Toroidal magnetic moments in Tb4 squares

Author(s):  
Qianqian Yang ◽  
Liviu Ungur ◽  
Wolfgang Wernsdorfer ◽  
Jinkui Tang

A series of Tb4 complexes isolated from reduced or dimerized Schiff base ligand share a similar µ4-O bridged Tb4 square core with the magnetic moments of the TbIII ions in...

Drug Research ◽  
2021 ◽  
Author(s):  
Preeti Sharma ◽  
Varun Kumar Singh ◽  
Gajendra Kumar

AbstractSchiff base ligand (E)-5-methyl-3-(1-(4-nitrophenylimino)ethyl)-1H-indol-2-amine was synthesized by the condensation of 1-(2-amino-5-methyl-1H-indol-3-yl)ethanone and 4-nitrobenzenamine in methanol at 70 oC. The prepared Schiff base ligand doped with Cr(III), Mn(III) and Fe(III) ion, respectively and it is denoted as [M(C34H32N8O4)X]X2. The complexes have been characterized with the help of elemental analysis, conductance measurements, magnetic measurements and their structural configuration have been determined by various spectroscopic (electronic, IR, 1H NMR, 13C NMR, GCMS) techniques. Electronic and magnetic moments of the complexes indicate that the geometry of the metal center was five coordinate square pyramidal. These metal complexes were also tested for their antimicrobial activities to assess their inhibiting potential against Staphylococcus aureus, Bacillus subtilis (positive bacteria) and Pseudomonas aeruginosa, Escherichia coli, Salmonella typhi (negative bacteria) and fungi Rizoctonia sp., Aspergillus sp., Penicillium sp. [Cr(C34H32N8O4)OAc](OAc)2 shows best antimicrobial activity against all the pathogens.


2012 ◽  
Vol 9 (4) ◽  
pp. 2119-2127 ◽  
Author(s):  
Gajendra Kumar ◽  
Rajeev Johari ◽  
Shoma Devi

A Schiff base ligand was synthesized by reacting 5-tert-butl-2-hydroxy-3-(3-phenylpent-3-yl) benzaldehyde and thiodihydrazide (2:1) and a series of metal complexes with this new ligand were synthesized by reaction with Cr (III), Mn (III), and Fe (III) metal salt in methanolic medium. The Schiff base ligand and its complexes have been characterized with the help of elemental analysis, conductance measurements, magnetic measurements and their structure configuration have been determined by various spectroscopic (electronic, IR,1H NMR,13C NMR, GCMS) techniques. Electronic and magnetic moments of the complexes indicate that the geometries of the metal centers were octahedral. IR spectral data suggest that ligand behaves as a tetradentate ligand with ONNO donor sequence towards the metal ion.


2014 ◽  
Vol 2014 ◽  
pp. 1-17 ◽  
Author(s):  
Aurora Reiss ◽  
Mariana Carmen Chifiriuc ◽  
Emilia Amzoiu ◽  
Cezar Ionuţ Spînu

New [ML2(H2O)2] complexes, where M = Co(II), Ni(II), Cu(II), and Zn(II) while L corresponds to the Schiff base ligand, were synthesized by condensation of cefotaxime with salicylaldehydein situin the presence of divalent metal salts in ethanolic medium. The complexes were characterized by elemental analyses, conductance, and magnetic measurements, as well as by IR and UV-Vis spectroscopy. The low values of the molar conductance indicate nonelectrolyte type of complexes. Based on spectral data and magnetic moments, an octahedral geometry may be proposed for Co(II), Ni(II), and Zn(II) complexes while a tetragonal geometry for Cu(II) complex. Molecular structure of the Schiff base ligand and its complexes were studied using programs dedicated to chemical modeling and quantomolecular calculation of chemical properties. All the synthesized complexes were tested forin vitroantibacterial activity against some pathogenic bacterial strains, namelyEscherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa, Bacillus subtilis,andStaphylococcus aureus. The MIC values shown by the complexes against these bacterial strains revealed that the metal complexes possess superior antibacterial activity than the Schiff base.


2013 ◽  
Vol 2013 ◽  
pp. 1-7 ◽  
Author(s):  
J. R. Anacona ◽  
Johan Calvo ◽  
Ovidio A. Almanza

Metal complexes of a Schiff base ligand derived from cefotaxime and salicylaldehyde were prepared. The salicilydene-cefotaxime ligand (H2L) and mononuclear [M(L)] (M(II) = Co, Ni and Cu), dinuclear [Ag2(L)(OAc)2], and tetranuclear metal complexes [M4(L)(OH)6] (M(II) = Ni, Cu) were characterized on the basis of analytical, thermal, magnetic, and spectral studies (IR, UV-visible, 1H NMR, 13C NMR, and EPR). The electronic spectra of the complexes and their magnetic moments suggesttetrahedral geometry for the isolated complexes. The complexes are nonelectrolytes and insoluble in water and common organic solvents but soluble in DMSO.


2021 ◽  
Author(s):  
Cyril Rajnák ◽  
Romana Mičová ◽  
Ján Moncoľ ◽  
Ľubor Dlháň ◽  
Christoph Krüger ◽  
...  

A pentadentate Schiff-base ligand 3,5Cl-L2− and NCSe− form a iron(iii) mononuclear complex [Fe(3,5Cl-L)(NCSe)], which shows a thermally induced spin crossover with a broad hysteresis width of 24 K between 123 K (warming) and 99 K (cooling).


2021 ◽  
Vol 157 ◽  
pp. 106329
Author(s):  
Tanlong Xue ◽  
Yang Li ◽  
Xiangchen Zhao ◽  
Jun Nie ◽  
Xiaoqun Zhu

Biochimie ◽  
2021 ◽  
Vol 186 ◽  
pp. 43-50
Author(s):  
María R. Rodríguez ◽  
Martín J. Lavecchia ◽  
Beatriz S. Parajón-Costa ◽  
Ana C. González-Baró ◽  
María R. González-Baró ◽  
...  

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