Metal ion – biomolecule interactions. X. Synthesis, spectroscopic and magnetic resonance investigations of methylmercury(II) complexes of the sulfur modified nucleosides 6- mercaptopurine riboside and 2-amino-6-mercaptopurine riboside

1986 ◽  
Vol 64 (3) ◽  
pp. 442-448 ◽  
Author(s):  
E. Buncel ◽  
R. Kumar ◽  
A. R. Norris
Keyword(s):  
Aqueous Solution ◽  
Metal Ion ◽  
Chemotherapeutic Agents ◽  
Modified Nucleosides ◽  
Coupling Constants ◽  
Heterocyclic Ligands ◽  
Methylmercury Poisoning ◽  
Insight Into ◽  
C Nmr ◽  
Ligand Bond

A number of methylmercurated complexes of 6-mercaptopurine riboside and 2-amino-6-mercaptopurine riboside (6-MNucH2) containing S-bound CH3Hg(II) in neutral and cationic complexes (as in [CH3Hg(6-MNucH)] and [CH3Hg(6-MNucH2)]NO3), S- and N-bound CH3Hg(II) (as in [(CH3Hg)2(6-MNucH)]NO3), and S-, N-, C-bound CH3Hg(II) (as in [(CH3Hg)3(6-MNuc)]NO3) have been prepared in aqueous solution at appropriate pH and mole ratios of the constituents. The complexes were characterized by means of 1H and 13C nmr and ir spectroscopy and elemental analysis. Formation of C-bound methylmercurated species extends our previous results obtained with xanthosine, inosine, and imidazole derivatives, and substantiates our proposal that activation through electrophilic coordination at N(7) is a requirement for C(8)—H abstraction. 2J(1H–199Hg) coupling constants, measured in (CD3)2SO for a number of CH3Hg(II) complexes of N-, S-, and C-donor heterocyclic ligands, including the 6-mercaptopurine riboside of the present study, correlate well with the 1J(13C–199Hg) coupling constants, according to 1J = 8.4602J − 155.6. The significance of this correlation in terms of the strength of the Hg–ligand bond is considered. The results could provide insight into the apparent selectivity of binding of CH3Hg(II) by bio-ligands, as well as in the design of chemotherapeutic agents for the treatment of methylmercury poisoning.

Bonding in Cyclobutabenzene Chromium Tricarbonyl Complexes Studied by 13C NMR. Evidence of π-Bond Localization from 1J(13C,13C)

1995 ◽  
Vol 50 (4) ◽  
pp. 483-487 ◽  
Author(s):  
H. Butenschön ◽  
B. Gabor ◽  
R. Mynott ◽  
H. G. Wey
Keyword(s):  
13C Nmr ◽  
Coupling Constants ◽  
Chromium Tricarbonyl ◽  
Chromium Complex ◽  
Nmr Parameters ◽  
Chromium Tricarbonyl Complexes ◽  
The One ◽  
Bond Localization ◽  
Insight Into ◽  
C Nmr

The 13C NMR parameters of several cyclobutabenzenes ( 1a - 1e ) and their corresponding complexes (cyclobutabenzene)M(CO)3 (M = Cr, Mo, W, 2 - 4 ) are presented and discussed. Two cyclobutabenzenes 1b and 1d and their chromium tricarbonyl complexes 2b and 2d have been examined in greater detail: the signal assignments have been confirmed by 2 D-INADEQUATE and the one bond coupling constants 1J(13C ,13C) measured at natural abundance using 1 D-INADEQUATE . Although the results provide no insight into why the chromium complex of 1,2 - dioxocyclobutabenzene (1e) is much more reactive at the keto groups than 1e itself, they do reveal a weak but not negligible alternation of the carbon s-character in the C - C bonds of the 6-membered rings both in the free cyclobutabenzenes and in the complexes, thus providing evidence for slight bond fixation (Mills-Nixon effect).

Sugar Interaction with Metals in Aqueous Solution: Indirect Determination from Infrared and Direct Determination from Nuclear Magnetic Resonance Spectroscopy

2003 ◽  
Vol 57 (4) ◽  
pp. 466-472 ◽  
Author(s):  
Philippe Rondeau ◽  
Sandrine Sers ◽  
Dhanjay Jhurry ◽  
Frederic Cadet
Keyword(s):  
Aqueous Solution ◽  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Metal Ion ◽  
Direct Determination ◽  
Resonance Spectroscopy ◽  
Absorption Bands ◽  
Ft Ir ◽  
C Nmr ◽  
Nuclear Magnetic

In this article, mid-infrared Fourier transform (Mid-FT-IR) and carbon thirteen nuclear magnetic resonance (13C NMR) spectroscopy have been used to determine possible interactions between sucrose and various alkali or alkaline earth metals in aqueous solution. In the presence of these metals, significant shifts in the absorption bands of sucrose were noted by mid-FT-IR coupled with principal component analysis (PCA). These shifts were explained on the basis of weakening of the H-bond network between sucrose and water and possible interactions between sucrose and the metal ion. Factorial maps were established and the spectral patterns obtained show that these interactions vary according to the nature of the metal ion. 13C NMR analysis showed that the carbon atoms of sucrose undergo shielding or deshielding in the presence of metal ions in aqueous solutions. Two factors were invoked to account for the variation of chemical shifts: the rupture of hydrogen bonds due to hydration of the metal ion and the possible coordination of the metal ion to the oxygen atoms of sucrose.

Carbohydrate metal ion complexes. Interaction of D-glucono-1,5-lactone with Zn(II), Cd(II), and Hg(II) ions in the solid and aqueous solution, studied by 13C-NMR, FT-IR, and X-ray powder diffraction measurements

1989 ◽  
Vol 67 (4) ◽  
pp. 651-654 ◽  
Author(s):  
H. A. Tajmir-Riahi
Keyword(s):  
Aqueous Solution ◽  
Metal Ions ◽  
Powder Diffraction ◽  
Metal Ion ◽  
Binding Mode ◽  
X Ray ◽  
Group Metal ◽  
Carboxylate Oxygen ◽  
Ft Ir ◽  
C Nmr

D-Glucono-1,5-lactone interaction with zinc group metal ions has been studied in aqueous solution and solid salts of the type Zn(D-gluconate)2.2H2O, Cd(D-gluconate)2 and Hg(D-gluconate)2 have been isolated. These metal sugar salts were characterized by elemental analysis, 13C-NMR, FT-IR spectroscopy, and X-ray powder diffraction measurements.X-ray powder diffraction diagrams and other spectroscopic evidence showed that Zn(D-gluconate)2.2H2O is isomorphous with the structurally identified Mn(D-gluconate)2.2H2O, suggesting a similar metal–sugar binding mode, through a carboxylate oxygen atom (O-1) and an OH group of the two sugars anions as well as to two H2O molecules, resulting in a six-coordinate Zn(II) ion. The Cd(II)- and Hg-D-gluconate salts are not similar and show dissimilarities to the Zn(II) compound. The Cd(II) ion binds to two D-gluconate anions possibly through the carboxylate O-1 and sugar O(2)—H, and O(3)—H groups of each anion, giving a six-coordinate Cd(II) ion. The Hg(II) ion is possibly four-coordinate, binding to two sugar anions via a carboxylate O-1 and O(2)—H groups of each D-gluconate anion. The zinc group metal-D-gluconate salts are aggregated through bridging sugar OCO− groups with sugar anion possibly having bent-chain conformation. Keywords: carbohydrate, metal ions, 13C-NMR, FT-IR, X-ray powder diffraction.

Conformational structure of ethylene glycol dibenzoate. Vibrational and NMR spectra

1981 ◽  
Vol 46 (8) ◽  
pp. 1913-1929 ◽  
Author(s):  
Bohdan Schneider ◽  
Pavel Sedláček ◽  
Jan Štokr ◽  
Danica Doskočilová ◽  
Jan Lövy
Keyword(s):  
Ethylene Glycol ◽  
Vibrational Spectra ◽  
Nmr Spectra ◽  
Coupling Constants ◽  
Conformational Structure ◽  
Infrared And Raman Spectra ◽  
H Nmr ◽  
Liquid States ◽  
Crystalline Forms ◽  
C Nmr

It was found that three crystalline forms of ethylene glycol dibenzoate can be prepared. Infrared and Raman spectra of these three forms, as well as of the glassy and liquid states, were measured. From 3JHH coupling constants obtained by analysis of the 13C satellite band of the -CH2- group in 1H NMR spectra, and from the 3JCH coupling constants of the -CO.O.CH2- fragment obtained by analysis of the carbonyl band in 13C NMR spectra it was found that in the liquid state the -CH2-CH2- group exists predominantly in the gauche conformational structure, and the bonds C-O-C-C assume predominantly a trans orientation. The results of the analysis of NMR and vibrational spectra were used for the structural interpretation of conformationally sensitive bands in vibrational spectra of ethylene glycol dibenzoate.

Carbon-13 and nitrogen-14 NMR spectra of 1-(substituted phenyl)pyridinium salts

1980 ◽  
Vol 45 (10) ◽  
pp. 2766-2771 ◽  
Author(s):  
Antonín Lyčka
Keyword(s):  
Heavy Water ◽  
Nmr Spectra ◽  
Chemical Shifts ◽  
Coupling Constants ◽  
Pyridinium Salts ◽  
Nmr Signals ◽  
C Nmr

The 13C and 14N NMR spectra of 1M solutions of 1-(substituted phenyl)pyridinium salts (4-CH3, 4-OCH3, H, 4-Cl, 4-Br, 4-I, 3-NO2, 4-NO2, 2,4-(NO2)2 (the 13C NMR only)) have been measured in heavy water at 30 °C. The 13C and 14N chemical shifts, the 1J(CH) coupling constants, some 3J(CH) coupling constants, and values of half-widths Δ 1/2 of the 14N NMR signals are given. The 13C chemical shifts of C(4) correlate with the σ0 constants (δC(4) = (1.79 ± 0.097) σ0 + (147.67 ± 0.041)), whereas no correlation of the nitrogen chemical shifts with the σ constants has been found. The half-widths Δ 1/2 correlate with the σ0 constants (Δ 1/2 = (76.2 ± 4.9) σ0 + (106.4 ± 2.2)) except for 1-phenylpyridinium chloride.

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.

Kinetics and mechanism of the reaction of iron(III) with 6-methyl-2,4-heptanedione and 3,5-heptanedione

1990 ◽  
Vol 55 (8) ◽  
pp. 1984-1990 ◽  
Author(s):  
José M. Hernando ◽  
Olimpio Montero ◽  
Carlos Blanco
Keyword(s):  
Aqueous Solution ◽  
Metal Ion ◽  
Activation Parameters ◽  
Enol Form ◽  
Kinetics And Mechanism ◽  
Kinetic Constants ◽  
Steric Factors ◽  
Kinetics Of ◽  
Mechanism Of The Reaction

The kinetics of the reactions of iron(III) with 6-methyl-2,4-heptanedione and 3,5-heptanedione to form the corresponding monocomplexes have been studied spectrophotometrically in the range 5 °C to 16 °C at I 25 mol l-1 in aqueous solution. In the proposed mechanism for the two complexes, the enol form reacts with the metal ion by parallel acid-independent and inverse-acid paths. The kinetic constants for both pathways have been calculated at five temperatures. Activation parameters have also been calculated. The results are consistent with an associative activation for Fe(H2O)63+ and dissociative activation for Fe(H2O)5(OH)2+. The differences in the results for the complexes of heptanediones studied are interpreted in terms of steric factors.

scholarly journals Meta-studtite stability in aqueous solutions. Impact of HCO3−, H2O2 and ionizing radiation on dissolution and speciation

2021 ◽  
Author(s):  
Junyi Li ◽  
Zoltán Szabó ◽  
Mats Jonsson
Keyword(s):  
Aqueous Solution ◽  
Ionizing Radiation ◽  
Aqueous Solutions ◽  
Carbonate Complexes ◽  
C Nmr

Four different uranyl-(peroxide)-carbonate complexes were identified during studtite and meta-studtite dissolution in aqueous solution containing 10 mM HCO3− by 13C NMR.

scholarly journals H2O coordination in macropa complexes of f elements (Ac, La, Lu): feasibility of the 11th coordination site

2021 ◽  
Author(s):  
Attila Kovács ◽  
Zoltán Varga
Keyword(s):  
Aqueous Solution ◽  
Metal Ion ◽  
Density Functional ◽  
Molecular Level ◽  
Density Functional Theory Calculations ◽  
Functional Theory ◽  
Coordination Site ◽  
Additional Ligand ◽  
Ligand Coordination ◽  
Bonding Properties

AbstractThe feasibility of an additional ligand coordination at the 11th coordination site of actinium, lanthanum, and lutetium ions in 10-fold coordinated macropa complexes has been studied by means of density functional theory calculations. The study covered the two main macropa conformers, Δ(δλδ)(δλδ) and Δ(λδλ)(λδλ), favoured by larger (Ac3+, La3+) and smaller (Lu3+) ions, respectively. At the molecular level, the coordination of H2O is the most favourable to the largest Ac3+ while only slightly less to La3+. Protonation of the picoline arms enhances the coordination by shifting the metal ion closer to the open site of the ligand. The choice of macropa conformer has only a slight influence on the strength and bonding properties of the H2O coordination. Aqueous solution environment decreases considerably the energy gain of H2O coordination at the 11th coordination site.

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