bluuebunny/crossref_metadata_2025_split huggingface dataset:
1H1H and 1H19F coupling constants of some styrene, benzaldehyde and benzylidene amine derivatives
Authors: Suntioinen Sirpa , Laatikainen Reino , Král Vladimir 
Published: May 2005

AbstractFive para‐fluorobenzene derivatives having a CHCR2 or a CHNR group were prepared and their 1H and 19F NMR spectra in acetone‐d6 were analysed. The 6J(Hα,F) and 4J(Hα,H) couplings of the nitrogen derivatives fall between those of the carbon and oxygen derivatives: the electronegativity of the side‐chain β‐atom seems to have a prominent role in the spin information transmission. The 6J(Hα,F) and 4(Hα,H) couplings indicate that the nitrogen derivatives are rigidly planar whereas the carbon derivatives are non‐planar.
Demonstration of the linear dependence of proton magnetization transfer on polymer concentration in aqueous gels at two different field strengths
Authors: Tessier Jean J. , Potter Kimberlee , Carpenter T. Adrian , Hall Laurance D. , Tyler Jenny A. 
Published: May 2005

AbstractSaturation transfer experiments were performed at both 85 and 300 MHz to measure the magnetization transfer (MT) rate as a function of macromolecular concentration. For this purpose calcium alginate gels with an internal concentration gradient were manufactured from aqueous sodium alginate and calcium ions. Although aqueous sodium alginate did not exhibit any MT, the proton magnetization transfer rate in calcium alginate gels was found to depend linearly on the concentration of polysaccharide. Since the rate did not depend on the field strength, the dominant mechanism of MT in these systems is either chemical exchange or a highly efficient intermolecular cross‐relaxation process. The high sensitivity of MT to variation in polysaccharide concentration and mobility suggests that it is an excellent tool to monitor changes in the chemistry, mobility and concentration of slowly moving polymers in aqueous gels.
1H and 13C NMR assignment of sodium chenodeoxycholate in aqueous solution. Polarization of bile salts steroid nucleus
Authors: Zakrzewska J. , Okon M. , Vučelić D. 
Published: May 2005

Abstract1H and 13C NMR assignments of sodium chenodeoxycholate in aqueous solution were obtained for three different bile salt concentrations. 1H and 13C NMR chemical shifts of sodium chenodeoxycholate and deoxycholate show slight concentration dependence due to micelle formation. Opposite trends in chemical shifts changes for α‐ and β‐protons cause polarization of the steroid nucleus.
1H and 13C NMR analysis of C‐23 and C‐24 diastereomers of 5α‐dinosterane
Authors: Stoilov Ivan , Smith Stanford L. , Watt David S. , Carlson Robert M. K. , Fago Frederick J. , Moldowan J. Michael 
Published: May 2005

AbstractDetailed analysis of the 1H and 13C NMR spectra of four diastereomers of the important geochemical biomarker (20R)‐5α‐dinosterane was completed using various two‐dimensional 1H1H and 1H13C correlation techniques.
15N NMR: Substituent effect analysis in para‐and meta‐substituted phenylhydrazines
Authors: Mezzina Elisabetta , Ferroni Fiammetta , Spinelli Domenico , Chimichi Stefano , Frenna Vincenzo 
Published: May 2005

Abstract15N NMR spectra of phenylhydrazine and of 14 para‐ and meta‐substituted phenylhydrazines were measured at natural isotope abundance in DMSO‐d6 solution. The substituent present exerts a larger influence on the chemical shift of the nitrogen atom directly bound to the aromatic ring (N‐1) than on the second one (N‐2), which shows an attenuated and inverted trend. The chemical shifts of N‐1 and N‐2 give a good cross correlation in both series of compounds if p‐NO2 and m‐F derivatives are excluded from the correlations of para‐ and meta‐substituted phenylhydrazines, respectively. Moreover, N‐1 SCS values show good linear correlations with Hammett substituent constants, with SCSs of directly bound hydrogen (H‐1) and with aniline nitrogen SCSs. The results of dual substituent parameter analysis are also reported together with a comparison of 13C and 15N chemical shifts with those of monosubstituted benzenes and substituted anilines.
Structural studies on chiral (π‐Allyl)Pd(II) complexes. 1H, 13C and 31P NMR Studies of [Pd(η3‐CH3CHCHCH2)(S, S‐Chiraphos)] CF3SO3
Authors: Pregosin Paul S. , Salzmann Renzo 
Published: May 2005

AbstractThe chiral (π‐allyl)Pd(II) complex [Pd(η3CH3CHCHCH2)(S, S‐Chiraphos)]CF3SO3 was shown to exist in four isomeric forms (two diastereomeric and two geometric). Aspects of their three‐dimensional structures were elucidated using 1H, 13C and 31P one‐ and two‐dimensional NMR methods. The assignment of the diastereomers, which differ with respect to the coordinated face of the allyl ligand, was achieved using 1H‐NOESY methods.
Enhanced diagnostic EPR and ENDOR spectroscopy of radical spin, adducts of deuterated α‐phenyl N‐tert‐butyl nitrone
Authors: Haire D. Lawrence , Janzen Edward G. 
Published: May 2005

AbstractDeuterated analogues of C‐phenyl N‐tert‐butyl nitrone (PBN) were synthesized to provide significant gains in spectral sensitivity and resolution in electron paramagnetic resonance (EPR) and electron nuclear double resonance (ENDOR) applications. Three deuterated α‐phenyl N‐tert‐butyl nitrones (PBNs) were prepared. EPR spectra of the corresponding radical spin adducts with the phenyl ring (PBN‐d5‐R˙) or tert‐butyl moiety (PBN‐d9‐R˙) deuterated were found to enhance disclosure of the structure of the added radical. The most dramatic increases in EPR resolution, however, were not realized until both the phenyl and tert‐butyl groups were deuterated (PBN‐d14‐R˙). Here, baseline resolution of unique long‐range (e.g. γ‐ and δ‐) hyperfine splittings from the radical addend could be displayed. Representative radical spin adducts of PBN‐d14 (methyl, hydroxyl, aminyl, cyanyl, carbamoyl, and vinyl) were prepared and compared with those of PBN to illustrate this point. It is also shown that when even higher spin adduct resolution is desired the combination of spin trap deuteration and ENDOR may be applied to advantage.
1H and 13C NMR spectral assignments of some phenothiazine derivatives
Authors: Pelecanou M. , Mikros E. , Catsoulacos P. 
Published: May 2005

Abstract1H and 13C NMR data for six pheno‐thiazine derivatives are reported. Spectral assignments were made on the basis of two‐dimensional homonuclear 1H,1H and heteronuclear 1H,13C correlation techniques (COSY, COSY‐LR, HETCOR, COLOC) and 13C,1H coupling constant measurements.
Structural assignment of the 1H and 13C NMR spectra of 3‐Cyano‐1,2,2‐trimethyl‐6‐azatricyclo [3.3.1.03,8] non‐6‐ene using two‐dimensional NMR spectroscopy
Authors: Caronna Tullio , Luogo Daniela Dal Pio 
Published: May 2005

Abstract1H NMR of the tricyclic molecule 3 ‐ Cyano ‐1,2,2‐ trimethyl ‐ 6 ‐ azatricyclo ‐[3.3.1.03,8]non‐6‐ene does not permit the distinction between this structure and the other regioisomer that can be formed in a photochemically induced reaction. The elucidation of the structure was possible via the assignment of the 1H and 13C NMR spectra of this compound obtained using two‐dimensional NMR spectroscopy.
55Mn, 13C coupling constants of some σ‐ and π‐organomanganese complexes
Authors: Torocheshnikov Vladimir , Rentsch Daniel , von Philipsborn Wolfgang 
Published: May 2005

Abstract55Mn, 13C coupling constants of σ‐ and π‐organomanganese pentacarbonyl, tetracarbonylphosphine and tricarbonyl complexes were determined by lineshape analysis of the 13CO and 13C(R) signals (R = alkyl, acyl or aryl) using the iterative lineshape fitting program QUADR. The 1J(55Mn, 13C) data are in the range 29–47 Hz for MnCO bonds and 2–28 Hz for MnR bonds. The 55Mn chemical shifts and linewidths are also reported.
14N NMR spectroscopy of NH4+ as a probe of ion‐exchange membranes
Authors: Haryadi  , Rankothge M. , Hook J. , van Gorkom L. , Moran G. 
Published: May 2005

Abstract14N NMR Spectroscopy of NH4+ is a convenient and sensitive probe of structure and mobility in Nafion, Dow and Neosepta cation‐exchange membranes. NH4+ ions bound to these commercially produced membranes give rise to small 14N quadrupolar splittings ranging from 10 to 160 Hz. Moderate stretching of Nafion and Dow membranes induces much larger splittings of up to 2 kHz. The splitting has also been found to be dependent on the orientation of the membranes in the magnetic field B0. In Nafion it reaches a minimum at an angle of 45–55° between the direction of stretch and B0. The quadrupolar splittings also increase with increase in temperature. 14N spin–lattice relaxation times in all three membranes at 300 K are about 20 times shorter than in aqueous solution, consistent with strongly bound NH4+ ions. The apparent activation energies for 14N relaxation, derived from the temperature dependence of the T1, data, show that reorientation of the bound NH4+ ions requires ca. 20 kJ mol−1 in Nafion and Dow membranes and ca. 30 kJ mol−1 in Neosepta, compared with 6.5 kJ mol−1 for free NH4+ in aqueous solution.
Study of the π‐electron distribution in push—pull alkenes by 1H and 13C NMR spectroscopy. Part III—the conformation of 3,4‐dihydro‐4‐oxo‐2H‐thiins
Authors: Kleinpeter E. , Heydenreich M. , Chatterjee S. K. , Rudorf W.‐D. 
Published: May 2005

AbstractThe 1H and 13C NMR spectra of a variety of differently 2,5,6‐trisubstituted 3,4‐dihydro‐4‐oxo‐2H‐thiins (integrated push–pull alkenes) were unequivocally assigned by means of a wide variety of 1D and 2D NMR spectroscopic methods. The NMR parameters thus obtained, together with the results of accompanying force‐field calculations, proved useful in determining the preferred ring conformation of 3,4‐dihydro‐4‐oxo‐2H‐thiin (half‐chair). Additionally, the 13C chemical shift difference, Δδ(C‐5, C‐6), could be employed to indicate the degree of bond polarization of the partial C‐5C‐6 double bond (push–pull character); the barrier to rotation, otherwise used to estimate this parameter characterizing the push–pull alkenes, cannot be applied owing to the ring fusion. Interestingly, NH2 proved less effective in C‐5C‐6 bond polarization than NHPh.
Substituent effects of 1H NMR parameters of chlorinated diphenyl ethers. A statistical approach
Authors: Nevalainen Tapio , Kolehmainen Erkki 
Published: May 2005

AbstractThe 1H NMR spectra of 64 polychlorinated diphenyl ethers (PCDEs) were measured and assigned. Multiple linear regression analysis was used to estimate the effects of chlorine atoms on the 1H NMR chemical shifts and coupling constants. The ‘simple sum rules’ were found to be inadequate for the prediction of 1H NMR chemical shifts of PCDEs. Therefore, corrective terms of two chlorine atoms were taken into account. The most important effects on chemical shifts were shown to be the steric interactions of two adjacent chlorine atoms and the intramolecular ring current effect observed in the ortho‐proton of tri‐ortho‐substituted PCDEs. The substituent effects on J(HH) coupling constants were found to be approximately additive. An interannular coupling between ortho‐protons [6J(HH) = 0.05–0.15 Hz] of adjacent rings was observed.
Nitrogen NMR of some sulphur diimide anions and calculated (GIAO) nitrogen shielding constants
Authors: Wrackmeyer Bernd , Gerstmann Silke , Herberhold Max , Webb Graham A. , Kurosu Hiromichi 
Published: May 2005

AbstractSulphur diimide anions of the type [NSN]2− (1), [RNSN]− (1), [R = tBu (3), SiMe3 (4), tBu2P (5)] were prepared with the counter ions [nBu4N]+ or [(Me2N)3S]+ (for 1, 3, 4) and K+ (for 5) and studied in solution by 14N NMR, and for assignment purposes by 15N NMR (4). The experimentally determined 14N chemical shifts (δN) were compared with nitrogen shielding constants calculated by the gauge included atomic orbitals (GIAO) technique, and a linear relationship between σN(calc) and δN was obtained. This correlation serves to support the Z configuration of the anions [RNSN]−, analogous to the isoelectronic N‐sulphinylamines. On this basis, two 14N resonance signals reported in the literature with uncertain assignment can be attributed to [HNSN]− (2), and the previously assigned δN values suggest that the anion [HNSNS]− (6) adopts the Z/E configuration.
1H and 13C NMR study of new organic nitrate esters. I. (2H)‐1,3‐benzoxazin‐4‐(3H)‐one derivatives
Authors: Bertolini Giorgio , Conti Sonia , Ferrario Francesco , Sala Alberto 
Published: May 2005

AbstractThe 1H and 13C NMR of a series of 3‐nitrooxyalkyl‐2H‐1,3‐benzoxazin‐4‐(3H)‐ones were measured and assigned on the basis of substituent chemical shifts, DEPT experiments and 13C/1H shift correlated spectra.
Characterization of the unsymmetrical trimer of indole‐5‐carboxylic acid by proton NMR spectroscopy
Authors: Mackintosh J. G. , Mount A. R. , Reed D. 
Published: May 2005

AbstractIndole‐5‐carboxylic acid trimer, a major product formed during the electro‐polymerization of indole‐5 carboxylic acid, was characterized by 1H NMR spectros‐copy, and a wide range of one‐ and two‐dimensional NMR techniques were employed to allow full analysis of the 1H spectrum. Homonuclear NOE experiments were carried out in different solvents and at different temperatures, owing to the unusual observation of negative enhancements in some experiments. This was shown to be due to the slow tumbling rate of the molecule.
Investigation of the electronic structure of 4‐chlorophenylisoxazole and 4‐chloroisoxazoline by NQR spectroscopy and quantum‐chemical calculations
Authors: Poleshchuk O. Kh. , Nogaj B. , Latosińska J. N. , Koput J. , Babushkina T. A. , Sokolov S. D. 
Published: May 2005

Abstract35Cl NQR spectra of substituted phenylisoxazoles and isoxazolines were analysed. For certain molecules the atom charges and orbital populations were calculated with the MINDO/3 method. It was proved that a chlorine atom at position 4 on an isoxazole ring transmits the influence from the phenyl ring at position 3 to the phenyl ring at position 5 on the isoxazole ring through the system of π‐bonds.
Synthesis of pentasubstituted pyridines. II—NMR study of the addition products of 1‐(N,N‐diethylamine)prop‐1‐yne to methyl 2‐isothiocyanato‐3‐phenylpropenoate
Authors: Peláez‐Arango Elvira , López‐Ortiz Fernando , Barluenga José , Ferrero Miguel , Palacios Francisco 
Published: May 2005

AbstractThe structure of the pentasubstituted pyridines obtained in the reaction of methyl 2‐isothiocyanato‐3‐phenylpropenoate with 1‐(N,N‐diethylamine)prop‐1‐yne were assigned based on 2D heteronuclear correlation experiments and NOE measurements. At 0°C a 2‐azabicyclo[2.2.2] octa‐2,7‐diene intermediate was isolated and spectroscopically characterized.
Comparative multinuclear (35Cl,79Br,81Br,127I and17O) magnetic resonance study of the perhalate anions XO4−(X  Cl, Br or I) in acetonitrile solution
Authors: Dove Michael F. A. , Sanders Jeremy C. P. , Appelman Evan H. 
Published: May 2005

AbstractThe NMR spectra (35Cl,79Br,81Br,127I and17O) of the tetrahedral perhalate anions XO4−(X  Cl, Br and I) were compared for the first time in acetonitrile solution, a medium in which the resonances are relatively sharp and in which no oxygen exchange occurs. Relaxation studies of the quadrupolar nuclei in these solutions at 24°C are reported and show that excellent spectra may be obtained at 0.1 M concentration; thus the observation of separate resonances for Cl16O4−and Cl18O16O3−represents the first reported instance of a35Cl secondary isotopic shift [1Δ35Cl(18.16O) = ‐0.090 ppm]. Enrichment with17O of all three ions was carried out and the1J(127I,17O) coupling constant (489 Hz) has been observed for the first time. The chemical shifts and coupling constants are discussed, especially in connection with the anomalous properties of the perbromate ion. Halogen chemical shifts for BrO3F, IF7and IF6+AsF6−are reported for the first time.
NMR study of iminophosphine oligomers by 31P, 15N and 31P, 13C heteronuclear shift correlation
Authors: Gudat D. , Link M. , Schröder G. 
Published: May 2005

Abstract2D 31P, 15N heteronuclear shift correlation, based on a non‐refocused INEPT pulse sequence with 15N detection, was applied to a 15N NMR study of the azadiphosphiridines 1‐5 which are formed by [2 + 1] cycloaddition of iminophosphines, RPNR′. The pulse sequence used allowed consistent assignment of both the 31P and 15N NMR spectra in one experiment; by a slight modification, also the signs of numerous 31P‐15N coupling constants across one or two bonds could be determined. Comparison of the data with those of the azatriphosphetidine 6 (obtained from ID 1H,15N and 31P,15N INEPT spectra) showed the influence of the ring size and conformational effects on the NMR parameters. 31P,13C shift‐correlated 2D spectra were further used to measure (including sign determination) and assign 31P‐13C coupling constants across one to three bonds in 1‐5. Based on the analysis of the coupling information and the known conformation of 4a, the relative stereochemistry of the diastereomers 4a and b could be derived; further, the comparison of the 31P‐13C coupling data of 1‐3 with those of the 4a and b allowed the conformations of these derivatives, which were previously unknown, to be determined. The derived information of the constitution and stereochemistry of 1‐5 gives insight into mechanistic details of the iminophosphine [2 + 1] cycloaddition.
NMR visibility of 35Cl− in human erythrocytes
Authors: Riddell Frank G. , Zhou Zhe 
Published: May 2005

AbstractContrary to previous reports, Cl− is visible by 35Cl NMR inside human erythrocytes. In spectra run at 49.01 MHz the intracellular chloride has a linewidth at half‐height of ca 700 Hz and shows double Lorentzian character. Mn2+ was used to relax the extracellular 35Cl− to allow the intracellular 35Cl− to be seen. The experimental protocol described should allow NMR observation of anion transport rates in human erythrocytes.
Complete assignment and additivity rule for 1H and 13C chemical shifts of non‐planar, nonacyclic aromatic hydrocarbons
Authors: Ueda Toyotoshi , Iwashima Satoshi , Aoki Junji , Takekawa Minoru 
Published: May 2005

AbstractComplete assignments of 1H and 13C NMR spectra were made for heptacyclic peropyrene and five isomers of dibenzoperopyrenes, using 2D correlation spectroscopic techniques of homonuclear HH‐COSY and NOESY and heteronuclear CH‐COSY and HMBC methods. New additivity rules of 1H and 13C chemical shift values were established for compounds having two types of benzene ring condensation. All 1H chemical shifts were satisfactorily interpreted by a very simple magnetic point dipole model. This model includes net contributions from each constituent benzene ring due to the ring current anisotropy and permits some ring planes to deviate from the mean molecular plane. The conjugated ring currents are consistent with the chemical shifts. Thus, the aromatic properties are normal even if the molecular skeleton is considerably deformed and becomes non‐planar.
Solid‐state 13C NMR investigations of monosubstituted cyclohexanes in thiourea inclusion compounds
Authors: Müller Klaus 
Published: May 2005

AbstractThiourea inclusion compounds with substituted cyclohexanes bearing polar or non‐polar substituents were studied by dynamic 13C magic angle spinning NMR spectroscopy. Variable‐temperature experiments were performed to evaluate the specific features of the guest molecules comprising both the kinetic and the thermodynamic aspects. Further information was also obtained about potential guest‐host interactions which might have a bearing on the molecular behaviour of the guest species. Quantitative analysis in these experiments revealed that within the temperature range covered, the relaxation behaviour is dominated by ring interconversions of the guest molecules. In addition, reorientational motions of the guest molecules exist on a very fast time‐scale which are responsible for the observed significant reduction in the anisotropic magnetic interactions. The most prominent results are the evaluated unusual conformational equilibria. It is shown that the thiourea host lattice obviously stabilizes the axial conformational state. This is true for all systems with polar substituents whereas for those with non‐polar substituents the conformational equilibria are not affected. These findings are related to specific guest‐host interactions, probably of a polar nature.
NMR studies of exchanging amide protons in 1‐desamino‐8‐D‐argininevasopressin by selective Hartmann‐Hahn transfer
Authors: Zangger Klaus , Sterk Heinz 
Published: May 2005

AbstractProton exchange rates between the solvent H2O and the amidic protons of a nonapeptide (1‐desamino‐8‐D)‐argininevasopressin in aqueous solution were determined by using selective nuclear magnetic double‐resonance methods. Transverse magnetization, the magnitude of which depends on the chemical exchange rate and the relaxation time T1, is transferred via doubly selective homonuclear Hartmann‐Hahn mixing to a scalar coupling partner. With respect to well established two‐dimensional experiments, this one‐dimensional alternative has two advantages: it is much less time consuming and, as a true benefit, it is even applicable when two signals which are in exchange with the same compound (solvent) are overlapping. The evaluation of amide proton exchange rates in the investigated peptide led to the assumption of an intramolecular hydrogen bond.
Conformational and configurational study of 1,3‐dioxolanes by proton and carbon NMR spectroscopy
Authors: Mucci A. , Schenetti L. , Brasili L. , Malmusi L. 
Published: May 2005

AbstractThe configurational and conformational properties of six 4‐trimethylammoniummethyl 2,2‐disubstituted 1,3‐dioxolanes were studied using NOE experiments and vicinal coupling constants. Selective 1D NOE experiments proved to be effective tools in the configurational assignment of C‐2 relative to C‐4. The preferred conformation of the dioxolane ring and the exocyclic group at C‐4 was obtained by employing vicinal coupling constants and NOE results. The 1H and 13C NMR chemical shifts show stereochemically dependent trends. Quantitative analysis of conformer populations was performed using Haasnoot et al's equation. The N+(CH3)3 group was found to be synclinal with respect to the heterocyclic O‐3 atom and points outside the ring. When a phenyl group is present at C‐2, the 4‐CH2N+— group in a trans relationship to the 2‐phenyl ring was found to occur prevalently in a pseudo‐axial orientation, whereas it was established to be prevalently pseudo‐equatorial when cis with respect to the phenyl ring.
Long‐range proton‐carbon coupling constants. Part II—norbornene systems
Authors: Parella Teodor , Sánchez‐Ferrando Francisco , Virgili Albert 
Published: May 2005

AbstractLong‐range proton‐carbon coupling constants, nJCH, were measured for some simple norbornene derivatives. Among the influence of substitution pattern, a study of the experimental influence of the double bond in the norbornene skeleton on 2JCH and 3JCH was made, taking into account the previously published experimental data for analogous saturated systems. These experimental data show that structural groups which are several bonds away from the coupling sites, but close in space, can provide important alternative mechanisms for transmission of the heteronuclear coupling.
Karplus‐type dihedral angle dependence for the coupling constants 3J(119SnCC119Sn) and 3J(119SnCC29Si)
Authors: Mitchell Terence N. , Kowall Bernd 
Published: May 2005

AbstractIn compounds of the type Me3SnCH2CHRSnMe3 and Me3SiCH2CHRSnMe3, there is a linear relationship between 3J(H,H) and 3J(119Sn,119Sn) or 3J(119Sn,29Si), respectively, thus providing unequivocal evidence for a Karplus‐type behaviour for the coupling constants 3J(119Sn,119Sn) and 3J(119Sn,29Si). Preliminary Karplus equations are presented on the basis of the available data.