bluuebunny/crossref_metadata_2025_split huggingface dataset:
Study of the formation of copper phthalocyanine by EPR spectroscopy
Authors: Döscher Burghard , Priess Renate , Gunsser Walter 
Published: May 2005

AbstractThe mechanism of the formation of copper phthalocyanine in the phthalic anhydride/urea process was elucidated by employing 14N, 15N or mixed nitrogen donors and enriched 63Cu for the synthesis of the pigment. Both EPR spectroscopy of the magnetically dilute complex and IR spectroscopy of oxidative fission products provide information about the isotopic composition of the inner chelate sphere. The range of superhyperfine interaction detectable by the EPR method was analysed by means of copper phthalocyanine labelled with 13C at positions 1, 4, 6, 9, 11, 14, 16 and 19. The results confirm a reaction mechanism which includes the formation of phthalonitrile as an intermediate product.
13C NMR studies of methylnucleosides
Authors: Chang Ching‐jer , Ashworth Dennis J. , Chern Lih‐Ju , Gomes Jose DaSilva , Lee Chi‐Gen , Mou Pih W. , Narayan Ramani 
Published: May 2005

AbstractThe 13C chemical shifts of 22 methylated ribonucleosides and deoxyribonucleosides have been measured and assigned. The chemical shift differences between methylated and unmodified nucleosides are correlated with their characteristic modifications of structure. The significance of the chemical shift and tautomeric variations is discussed.
Additive chemical shift parameters for methylene protons. Shoolery's constants reinvestigated
Authors: Bell Harold M. , Berry Linda K. , Madigan Elizabeth A. 
Published: May 2005

AbstractMethylene proton chemical shifts have been studied using multiple linear regression analysis, and additive chemical shift parameters have been determined. Using a data set of 1007 chemical shifts, involving 48 different substituents, a standard error of estimate of 0.15 ppm was found for protons spread between 2.0 and 5.9 ppm. Provision was made in the data matrix for substituent effects for directly attached groups (α) and for groups attached via one intervening saturated carbon (β‐substituents). The influence of groups more remotely located was assumed to be negligible. Although the parameters were optimized for deshielded methylene proton shifts, they also serve satisfactorily for the estimation of shifts in more shielded methylene cases.
13C and 77Se NMR of some organometallic derivatives with Ti, Zr and Hf
Authors: Granger P. , Gautheron B. , Tainturier G. , Pouly S. 
Published: May 2005

Abstract13C and 77Se NMR was carried out on dicyclopentadienyl derivatives of Ti, Zr and Hf with selenium bonded directly to the metal. Although 13C NMR is not sensitive to different substitution, 77Se NMR is valuable and reflects the influence of the different organic substituents and the nature of the metals bonded to the selenium atom.
Oxygen‐17 nuclear magnetic resonance spectral investigation of 3‐alkoxy‐trans‐3,4‐disubstituted‐thiolane 1,1‐dioxides and related compounds
Authors: Sammakia Tarek H. , Harris David L. , Evans Slayton A. 
Published: May 2005

AbstractThe 17O NMR spectra of 3‐alkoxythiolane 1,1‐dioxides indicate that the sulfonyl oxygens are diastereotopic but their chemical shift differences are essentially independent of the structure of the alkyl group in the alkoxy moiety. Eu(fod)3 enhances the 17O chemical shift differences between the diastereotopic sulfonyl oxygens in 3‐isopropoxythiolane 1,1‐dioxide and shifts both oxygens upfield. α,β‐Unsaturation deshields the sulfonyl oxygens in both five‐ and six‐membered rings.
EPR and ENDOR study of thermally produced triphenylmethyl radicals
Authors: Lewis I. C. , Singer L. S. 
Published: May 2005

AbstractThe ENDOR spectrum of the triphenylmethyl radical formed by heat treatment of triphenylmethane has been measured in solution at 131°C. The derived hyperfine coupling constants of 2.770, 2.556 and 1.138 G were used to simulate the extremely well resolved EPR spectrum. These coupling constants are in good agreement with spin densities determined for the planar radical by the McLachlan method.
AAEE case report #4: Guillain‐Barré syndrome
Authors: Albers James W. 
Published: May 2005

AbstractA case report is presented of a 33‐year‐old woman who awoke with distal paresthesias, mild incoordination, and progressive weakness. Examination 3 days later demonstrated weakness of the extremities, which was greater in distal muscles than in proximal ones, mild facial weakness, distal vibratory loss, and areflexia. Electrodiagnostic studies provided evidence of an acquired demyelinating polyradiculoneuropathy of recent onset. Motor conduction studies revealed abnormal temporal dispersion and partial conduction block. Preserved sural responses with abnormal median sensory conduction studies supported the diagnosis of Guillain‐Barré syndrome, as did subsequent cerebrospinal fluid examinations documenting increasing total protein, identification of preceding cytomegalovirus injection with increasing serum convalescent titer, and progressive clinical improvement after a brief plateau. The role of electrodiagnosis in establishing the diagnosis and prognosis in Guillain‐Barré syndrome is reviewed.
The relationship of cold and warmth cutaneous sensation to age and gender
Authors: Doeland Herman J. , Nauta Jos. J. P. , van Zandbergen Johannes B. , van der Eerden Harriët A. M. , van Diemen Nico G. J. , Bertelsmann Frits W. , Heimans Jan J. 
Published: May 2005

AbstractTo evaluate cold and warmth cutaneous sensation separately, thermal discrimination thresholds (TDTs) for the foot were estimated for cold and warm stimuli in 71 normal subjects aged between 21 and 92 years. A “thermoaesthesiometer” operating on the Peltier principle was used. A rise of TDTs with age was found. Furthermore, female subjects appeared to have lower thresholds than males. Independent of age or gender, TDTs for cold stimuli were on average lower than for warm stimuli. In accordance with other studies, a large intraindividual variability was found, which emphasizes the necessity for repeated measurements.
Lipid peroxide and antioxidant enzymes in muscle and nonmuscle of dystrophic mouse
Authors: Asayama Kohtaro , Hayashibe Hidemasa , Dobashi Kazushige , Kato Kiyohiko 
Published: May 2005

AbstractTo determine whether abnormality in redox metabolism occurs specifically in certain individual dystrophic muscles, thiobarbituric acid reactivity, free radical scavengers, and oxidative marker enzymes were measured in the liver, kidney, erythrocytes, heart, and four different individual skeletal muscles from‐C57BL/6J dy/dy mice. Superoxide dismutases were assayed by specific radioimmunoassays, which enabled the study of a small individual murine muscle. Glutathione peroxidase and catalase were increased markedly in each individual dystrophic skeletal muscle studied and less markedly in the heart. Manganosuperoxide dismutase and thiobarbituric acid reactivity were decreased to a similar extent in each dystrophic skeletal muscle. Cuprozinc superoxide dismutase was decreased in the soleus muscle. Only a minimal biochemical change occurred in nonmuscles. Fumarase activity correlated closely with the level of manganosuperoxide dismutase. These results suggest that muscle protein breakdown occurs independently of lipid peroxidation despite the presence of tissue‐specific abnormality of redox metabolism in dystrophic muscle.
The effect of the internal reference on ASIS correlations: 2—The intrinsic ASIS of TMS protons in aromatic hydrocarbon solvents
Authors: Bertrán J. Fernández , Rodríguez Mario 
Published: May 2005

AbstractA method is developed to calculate the intrinsic ASIS of TMS protons used as internal reference, based on linear correlation of the ASIS of a group of sensor protons in two fixed aromatic solvents. Several solute systems (p‐X‐benzaldehydes, camphor, α‐Br‐camphor, 5‐X‐furfurals, p‐X‐acetophenones and methyl ketones) are used to calculate a series of intrinsic ASIS values of TMS in 12 aromatic hydrocarbon solvents. The Δα TMS values are used, in turn, to calculate the intrinsic ASIS of CHO protons in dimethylformamide and diphenylformamide, and of the CH3 protons in diethyl ether and diisopropyl ether.
18O‐isotope effect in 13C nuclear magnetic resonance spectroscopy: 5—Substituent group electronic effects in substituted acetophenones
Authors: Risley John M. , DeFrees Shawn A. , Van Etten Robert L. 
Published: May 2005

AbstractA series of para‐ and meta‐substituted acetophenones were prepared which were highly labeled with 18O at the carbonyl function. The natural abundance 13C NMR spectra of the compounds were recorded and the 18O‐isotope‐induced shifts of the carbonyl carbon were measured in order to determine possible substituent group electronic effects on the 18O‐isotope shift. The isotope shifts were found to be correlated with a number of properties which demonstrate the molecular basis of the isotope shift. Good correlations were obtained for the isotope shift as a function of σp+, the carbonyl stretching frequency, the carbonyl group bond order, the n→π**transition of the carbonyl group and the chemical shift of the ipso carbon. In contrast, no correlation was observed between the magnitude of the 18O‐induced isotope shift and the 13C chemical shift of the carbonyl carbon. These properties are discussed in connection with the theoretical basis of the isotope shift.
Accurate referencing of 13C NMR spectra from glycosaminoglycan and other polysaccharides in aqueous medium
Authors: Huckerby T. N. 
Published: May 2005

AbstractThe use of the water‐soluble reference materials sodium 2,2‐dimethylsilapentane sulphonate (DSS) and sodium 2,2,3,3,‐tetradeuterio‐3‐trimethysilyl propionate (TSP‐d4) as internal standards for the calibration of carbon spectra determined in D2O is proposed. Problems arising from the use of secondary or external references are eliminated; very high field spectra (13C at 100 MHz) may be calibrated to 0.01 ppm.
29Si NMR spectra of trimethylsilylated cyclic acyloins and ketones. 29Si chemical shifts as a measure of ring size
Authors: Schraml J. , Šraga J. , Hrnčiar P. 
Published: May 2005

Abstract29Si chemical shifts are reported for nine 1,2‐bis(trimethylsiloxy)cycloalkenes and four 1‐trimethylsiloxycycloalkenes, (Me3SiO)xCnH2n–2–x (x=1, 2). For cycloalkene derivatives with n⩽8 the silicon shift exhibits a strong dependence on the ring size, although the silicon is exocyclic and is separated by two bonds from the olefinic carbon atom. The dependence can be exploited for ring size determination of cyclic ketones after trimethylsilylation.
Differentiation of diastereomeric bornane derivatives by 13C NMR spectroscopy
Authors: Duddeck Helmut , Blagoev Blagoy , Berova Nikolina D. , Vassilev Vassil 
Published: May 2005

AbstractThree diastereomeric bornane derivatives have been assigned configurational structures by 13C NMR measurements in the presence of Yb(dpm)3.
Influence of the Z/E configuration on the 13C15N coupling conditions 1J(13C15N) in aromatic azo and diazo compounds
Authors: Simova S. , Fanghänel E. , Radeglia R. 
Published: May 2005

AbstractThe 13C NMR spectra of singly 15N‐labelled Z/E isomers of azo and diazo compounds were recorded. The 1J(13C15N) coupling constants are strongly dependent on the geometrical configuration of the azo group, the relative position of the lone pair of electrons at the non‐coupling azo nitrogen atom having a decisive influence.
Aza‐polycyclic aromatic hydrocarbons: 1—Elucidation of the regiochemistry of 1,2,3,4‐tetrahydroazabenz‐[a]anthracene‐7,12‐diones by long‐range carbon–proton coupling constants
Authors: Haber Arthur , Hilton Bruce D. 
Published: May 2005

AbstractThe 13C NMR spectra of 5,8‐quinolinedione, 6‐chloro‐5,8‐quinolinedione and 7‐chloro‐5,8‐quinolinedione have been examined in detail. Utilization of long‐range proton‐carbon coupling constants have allowed the unambiguous identification of the regioisomeric 8‐aza‐1,2,3,4‐tetrahydrobenz[a]anthracene‐7,12‐dione and 11‐aza‐1,2,3,4‐tetrahydrobenz[a]anthracene‐7,12‐dione.
13C chemical shifts of Δ1‐pyrrolines
Authors: Gawley Robert E. , Termine Enrico J. , Goicoechea‐Pappas Marta 
Published: May 2005

Abstract13C chemical shifts are reported for the ring carbons of several substituted Δ1‐pyrrolines. Average values for methine and methylene ring carbons facilitate structure elucidation of substituted δ1‐pyrrolines by 13C NMR spectroscopy.
13C NMR spectra of benzothiazepinone, benzothiazinone and benzosulphonamide N‐substituted derivatives
Authors: Stassinopoulou C. I. , Catsoulacos P. , Camoutsis Ch. 
Published: May 2005

AbstractA comparative study of the 13C NMR spectra of benzothiazinone and benzothiazepinone dioxide derivatives and of some structurally related benzosulphonamides is presented. The size of the heterocyclic ring is reflected in the 13C chemical shifts and in the one‐bond carbon‐proton aromatic coupling constants. An upfield γ‐effect of sulphur on the 13C chemical shifts in N‐substituted carboxyethylbenzene‐4,5‐dimethoxysulphonamides is reported.
A model for the complex of the (R)‐MTPA ester oftrans‐4‐tert‐butylcyclohexanol with Eu(fod)39based on lanthanide induced shifts
Authors: Vanhoeck L. , Merckx E. M. , Bossaerts J. , Lepoivre J. A. , Alderweireldt F. C. 
Published: May 2005

AbstractIt is shown that the complexation of Eu(fod)3with the MTPA ester oftrans‐4‐tert‐butylcyclohexanol is very similar to that of ketones with Eu(fod)3. It is found to be more likely that the MTPA moiety can exist as two rotamers, suggesting that earlier models for correlating LIS and absolute configuration are inadequate.
13C NMR spectra of some monosubstituted quinolizinium bromides
Authors: Van Veldhuizen A. , Van Dijk M. , Sanders G. M. 
Published: May 2005

AbstractChemical shifts are reported for quinolizinium bromide and 12 monosubstituted derivatives, carrying a bromohydroxy, diethylamino or piperidino group as the substituent. In addition, 1J(CH) values and long‐range coupling constants are given.
Electron spin resonance spectra and hyperfine coupling constants of the α‐tocopheroxyl and 2,2,5,7,8‐pentamethyl‐chroman‐6‐oxyl radicals derived from vitamin E and its model and deuterated model compounds
Authors: Matsuo Mitsuyoshi , Matsumoto Shigenobu , Ozawa Toshihiko 
Published: May 2005

AbstractHighly resolved electron spin resonance spectra of the α‐tocopheroxyl or 2,2,5,7,8‐pentamethylchroman‐6‐oxyl radicals were obtained from the oxidation of α‐tocopherol (vitamin E) or its model compound, 2,2,5,7,8‐pentamethylchroman‐6‐ol, with 2,2‐diphenyl‐1‐picrylhydrazyl or superoxide ion. Complete assignments of the hyperfine coupling constants of these radicals were made on the basis of the spectra of the deuterated isotopomers of the 2,2,5,7,8‐pentamethylchroman‐6‐oxyl radical. The large coupling constant due to the methyl group at C‐5 in the α‐tocopheroxyl radical may have implications for the high reactivity toward radicals of C‐5 in α‐tocopherol.
Fluoroimines from the reaction of fluoro amino acids or fluoroketo acids with the aldehyde or amine form of vitamin B6: 2—Stereochemical aspects of their formation from β‐fluoroaspartates or β‐fluorooxaloacetate, using 19F NMR
Authors: Salon M. C. , Hamman S. , Beguin C. G. 
Published: May 2005

AbstractThe fluorine NMR spectra of systems initially containing 0.05–0.1 M of pyridoxal 5′‐phosphate and erythro‐β‐fluoroaspartate (or threo‐β‐fluoroaspartate) in D2O solution were examined over the pD range 1–12. The formation of the aldimine Schiff base gave only one stereoisomer, whcih was trapped with sodium borohydride. Reactions of pyriodoxamine 5′‐phosphate and fluorooxaloacetate were examined under the same conditions. A mixture of two products was given, identified as two ketimine Schiff bases (E and Z isomers) with well characterized fluorine chemical shifts and 2J(DF) values. This mixture, trapped with sodium borohydride, gives the two reduced erythro and threo aldimines. The configurations and conformations of all reaction products were determined using the 3J(HF) values and their correlation with the fluorine chemical shift. The role of the 3‐phenolate oxygen of the pyridine ring, of the conjugate acid of the iminium nitrogen and of the carboxylate oxygen in ionic or hydrogen bond interactions in the determination of the stereochemistry is discussed.
13C NMR studies of conformational isomerism in thioureas: Signal assignments via chemical shift and population trends
Authors: Sullivan Richard H. , Nix Pamela , Jun. Eddie L. Summers , Parker Stanley L. 
Published: May 2005

AbstractThe 22.63 MHz 13C NMR spectra of a series of alkylated thioureas are reported. Characteristic Z and E spectral regions were found for the 13C  S resonances. The two regions were generally found to be non‐overlapping for the series, with the region of the Z, Z resonances occurring more downfield than those of either the Z, E or E, Z conformers in the cases of 1,3‐disubstitution. The Z, Z configuration became favored and the relative chemical shift difference (Rδ) increased linearly with increasing substituent size. At 217 K, hindered internal rotation caused a multiplicity of resonances which were normally single peaks in the broad band 1H decoupled 62.86 MHz 13C spectrum of CH3NHCSNH(CH2)2NHCSNHCH3 (2MTE) at room temperature. The trends in chemical shifts and populations were employed to assign tentatively the resonances of five of the six possible configurational isomers contributing to the 2MTE spectra at 217 K. The isomer populations are given. The 13C NMR spectra reported here led to signal assignments of Z and E isomers which supported prior 1H NMR results and contradicted more recent results of another 13C NMR study of N‐methylthiourea. The major peak of the exchange doublet occurs at relatively high field strengths in both methanol‐d5.
1H NMR study of 2,8‐dithia‐1,5‐dielementbicyclo[3.3.0]octanes
Authors: Zschunke A. , Mügge C. , Meyer H. , Tzschach A. , Jurkschat K. 
Published: May 2005

AbstractThe analysis of the 1H NMR spectra of 2,8‐dithia‐1,5‐diphosphabicyclo[3.3.0]octane, 2,8‐dithia‐1‐phospha‐5‐azabicyclo[3.3.0]octane and 2,8‐dithia‐1‐arsa‐5‐phosphabicyclo[3.3.0]octane is supported by means of 2D‐ J‐resolved NMR measurements. The spectra suggest a preferred conformer with strong puckering of the fused five membered rings.
A carbon‐13 NMR study of the ion pair structure of the dibenzo[b,f]pentalene dianion
Authors: Eliasson Bertil , Edlund Ulf 
Published: May 2005

AbstractThe 1H and 13C NMR chemical shifts of dibenzo[b, f]pentalene and its 5,10‐dimethyl derivative are presented and compared with those of the corresponding dilithium dianions. As probed by the relative 13C NMR chemical shifts, the charge distribution within the dianion system is clearly dependent on the actual ion pair state. This condition is demonstrated by varying the solvent and temperature. The polarization of charge towards the pentalene carbons, i.e. the preferred cation positions, is observed on going to tight ion pair conditions. Further support for this model is gained from 7Li NMR. The limitations of the use of 1H and 13C NMR chemical shifts to measure charge distributions within anion systems are discussed.
Solution conformation and dynamics of L‐6‐methylperhydroimidazo[1,5‐c]thiazole‐5,7‐dione (γ‐thiaprolinehydantoin). A 1H and 13C NMR study
Authors: Borremans Frans A. M. , Buděšínský Milos , Callens Roland E. A. , Anteunis Marc J. O. 
Published: May 2005

AbstractThe solution conformation of L‐6‐methylperhydroimidazo[1,5‐c]thiazole‐5,7‐dione (γ‐thiaprolinehydantoin) has been determined from an extensive 1H and 13C NMR study, allowing the extraction of vicinal inter‐proton and carbon‐hydrogen coupling constants. The major conformation of the thiazolidine ring is an envelope with C‐δ as the flap exo (δ−). In solution the preferred solid state (twist) conformer with C‐α exo and C‐β endo (αβT) is only a minor contributor. 13C spin–lattice relaxation data reveal the flexibility of the thiazolidine ring.
13C and 31P NMR studies of configurational and conformational effects in 1‐Phenyl‐4‐phosphorinanones and their 1‐selenides
Authors: Pietrusiewicz K. Michał 
Published: May 2005

AbstractCarbon‐13 and 31P NMR data are reported for 1‐phenyl‐4‐phosphorinanone and its 1‐selenide, as well as for two anancomeric 1‐phenyl‐3,5‐dimethyl‐4‐phosphorinanones and their 1‐selenides. The conformational free energy of the P‐phenyl substituent in 1‐phenyl‐4‐phosphorinanone is estimated to be ΔG° = 0.81 kcal mol−1 (ca 80% axial) in chloroform, and this result is consistent with both 13C NMR shielding and coupling data. The γ effects of a single atom substituent on phosphorus are found to be small in the case of selenium; information in the literature indicates significant downfield‐shifting γe effects due to equatorial oxygen and sulphur substituents in phosphorinanes. In selenides, the shift for the aromatic C‐ipso carbon in the axial isomer is further downfield than in the equatorial isomer, an observation not precedented in the literature. In the discussion of P‐C coupling data a ‘second order’ Karplus‐like relationship is invoked for 3J(PC), which is dependent both on the dihedral angle and on the orientation of the phosphorus lone pair in phosphines. The one‐bond P‐C‐ipso coupling in selenides is identical for all three selenides studied, regardless of the stereochemistry at phosphorus. Similar lack of substantial differentiation is noted for one‐bond P‐Se coupling. A possible origin of this phenomenon is discussed in terms of diminution of the phosphorus charge contribution to the Fermi contact term. From 31P NMR data a high stereodependence of selenylation shifts is apparent, and greater shifts (by ca 20 ppm) are observed when selenium is bound to phosphorus in the more crowded (axial) position. In anancomeric (conformationally biased) phosphines, the isomer with the axial phenyl group has the 31P signal at lower field. This is consistent with observations made previously for rigid 1‐phenylphosphorinanes.
The carbon‐13 nuclear magnetic resonance spectra of some α‐spirocyclopropyl ketones and related cyclohex‐2‐en‐1‐ones and 2‐ethylidenecyclohex‐3‐en‐1‐ones
Authors: Helferty Patrick Hugh , Yates Peter 
Published: May 2005

AbstractThe 13C NMR spectra of a series of β,γ‐unsaturated α‐spirocyclopropylcyclohexanones and saturated α‐spirocyclopropylcycloalkanones have been analyzed and compared with the spectra of diethyl cyclopropanedicarboxylate and a corresponding spiro acylal. The chemical shifts of the cyclopropane methylene carbons are correlated with spiroactivation of the cyclopropane ring to nucleophilic attack. In the case of the saturated spiro ketones these chemical shifts can also be correlated with their photochemistry. In the SFORD spectra of the spiro ketones the signals of the cyclopropane methylene carbons appear as complex multiplets: this is attributed to second‐order coupling resulting from strong coupling between the vicinal cyclopropane protons. The 13C NMR spectra of a series of related cyclohex‐2‐en‐1‐ones and 2‐ethylidenecyclohex‐3‐en‐1‐ones have also been analyzed; the chemical shift assignments for the latter corroborate the configurational assignments made on the basis of 1H NMR spectroscopy.