bluuebunny/crossref_metadata_2025_split huggingface dataset:
1H and 13C chemical shift assignments of para‐substituted aryl 2‐acetamido‐2‐deoxy‐β‐D‐glucopyranosides
Authors: Roy René , Tropper François D. , Williams Antony J. 
Published: May 2005

AbstractThe 1H and 13C NMR spectra of twenty aryl 2‐acetamido‐2‐deoxy‐β‐D‐glucopyranosides and eighteen aryl 3,4,6‐tri‐O‐acetyl‐2‐acetamido‐2‐deoxy‐β‐D‐glucopyranosides have been obtained and assigned. The three‐bond proton coupling constants of these compounds were also obtained.
Structure and conformation of the hypermodified purine nucleoside wyosine and its isomers: A comparison of coupling constants and distance geometry solutions
Authors: Sierzputowska‐Gracz Hanna , Guenther R. H. , Agris P. F. , Folkman W. , Golankiewicz B. 
Published: May 2005

AbstractThe structural determination of modified mononucleosides is important for understanding the chemistry, structure and functional changes that they impart to the nucleic acids in which they occur. Empirical analyses of J(HH) couplings have been used to describe nucleoside conformational equilibria for the glycosidic angle (syn‐anti), the C‐4′C‐5′ exocyclic rotamers (gauche+, gauche− and trans) and the sugar pucker (N–S). Distance geometry calculations with distance constraints determined from nuclear Overhauser effects (NOE) should provide equally satisfactory structural information. Proton and carbon chemical shifts and coupling constants were used to describe structural parameters for the tricyclic nucleosides wyosine, 4,9‐dihydro‐4,6‐dimethyl‐9‐oxo‐3‐(β‐D‐ribofuranosyl)imidazo(1,2‐a)purine, and three of its isomers. Using distance geometry calculations with the 14‐19 observed NOEs per nucleoside as distance constraints, multiple structures could be produced with less than 1 Å relative mean standard deviation for the positioning of all atoms. The two methods of structural determination were consistent in their qualitative determination of syn‐anti conformation and sugar pucker.
Measurement of one‐bond proton‐carbon coupling constants of saccharides
Authors: Uhrínova Stanislava , Uhrían Dušan , Liptaj Tibor , Bella Juraj , Hirsch Ján 
Published: May 2005

AbstractSeveral NMR experiments, one proton and several carbon detected, were used for the determination of 1J(C,H) values in saccharides. Couplings of anomeric carbons were measured from the 13C satellites in 1H NMR spectra. The simultaneous application of several purging schemes resulted in a very good suppression of the proton signals from 12C molecules. 1J(C,H) values of all saccharides were determined by 2D J‐resolved spectroscopy using an INEPT‐type pulse sequence with a BIRD pulse for the suppression of nJ(C,H) and folding in F1. Rules for the calculation of the correct values of 1J(C,H) from the observed reduced splittings are proposed. 1J(C,H) values were also obtained from a set of J‐modulated one‐dimensional 13C spectra. A procedure for the determination of 1J(C,H) values from only two one‐dimensional experiments is proposed. Mannose derivatives (mono‐ and poly‐saccharides) were used to test and compare the individual methods. Differences in 1J(C,H) values for C‐2 and C‐3 were used for the chemical shift assignment of these carbons.
Intermolecular and intramolecular effects on the 1H and 13C shielding in some gaseous hydrocarbons at various temperatures—theory and discussion
Authors: Raynes William Thomas , Bennett Brian 
Published: May 2005

AbstractValues of the first‐order derivatives of proton and 13C shielding with respect to gas density for several hydrocarbons over the temperature range 180–370 K are fitted to a long‐standing theory. The theory includes consideration of (a) the ‘site factor’ allowing for the position of the resonating nucleus in the molecule and (b) the presence of higher order interactions in the intermolecular potential. The resulting B coefficients are improved as a result of (b) and in the case of 13C shielding there is almost totally satisfactory agreement. Values of dσ0/dT, the temperature dependence of the 1H and 13C shielding extrapolated to zero density, are discussed in terms of the displacements of the nuclei from equilibrium geometry. The results suggest that attempts to relate the temperature dependence of chemical shifts of conformationally mobile compounds to the varying populations of a small number of conformers are naive. It is also necessary to take account of contributions from distorted conformers which proliferate increasingly at higher temperatures. The positive values of dσ0/dT observed for some carbon nuclei are also believed to be related to torsional motion.
Two‐dimensional nuclear magnetic resonance of sesquiterpenes. 4—Application to complete assignment of 1H and 13C NMR spectra of some aromadendrane derivatives
Authors: Faure Robert , Ramanoelina Armand R. P. , Rakotonirainy Olivier , Bianchini Jean‐Pierre , Gaydou Emile M. 
Published: May 2005

AbstractThe total assignment of the 1H and 13C NMR spectra of five aromadendrane derivatives, (+)‐aromadendrene (1), (−)‐alloaromadendrene (2), (+)‐ledene (3), (−)‐dehydroaromadendrane (4), (−)‐globulol (5) and (+)‐viridiflorol (6) has been performed. The 13C spectral assignment of globulol was achieved from DEPT and double quantum coherence measurements. The concerted application of 1H1H homonuclear and 1H13C heteronuclear two‐dimensional chemical shift correlations provided other 13C and all 1H chemical shifts. Moreover, the 1H assignment for compounds 13 was reexamined from the high‐field analysis of proton‐proton coupling constants.
Synthesis and 1H, 13C and 31P NMR studies of 2,10‐dichloro‐6‐aryloxy‐12H‐dibenzo [d,g] [1,3,2]‐dioxaphosphocin 6‐oxides
Authors: Reddy C. Devendranath , Reddy R. S. N. , Raju C. Naga , ElMasri Marwan , Berlin K. Darrell , Subramanian Shankar 
Published: May 2005

AbstractThe spectral analyses and syntheses of several novel 2,10‐dichloro‐6‐aryloxy/alkyl‐12H‐dibenzo [d,g] [1,3,2] dioxaphosphocin 6‐oxides have been achieved. Long‐range coupling [5J(H,P) = 2.4 Hz] was observed between phosphorus and the bridged methylene protons. Based upon NMR data, a tub‐like conformation is proposed for the central eight‐membered dioxaphosphocin ring. Long‐range 2J(P,O,C) and 3J(P,O,C,C) couplins were determined, as were the 31P chemical shifts for sixteen members of these new heterocycles. A variable‐temperature study of one member suggested the presence of a tub form as a reasonable candidate for one major conformer but the presence of other forms was also implied.
39K NMR study of potassium naphthalenide solutions
Authors: Sokói Maria , Grobelny Janusz , Kowalczuk Marek 
Published: May 2005

AbstractPotassium naphthalenide solutions in tetrahydrofuran were studied by means of 39K NMR spectroscopy. The effect of temperature, concentration and potassium cation complexation on paramagnetic shift and relaxation behaviour was demonstrated and is discussed. An attempt was made to assess the contributions due to the various relaxation mechanisms operating at different temperatures in the systems studied.
Large CC spin–spin coupling constants across double bonds. Validity of the multiplicative approach
Authors: Kamieńska‐Trela Krystyna , Biedrzycka Zenobia , Da̧browski Andrzej 
Published: May 2005

Abstract13C13C spin–spin coupling constants have been measured for a series of variously substituted ethenes. The largest 1J(CC) value, 172 Hz, was found in chlorotrifluoroethene and the smallest, 45.3 Hz, in tris(trimethylsilyl)ethene, which covers a range of 127 Hz for the 1J(CC) values. An analysis of the data revealed a large discrepancy between the experimental 1J values and those estimated by the commonly used additive increment scheme. Good agreement was found, however, between the experimental values and those calculated by means of a multiplicative scheme.
Characterization of partially deuteriated transition metal polyhydrido complexes by heteronuclear 2D NMR techniques
Authors: Nanz Daniel , Philipsborn Wolfgang Von , Bucher Urs E. , Venanzi Luigi M. 
Published: May 2005

Abstract(1H, 103Rh) and (1H, 103Rh){2H} inverse correlation techniques, which profit from the presence of a magnetically active central metal nucleus, were applied to the complex [RhY2(Y2){HB(3,5‐Me2pz)3}] (Y = H or D; pz = pyrazolyl) containing both ‘classical’ and ‘non‐classical’ hydrogen ligands. The sample examined was a mixture of all species ranging from the perprotio to the perdeuterio compound. It is shown that the large isotope chemical shifts of the Rh nucleus can be used to separate the 1D 1H and 1H{2H} NMR spectra of the different H/D isotopomers. The observed isotope effects are discussed.
1H NMR studies of human urine: Urinary elimination of the anticancer drug carboplatin
Authors: Ranford John D. , Sadler Peter J. , Balmanno Katherine , Newell David R. 
Published: May 2005

AbstractSamples of urine from a patient obtained before and after treatment with 300 mg of the anticancer drug [Pt(II)(NH3)2(CBDCA)] (carboplatin, “Paraplatin”, where CBCDA is 1,1‐dicarboxycyclobutane) have been analysed using 500 MHz 1D and 2D 1H NMR spectroscopy. Peaks for the intact drug and the free ligand CBDCA have been assigned and are present in a mol ratio of ca. 5:1. Only about one half of the total Pt in the sample was present as intact drug. Relative to creatinine and citrate, the excretion of hippurate increased by a factor of ca. 4 after drug treatment. This work suggests that NMR spectroscopy can play a valuable rǒle in studies of carboplatin metabolism.
Natural abundance 17O NMR spectroscopic study of quinone methides
Authors: Boykin David W. , Kumar Arvind , Shevchenko Sergey M. 
Published: May 2005

AbstractThe 17O NMR chemical shift data for a series of substituted 10‐methyleneanthrones and related 10‐alkylanthrones in acetonitrile solution at 75°C are reported. The 17O NMR chemical shift value of 10‐methyleneanthrone is shielded by ca. 35 ppm compared with that of anthraquinone. The chemical shifts of the 10‐methyleneanthrones range from 493 ppm for 10‐bromomethyleneanthrone to 440 ppm for 10‐diethylaminomethyleneanthrone. A correlation of the 17O NMR chemical shifts of the 10‐substituted methyleneanthrones with σ+ constants is noted.
Vicinal 13C13C coupling constants in bicyclic monoterpenes
Authors: Denisov Aleksej Y U. , Tkachev Aleksej V. , Mamatyuk Viktor I. 
Published: May 2005

AbstractCarbon–carbon coupling constants in monoterpene hydrocarbons (3‐carene, α‐pinene and camphene) were investigated. A selective version of the INADEQUATE experiment was used for measurements of the long‐range nJ(CC) values. The dependence of the vicinal 13C13C coupling constants on the dihedral angles and the types of molecular framework involved within the direct coupling path is discussed. The configuration of a heteroatomic derivative from α‐pinene was determined from its 3J(CC) values.
Selective long‐range 1H13C polarization transfer in nucleosides
Authors: Gmeiner William H. , Lown J. William 
Published: May 2005

AbstractSelective INEPT (INAPT) experiments were used to correlate the nitrogen‐ and carbon‐bound hydrogens of nucleosides with 13C resonances via 2J(C, H) and 3J(C, H). Such experiments are useful as part of a strategy to distinguish the imino hydrogens of uridine and thymidine, which cannot be accomplished on the basis of chemical shift. The strategy involves correlation of the imino hydrogen with C‐5 using INAPT and testing whether or not the C‐5 resonance is quaternary. Polarization transfer is ineffecient for most positions in nucleosides owing to the small long‐range couplings, except the H‐6C‐5 transfer in adenosine, which results in enhancement of the 13C resonance over its equilibrium value. The efficiency of polarization transfer from H‐3 to C‐5 of thymidine depends on the base‐paired status of the nucleoside indicating a change in the 3J(C, H) on base‐pair formation. This sensitivity to electronic reorganization on base‐pair formation makes the INAPT experiment a useful probe for the base‐paired status of nucleosides and of the electronic properties of uridine and thymidine analogues.
14N and 15N NMR spectroscopic characterization and analysis of cyclic sulfur imides
Authors: Chivers Tristram , Edwards Mark , McIntyre Deane D. , Schmidtt Kenneth J. , Vogel Hans J. 
Published: May 2005

AbstractThe 14N and 15N NMR spectra of natural abuadance and 15N‐enriched samples of S7NH and S4(NH)4 were obtained by direct detection and by a variety of polarization transfer techniques. Sensitivity enhancements of ca 10 (compared with direct detection) for the INEPT pulse sequence and ca 100 for the HMQC (heteronuclear multiple quantum coherence) + BIRD (bilinear rotation decoupling) sequence were observed for the imides. 15N spin–lattice relaxation constants (T1) of 10.2 ± 0.1 and 12.6 ± 0.1 s were determined for S7NH and S4(NH)4, respectively. The HMQC procedure was used to obtain the 15N and 1H NMR chemical shifts and 11J(15N, 1H) values for 1,3‐,1,4‐ and 1,5‐S6(NH)2, 1,3,5‐ and 1,3,6‐S5(NH)3. The trends in NMR chemical shifts and coupling constants are discussed in the context of the known molecular structurts of cyclic sulfur imides. The use of NMR techniques for the analysis of mixtures of cyclic sulfur imides is compared with the well established methods of infrared spectroscopy and thin‐layer chromatography.
NMR spectroscopic characterization of maleic anhydride–α‐methylstyrene adducts
Authors: Komber Hartmut , Steinert Volker , Zschoche Stefan , Rätzsch Manfred , Grossmann Gisbert 
Published: May 2005

AbstractTwo 2:1 maleic anhydride–α‐methylstyrene adducts and two naphthalene derivatives were isolated as low molecular weight by‐products of thermal copolymerizations of maleic anhydride and α‐methylstyrene under different conditions. Their structures were deduced by means of 1H1H and 1H13C shift correlation NMR spectroscopy. The complete 1H and 13C NMR assignments are presented.
Chemical shift anisotropy and indirect coupling in SnO2 and SnO
Authors: Cossement Christophe , Darville Jacques , Gilles Jean‐Marie , Nagy Janos B. , Fernandez Christian , Amoureux Jean‐Paul 
Published: May 2005

AbstractThe magic angle solid‐state NMR spectra of SnO2 and SnO were recorded and analysed. The chemical shift tensor anisotropy is much smaller for SnO2 (136 ppm) than for SnO (975 ppm). Simple calculations suggest that the latter is mainly due to the asymmetry in the valence electron cloud of the tin atom in SnO. An SnSn indirect coupling of 8300 Hz was found in SnO, indicating the possibility of Sn 5s orbitals at the top of the valence band of SnO.
Hydrogen‐1 and aluminum‐27 NMR study of Al(ClO4)3 in aqueous mixtures of dimethylformamide and urea
Authors: Fratiello Anthony , Kubo‐Anderson Vicki , Azimi Soheil , Fowler Cynthia , Marinez Eric , Perrigan Richard , Shayegan Shadi , Yao Betty 
Published: May 2005

AbstractA competitive solvation study of Al(III) in water–dimethylformamide (DMF) and water–urea mixtures was carried out by 1H and 27Al NMR spectroscopy. At temperatures low enough to slow proton and ligand exchange, separate 1H resonance signals were observed for bulk and coordinated ligand molecules, and for 27Al in different solvation complexes. The 1H NMR data confirmed hexacoordination of Al(III) at all concentrations, monodentate binding at the oxygen atom of both DMF and urea, preferential solvation by both organic ligands, the presence of steric hindrance to complexation, particularly by DMF, and the identification of the complexes responsible for the 27Al spectra. It also showed a non‐equivalence of the amido groups in urea, in both the complex and free states, presumably owing to hindered rotation about the carbon—oxygen bond. In contrast to previous reports, the 27Al spectra for the water–DMF and water–urea solutions showed well resolved signals for the species [Al(H2O)n–6Ln]3+ (n = 0–6; L = DMF or urea), including two isomers for one of the water–urea complexes. The 27Al NMR data reflected the stronger preferential solvation by urea.
1H, 13C and 17O NMR spectral study of 4,1‐disubstituted naphthalenes
Authors: Perumal Subbu , Vasuki Gnanasambandam , Wilson David A. , Boykin David W. 
Published: May 2005

AbstractThe 1H, 13C and 17O NMR spectra of several 4,1‐disubstituted naphthalenes, viz. 4‐substituted 1‐ acetylnaphthalenes (series 1), 4‐substituted 1‐nitronaphthalenes (series 2), 4‐substituted 1‐methoxynaphthalenes (series 3) and 4‐substituted 1‐naphthyl methyl sulphides (series 4), were measured. The 17O and 13C chemical shifts of these 4,1‐disubstituted naphthalenes were compared with those of the corresponding 4,1‐disubstituted benzenes and analysed using the dual substituted parameter (DSP) equation. It is concluded that in series 1, 2 and 4 the substituent effects from the 4‐substituent to the C‐1 carbon and the side‐chain atoms are transmitted more effectively than those in the corresponding 4,1‐disubstituted benzenes, whereas the transmission in series 3 is almost equal to that in the analogous benzene series, viz. 4‐substituted anisoles. The reverse substituent effects displayed by the H‐8 chemical shifts of series 1 and 2 and the existence of linear relationships between the chemical shifts of H‐8 and the 17O chemical shifts of the oxygen of both the acetyl and nitro groups in series 1 and 2, respectively, are ascribed mainly to changes in the electron densities on the oxygen of the carbonyl and nitro groups affecting the diamagnetic screening of the proton.
Full assignments of the 13C and 1H NMR spectra of azithromycin in buffered D2O and DMSO‐d6
Authors: Brennan Richard J. , Barber Jill 
Published: May 2005

AbstractThe 13C and 1H NMR spectra of azithromycin in D2O and DMSO‐d6 have been unambiguously assigned using a range of 1 and 2D NMR methods. Similarities to the spectra of azithromycin in CDCl3 and of erythromycin A ketone in the same solvents are discussed.
On‐line monitoring of the Krebs cycle in isolated heart mitochondria by 13C NMR spectroscopy
Authors: Offermann Werner , Fiedler Evi , Helmle‐Kolb Corinna , Hofer Werner , Kugel Harald , Reese Torsten , Werk Willi , Leibfritz Dieter 
Published: May 2005

AbstractWhen isolated rat heart mitochondria were incubated with [3‐13C]pyruvate in the presence of oxygen and aspartate or malate, the spin label 13C was incorporated into the components of the Krebs cycle, which we monitored in situ by 13C NMR spectroscopy. In the spectra 21 isotopomers of citrate, 2‐ketoglutarate, glutamate, succinate, fumarate, malate and aspartate were conclusively found and the presence of ten more isotopomers could be inferred from metabolic reasons. Chemical shifts, δ, carbon–carbon coupling constants, J, and spin–lattice relaxation rates, T1, of these compounds were measured in suspensions of isolated mitochondria during respiration. It is demonstrated that the 13C signal of Tris buffer can be used to follow the respirational change in pH. It is shown by comparison of the spectra of a complete suspension and its fluid and solid components, that the observed signals are entirely due to the supernatant solution, and not to the mitochondrial matrix. By supplying different cosubstrates it was possible to emphasize various parts of the Krebs cycle. Mitochondria incubated with aspartate released only labelled glutamate and aspartate, whereas the cosubstrate malate allowed the observation of all the metabolites mentioned above. The appearance of multiplet signals indicated recycling of metabolites and can be understood in terms of known metabolic pathways and trans‐membrane transport. The spectroscopic and biochemical information which is necessary in order to evaluate series of carbon spectra recorded during stimulus experiments performed with suspensions of isolated mitochondria is presented.
Correlation of oxygen‐17 substituent‐induced chemical shifts: Meta‐ and para‐substituted methyl benzoates
Authors: Exner Otto , Dahn Hans , Péchy Péter 
Published: May 2005

AbstractOxygen‐17 NMR spectra of 45 substituted methyl benzoates in acetonitrile were measured at natural abundance. The substituent‐induced chemical shifts (SCS) of the carbonyl oxygen correlate well with the σm and σ substituent constants in two separate correlations for meta and para derivatives; principal component analysis (PCA) is only slightly better [particularly for the N(CH3)2 substituent]. The 17O SCS generally depend on the same factors as the 13C SCS of the β‐carbon of alkenes, provided comparison is made between compounds of similar polarity. SCS of the methoxyl oxygen depend less precisely on σm or σp, with some unexplained deviations.
Trimethylstannylboranes—inverse detection of broad 119Sn NMR signals in solution and solid‐state 119Sn cross‐polarization magic angle spinning NMR
Authors: Wrackmeyer Bernd , Kupče Ēriks , Kümmerlen Jörg 
Published: May 2005

AbstractExtremely broad 119Sn resonances, as the result of 1J(119Sn,11B) scalar coupling, were readily detected, even for diluted samples (5 mg in 0.5 ml of C6D6), via inverse two‐dimensional 1H{119Sn} NMR experiments. Two bis(amino)trimethylstannylboranes and four dialkylaminobis(trimethylstannyl)boranes were studied. The reaction between diisopropylaminobis(trimethylstannyl)borane and trimethoxyborane was monitored by the same technique, leading to the detection of diisopropylaminomethoxytrimethylstannylborane and dimethoxytrimethylstannylborane as reaction products. Crystalline dicyclohexylaminobis(trimethylstannyl)borane was studied by 119Sn CP/MAS NMR. In spite of the proximity of 119Sn to the quadrupolar 11B nucleus, meaningful spectra could be obtained in a short time (≤ 2 h).
Differential rates of NH proton exchange reactions of two isomeric enamines
Authors: Yavari Issa , Hosain‐Nia Azar 
Published: May 2005

AbstractProton NMR spectra of (E)‐ and (Z)‐[1,2‐bis(methoxycarbonyl)vinyl]aminotoluene were obtained in neutral and basic solutions at 25°C. Base‐catalysed NH proton exchange of the E isomer was found to be about 50 times faster than for the Z isomer. The results are rationalized by consideration of electronic and hydrogen bonding effects.
Regular and relayed heteronuclear correlations by a single two‐dimensional experiment involving an RF gradient
Authors: Canet D. , Brondeau J. , Montigny F. , Humbert F. 
Published: May 2005

AbstractIn order to achieve a better suppression of signals arising from protons non‐bonded to the considered heteronucleus, two (π/4) proton pulses are used in the HMQC sequence: one, at the very beginning, replaces the classical (π/2) pulse and the other is at the end of the sequence. In addition, a spin‐lock purging period improves the elimination process. This novel sequence is shown to provide the conventional heteronuclear correlations and, in addition, relayed homonuclear (proton–proton) correlations. A simple methodology capable of sorting out both types of correlations is proposed. However, this procedure entails a sensitivity loss by a factor of two.
Stereochemical study of imines and their N‐borane adducts by 1H, 11B, 13C and 15N NMR
Authors: Ariza‐Castolo Armando , Paz‐Sandoval M. Angeles , Contreras Rosalinda 
Published: May 2005

AbstractThe synthesis and NMR spectra of the N‐borane adducts of two diimines, N‐borane‐bis(α‐phenylethylidene)ethylenediamine and N‐borane‐bis(α‐phenylbenzylidene)ethylenediamine, and four imines, N‐borane‐α‐methylethylidene‐2‐phenylethylamine, two N‐borane‐α‐phenylethylidene‐n‐butylamines and N‐borane‐α‐phenylbenzylidene‐n‐butylamine, are reported. The NMR spectra of the N‐borane adducts of these imines can be used to determine their configuration.