine bis(isonicotinoylhydrazone) were synthesized. The spectroscopic and structure characterisation, as well as their biological properties, are presented. All tested coordination compounds, caused an inhibitory effect on the biosynthesis of hydrolases of the producer Aspergillus niger CNMN FD-10. The effect increased with the raise of the concentration from 5 mg/L to 15 mg/L. The complexes largely inhibited cellobiohydrolase and less-β-glucosidase. The inhibitory effect of the coordination compounds was quite similar in the case of endoglucanase and xylanase. Compound I, containing both chloride ions and dig, demonstrated a stronger inhibitory effect, while compound III, containing NO 3 -ions, showed the weakest inhibitory action.Keywords: iron complexes, nitrogen-containing ligands, structure, biological properties. IntroductionIn the modern microbiology, investigation of the effects of external factors on the physiology of microorganisms remains an actual issue. Such studies allow solving the practical problems and implementation of the new technologies in biology and medicine.The literature, in the last decades, denotes high physiological activity of the coordination compounds of transition metals on biological objects, including microorganisms [1][2][3][4][5][6][7][8][9][10][11][12][13]. Some authors note a signifi cant role of these compounds in the directed synthesis of biologically active substances from microalgae and cyanobacteria, fi lamentous fungi and yeast [1][2][3][4][5][6][7][8][9][10]12].Studies of the effects of coordination compounds on biosynthesis of extracellular hydrolases in fi lamentous fungi have been previously carried out [3][4][5][6][7]14]. It was established that these effects depend both on the properties of compounds (chemical composition, molecular structure, nature of the ligand and coordinated metal atom) and genus and species of the micromycetes strains, and specifi city of the synthesized enzymes [3][4][5][6][7]14]. Some coordination compounds exhibit a selective action on the components of the synthesized enzyme complex. Thus, by adding the molybdenum complex with valine -MoO 2 (acac) 2 Val (acac=acetylacetone, Val=valine) into the nutrient medium, the biosynthesis of β-glucosidase in micromycete Penicillium expansum CNMN FD 5C -producer of cellulases was enhanced by 69.4%, while the level of endoglucanase and cellobiohydrolase was not modifi ed. Study of the infl uence of (NH 4 ) 2 VO 2 Gly (Gly=glycine) on biosynthesis of cellulases of the same strain showed that the dioxovanadium complex increased the activity of all components of cellulase complex by 17.6-40.3% [14].The targeted application of the coordination compounds of 3d-elements as regulators of the microbial synthesis of bioactive substances requires accumulation of factual material on the nature of their infl uence on all phases of the development of microorganisms and also identifi ca...

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“…The vast majority of the work that has been reported since then has focused on the development of new chemical systems that exhibit the same property above liquid helium temperatures. Although initial work in this direction involved transition metal clusters, the discovery of SMM behaviour in monometallic complexes-firstly in lanthanides [2,3], but more recently in transition metals [4][5][6]-has caused a shift away from cluster compounds due to the comparative ease with which monometallic systems can be chemically tuned.…”

Section: Introductionmentioning

confidence: 99%

Evidence of Slow Magnetic Relaxation in Co(AcO)2(py)2(H2O)2

et al. 2016

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Abstract:The monometallic pseudo-octahedral complex, [Co(H 2 O) 2 (CH 3 COO) 2 (C 5 H 5 N) 2 ], is shown to exhibit slow magnetic relaxation under an applied field of 1500 Oe. The compound is examined by a combination of experimental and computational techniques in order to elucidate the nature of its electronic structure and slow magnetic relaxation. We demonstrate that any sensible model of the electronic structure must include a proper treatment of the first-order orbital angular momentum, and we find that the slow magnetic relaxation can be well described by a two-phonon Raman process dominating at high temperature, with a temperature independent quantum tunnelling pathway being most efficient at low temperature.

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Single-ion magnet behaviour of heptacoordinated Fe(ii) complexes: on the importance of supramolecular organization

Cited by 99 publications

References 23 publications

Effect of Axial Ligands on Easy‐Axis Anisotropy and Field‐Induced Slow Magnetic Relaxation in Heptacoordinated Fe^II Complexes

Effect of Axial Ligands on Easy‐Axis Anisotropy and Field‐Induced Slow Magnetic Relaxation in Heptacoordinated Fe^II Complexes

Structure and Some Biological Properties of Fe(III) Complexes with Nitrogen-Containing Ligands

Evidence of Slow Magnetic Relaxation in Co(AcO)2(py)2(H2O)2

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Single-ion magnet behaviour of heptacoordinated Fe(ii) complexes: on the importance of supramolecular organization

Cited by 99 publications

References 23 publications

Effect of Axial Ligands on Easy‐Axis Anisotropy and Field‐Induced Slow Magnetic Relaxation in Heptacoordinated FeII Complexes

Effect of Axial Ligands on Easy‐Axis Anisotropy and Field‐Induced Slow Magnetic Relaxation in Heptacoordinated FeII Complexes

Structure and Some Biological Properties of Fe(III) Complexes with Nitrogen-Containing Ligands

Evidence of Slow Magnetic Relaxation in Co(AcO)2(py)2(H2O)2

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Effect of Axial Ligands on Easy‐Axis Anisotropy and Field‐Induced Slow Magnetic Relaxation in Heptacoordinated Fe^II Complexes

Effect of Axial Ligands on Easy‐Axis Anisotropy and Field‐Induced Slow Magnetic Relaxation in Heptacoordinated Fe^II Complexes