A kinetic and nuclear magnetic resonance study of methylated pyrimidine nucleosides

1983 ◽  
Vol 61 (10) ◽  
pp. 2397-2402 ◽  
Author(s):  
B. D. Allore ◽  
A. Queen ◽  
W. J. Blonski ◽  
F. E. Hruska
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Ph Dependence ◽  
Nuclear Magnetic Resonance Study ◽  
Magnetic Resonance Study ◽  
Pyrimidine Nucleosides ◽  
Spectrophotometric Methods ◽  
H Nmr ◽  
Nmr Data ◽  
The Stability ◽  
C Nmr

Alkylated pyrimidine nucleosides are of interest from the viewpoint of mutagenesis and carcinogenesis. 1H and 13C nmr data are presented for a series of 2′-deoxynucleosides methylated at the O2-, O4-, and N3-positions of the base, and discussed in terms of their physical properties. The pH dependence of the stability of the O2- and O4-methylated 2′-deoxyribosides as well as the corresponding ribosides was examined by 1H nmr and ultraviolet (uv) spectrophotometric methods.

A 19F nuclear magnetic resonance study of the conjugate Brönsted-Lewis superacid HSO3F-SbF5. Part 1

1999 ◽  
Vol 77 (11) ◽  
pp. 1869-1886 ◽  
Author(s):  
Dingliang Zhang ◽  
Markus Heubes ◽  
Gerhard Hägele ◽  
Friedhelm Aubke
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Nmr Spectra ◽  
Nuclear Magnetic Resonance Study ◽  
Magnetic Resonance Study ◽  
Formation Reaction ◽  
H Nmr ◽  
Acid Conjugate ◽  
Nmr Methods ◽  
Cis And Trans

The Brönsted-Lewis superacid HSO3F-SbF5 or "magic acid" is re-investigated by modern 19F NMR methods over a wide concentration range. The system is found to be considerably more complex than had been assumed previously. A total of 13 different anions are identified of which only five have previously been identified in magic acid. With increasing SbF5 contents the concentration of monomeric anions like [SbF6]-, [SbF5(SO3F)]-, cis- and trans-[SbF4(SO3F)2]-, and mer-[SbF3(SO3F)3]- gradually decreases. Except for [Sb2F11]-, which is present in very small concentrations only, the formation of oligomers involves exclusively μ-fluorosulfato bridges. In addition to donor (SO3F)- and acceptor (SbF5) complex formation to give [SbF5(SO3F)]- and possibly ligand redistribution, the solvolysis of SbF5 or SbF4(SO3F) in HSO3F appears to be the principal formation reaction for polyfluorosulfatofluoroantimonate(V) anions. In glass (NMR tubes) the solvolysis product HF is converted to the oxonium ion [H3O]+, which has previously been identified by 1H NMR and structurally characterized as [H3O][Sb2F11] by us.Key words: magic acid, conjugate superacid, fluorosulfuric acid, 19F NMR spectra.

A 19F nuclear magnetic resonance study of the conjugate Brønsted–Lewis superacid HSO3F–SbF5. Part II.

2002 ◽  
Vol 80 (9) ◽  
pp. 1265-1277 ◽  
Author(s):  
Jobst Kühn-Velten ◽  
Matthias Bodenbinder ◽  
Raimund Bröchler ◽  
Gerhard Hägele ◽  
Friedhelm Aubke
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Nuclear Magnetic Resonance Study ◽  
Acid System ◽  
Exchange Reactions ◽  
Magnetic Resonance Study ◽  
Dilute Solutions ◽  
H Nmr ◽  
Anionic Species ◽  
High Concentrations ◽  
Initial Process

Solutions of SbF5 in HSO3F with xSbF5 = 0.012 to 0.405 are studied by 500 MHz 1H NMR (299 K) and 471 MHz 19F NMR (213–250 K), using NMR tubes fitted with fluoropolymer lining. The initial process during dissolution is the fast solvolysis of monomeric SbF5 in HSO3F according to SbF5 + nHSO3F [Formula: see text] SbF5 – n(SO3F)n + nHF (n = 1, 2). All HF formed during solvolysis will no longer be removed by reaction with glass, but will remain in the superacid system. Besides participation in the fast formation of various fluoro-fluorosulfato anions [SbF6 – n(SO3F)n]– (n = 0, 1, 2) and acidium ions [H2X]+(solv.) (X= F, SO3F), HF is involved in slow-exchange reactions of the type [SbF6 – n(SO3F)n]–(solv.) + HF [Formula: see text] [SbF7 – n(SO3F)n– 1]–(solv.) + HSO3F (n = 1, 2) detected because of a delay of 3 months between sample preparation and measurements and confirmed by repeating theses measurements after a further 3 months. There are three notable differences to our earlier study, affecting concentrations of the fluoro-fluorosulfato antimonate anions observed: (i) in dilute solutions [SbF6]– is formed in high concentrations (34.7–76.1%), with [Sb2F11]– now clearly detected at intermediate to high SbF5 concentrations (up to 5.8%); (ii) bis-fluorosulfato anions (cis-, trans-[SbF4(SO3F)2]–) are found in much lower concentrations only, which decrease further with time, while tris-fluorosulfato anions ([SbF3(SO3F)3]–) are now no longer observed; (iii) these reduced concentrations of poly-fluorosulfato anions in dilute solutions are responsible for the formation of fewer µ-SO3F-oligomers at lower concentrations, when more SbF5 is added. As a consequence, the HSO3F–SbF5 magic acid system is now less complex than found previously and only seven anionic species are clearly observed. Key words: superacids, antimony(V) fluoroanions, 1H NMR, 19F NMR, solvolysis.

A Carbon-13 Nuclear Magnetic Resonance Study of Binding of Copper(II) to Pyrimidine Nucleotides and Nucleosides

1974 ◽  
Vol 52 (6) ◽  
pp. 924-929 ◽  
Author(s):  
George Kotowycz
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Nuclear Magnetic Resonance Study ◽  
Relaxation Rates ◽  
Magnetic Resonance Study ◽  
Pyrimidine Nucleotides ◽  
Pyrimidine Nucleosides ◽  
Nucleotides And Nucleosides ◽  
Longitudinal Relaxation ◽  
Nuclear Magnetic

The influence of paramagnetic Cu2+ ions on the proton decoupled 13C n.m.r. spectra of pyrimidine nucleosides and nucleotides has been studied. For 5′-CMP, the C5 resonance is broadened first on the addition of Cu2+ ions followed by the C2, C4, and C1′ resonances. From a comparison of the transverse and longitudinal relaxation rates of the base carbon nuclei due to the presence of Cu2+ ions, binding of Cu2+ to the N3 nitrogen of 5′-CMP is predicted. A similar broadening behavior is observed for 5′-UMP, 5′-TMP, cytidine, and uridine. This indicates that the Cu2+ ion is located near the N3 nitrogen in these Cu2+-nucleoside and -nucleotide complexes.

1H and 13C nuclear magnetic resonance study of the complexation of uranyl ion with malic acid

1982 ◽  
Vol 60 (8) ◽  
pp. 1007-1018 ◽  
Author(s):  
M. Teresa Nunes ◽  
Victor M. S. Gil ◽  
António V. Xavier
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Malic Acid ◽  
Nuclear Magnetic Resonance Study ◽  
Magnetic Resonance Study ◽  
Molar Ratios ◽  
Nmr Study ◽  
13C Nuclear Magnetic Resonance ◽  
Ph Range ◽  
C Nmr

A full pH range 1H and 13C nmr study was performed of the complexation of UO22+ with malic acid, for variable concentrations and molar ratios. Spectral evidence for the existence of at least five complexes was found, and their stoichiometry and dependence on pH were investigated. Information on the conformation of the bound ligand molecules was also obtained.

NMR Complexation Study of Several Oxyethylated Calix[4]arenes with Lithium, Sodium and Potassium Ions

1996 ◽  
Vol 61 (12) ◽  
pp. 1783-1797 ◽  
Author(s):  
Jaroslav Havlíček ◽  
Marcela Tkadlecová ◽  
Michaela Vyhnánková ◽  
Evgueni Pinkhassik ◽  
Ivan Stibor
Keyword(s):  
Sodium Cation ◽  
H Nmr ◽  
Nmr Data ◽  
Constant Determination ◽  
Close Proximity ◽  
Dinitro Derivative ◽  
The Stability ◽  
Upper Rim ◽  
Sodium And Potassium ◽  
C Nmr

The influence of calix[4]arene upper rim substitution on the complexation with Li+, Na+, K+ was studied by 1H NMR spectroscopy. Calix[4]arenes 1-4 namely 25,26,27,28-tetrakis(3-oxapentyloxy)calix[4]arene (1), its 5,17-diamino (2) and 5,17-dinitro derivative (3) as well as 25,26,27,28-tetrakis(3,6,9-trioxadecyloxy)calix[4]arene (4) having four monoalkyloligoethylene glycol chains on the lower rim have been studied. No complexation has been observed for Li+. Two electron-donating NH2 groups on the calixarene upper rim (compound 2) improve the complexation ability for Na+ and K+ compared with parent calixarene 1. The electron-withdrawing nitro groups in 3 have the opposite influence. It seems that the complexation of alkali metal ions studied is not significantly influenced by the increasing number of donor atoms (from eight in 1 to sixteen in 4) available for complexation on the lower rim. The position of sodium cation in 1 . Na+ and 4. Na+ is supposed to be in close proximity of phenolic oxygens based on 1H and 13C NMR data. The error analysis is given for the stability constant determination from NMR data.

15N and 77Se Nuclear Magnetic Resonance Study of Selenium Diimides and Aminoselenanes

1993 ◽  
Vol 48 (10) ◽  
pp. 1307-1314 ◽  
Author(s):  
Bernd Wrackmeyer ◽  
Berthold Distler ◽  
Silke Gerstmann ◽  
Max Herberhold
Keyword(s):  
Crystal Structure ◽  
Nuclear Magnetic Resonance ◽  
Nmr Spectra ◽  
Decomposition Product ◽  
Nuclear Magnetic Resonance Study ◽  
Coupling Constants ◽  
Magnetic Resonance Study ◽  
Nmr Data ◽  
Cp Mas Nmr ◽  
Membered Heterocycle

Selenium diimides R(NSeN)R [R = tBu (1a), tOct (1b)], the eight-membered heterocycle tBuN(SeSeSe)2NtBu (2) and the aminoselenanes of the type [R(Cl3Si)N]2Se (4a,b) and [(Me3Si)2N]2Se (5) were studied by multinuclear NMR with emphasis on 15N NMR for detection of coupling constants J(77Se15N). The selenium diimides possess the largest values of 1J(77Se15N) observed so far (1a: 158.4 and 163.5 Hz; 1 b: 158.6 and 162.8 Hz). Compound 1 b was found to be much more stable than 1a, the heterocycle 2 being the major decomposition product of 1a. The selenium diimides (1a,b) react readily with hexachlorodisilane to give the bis[alkyl(trichlorosilyl)amino]selenanes 4a,b. The solid state 13C, 15N, 29Si and 77Se CP/MAS NMR spectra of bis[bis(trimethylsilyl)amino]selenane (5) gave results in accord with the known crystal structure, and there is agreement with the solution state NMR data

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