Magnetic concentration and polymorphism in di-n-octyl-, di-n-decyl-, and di-n-dodecylphosphinates of copper(II)

1985 ◽  
Vol 63 (5) ◽  
pp. 1111-1117 ◽  
Author(s):  
John S. Haynes ◽  
Katherine W. Oliver ◽  
Robert C. Thompson
Keyword(s):  
Differential Scanning Calorimetry ◽  
Magnetic Susceptibility ◽  
Heisenberg Model ◽  
Variable Temperature ◽  
Electronic Spectroscopy ◽  
Chain Structure ◽  
Magnetic Data ◽  
Scanning Calorimetry ◽  
Extended Chain ◽  
Linear Chains

Phosphinates of copper(II) of the type Cu(R2PO2)2 where R is n-octyl, n-decyl, and n-dodecyl have been synthesized and characterized by differential scanning calorimetry, vibrational and electronic spectroscopy, and variable temperature (300 to 4.2 K) magnetic susceptibility studies. Each of these compounds was obtained in distinct α and β structural forms. All materials appear to have the double phosphinate bridged extended chain structure and the magnetic data have been successfully analyzed according to the isotropic Heisenberg model for linear chains. The α forms exhibit antiferromagnetic behaviour with J values of −25, −29, and −29 cm−1 for the octyl, decyl, and dodecyl derivatives respectively. The β forms are ferromagnetic and have corresponding J values of 1.8, 2.1, and 2.3 cm−1 respectively. Magneto-structural correlations in these extended chain coordination polymers are discussed.

Synthesis, spectroscopic and magnetic properties of some pyrazine-bridged iron(II) sulfonate complexes

1988 ◽  
Vol 66 (8) ◽  
pp. 2079-2087 ◽  
Author(s):  
John S. Haynes ◽  
John R. Sams ◽  
Robert C. Thompson
Keyword(s):  
Heisenberg Model ◽  
Hyperfine Splitting ◽  
Variable Temperature ◽  
Magnetic Data ◽  
Antiferromagnetic Coupling ◽  
Antiferromagnetic Exchange ◽  
Two Dimensional ◽  
Scanning Calorimetry ◽  
Best Fit ◽  
Magnetic Hyperfine Splitting

Six new pyrazine-bridged complexes of iron(II) have been prepared and studied using magnetic susceptibility, differential scanning calorimetry, and vibrational, electronic, and Mössbauer spectroscopic methods. Fe(pyz)(CF3SO3)2 exhibits a susceptibility maximum at 4.4 K and analysis of the magnetic data according to a two-dimensional S = 2 system in the (isotropic) Heisenberg limit yields best-fit values of J = −0.26 cm−1 and g = 2.20. Variable temperature Mössbauer spectra between 4.2 and 1.6 K are also reported for this compound and show the onset of magnetic hyperfine splitting below ~3.8 K. Analysis of magnetic data for Fe(pyz)2(CH3SO3)2 and Fe(pyz)2(CF3SO3)2•CH3OH according to the two-dimensional Heisenberg model also indicates the presence of weak antiferromagnetic exchange in these complexes (J = −0.18 and −0.20 cm−1, respectively). No clear evidence for magnetic concentration was obtained from our studies on Fe(pyz)2(CIO4)2, Fe(pyz)(p-CH3C6H4SO3)2, and Fe(pyz)(p-CH3C6H4SO3)2•2CH3OH; any antiferromagnetic coupling in these complexes must be considerably weaker than in the other complexes studied.

Antiferromagnetic exchange in manganese(II) monophenylphosphinate and the effects of cadmium doping

1989 ◽  
Vol 67 (7) ◽  
pp. 1239-1243 ◽  
Author(s):  
Jlng-Long Du ◽  
Robert C. Thompson
Keyword(s):  
Magnetic Susceptibility ◽  
Theoretical Models ◽  
Magnetic Data ◽  
Coupling Constant ◽  
Scanning Calorimetry ◽  
Manganese Compound ◽  
Linear Chains ◽  
Magnetic Chain ◽  
Metal Materials ◽  
Polymeric Structures

Mn[H(C6H5)PO2]2, its cadmium analogue, and mixed metal materials of composition Mn1−xCdx[H(C6H5)PO2]2 (x = 0.005, 0.01, 0.09, 0.27, and 0.47) have been synthesized and characterized by X-ray powder diffraction, infrared spectroscopy, differential scanning calorimetry and low-temperature (4.2 to 80 K) magnetic susceptibility studies. The materials are shown to be isomorphous and are considered to have polymeric structures in which chains of metal atoms are linked by bridging phosphinate groups. The pure manganese compound is antiferromagnetic (maximum in xm at ~35 K) and the magnetic data for the compound have been analyzed according to two theoretical models for linear chains of antiferromagnetically coupled manganese(II) (d5, spin-free) ions. The Wagner and Friedberg model gives J = −3.00 cm−1 and the Weng model gives J = −2.78 cm−1. The effects of replacing Mn2+ by Cd2+ ions in the polymer is to increase the magnetic susceptibility (per mol of Mn) at all temperatures. Analysis of the data as a function of Cd doping indicates the incorporation of a paramagnetic component to the susceptibility which increases with increasing Cd content. In addition, the absolute value of the exchange coupling constant appears to decrease as the Cd content increases. These effects are considered in terms of a random defect model in which the replacement of Mn ions in the polymer by Cd ions results in the formation of Cd ion separated finite magnetic chain fragments. Keywords: manganese(II) monophenylphosphinate, magnetic properties, coordination polymer, cadmium doped antiferromagnet.

Evidence for room temperature mesomorphism in a mixed-valent diruthenium(II,III) quintapalmitoleate polymer

1998 ◽  
Vol 76 (11) ◽  
pp. 1520-1523
Author(s):  
Jennifer F Caplan ◽  
Christopher A Murphy ◽  
Susan Swansburg ◽  
Robert P Lemieux ◽  
T Stanley Cameron ◽  
...  
Keyword(s):  
Differential Scanning Calorimetry ◽  
Liquid Crystal ◽  
Powder Diffraction ◽  
Strong Evidence ◽  
Room Temperature ◽  
Variable Temperature ◽  
Mixed Valence ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Crystal Transition

The synthesis of Ru2(μ-O2CR)4(μ´-O2CR) (1), R = -CH2(CH2)6CH=CH(CH2)5CH3, has been achieved and characterization using elemental analysis and FTIR and UV-Vis spectroscopies undertaken. Strong evidence for a hexagonal discotic mesophase has been found using differential scanning calorimetry, variable-temperature polarizing optical microscopy, and X-ray powder diffraction. A solid to liquid crystal transition was found upon heating at 128°C and the mesophase is found to persist to room temperature upon cooling from 150°C. This is the first report of room temperature mesomorphism in a mixed-valent metallomesogen. Key words: ruthenium carboxylate, liquid crystal, metallomesogen, mixed valence, polymer.

The Synthesis and Solubility of a Wholly Aromatic Polyamide Containing Para- and Meta-Substituted Phenylene Rings

2013 ◽  
Vol 320 ◽  
pp. 488-494 ◽  
Author(s):  
Yi Fan Wang ◽  
Jun Sun ◽  
Li Xing Dai
Keyword(s):  
Differential Scanning Calorimetry ◽  
Aromatic Polyamide ◽  
Chain Structure ◽  
Aminobenzoic Acid ◽  
Transformation Behavior ◽  
Scanning Calorimetry ◽  
Aromatic Polyamides ◽  
Ft Ir ◽  
Chain Transformation ◽  
Ir And Raman

A series of wholly aromatic polyamides (aramid) containingpara- andmeta-substituted phenylene rings was copolymerized via phosphorylation method with different ratio of 4-aminobenzoic acid and 3-aminobenzoic acid. The inherent viscosities (ηinh) of products were 0.52-0.99 dL/g. The chain structure of the polymers was characterized by Fourier transform infrared spectroscopy (FT-IR) and Raman spectrum. The differential scanning calorimetry (DSC) was also performed to investigate the chain transformation behavior of aramid. With increasing the content ofmeta-substituted phenylene rings in macromolecular chain, the solubility of the polymers was improved obviously without appreciable loss for their original thermal property.

scholarly journals Binding of a substrate analogue can induce co-operative structure in the plasmin serine-proteinase domain

1993 ◽  
Vol 293 (2) ◽  
pp. 567-572 ◽  
Author(s):  
A J Teuten ◽  
A Cooper ◽  
R A Smith ◽  
C M Dobson
Keyword(s):  
Differential Scanning Calorimetry ◽  
Structural Properties ◽  
Direct Evidence ◽  
Conformational Transition ◽  
Variable Temperature ◽  
Serine Proteinase ◽  
Scanning Calorimetry ◽  
Affinity Label ◽  
Substrate Analogue ◽  
Kringle 5

Human miniplasminogen and miniplasmin were studied by n.m.r. spectroscopy and differential scanning calorimetry (d.s.c.) in order to investigate the structural properties of the serine-proteinase domain. The d.s.c. thermograms of both miniplasminogen and non-inactivated miniplasmin at pH 4.0 can be closely fitted to two transitions, at 62 +/- 2 and 72 +/- 2 degrees C, corresponding to unfolding of the kringle 5 and proteinase domains respectively. No evidence was found, under these conditions, for non-co-operative unfolding of the proteinase domain. On inactivation of miniplasmin with an affinity label, a number of additional resonances arising from residues of the proteinase domain are observed in resolved regions of the n.m.r. spectrum. A combination of variable-temperature n.m.r. and d.s.c. has shown that part of the proteinase domain undergoes a major conformational transition on heating which is distinct from the unfolding of the remainder of the proteinase domain or the kringle 5 domain. This additional transition occurs at a temperature that depends on the nature of the affinity label present and is not observed in the absence of an inactivating agent. These results provide direct evidence for the existence of a region of the proteinase domain which, under these conditions, becomes structured only in the presence of a bound substrate.

scholarly journals Synthesis, Crystal Structures and Magnetic Properties of Mixed-Valent Tetranuclear Complexes with Y-Shaped MnII2MnIII2 Core

2019 ◽  
Vol 5 (1) ◽  
pp. 8 ◽  
Author(s):  
Masahiro Mikuriya ◽  
Satoshi Kurahashi ◽  
Seiki Tomohara ◽  
Yoshiki Koyama ◽  
Daisuke Yoshioka ◽  
...  
Keyword(s):  
Magnetic Properties ◽  
Magnetic Susceptibility ◽  
Crystal Structures ◽  
Variable Temperature ◽  
Magnetic Interactions ◽  
Magnetic Data ◽  
Schiff Base Ligands ◽  
Tetranuclear Cluster ◽  
Variable Temperature Magnetic Susceptibility ◽  
Tetranuclear Complexes

Tetranuclear MnII2MnIII2 complexes with 1,3-bis(5-bromo-3-metoxysalicylidenaminomethyl)-2-propanol (H3bmsap) and 1,3-bis(5-chloro-3-methoxysalicylidenaminomethyl)-2-propanol (H3cmsap), [Mn4(bmsap)2(CH3CO2)3(CH3O)] (3) and [Mn4(cmsap)2(CH3CO2)3(CH3O)] (4), were synthesized and characterized by elemental analysis, infrared and diffused reflectance spectra and variable-temperature magnetic susceptibility measurements in the 2–300 K range. The crystal structures of 3 and 4 revealed a Y-shaped tetranuclear manganese cluster formed by the two Schiff-base ligands, three kinds of acetato ligands (bidentate, syn–anti-bridging, and syn–syn-bridging), and µ-methoxido ligand. The magnetic data showed the magnetic interactions among the four manganese atoms are antiferromagnetic as a whole within the tetranuclear cluster.

Morphology of Polymer-Salt Complex Films Crossover from Fractal to Compact Aggregation

Fractals ◽  
1998 ◽  
Vol 06 (03) ◽  
pp. 285-292 ◽  
Author(s):  
Aninda Jiban Bhattacharyya ◽  
S. Banerjee ◽  
T. R. Middya ◽  
S. Tarafdar
Keyword(s):  
Differential Scanning Calorimetry ◽  
Polyethylene Oxide ◽  
Salt Concentration ◽  
Variable Temperature ◽  
Weight Fraction ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Polarizing Microscopy ◽  
X Ray ◽  
Salt Complex

In this paper we present a study of the variation of morphology of polyethylene oxide (PEO) films complexed with ammonium perchlorate ( NH 4 ClO 4) formed by evaporating a methanolic solution. Films with salt concentration x = 0 - 0.35 (x is the weight fraction of salt) were prepared for the morphology study. The wide varitey of structures obtained were systematically studied by photographs and polarizing microscopy. Some preliminary studies of x-ray diffraction, differential scanning calorimetry and variable temperature polarizing microscopy have also been done to identify the various phases present in the films.

scholarly journals Novel Series of 1,3,4- Oxadiazole Derivatives: Evaluation of Thermal Properties and Antibacterial Activity

2021 ◽  
Vol 10 (3) ◽  
pp. 2370-2381
Keyword(s):  
Differential Scanning Calorimetry ◽  
Antibacterial Activity ◽  
Thermal Properties ◽  
Variable Temperature ◽  
Isotropic Phase ◽  
Aliphatic Acid ◽  
Scanning Calorimetry ◽  
Good Antibacterial Activity ◽  
Oxadiazole Derivatives ◽  
Chloramine T

A new series of 1,3,4-oxadiazole derivatives were synthesized 6(a-i) by the reaction between respective aliphatic acid hydrazides with p-alkoxy aldehydes using chloramine-T (CAT). The synthesized compounds were evaluated for their thermal properties using Polarising Optical Microscopy (POM), Differential Scanning Calorimetry (DSC), and variable temperature Powder X-RD (PXRD). The compounds exhibited spherulitic textures associated with the crystal to isotropic phase. No mesophase was detected upon heating or cooling cycles. Also, the synthesized compounds showed moderate to good antibacterial activity.

scholarly journals Exceptionally High Temperature Spin Crossover in Amide-Functionalised 2,6-bis(pyrazol-1-yl)pyridine Iron(II) Complex Revealed by Variable Temperature Raman Spectroscopy and Single Crystal X-ray Diffraction.

2021 ◽  
Author(s):  
Max Attwood ◽  
Hiroki Akutsu ◽  
Lee Martin ◽  
Toby J Blundell ◽  
Pierre LeMagueres ◽  
...  
Keyword(s):  
Differential Scanning Calorimetry ◽  
Raman Spectroscopy ◽  
High Temperature ◽  
Spin Crossover ◽  
Variable Temperature ◽  
Squid Magnetometry ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Complex Salts

The synthesis of a novel amide-functionalised 2,6-bis(pyrazol-1-yl)pyridine-4-carboxamide ligand (bppCONH2) is described. The complex salts [Fe(bppCONH2)2](BF4)2 and [Fe(bppCONH2)2](ClO4)2 were synthesised and characterised by SQUID magnetometry, differential scanning calorimetry, variable temperature Raman...

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