scholarly journals Ten-Coordinate Lanthanide [Ln(HL)(L)] Complexes (Ln = Dy, Ho, Er, Tb) with Pentadentate N3O2-Type Schiff-Base Ligands: Synthesis, Structure and Magnetism

2020 ◽  
Vol 6 (4) ◽  
pp. 60 ◽  
Author(s):  
Tamara A. Bazhenova ◽  
Ilya A. Yakushev ◽  
Konstantin A. Lyssenko ◽  
Olga V. Maximova ◽  
Vladimir S. Mironov ◽  
...  
Keyword(s):  
Schiff Base ◽  
Single Molecule ◽  
Magnetic Measurements ◽  
Magnetic Behavior ◽  
Molecular Structures ◽  
Magnetic Characteristics ◽  
Terbium Complex ◽  
Schiff Base Ligands ◽  
The Difference ◽  
Lanthanide Salts

A series of five neutral mononuclear lanthanide complexes [Ln(HL)(L)] (Ln = Dy3+, Ho3+ Er3+ and Tb3+) with rigid pentadentate N3O2-type Schiff base ligands, H2LH (1-Dy, 3-Ho, 4-Er and 6-Tb complexes) or H2LOCH3, (2-Dy complex) has been synthesized by reaction of two equivalents of 1,1′-(pyridine-2,6-diyl)bis(ethan-1-yl-1-ylidene))dibenzohydrazine (H2LH, [H2DAPBH]) or 1,1′-(pyridine-2,6-diyl)bis(ethan-1-yl-1-ylidene))di-4-methoxybenzohydrazine (H2LOCH3, [H2DAPMBH]) with common lanthanide salts. The terbium complex [Tb(LH)(NO3)(H2O)2](DME)2 (5-Tb) with one ligand H2LH was also obtained and characterized. Single crystal X-ray analysis shows that complexes 1–4 have the composition {[Ln3+(HL)−(L)2−] solv} and similar molecular structures. In all the compounds, the central Ln3+ ion is chelated by two interlocked pentadentate ligands resulting in the coordination number of ten. Each lanthanide ion is coordinated by six nitrogen atoms and four oxygen atoms of the two N3O2 chelating groups forming together a distorted bicapped square antiprismatic polyhedron N6O4 with two capping pyridyl N atoms in the apical positions. The ac magnetic measurements reveal field-induced single-molecule magnet (SMM) behavior of the two dysprosium complexes (with barriers of Ueff = 29 K at 800 Oe in 1-Dy and Ueff = 70 K at 300 Oe in 2-Dy) and erbium complex (Ueff = 87 K at 1500 Oe in 4-Er); complex 3-Ho with a non-Kramers Ho3+ ion is SMM-silent. Although 2-Dy differs from 1-Dy only by a distant methoxy-group in the phenyl ring of the ligand, their dynamic magnetic properties are markedly different. This feature can be due to the difference in long-range contributions (beyond the first coordination sphere) to the crystal-field (CF) potential of 4f electrons of Dy3+ ion that affects magnetic characteristics of the ground and excited CF states. Magnetic behavior and the electronic structure of Ln3+ ions of 1–4 complexes are analyzed in terms of CF calculations.

scholarly journals Lanthanide-Based Single-Molecule Magnets Derived from Schiff Base Ligands of Salicylaldehyde Derivatives

Inorganics ◽  
2020 ◽  
Vol 8 (12) ◽  
pp. 66
Author(s):  
Mamo Gebrezgiabher ◽  
Yosef Bayeh ◽  
Tesfay Gebretsadik ◽  
Gebrehiwot Gebreslassie ◽  
Fikre Elemo ◽  
...  
Keyword(s):  
Schiff Base ◽  
Single Molecule ◽  
Magnetic Behavior ◽  
Point Of View ◽  
Schiff Base Complexes ◽  
Magnetic Interactions ◽  
Single Molecule Magnets ◽  
Schiff Base Ligands ◽  
Synthetic Strategy ◽  
Slow Magnetic Relaxation

The breakthrough in Ln(III)-based SMMs with Schiff base ligands have been occurred for the last decade on account of their magnetic behavior, anisotropy and relaxation pathways. Herein, we review the synthetic strategy, from a structural point of view and magnetic properties of mono, di, tri and polynuclear Ln(III)-based single-molecule magnets mainly with Schiff bases of Salicylaldehyde origin. Special attention has been given to some important breakthroughs that are changing the perspective of this field with a special emphasis on slow magnetic relaxation. An overview of 50 Ln(III)-Schiff base complexes with SMM behavior, covering the period 2008–2020, which have been critical in understanding the magnetic interactions between the Ln(III)-centers, are presented and discussed in detail.

scholarly journals A Series of Novel Pentagonal-Bipyramidal Erbium(III) Complexes with Acyclic Chelating N3O2 Schiff-Base Ligands: Synthesis, Structure, and Magnetism

Molecules ◽  
2021 ◽  
Vol 26 (22) ◽  
pp. 6908
Author(s):  
Tamara A. Bazhenova ◽  
Vyacheslav A. Kopotkov ◽  
Denis V. Korchagin ◽  
Yuriy V. Manakin ◽  
Leokadiya V. Zorina ◽  
...  
Keyword(s):  
Experimental Study ◽  
Magnetic Properties ◽  
Schiff Base ◽  
Theoretical Analysis ◽  
Single Molecule ◽  
Theoretical Study ◽  
Magnetic Measurements ◽  
Single Molecule Magnets ◽  
Schiff Base Ligands ◽  
Axial Ligands

A series of six seven-coordinate pentagonal-bipyramidal (PBP) erbium complexes, with acyclic pentadentate [N3O2] Schiff-base ligands, 2,6-diacetylpyridine bis-(4-methoxybenzoylhydrazone) [H2DAPMBH], or 2,6-diacethylpyridine bis(salicylhydrazone) [H4DAPS], and various apical ligands in different charge states were synthesized: [Er(DAPMBH)(C2H5OH)Cl] (1); [Er(DAPMBH)(H2O)Cl]·2C2H5OH (2); [Er(DAPMBH)(CH3OH)Cl] (3); [Er(DAPMBH)(CH3OH)(N3)] (4); [(Et3H)N]+[Er(H2DAPS)Cl2]− (5); and [(Et3H)N]+[Y0.95Er0.05(H2DAPS)Cl2]− (6). The physicochemical properties, crystal structures, and the DC and AC magnetic properties of 1–6 were studied. The AC magnetic measurements revealed that most of Compounds 1–6 are field-induced single-molecule magnets, with estimated magnetization energy barriers, Ueff ≈ 16–28 K. The experimental study of the magnetic properties was complemented by theoretical analysis based on ab initio and crystal field calculations. An experimental and theoretical study of the magnetism of 1–6 shows the subtle impact of the type and charge state of the axial ligands on the SMM properties of these complexes.

scholarly journals Ni(II) Dimers of NNO Donor Tridentate Reduced Schiff Base Ligands as Alkali Metal Ion Capturing Agents: Syntheses, Crystal Structures and Magnetic Properties

2018 ◽  
Vol 4 (4) ◽  
pp. 51 ◽  
Author(s):  
Monotosh Mondal ◽  
Maharudra Chakraborty ◽  
Michael G. B. Drew ◽  
Ashutosh Ghosh
Keyword(s):  
Schiff Base ◽  
Metal Ion ◽  
Magnetic Measurements ◽  
Dft Method ◽  
Distorted Octahedral Geometry ◽  
Schiff Base Ligands ◽  
Reduced Schiff Base ◽  
Ferromagnetic Interactions ◽  
Experimental Values ◽  
Reduced Schiff Base Ligands

Three trinuclear Ni(II)-Na(I) complexes,[Ni2(L1)2NaCl3(H2O)]·H2O (1), [Ni2(L2)2NaCl3(H2O)] (2), and [Ni2(L3)2NaCl3(OC4H10)] (3) have been synthesized using three different NNO donor tridentate reduced Schiff base ligands, HL1= 2-[(3-methylamino-propylamino)-methyl]-phenol, HL2= 2-[(3-methylamino-propylamino)-methyl]-4-chloro-phenol, and HL3= 2-[(3-methylamino-propylamino)-methyl]-6-methoxy-phenol that had been structurally characterized. Among these complexes, 1 and 2 are isostructural in which dinuclearNi(II) units act as metalloligands to bind Na(I) ions via phenoxido and chlorido bridges. The Na(I) atom is five-coordinated, and the Ni(II) atom possesses hexacordinated distorted octahedral geometry. In contrast, in complex 3, two -OMe groups from the dinuclear Ni(II) unit also coordinate to Na(I) to make its geometry heptacordinated pentagonal bipyramidal. The magnetic measurements of complexes 1–3 indicate ferromagnetic interactions between dimeric Ni(II) units with J = 3.97 cm−1, 4.66 cm−1, and 5.50 cm−1for 1–3, respectively, as is expected from their low phenoxido bridging angles (89.32°, 89.39°, and 87.32° for 1–3, respectively). The J values have been calculated by broken symmetry DFT method and found to be in good agreement with the experimental values.

scholarly journals Spectral, thermal and magnetic properties of Cu(II) and Ni(II) complexes with Schiff base ligands

2011 ◽  
Vol 76 (12) ◽  
pp. 1639-1648 ◽  
Author(s):  
Beata Cristóvão
Keyword(s):  
Thermal Analysis ◽  
Magnetic Properties ◽  
Magnetic Susceptibility ◽  
Schiff Base ◽  
Ir Spectroscopy ◽  
Magnetic Measurements ◽  
Magnetic Moments ◽  
Schiff Base Ligands

Mononuclear copper(II) and nickel(II) complexes of the formulae [Cu(L1)] (1), [Ni(L1)] (2), [Cu(L2)] (3) and [Cu(L3)H2O] (4) (where L1 = N,N?-ethylenebis(4,6-dimethoxysalicylidenaminato), L2 = N,N?-ethylenebis(5-bromosalicylidenaminato) and L3 = N,N?-ethylenebis(5-bromo-3-methoxysalicylidenaminato)) were synthesized as microcrystalline powders and characterized by IR spectroscopy, thermal analysis and magnetic measurements. The magnetic susceptibility of the Cu(II) complexes changed with temperature according to the Curie-Weiss law. The complexes 1, 3 and 4 exhibit magnetic moments of 2.29, 2.20 and 1.88 ?B, respectively, at 303 K. These values practically do not change with lowering the temperature to 77 K. The nickel(II) complex 2 is diamagnetic.

Using Magnetic Measurements to Trace Sediment Sources in Jiangjiagou Valley of Yunnan Province

2013 ◽  
Vol 295-298 ◽  
pp. 2097-2101
Author(s):  
Song Wei Jia
Keyword(s):  
Debris Flow ◽  
Yunnan Province ◽  
Magnetic Measurements ◽  
Main Channel ◽  
Magnetic Characteristics ◽  
Tracer Technique ◽  
Sediment Sources ◽  
Isotope Tracing ◽  
The Difference ◽  
Landslide Debris

Jiangjiagou valley is an area with most developed debris flow valleys in China. Based on Jiangjiagou valley, according to the difference of magnetic characteristics in sediment and soil, this paper studied quantitatively the sediment sources. The results showed that sediments mainly came from landslide debris, accounting for 97.56%; the contributive ratio of grassland and sloped farmland for main channel sediments was very low. It was accordance with using 137Cs tracer technique. But there are still some limitations, and further strengthen research and discussion with combination of 137Cs isotope tracing.

Synthesis and Characterization of Some Functional Schiff Base Derivatives with Azobenzene Substituted Groups

2011 ◽  
Vol 197-198 ◽  
pp. 623-626 ◽  
Author(s):  
Ti Feng Jiao ◽  
Xu Hui Li ◽  
Jing Xin Zhou ◽  
Jing Ya Liang ◽  
Jing Ren
Keyword(s):  
Thermal Stability ◽  
Schiff Base ◽  
Aromatic Aldehydes ◽  
Molecular Structures ◽  
Aromatic Substituent ◽  
Schiff Base Derivatives ◽  
The Difference ◽  
Base Group ◽  
Thermal Stability Of

Some functional Schiff base derivatives with azobenzene substituted groups have been designed and synthesized from the reaction of aminoazobenzene with different aromatic aldehydes. It has been found that depending on the size of aromatic groups, the formed Schiff base derivatives showed different properties, indicating distinct regulation of molecular skeletons. UV and IR data confirmed commonly the formation of Schiff base as well as aromatic segment in molecular structures. Thermal analysis showed that the thermal stability of Schiff base molecules with naphthalene segment increased slightly in comparison with other derivatives. The difference of thermal stability is mainly attributed to the formation of Schiff base group and aromatic substituent groups in molecular structure. The present results have demonstrated that the special properties of Schiff base derivatives can be turned by modifying molecular structures of objective compounds with proper substituted groups, which show potential application in functional material field.

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