Coordination of Hydrazone Derivatives of 2,2'-Bipyridine-6-carbaldehyde. Electronic and Structural Aspects of the Iron(II), Cobalt(II) and Nickel(II) Complexes

1991 ◽  
Vol 44 (3) ◽  
pp. 331 ◽  
Author(s):  
D Onggo ◽  
DC Craig ◽  
AD Rae ◽  
HA Goodwin
Keyword(s):  
Metal Atom ◽  
Magnetic Moments ◽  
Spin Transition ◽  
Azomethine Nitrogen ◽  
Ligand Molecule ◽  
Monoclinic Space Group ◽  
Temperature Dependent ◽  
Thermally Induced ◽  
Derivatives Of ◽  
Structural Aspects

Iron(II), cobalt(II) and nickel(II) [MN6]2+ type complexes of the tridentate terimine ligands 2,2′-bipyridine-6-carbaldehyde phenylhydrazone ( bph ) and 2,2′-bipyridine-6-carbaldehyde 2-pyridylhydrazone ( bpyh ) have been prepared. The electronic spectrum of the [NiN6]2+ species indicates that the field strength of these ligands is near that at the iron(II) singlet/quintet crossover. Magnetic and Mossbauer spectral data reveal that salts of [Fe( bph )2]2+ are essentially low spin, while those of [Fe( bpyh )2]2+ are high spin. Salts of [Co( bph )2]2+ have strongly temperature-dependent magnetic moments which indicate a thermally induced doublet ↔ quartet spin transition in the metal atom. The structure of [Ni( bph )2][ClO4]2 reveals meridional coordination of the tridentate units, the azomethine nitrogen of the hydrazone moiety being bound to the metal atom. There is significant twisting (8.3°) of the two pyridyl rings in each ligand molecule about the interring bridge. The [NiN6]2+ fragment is tetragonally compressed and the mean Ni-N distance is 2.09 Ǻ. [Ni( bph )2][ClO4]2 is monoclinic, space group C2/c, Z = 4, a 23.949(3), b 7.868(1), c 21.303(3)Ǻ, β 117.95(2)°.

The singlet-quintet transition in Tris[2-(pyridin-2-yl)benzothiazole]iron(II) Bis(tetraphenylborate)

1984 ◽  
Vol 37 (6) ◽  
pp. 1157 ◽  
Author(s):  
AT Baker ◽  
HA Goodwin
Keyword(s):  
Field Strength ◽  
Spectral Data ◽  
Magnetic Moment ◽  
Spin Transition ◽  
Empirical Treatment ◽  
Temperature Dependent ◽  
Thermally Induced ◽  
Thiazole Derivative

The tris[2-(pyridin-2-yl)benzothiazole]iron(II) ion has been isolated as the tetraphenylborate salt which is stable in the atmosphere for short periods. The deep red complex displays a temperature-dependent magnetic moment and thermochroism which are associated with a thermally induced singlet (1A1) ↔ quintet (5T2) spin transition. An empirical treatment of the transition, which is continuous, yields ∆H and ∆S values of 22.7 kJ mol-1 and 91 JK-1 mol-1 over the range 275-364 K. Spectral data for the corresponding nickel(11) complex confirm the intermediate nature of the field strength of the benzothiazole and indicate that it is a weaker ligand than the corresponding thiazole derivative.

Metallkomplexe mit paramagnetischen Derivaten des Piperidin-1-oxyls / Metal Complexes of Paramagnetic Derivatives of Piperidine-1-oxyl

1973 ◽  
Vol 28 (1-2) ◽  
pp. 55-62 ◽  
Author(s):  
Dieter Jahr ◽  
Karl Heinz Rebhan ◽  
Karl E. Schwarzhans ◽  
Josef Wiedemann
Keyword(s):  
Free Radicals ◽  
Solid State ◽  
Metal Ion ◽  
Magnetic Moments ◽  
Transition Metal Ions ◽  
Epr Spectra ◽  
Temperature Dependent ◽  
Derivatives Of ◽  
Stable Free Radicals ◽  
Dependent Interaction

A series of complexes formed between transition metal ions and the stable free radicals 2,2,6,6- tetramethyl-4-amino-4-caboxypiperidine-1-oxyl, 2,2,6,6-tetramethyl-4-aminopiperidine-l -oxyl, 2,2,6,6-tetram ethyl-piperidine-l-oxyl and glyoxal-bis(2,2,2,6,6-tetramethyl-4-iminopiperidine-1- oxyl) has been prepared. The magnetic moments and the epr-spectra of the complexes have been investigated. Some of the complexes show a temperature dependent interaction between the radicalic nitroxyl groups of the ligands. By analysis of the epr-spectra in the solid state there was found in some cases an interaction between the metal ion and the unpaired electrons of the ligands.

Steric Influences on the Ground State of Iron(II) in the Tris(3,3'-dimethyl-2,2'-bipyridine)Iron(II) Ion

1988 ◽  
Vol 41 (8) ◽  
pp. 1157 ◽  
Author(s):  
DC Craig ◽  
HA Goodwin ◽  
D Onggo
Keyword(s):  
Spin Transition ◽  
Spectroscopic Properties ◽  
Monoclinic Space Group ◽  
Crystal Data ◽  
Complex Ions ◽  
Temperature Dependent ◽  
Ligand Complex ◽  
Metal Atoms ◽  
Donor Nitrogen ◽  
Complex Salts

The tris ( ligand ) complex ions of iron(II) and nickel(II) with 3,3′-dimethyl-2,2′-bipyridine (L) are described. Salts of [FeL3]2+ display anomalously temperature-dependent magnetic and spectroscopic properties which arise from a temperature-induced singlet (1A1) ↔ quintet (5T2) spin transition. The structures of [ML3][ClO4]2(M = Fe, Ni) have been determined and these reveal a strong twist (c. 37°) of the pyridine rings about the C-C bridge. This forces the metal atoms out of the bonding planes of the donor nitrogen atoms and effectively reduces the interaction between L and the metal atoms. The average M-N distances are 2.064 Ǻ (M = Fe) and 2.102 Ǻ (M = Ni). Crystal data: the two complex salts are isostructural in monoclinic space group C2/c. [FeL3][ClO4]2: a 12.252(8), b 15.568(5), c 19.288(11) Ǻ, β 93.62(3)°; Z 4; [NiL3][ClO4]2: a 12.255(5), b 15.619(4), c 19.419(9) Ǻ, β 93.23(2); Z 4.

scholarly journals Solvent-induced on/off switching of intramolecular electron transfer in a cyanide-bridged trigonal bipyramidal complex

2016 ◽  
Vol 45 (43) ◽  
pp. 17104-17107 ◽  
Author(s):  
Rong-Jia Wei ◽  
Ryohei Nakahara ◽  
Jamie M. Cameron ◽  
Graham N. Newton ◽  
Takuya Shiga ◽  
...  
Keyword(s):  
Electron Transfer ◽  
Spin Transition ◽  
Intramolecular Electron Transfer ◽  
Thermally Induced ◽  
Trigonal Bipyramidal ◽  
Transition Behaviour

A cyanide-bridged trigonal bipyramidal [Co3Fe2] cluster shows solvent-driven reversible on/off switching of its thermally induced electron-transfer-coupled spin transition behaviour.

scholarly journals Template Synthesis, Characterization and Biological Activity of Cu(II), Ni(II), Co(II), Zn(II)Complexes with Isonicotinoylhydrazone--2-aldehydefluorene Ligand

2010 ◽  
Vol 7 (1) ◽  
pp. 227-233
Keyword(s):  
Experimental Data ◽  
Escherichia Coli ◽  
Thermal Analysis ◽  
Biological Activity ◽  
Nmr Spectra ◽  
Magnetic Moments ◽  
Analytical Data ◽  
Azomethine Nitrogen ◽  
Tetrahedral Geometry ◽  
Metal Ligand

This is about synthesizing new complex combinations of Cu(II), Ni(II),Co(II), Zn(II) with aroylhydrazone ligand isonicotinoylhydrazone-2-aldehydefluorene (INHAF) made by condensation of isonicotinoylhydrazine with 2-aldehydefluorene. The complexes have been characterized by analytical data, IR, UV-Vis, NMR spectra, magnetic susceptibility values, thermal analysis and for the Cu(II) complex the ESR spectrum has been registered. For all complexes the biological activity against theStaphylo-coccus aureus, Escherichia coli, Klebssiella pneumoniaebacteria has been investigated. The experimental data sustain stoichiometry of 1:2 (metal/ligand) for the Cu(II), Ni(II), Zn(II) complexes and of 1:1 for the complex with Co(II). The electronic spectra and the magnetic moments suggest octahedral stereochemistry at the complexes with Cu(II), Ni(II) and the tetrahedral geometry for the Co(II) complex. The INHAF ligand is coordinated bidentate by the O=C amide oxygen and the azomethine nitrogen in the complexes of Cu(II), Ni(II), Co(II) and monodentate by the azomethine nitrogen in the complex of Zn(II).

Structural and Electronic Properties of the Iron(II) and Nickel(II) Bis(ligand) Complexes of 6-(5-Methyl-1,2,4-oxadiazol-3-yl)-2,2′-bipyridine— a Terpyridine-Based Tridentate

1999 ◽  
Vol 52 (7) ◽  
pp. 673 ◽  
Author(s):  
Bradley J. Childs ◽  
Marcia L. Scudder ◽  
Donald C. Craig ◽  
Harold A. Goodwin
Keyword(s):  
Electronic Properties ◽  
Spectroscopic Data ◽  
Room Temperature ◽  
Spin Transition ◽  
Iron Complex ◽  
Ligand Field ◽  
Monoclinic Space Group ◽  
Space Group ◽  
C 23 ◽  
Structural And Electronic Properties

Iron(II) and nickel(II) bis(ligand) complexes of 6-(5-methyl-1,2,4-oxadiazol-3-yl)-2,2′-bipyridine (L) are described. The ligand field in the iron complex is close to that at the singlet ( 1 A1) ? quintet ( 5 T2) crossover and magnetic and Mössbauer spectral evidence indicates that a spin transition occurs in salts of the iron complex but is centred above room temperature. The structures of [FeL2] [CF3SO3]2.CH3CN and [NiL2] [BF4]2.CH3CN were determined and both are very similar to the structures of the corresponding terpyridine complexes. Spectroscopic data indicate that for the iron complex π-interaction between the metal and the ligand is less than that in the terpyridine system. [FeL2] [CF3SO3]2.CH3CN is monoclinic, space group P 21/c; a 8 . 232(5), b 25 . 273(10), c 17 . 306(10) Å, β 92 . 37(3)°, Z 4; [NiL2] [BF4]2.CH3CN is monoclinic, space group P 21/c; a 8 . 136(2), b 17 . 558(2), c 23 . 783(7) Å, β 109 . 32(1)°, Z 4.

Iron(II) and Nickel(II) Complexes of 2,6-Di(thiazol-2-yl)pyridine and Related Ligands

1991 ◽  
Vol 44 (8) ◽  
pp. 1041 ◽  
Author(s):  
AT Baker ◽  
P Singh ◽  
V Vignevich
Keyword(s):  
High Spin ◽  
Room Temperature ◽  
Spin Transition ◽  
Magnetic Behaviour ◽  
Diethyl Acetal ◽  
Thermally Induced ◽  
Field Strengths

2,6-Di(thiazol-2-yl]pyridine (1a), 2,6-di(4-methylthiazol-2-yl)pyridine (1b) and 2,6-di(2-imid-azolin-2-yl)pyridine (3) have been prepared by the reaction of pyridine-2,6-dicarbothioamide with bromoacetaldehyde diethyl acetal, bromoacetone and ethylenediamine, severally. Bis ( ligand ) iron(II) and nickel(II) complexes of all ligands have been prepared. The bis ( ligand ) iron(II) complexes of (1a) and (3) are low-spin whereas that of (1b) is high-spin at room temperature and undergoes a thermally induced spin transition. The field strengths of the ligands , determined from the spectra of their nickel(II) complexes, correlate well with the observed magnetic behaviour of their iron(II) complexes. The field strengths of (1a) and (1b) are found to be marginally less than those of the isomeric ligands 2,6-di(thiazol-4-yl)pyridine (2a) and 2,6-di(2-methylthiazol-4-yl)pyridine (2b).

scholarly journals Temperature-dependent nanomechanics and topography of bacteriophage T7

2018 ◽  
Author(s):  
Zsuzsanna Vörös ◽  
Gabriella Csík ◽  
Levente Herényi ◽  
Miklós Kellermayer
Keyword(s):  
Structural Changes ◽  
Mechanical Stability ◽  
Genetic Material ◽  
Heat Inactivation ◽  
Infectious Agents ◽  
Temperature Dependent ◽  
Thermally Induced ◽  
Partial Denaturation ◽  
Induced Changes ◽  
T7 Bacteriophage

AbstractViruses are nanoscale infectious agents which may be inactivated by heat treatment. Although heat inactivation is thought to be caused by the release of genetic material from the capsid, the thermally-induced structural changes in viruses are little known. Here we measured the heat-induced changes in the properties of T7 bacteriophage particles exposed to two-stage (65 °C and 80 °C) thermal effect by using AFM-based nanomechanical and topographical measurements. We found that exposure to 65 °C caused the release of genomic DNA due to the loss of the capsid tail which leads to a destabilization of the T7 particles. Further heating to 80 °C surprisingly led to an increase in mechanical stability due to partial denaturation of the capsomeric proteins kept within the global capsid arrangement.

Optical Microscopy Imaging of the Thermally-Induced Spin Transition and Isothermal Multi-stepped Relaxation in a Low-Spin Stabilized Spin-Crossover Material

2021 ◽  
Author(s):  
Pradip Chakraborty ◽  
Mouhamadou Sy ◽  
Houcem Fourati ◽  
Maria Teresa Delgado Pérez ◽  
Mousumi Dutta ◽  
...  
Keyword(s):  
Optical Microscopy ◽  
High Spin ◽  
Spin Relaxation ◽  
Spin Crossover ◽  
Spin Transition ◽  
Host Lattice ◽  
Microscopy Imaging ◽  
Thermally Induced ◽  
Optical Microscopy Imaging

The thermal spin transition and the photo-induced high-spin → low-spin relaxation of the prototypical [Fe(ptz)6](BF4)2 spin-crossover compound (ptz = 1-propyltetrazole) diluted in the isostructural ruthenium host lattice [Ru(ptz)6](BF4)2, which stabilizes...

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