Metal ion – biomolecule interactions. IV. Methylmercury(II) complexes of l-methylimidazoline-2-thione (methimazole), a potentially useful protective agent in organomercurial intoxication

1982 ◽  
Vol 60 (24) ◽  
pp. 3033-3038 ◽  
Author(s):  
Erwin Buncel ◽  
Albert R. Norris ◽  
Spencer E. Taylor ◽  
William J. Racz
Keyword(s):  
Metal Ion ◽  
Analytical Data ◽  
Free Ligand ◽  
Binding Mode ◽  
Protective Agent ◽  
Nmr Spectrum ◽  
H Nmr ◽  
High Affinity ◽  
Nmr Data ◽  
Tautomeric Forms

Two 1:1 methylmercury(II)-1-methylimidazoline-2-thione (methimazole, MeImSH) complexes, [MeHg(MeImSH)]NO3 and [MeHg(MeImS)], have been isolated from aqueous solution under acidic and basic conditions, respectively. 1H nmr and ir spectroscopy, as well as analytical data, were used to characterize the complexes. The nmr data, in particular, lead to the conclusion that the principal binding mode under both sets of conditions involves the sulfur atom at C2. However, under conditions of 2:1 (MeHgII:MeImSH) stoichiometry, binding to N3 is also found to occur. These interpretations have necessitated a reexamination of the 1H nmr spectrum of the free ligand, in particular with respect to assignment of NH and SH resonances corresponding to the two possible tautomeric forms. It has been found in this work that 1-methylimidazoline-2-thione shows a high affinity for MeHgII binding, which may be pertinent with respect to a previous report concerning the protective nature of this compound in organomercurial intoxication.

scholarly journals Axial Coordination of Phosphine or Phosphite to Iron(III) Chlorophyll a

1995 ◽  
Vol 50 (8) ◽  
pp. 1222-1228 ◽  
Author(s):  
Hidenari Inoue ◽  
Hiromi Akahori ◽  
Yuri Ohno ◽  
Katsuo Nakazawa ◽  
Yoshimune Nonomura ◽  
...  
Keyword(s):  
Chlorophyll A ◽  
Iron Atom ◽  
Free Ligand ◽  
Electronic Configuration ◽  
Photoelectron Spectra ◽  
Field Range ◽  
Nmr Spectrum ◽  
X Ray ◽  
Axial Coordination ◽  
H Nmr

The adduct formation of iron(III) chlorophyll a with phosphines or phosphites has been studied by spectroscopic methods. The red-shift in the Soret and Q bands caused by the axial coordination of phosphine or phosphite to iron(III) chlorophyll a is an evidence for the autoreduction of the central iron(III) ion. The 31P{1H} NMR spectrum of bis-adducts measured in the presence of excess phosphine or phosphite ligands gave a single peak in the down field range compared to that of the corresponding free ligand. The ESR and X-ray photoelectron spectra have revealed that the central iron atom of the bis-adduct of iron chlorophyll a with phosphines or phosphites is divalent and in the low-spin state. The axial coordination of phosphine or phosphite influences the electronic configuration of the central iron atom and the macrocyclic chlorine ligand to induce the autoreduction of the central iron(III) ion.

scholarly journals THE METAL COMPLEXES OF NOVEL SCHIFF BASE CONTAINING ISATIN: CHARACTERIZATION, ANTIMICROBIAL, ANTIOXIDANT AND CATALYTIC ACTIVITY STUDY

2019 ◽  
pp. 206-210
Author(s):  
VAIRALAKSHMI M ◽  
PRINCESS R ◽  
JOHNSON RAJA S
Keyword(s):  
Catalytic Activity ◽  
Metal Complexes ◽  
1H Nmr ◽  
Metal Ion ◽  
Analytical Data ◽  
Free Ligand ◽  
Molar Conductance ◽  
Diffusion Method ◽  
Spectral Studies ◽  
Standard Drug

Objectives: The aim of our work was to synthesize novel mixed ligand-metal complexes and evaluation of antimicrobial, antioxidant assay, and analysis of catalytic oxidation of cyclohexane. Methods: The complexes were characterized by means of various physicochemical techniques such as elemental analysis, molar conductance, magnetic susceptibility, infrared (IR), electronic absorption, 1H NMR (proton magnetic resonance), and mass spectral studies. The antimicrobial screening study was done by disc diffusion method. The catalytic activity of the complexes was observed in the oxidation of cyclohexane using eco-friendly hydrogen peroxide as oxidant. Results: On comparing the 1H NMR and IR spectral data of free ligand and its complexes, it was found to be azomethine (CH=N) proton which is formed in the free ligand. During complexation, the azomethine proton is coordinated to the metal ion and the phenolic oxygen is coordinated to the metal ion by deprotonation. The analytical data and mass spectra of the ligand and the complexes confirm the stoichiometry of metal complexes as being of the (MLY)Cl type and the metal to ligand ratio is 1:1. The antimicrobial, antioxidant, and catalytic potential were evaluated and the result shows the better activity of the complexes than the ligand. Conclusion: It was found to be copper(II) and zinc(II) complexes which are effective against all the bacteria when compared to standard drug streptomycin. Copper(II) complex was found to be effective antibacterial agent against Aspergillus niger and Aspergillus flavus in comparison to the standard drug Nystatin. The zinc complex exhibited good catalytic activity.

Complexes of lanthanide iodides with 3-methylpyridine-1-oxide

1976 ◽  
Vol 54 (20) ◽  
pp. 3169-3174 ◽  
Author(s):  
Lakshminarayanan Ramakrishnan ◽  
Sundaresa Soundararajan
Keyword(s):  
Metal Ion ◽  
Pyridine Ring ◽  
Proton Nmr ◽  
Chemical Analyses ◽  
Nmr Spectrum ◽  
Restricted Rotation ◽  
Group Proton ◽  
Nmr Data

Complexes of lanthanide iodides with 3-methylpyridine-1-oxide of the formula Ln(3-MePyO)8I3.xH2O where x = 0 for Ln = La and Tb, x = 1 for Ln = Pr, and x = 2 for Ln = Nd, Sm, Dy, Yb, and Y have been prepared and characterized by chemical analyses, conductance, infrared, proton nmr, and DTA data. Infrared and proton nmr data have been interpreted in terms of the coordination of the ligand to the metal ion through the oxygen of the N—O group. Proton nmr spectrum of the Yb(III) complex is indicative of a restricted rotation of the pyridine ring about the N—O bond.

scholarly journals Spectroscopic, Thermal and Antimicrobial Study of Some Transition Metal(II) Complexes of β-Diketones

2020 ◽  
Vol 32 (12) ◽  
pp. 3173-3178
Author(s):  
Rekha Rani ◽  
Umesh Kumar ◽  
Deepak Kumar ◽  
Siteshwar Pd. Yadav ◽  
Arjun Kr. Sinha ◽  
...  
Keyword(s):  
Antimicrobial Activity ◽  
Metal Complexes ◽  
Metal Ion ◽  
Free Ligand ◽  
Octahedral Symmetry ◽  
Enolic Form ◽  
Antifungal Activities ◽  
Tautomeric Forms ◽  
Distorted Octahedral ◽  
Antimicrobial And Antifungal Activities

A novel heterocyclic based β-diketone has been synthesized by the condensation of pyrazole-1-acetylchloride and sodium acetophenone. The product 1-phenyl-4-(pyrazole-1-yl)butane- 1,3-dione has been used for complexation with Mn(II), Fe(II) and Co(II) metal ions. The ligand β-diketone is found to exist in keto-enol tautomeric forms. The comparision of infrared spectra of complexes clearly indicates the coordination of the ligand from its enolic form. The magnetic moment and electronic spectra of all the metal complexes leads to the distorted octahedral symmetry around the metal ion. The ligand as well as its metal complexes has been screened for antimicrobial activity and antifungal activities. It is observed that the antimicrobial and antifungal activities get enhanced in complexes in respect to the free ligand.

Divalent Transition Metal Complexes of Potentially Polynucleating 8-Hydroxyquinoline-5-sulfonyl Hydrazone

1994 ◽  
Vol 59 (8) ◽  
pp. 1800-1808
Author(s):  
Said A. Ibrahim ◽  
Sahar A. El-Gyar ◽  
Aly A. Abdel-Hafez ◽  
Mostafa K. Rabia
Keyword(s):  
Antimicrobial Activity ◽  
Nmr Spectroscopy ◽  
Transition Metal Complexes ◽  
Elemental Analysis ◽  
Metal Ion ◽  
Free Ligand ◽  
Chelating Agent ◽  
Conductivity Measurements ◽  
H Nmr ◽  
Trinuclear Complexes

The Co(II), Ni(II), Cu(II) and Zn(II) complexes with 8-hydroxyquinoline-5-sulfonylhydrazone are described. It has been found that the ligand can coordinate to metal ion as a monobasic bidentate chelating agent and it can form di- and trinuclear complexes while acting as a dibasic tetradentate one. The structure of the isolated complexes have been suggested on the basis of elemental analysis, IR, 1H NMR spectroscopy and conductivity measurements. The complexes are all formulated as four-coordinate. Some complexes showed enhanced antimicrobial activity relative to the free ligand.

Application of NMR Spectroscopy to the Study of Piperidine Derivatives. Part III: Molecular Dynamics Study of N-Benzyl-4-[N-Benzyloxyacetyl)-(2-Fluorophenyl)]Amino-3-Methyl Piperidine

1993 ◽  
Vol 47 (3) ◽  
pp. 357-359 ◽  
Author(s):  
A. L. Cholli ◽  
M. L. Lau
Keyword(s):  
Molecular Dynamics ◽  
Nmr Spectroscopy ◽  
High Resolution ◽  
Detailed Analysis ◽  
Room Temperature ◽  
Variable Temperature ◽  
Proton Nmr ◽  
Nmr Spectrum ◽  
H Nmr ◽  
Nmr Data

High-resolution 1H NMR has been used to study the molecular dynamics of the piperidine derivative. Detailed analysis of variable temperature NMR data allowed the identification of the origin of two sets of methyl resonance peaks with unequal intensities in the room-temperature proton NMR spectrum of the compound.

scholarly journals Synthesis, Characterization, and Photophysical Studies of Some Novel Ruthenium(II) Polypyridine Complexes Derived from Benzothiazolyl hydrazones

2013 ◽  
Vol 2013 ◽  
pp. 1-7 ◽  
Author(s):  
Shaikh Khaled ◽  
Mohammed Zamir Ahmed ◽  
Firdous G. Khan ◽  
Shaikh Kabeer Ahmed
Keyword(s):  
Electronic Absorption ◽  
Elemental Analysis ◽  
Metal Ion ◽  
Analytical Data ◽  
Azomethine Nitrogen ◽  
Spectral Studies ◽  
H Nmr ◽  
Phenolic Oxygen ◽  
Photophysical Studies ◽  
Polypyridine Complexes

A series of five benzothiazolylhydrazone ligands 3a–3e and their seven novel Ru(II) polypyridine complexes 4a–4d, 5a, 5d, 5e of the type [Ru(N–N)2(L)]Cl2, where (N–N)2 is 2,2′-bipyridine (bpy)2 or 1,10-phenanthroline (phen)2 and (L) is ligands 3a–3e, have been synthesized and characterized by elemental analysis, IR, 1H NMR, electronic absorption, and emission spectral studies. The interpretation of the analytical data revealed that the ligands coordinate with the metal ion in a bidentate fashion through azomethine nitrogen and phenolic oxygen to form complexes. These ligands and complexes also exhibit absorption and luminescence properties.

Solvent-dependent rotational phenomena in μ-nitrido-[2,3,9,10,16,17,23,24-octa(n-pentoxy)phthalocyaninato]diiron complex

2011 ◽  
Vol 15 (07n08) ◽  
pp. 583-591 ◽  
Author(s):  
Evgeny V. Kudrik ◽  
Pavel Afanasiev ◽  
Denis Bouchu ◽  
Alexander B. Sorokin
Keyword(s):  
Spectroscopic Properties ◽  
Oxidation States ◽  
Mutual Orientation ◽  
Nmr Spectrum ◽  
H Nmr ◽  
Nmr Data ◽  
Significant Difference ◽  
Green Form ◽  
The Difference ◽  
X Ray Absorption

The syntheses and spectroscopic properties of new μ-nitrido-[2,3,9,10,16,17,23,24-octa(n-pentoxy)phthalocyaninato]diiron complexes in Fe(IV)Fe(IV) and Fe(+3.5)Fe(+3.5) oxidation states are reported. UV-vis spectra of both dimers demonstrate a strong solvatochromic behavior. UV-vis and 1H NMR data reveal the presence of two different forms for both oxidation states in apolar and polar solvents. Fe K-edge X-ray absorption near-edge structures (XANES) spectra of two Fe(IV)Fe(IV) forms also show a significant difference: pre-edge feature in toluene is shifted to higher energy compared to that in tetrahydrofuran. The difference of properties between two forms is explained by solvent-dependent mutual orientation of two phthalocyanine rings. A strong sharp Q-band in UV-vis spectrum at 642 nm and small splitting of aromatic protons (0.18 ppm) in 1H NMR spectrum observed in apolar solvents (toluene, benzene, cyclohexane) imply that the green form is in more symmetric D4d configuration. In turn, a broad multipreaked Q-band and relatively high splitting of aromatic protons (0.56 ppm) observed in THF and CH2Cl2 for the blue form are in agreement with less symmetric D4 conformation. The Fe(μ-N)Fe structure is relatively rigid showing no free rotation at room temperature in NMR time scale. Tuning of the structure of N-bridged diiron macrocyclic complexes by introduction of substituents and modification of electronic properties of the complexes via conformation changes might be useful for optimization of their catalytic properties as well as for their potential application in sensors.

Unexpected Keto-enol Tautomerism in the Cyclopyridinophane Class Direct and indirect proofs

2008 ◽  
Vol 59 (10) ◽  
Author(s):  
Paul Ionut Dron ◽  
Neculai Doru Miron ◽  
Gheorghe Surpateanu
Keyword(s):  
Nmr Spectroscopy ◽  
1H Nmr ◽  
Stable Conformer ◽  
Ph Measurements ◽  
Theoretical Methods ◽  
Nmr Data ◽  
Tautomeric Forms ◽  
New Compounds

The paper presents the synthesis of cyclo (bis-paraquat p-phenylene p-phenylene-carbonyl) tetrakis (hexafluorophosphate), named �CETOBOX�, and the closely related structural determinations. This compound exists in three tautomeric forms. These forms were evidentiated by NMR-data (1H-NMR, TOCSY, COSY, NOESY), UV-Vis spectra coupled with pH measurements and by synthesis. As the �CETOBOX� gives �in situ� only the corresponding monoylide, the synthesis of a new fluorescent indolizine cyclophane has been performed by a 3+2 cycloaddition. All structures of the new compounds presented herein have been established by NMR spectroscopy. Also, theoretical methods (MM3, AM1, AM1-COSMO and B88LYPDFT) have been used to determine the most stable conformer structures.

21,22-Disubstituted 18α,19βH-Ursane Derivatives with Oxabicyclooctane System in Ring E

1993 ◽  
Vol 58 (1) ◽  
pp. 173-190 ◽  
Author(s):  
Eva Klinotová ◽  
Jiří Klinot ◽  
Václav Křeček ◽  
Miloš Buděšínský ◽  
Bohumil Máca
Keyword(s):  
Spectral Data ◽  
Spin Systems ◽  
Coupling Constants ◽  
Complete Analysis ◽  
Nmr Spectrum ◽  
Proton Proton ◽  
H Nmr ◽  
Proton Coupling ◽  
C Nmr

Reaction of 3β-acetoxy-21,22-dioxo-18α,19βH-ursan-28,20β-olide (IIIa) and 20β,28-epoxy-21,22-dioxo-19α,19βH-ursan-3β-yl acetate (IIIb) with diazomethane afforded derivatives XII-XIV with spiroepoxide group in position 21 or 22, which were further converted into hydroxy derivatives XV and XVII. Ethylene ketals VIII-X were also prepared. In connection with the determination of position and configuration of the functional groups at C(21) and C(22), the 1H and 13C NMR spectral data of the prepared compounds are discussed. Complete analysis of two four-spin systems in the 1H NMR spectrum of bisethylenedioxy derivative Xb led to the proton-proton coupling constants from which the structure with two 1,4-dioxane rings condensed with ring E, and their conformation, was derived.

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