bluuebunny/crossref_metadata_2025 huggingface dataset:
13C NMR spectroscopy of keratan sulphates: Assignments for the reduced form of a repeat unit tetrasaccharide derived from keratan sulphate by keratanase digestion and partial assignments for two fucosylated pentasaccharides
Authors: Huckerby Thomas N. , Dickenson John M. , Tai Gui‐Hua , Lauder Robert M. , Brown Gavin M. , Nieduszynski Ian A.
Published: May 2005

A full assignment of the 60°C 13C NMR spectrum for the reduced form of a repeat unit β‐linked tetrasaccharide derived by keratanase digestion from keratan sulphate, GlcNAc(6SO4)β1–3Gal(6SO4)β1–4GlcNAc(6SO4)β1–3‐Gal‐ol, was achieved via two‐dimensional C/H correlation and 1H COSY experiments, and a complete first‐order analysis of the 600 MHz proton spectrum. Partial 13C assignments for two fucosylated keratan sulphate pentasc‐charides derived using hydrazinolysis and nitrous acid treatment are discussed.
Use of cyclodextrins in chiral discrimination by NMR spectroscopy: An example of atropisomerism
Authors: Casy Alan F.
Published: May 2005

The influence of α‐, β‐ and γ‐cyclodextrin (CD) on the 1H NMR spectrum of the muscarinic antagonist telenzepine dihydrochloride in D2O is reported. Duplication of thienyl‐H and thienyl‐Me signals was observed in the presence of β‐ and γ‐CD, with regard to the minor amido conformer in the former case and both major and minor amido conformers in the latter case. Use of CDs in chiral discrimination by NMR is now well known; the present results provide the first example of their application to an atropisomeric example.
Interpretation of the 13C NMR spectra of 3‐benzylideneflavanones, 3‐benzylflavone and 3‐benzyl‐1‐thioflavone derivatives
Authors: Szabó Zoltán , Lévai Albert
Published: May 2005

13C NMR spectra of 3‐benzylflavones, 3‐benzylideneflavanones, 3‐benzyl‐4‐thioflavones, 3‐benzyl‐1‐thioflavones, 3‐benzyl‐1,4‐dithioflavones and 3‐benzyl‐1‐thioflavone‐1,1‐dioxides were analysed and correlated to evaluate the consequences of the replacement of oxygen with sulphur.
1H and 13C NMR relaxation investigation of methotrexate in [2H6]dimethyl sulphoxide solution
Authors: Gaggelli Elena , Valensin Gianni , Vivi Antonio , Macotta Antonella
Published: May 2005

1H and 13C NMR parameters of methotrexate in [2H6]dimethyl sulphoxide were obtained and analysed in terms of a ‘preferred’ conformation. The effective correlation time of the anisotropic motion of the pteridinylbenzoyl moiety was evaluated as ca. 10 ns at 300 K. The 1H1H and 13C1H distances obtained were used to construct the molecular structure in solution.
Determining C‐7 stereochemistry in C‐7‐substituted 6α,14α‐endo‐ethano‐ and 6α, 14α‐endo‐ethenotetrahydrothebaines by 13C NMR; a re‐analysis
Authors: Mazza Samuel M.
Published: May 2005

A re‐analysis of previously published 13C NMR data on C‐7‐substituted 6α,14α‐endo‐ethanotetrahydrothebaines shows that the 13C chemical shift of C‐18 in these medicinally important compounds can be used as an indicator of C‐7 stereochemistry, this being due to a steric gamma effect between C‐18 and C‐7 substituents in an α orientation. In seven examples of α‐isomers the C‐18 chemical shift ranges from δ17.02 to δ18.42 (average δ17.72), whereas in four examples of β‐isomers the C‐18 chemical shift ranges from δ22.09 to δ24.00 (average δ22.73‐23.40). Since suitable etheno compounds can be chemically reduced to ethano compounds, C‐7 stereochemistry in such 6α,14α‐endo‐etheno compounds can be determined indirectly.
High‐field NMR techniques and molecular modelling in the study of the inclusion complex of the cognition activator suronacrine (HP‐128) with cyclodextrins
Authors: Amato Maria E. , Pappalardo Giuseppe C. , Perly Bruno
Published: May 2005

The structural features of the inclusion complexes of cyclodextrins (CDs) with the chiral cognition activator drug (±)9‐[(phenylmethyl)amino]‐1,2,3,4‐tetrahydroacridin‐1‐ol maleate (suronacrine maleate, HP‐128) were studied using both high‐resolution 1H NMR spectroscopy and molecular modelling methods. The partial inclusion of the guest from the secondary hydroxyl side of α‐CD was demonstrated in aqueous solution, in addition to a higher degree of penetration into the cavity of β‐CD from the same side. NMR‐ROESY experiments allowed the unambiguous location of the benzylic ring of the guest inside the β‐CD cavity. The formation of diastereoisomeric pairs was demonstrated by the duplication of the benzylic proton signals. Molecular mechanics calculations were used to complement the NMR analysis. Molecular modelling procedures (MacroModel interactive computer program) allowed the prediction of the most stable structures of the complexes, and showed that specific site interactions, provided by hydrogen bond formation, are capable of differentiating the diastereoisomeric intramolecular inclusion complexes according to available experimental NMR data.
Conformations of triglycyl‐lysylvasopressin: 1H NMR spectroscopic and molecular dynamics study
Authors: Nutz K. I. , Fabian W. M. F. , Sterk H.
Published: May 2005

The conformation of N‐(Gly‐Gly‐Gly)‐Lys‐vasopressin (TGVP) in aqueous solution was determined by 1H NMR spectroscopy. The structural data were compared with those obtained in DMSO. Refinement of the structure derived from NMR data and a description of the conformational dynamics were accomplished by molecular dynamics simulations in aqueous solution.
Compounds with bridgehead nitrogen. Part 72—NMR spectra and stereochemistry of 8,9,10,11,11a,11b,12,13‐octahydro‐7aH‐quino [1,2‐c][1,3]benzoxazines and perhydropyrido [1,2‐c][1,3]benzoxazines. NMR chemical shifts of methylene group protons adjacent to a nitrogen atom
Authors: Crabb Trevor A. , Ingate Simon T. , Nevell Thomas G. , Sumner Steven
Published: May 2005

The positions of conformational equilibria in the four diastereoisomers of 8,9,11,11a,11b,12,13‐octahydro‐7aH‐quino [1,2‐c] [1,3] benzoxazines were investigated using 13C and 1H NMR spectroscopy. Comparison of the NMR chemical shifts of these isomers with those in the corresponding isomers of perhydropyrido [1,2‐c] [1,3]benzoxazine shows the effect on NMR shifts of fusion of the aromatic ring on to the fully saturated system. The Δδ values are discussed in terms of degree of overlap of the nitrogen lone pair orbitals with the aromatic π‐system.
Selective 2H, 2H 1D‐TOCSY NMR spectroscopy for signal assignment in perdeuteriated compounds
Authors: Mons Hans‐Egbert , Bergander Klaus , Günther Harald
Published: May 2005

The 1D‐TOCSY experiment for 2H NMR is introduced and applications for signal assignments are illustrated with the spectra of pyridine‐d5 and iodo‐ and chlorocyclohexane‐d11. The potential of the method for the analysis of overlapping 2H spectra is demonstrated.
1H, 13C, 17O and 19F NMR spectroscopic study of isomeric ring‐substituted monofluoro‐(E)‐3‐phenylpropenals
Authors: Laihia K. , Kolehmainen E. , Mänttäri P. , Kauppinen R.
Published: May 2005

Isomeric ring substituted monofluoro‐(E)‐3‐phenylpropenals (cinnamaldehydes) were synthesized in order to provide, with the NMR‐active 19F nucleus, an insight into the influence of substituents and the transmission of electronic effects between the aromatic ring and the side‐chain. Their 1H, 13C and 17O NMR chemical shifts and their nJ(H,H), nJ(H,F), nJ(C,H) and nJ(C,F) values were determined. Generally, the nJ(C,F) coupling constants correlate with the length of the coupling route and thus simplify the assignments of the 13C NMR spectra. Only the side‐chain carbons C‐2 and C‐3 in the ortho‐substituted compounds showed an exception to this rule. Many long‐range nJ(H,F) (n = 4–7) values were easily observed. The 17O NMR chemical shift of the carbonyl oxygen in the o‐ and m‐fluoro derivatives show clear substituent effects, whereas p‐fluorocinnamaldehyde shows a value comparable to that of that parent compound.
NMR chemical shift assignments for 7′‐substituted aromatic‐7′‐apo‐β‐caro‐tenes
Authors: Hand E. S. , Belmore K. A. , Kispert L. D.
Published: May 2005

Chemical shifts of all protons at 8.46 T and 13C atoms are presented for substituted 7′‐aryl‐7′‐apo‐β‐carotenes, where aryl = C6H5, 4‐C6H4NO2, 4‐C6H4OCH3, 4‐C6H4CO2CH3, C6F5 and 2,4,6‐C6H2(CH3)3. Assignments were established by NOE, COSY, HMBC and HETCOR studies.
Thermodynamic characterization of tautomeric equilibria by multinuclear magnetic resonance. Application to 3‐hydroxypyridine
Authors: Llor Juan , Lopez‐Mayorga Obdulio , Muñoz Luis
Published: May 2005

A marked temperature dependence of the 13C and 15N chemical shifts of 3‐hydroxypyridine in D2O (pD = 7.0) was observed. This dependence is explained in terms of thermally induced equilibrium shifts between the neutral form and the zwitterionic form of 3‐hydroxypyridine. A method was developed to characterize the thermodynamics of the equilibria that are rapid on the NMR time scale, using the observed average 13C and 15N chemical shifts at different temperatures. This method was applied to the thermodynamics of the tautomerization equilibria of 3‐hydroxypyridine. The equilibrium constants and the standard enthalpy change of the tautomerization equilibrium obtained by 13C and 15N methods agree very well with the results obtained by other spectroscopic methods.
Substituent‐induced chemical shifts along CC double bonds
Authors: Knorr Rudolf , von Roman Therese , Freudenreich Johannes , Hoang Thi Phung , Mehlstäubl Johann , Böhrer Petra , Stephenson David S. , Huber Helmut , Schubert Bernhard
Published: May 2005

1H and 13C NMR signals were assigned and CH coupling constants (1J, 2J, 3J) determined for a series of α‐mono‐and α,α‐disubstituted (1,1,3,3‐tetramethyl‐2‐indanylidene)methanes with the following α‐substituents: (mesityl)2B, n‐propyl, phenyl, tert‐butyl‐C(NH), cyano, (tert‐butyl)2C(OH), pivaloyl, H2N‐CO, PhNH‐CO, carboxy, ritro, acetoxy, Me3SiO, Me3Si, PhS, PhSMe+, PhSO, PhSO2, bromo and trimethylstannyl. The 1J couplings with the olefinic proton span the range 124.3–193.7 Hz. Substituent‐induced chemical shifts (SCS) of most of the nuclei with respect to the α‐unsubstituted olefin obey simple additivity in the α,α‐disubstituted compounds and are very similar to the SCS values along the CN double bond in the isoelectronic (1,1,3,3‐tetramethyl‐2‐indanylidene)amines within the error limits. The exceptions concern nuclei in the immediate vicinity of the perturbing substituent. A dominant mechanistic contribution of electric field effects appears likely for the more distant aromatic part of the indanylidene moiety. The chemical shifts of two (2,2,5,5‐tetramethylcyclopentylidene)methanes are shown to be compatible with the SCS parameters from the indanylidene series.
NMR 1H relaxation and NOESY studies of spiperone conformational features in solution
Authors: Keller Charles E. , Carper W. Robert
Published: May 2005

The high‐field 1H, 19F and 13C NMR spectra of spiperone in CDCl3 solution were analyzed with the aid of homonuclear (H‐H‐COSY) and heteronuclear (H,C‐COSY) chemical shift correlation experiments. Multiple through‐space intersections were identified using phase‐sensitive nuclear Overhauser and exchange spectroscopy (NOESY). Proton relaxation rates and activation energies were determined over the temperature range −60 to 50°C. The chemical shift, NOESY and proton relaxation rate results support the formation of cyclic dimers and multiple spiperone conformations in solution.
Conformational analysis of substituted 5,6‐dihydro‐4H‐1,3‐oxazines
Authors: Katritzky Alan R. , Shcherbakova Irina V. , Mancheño Balbino , Tack Robert D.
Published: May 2005

The assignment of the proton and carbon signals and conformations of substituted 5,6‐dihydro‐4H‐1,3‐oxazines were determined by the combination of 1H, 13C, COSY and HETCOR spectral data.
Broadband excitation composite pulses for pure NQR spectroscopy in powders
Authors: Li Geng‐Ying , Xu Liang , Wu Xue‐Wen
Published: May 2005

Composite pulses that compensate for resonance offset and electric field gradient inhomogeneity are proposed for broadband excitation of pure nuclear quadrupole resonance systems in powders. The excitation band width of the composite pulse sequences was obtained with a numerical calculation procedure and confirmed by 35Cl experimental spectra of powdered NaClO3.
1H and 13C NMR spectra of multibridged [2n]cyclophanes
Authors: Ernst Ludger , Boekelheide Virgil , Hopf Henning
Published: May 2005

The 1H and 13C NMR spectra of all [2n] cyclophanes with the same substitution pattern in both benzene rings and of the skew [2.2.2](1,2,4)(1,2,5)cyclophane were assigned by one‐dimensional NOE difference and two‐dimensional correlation spectroscopy. The 1H NMR spectra of the bridge protons including the 13C satellites of the symmetrical compounds [2.2]paracyclophane, [2.2.2](1,3,5)cyclophane and superphane were analysed by iterative methods. Chemical shifts and H,H coupling constants are discussed with regard to molecular geometries.
Schiff's base formation rater than molecular association between acetone and 3‐amino‐6‐methoxypyridine
Authors: Maguire John , Morris David G. , Rycroft David S. , Ortiz F. S.
Published: May 2005

A previous report of a complex between 3‐amino‐6‐methoxypyridine and acetone has been shown to be incorrect. The 1H and 13C NMR signals that were attributed to the complex have been shown to be due to the formation of a Schiff's base.
Experimental (13C and 15N NMR spectroscopy) and theoretical (6–31G) study of the protonation of N‐methylazoles and N‐methylbenzazoles
Authors: Claramunt Rosa Maria , Sanz Dionisia , Boyer Gérard , Catalän Javier , de Paz José Luis G. , Elguero José
Published: May 2005

The 13C and 15N NMR spectra of 11 N‐methyl derivatives of azoles and benzazoles (imidazole, pyrazole, 1,2,4‐triazole, indole, benzimidazole, 2H‐indazole, 1H‐indazole, 2H‐benzotriazole, 1H‐benzotriazole and carbazole) in trifluoroacetic and sulphuric acid are reported. Quaternary salts were used as model compounds. In the case of azoles (from pyrrole to pentazole) ab initio calculations at the 6–31G level were carried out to determine the protonation site.
Deuterium isotope effects on nuclear shielding. Cross‐ring effects in rigid cyclic molecules
Authors: Mlinarić‐Majerski Kata , Vinković Vladimir , Chyall Leonard J. , Gassman Paul G.
Published: May 2005

Deuterium isotope effects on 13C NMR chemical shifts, (2H/1H)nΔ(13C), of 2‐methylene‐d2‐adamantane, 4‐methylene‐d2‐2‐adamantanone and 6‐methylene‐d2‐2‐adamantanone are presented. Long‐range effects (4Δ, 5Δ and 6Δ) in a range from 5 to – 23 ppb were observed. The results for 5Δ and 6Δ are explained in terms of cross‐ring field effects resulting from the change of dipole due to deuterium substitution.
Solution conformation of the ketone and epoxide synthetic precursors of β‐chamigrene determined by 1H and 13C NMR spectroscopy and distance geometry
Authors: Leonard Scott F. , Jones Paul‐James , Spero Denice M. , Pitner T. Phil
Published: May 2005

Utilizing 2D NMR spectroscopy (COSY, NOESY, TOCSY, inverse detected 1H/13C correlation spectroscopy), the 1H and 13C NMR spectra of the ketone and epoxide precursors of β‐chamigrene were assigned. The dihedral angles and distances determined from NMR measurements provide input parameters to calculate the molecules' solution conformation by distance geometry. The factors which are important in influencing the conformation of these molecules are discussed.
Evidence for a novel β‐bend structure with prolines at the corner: 1H and 13C NMR study of cyclo(Pro‐Pro‐Gly)2
Authors: Prachand Mamta S. , Singh Shanteri , Dhingra M. M. , Singh Usha , Ghosh Sunil K. , Mamdapur V. R. , Chadha M. S.
Published: May 2005

The solution conformation of cyclo‐(Pro‐Pro‐Gly)2 in CDCl3 and DMSO‐d6 was investigated by 1H and 13C NMR spectroscopy. In CDCl3 solution the peptide maintains a conformational homogeneity at 300 K and the single asymmetric conformation observed is characterized by a single Pro‐Pro cis‐peptide bond and an intramolecularly hydrogen‐bonded β‐bend structure involving CO of one glycine to the NH of the other glycine. The segment Gly‐Pro‐Pro‐Gly responsible for the β‐bend has a Pro‐Pro peptide bond in the trans configuration. However, in DMSO‐d6 solution, there is a conformational heterogeneity and the population of the two main conformers present is in the ratio of ca. 80:20. The major component is characterized as having two contiguous cis‐peptide bonds involving Gly‐Pro and Pro‐Pro peptide bonds, while the minor component has a conformation characterized by a single Pro‐Pro cis‐peptide bond which is included in the β‐bend structure. The equilibrium between the major and minor components is insensitive to temperature in the range 300‐‐360 K. However, the conformational homogeneity in CDCl3 solution appears to be disturbed by addition of DMSO‐d6 and becomes detectable beyond 20% (v/v) of DMSO‐d6 and at 50:50 (v/v) the populations of the major and minor components become almost equal.
Synthesis and NMR spectrum of [13C18]‐meso‐hexestrol, a fully carbon‐13 substituted ligand for NMR studies of the estrogen receptor
Authors: Kochanny Monica J. , Härd Torleif , Katzenellenbogen John A.
Published: May 2005

The estrogen receptor ligand meso‐hexestrol has been synthesized with 13C enrichment (98 at.%) at every position. 13C NMR spectra of the intermediates were obtained and 13C−13C coupling patterns analyzed. The complex 13C NMR spectrum of [13C18]‐meso‐hexestrol was simplified through the use of selective 13C decoupling. Several 13C−13C coupling constants were estimated from the decoupled spectra and refined via iterative simulation. Some additional coupling constants were measured in selective one‐dimensional 13C COSY spectra. Coupling constants are reported to an accuracy of ±0.4–1 Hz. This study demonstrates the feasibility of determining 13C−13C coupling constants in highly 13C−substituted compounds; such compounds are expected to be used with increased frequency in studying receptor‐ligand interactions by polarization transfer methods.
Proton magnetic resonance study of the conformations of 3′,5′‐O‐(di‐tert‐butylsilanediyl) nucleosides
Authors: Katsura Tatsuo , Ueno Katsuhiko , Furusawa Kiyotaka
Published: May 2005

The solution conformations of nine 3′,5′‐O‐(di‐tert‐butylsilanediyl) nucleosides, new sila analogues of cyclic nucleotides, were studied by proton NMR spectroscopy. The furanose rings of all the compounds studied are forced to take on the C‐3′‐endo conformation by the 3′,5′‐cyclization. The conformations at the glycosidic bond of the adenosine and deoxyadenosine derivatives were determined as mixtures of syn and anti conformations by the DESERT method; the fractions of anti conformation for these derivatives were 0.58 and 0.41, respectively.
NMR spectroscopic characterization of ZE isomers of cyclododeca‐1,5,9‐triene
Authors: Radeglia Reiner , Poleschner Helmut , Haufe GÜNter
Published: May 2005

The four ZE isomers of cyclododeca‐1,5,9‐triene were examined by 13C NMR spectroscopy. The vicinal 1H1H coupling constants of the olefinic protons were used to determine the stereochemistry at the double bonds. For the symmetrically substituted CHCH fragments (chemically equivalent H atoms) this parameter was obtained from the 13C NMR multiplets which are observed in 1H continuous‐wave off‐resonance 13C NMR experiments. The precise assignment of the 1H and 13C chemical shifts, in particular for the Z,Z,E and Z,E,E isomers, was possible on the basis of off‐resonance measurements in combination with 13C/1H heteronuclear correlated and 1H/1H‐COSY‐45 2D experiments.
High‐field nuclear magnetic resonance of thallium in zeolites
Authors: Groombridge Christopher J. , Coker Eric N. , Rees Lovat V. C.
Published: May 2005

Thallium‐205 NMR is reported for several zeolite samples (A, X and Y; hydrated and dehydrated) with thallium(I) exchanged for sodium. Detection at high field (7.05 T) clarifies the spectrum appearance, and it is seen that chemical shift anisotropy (CSA) dominates some of the band shapes. The large CSAs dictate that the spectrum is recorded piecewise by a frequency‐stepped spin‐echo integral (FUSSI) method. Magic‐angle sample spinning has been observed to give only a very minor line‐narrowing effect. Threefold‐coordinated zeolite A Tl+ sites adjacent to six‐membered rings [Tl(1) and Tl(3)] are both assigned to a resonance which has large CSA (δiso 1183, δδ—1842), while the remaining zeolite A site [Tl(2)] gives an isotropic line shape (δiso 300). Dehydrated zeolite X gives an isotropic peak (δiso 854) which is assigned to the double six‐ring Tl(I), and a broader anisotropic resonance which is tentatively attributed to supercage Tl(III). Data for dehydrated zeolite Y indicate that this has a disordered cation distribution.
Carbon‐13 NMR spectroscopy of some 4‐substituted 3‐halo‐2,6‐dimethylpyridine N‐Oxides
Authors: Ban‐Oganowska Hanna
Published: May 2005

13C NMR spectra of 4‐substituted 3‐chloro‐ and 3‐bromo‐2,6‐dimethylpyridine N‐oxides in CDCI3 and their chemical shifts are reported. The influence of the electronic properties of the substituent in the 4‐position and the ortho effect on the direction of chemical shifts and the values of coupling constants 1J(C‐5,1H) is discussed.
Paramagnetic 1H NMR saturation transfer study of ligand exchange in iron(III) myoglobins
Authors: Yamamoto Yasuhiko , Inoue Yoshio , Suzuki Tomohiko
Published: May 2005

1H NMR saturation transfer experiments were successfully used in connecting iron(III) high‐ and low‐spin forms of equine, the mollusc Dolabella auricularia and the shark Mustelus japonicus myoglobins. With the known signal assignments in the high‐spin form, a haem peripheral proton resonances in met‐azido and met‐imidazole complexes of the myoglobins have been straightforwardly assigned via the saturation transfer connectivities. Analysis of the extent of the saturation transfer provided the kinetics of the ligand exchange.
Copper‐cobalt superoxide dismutase: A re‐examination of the 1H NMR spectrum through a novel selectively deuteriated derivative
Authors: Bertini Ivano , Piccioli Mario , Scozzafava Andrea , Viezzoli Maria Silvia
Published: May 2005

Through 1D and 2D NOESY experiments, samples of copper‐cobalt superoxide dismutase in which the histidines had been completely deuteriated except for the β‐CH2 protons were investigated. In this way a simplified spectrum was obtained which allowed the detection of the His NHs of the cobalt domain and their assignment through the kinetics of the proton‐deuterium exchange. Further, the β‐CH2 protons of Asp 83 were stereospecifically assigned through T1 measurements. Some backbone protons were also assigned.
NMR relaxometric studies of water accessibility to haem cavity in horse heart and sperm whale myoglobin
Authors: Aime Silvio , Ascenzi Paolo , Fasano Mauro , Paoletti Silvia
Published: May 2005

The measurement of longitudinal relaxation rates of water protons in solutions containing horse heart and sperm whale metmyoglobins at various pH values and temperatures shows that the two species differ essentially in the exchange lifetime, τM, of the water molecule in the haem cavity. The 1/T1 nuclear magnetic relaxation dispersion dispersion profiles support this view whereas 17O NMR spectroscopy shows that the exchange mechanism involves the whole water molecule. The lack of any 1H/2H isotope effect on the exchange rate suggests that the displacement of the coordinated water molecule from Fe(III) is not the rate‐determining step in the overall exchange process. In contrast to the parent species, no difference is detectable from the relaxometric investigations on the corresponding fluorometmyoglobin derivatives.
Establishment of two distinct protein domains in blue crab Callinectes sapidus metallothionein‐I through heteronuclear (1H113Cd) and homonuclear 1H1H) correlation NMR experiments
Authors: Narula Surinder S. , Armitage Ian M. , Brouwer Marius , Enghild Jan J.
Published: May 2005

Metallothionein is a cysteine‐rich metal‐binding protein whose biosynthesis is closely regulated by the level of exposure of an organism to zinc, copper, cadmium, etc., metal salts. The metallothionein from the crab Callinectes sapidus is known to bind six divalent metal ions. The 113Cd NMR spectrum of the 113Cdsubstituted protein shows six distinct 113Cd resonances spanning a chemical shift range of 620–665 ppm, indicating the presence of six distinct tetrahedrally coordinated divalent metal ion binding sites. Heteronuclear 1H113Cd correlation experiments revealed all the metal‐to‐cysteine connectivities present in this protein and the 2X(2113Cd)‐;filtered COSY experiment revealed that six cysteines are involved in the ligation of two Cd2+ ions. Additionally, following the complete sequential resonance assignment of the 1H NMR data, the two separate Cd3Cys9 metal binding clusters can be shown to reside in two distinct protein domains.
113Cd NMR spectra of human serum transferrin
Authors: Kiang William , Sadler Peter J. , Reid David G.
Published: May 2005

The binding of Cd2+ to human serum transferrin (80 kDa) was studied by 113Cd NMR spectroscopy. At pH 7 in the presence of hydrogen‐carbonate as synergistic anion, two resonances of similar intensity at 38.1 and 43.6 ppm were observed, consistent with Cd2+ binding to oxygen ligands and one nitrogen ligand in the specific metal‐binding clefts of the N‐ and C‐lobes of the protein.
NMR study of haem exchange reaction of native myoglobin and haemoglobin
Authors: Ishimori Koichiro , Morishima Isao
Published: May 2005

A proton NMR study of the haem exchange reactions of native myoglobin and haemoglobin with the various haems revealed that the haem displacement reaction occurs in native haemoproteins as has been detected in the reconstituted haemoproteins. In the presence of an excess amount of the modified haem, protohaem was excluded from a native haemoprotein to yield a reconstituted haemoprotein containing the modified haem, suggesting that the conformational fluctuations in native haemoprotein are large enough to dissociate its haem from the haem crevice. Although the haemoglobin subunits and myoglobin exhibit very similar three‐dimensional structures as revealed by x‐ray diffraction studies, the rates of the haem exchange reactions in myoglobin were larger than those in the haemoglobin β‐subunit. Such differences in the dynamic properties suggest that these haemoproteins have different interactions between the haem and amino acid residues inside the haem pocket.
Determination of long‐range 13C, 1H coupling constants of macrolide antibiotics by 2D J—δ selective INEPT experiments
Authors: Ladam Patrick , Gharbi‐Benarous Josyane , Piotto Martial , Delaforge Marcel , Girault Jean Pierre
Published: May 2005

2D J—δ selective INEPT experiments were used to measure long‐range 13C,1H coupling constants for the macrolide antibiotics roxithromycin, erythromycin and their metabolites, RU 39001 and erythralosamine, respectively. The 2D J—δ selective INEPT experiment was performed using selective excitation by a DANTE pulse train. In some cases, to avoid truncation problems in the t1 domain, treatment of the data using a linear prediction method was adopted. Dihedral angles for the glycosidic bonds and the erythronolid unit were deduced from a Karplus‐type equation for conformational study. The apparent equilibrium between different conformers is discussed by comparison of experimental results and theoretical calculations by molecular dynamics.
Long‐range proton spin‐spin coupling in rigid cyclic structures by 2D NMR/‘through‐space coupling’
Authors: Schröder Harald , Haslinger Ernst
Published: May 2005

In H,H COSY spectra of rigid cyclic terpenes, many long‐range couplings can be observed. The coupled nuclei are connected either by a zig‐zag coupling path or they are close in space. The latter are called ‘through‐space’ coupling. A certain stereospecific relationship between the coupling partners is necessary. This phenomenon is in accordance with the theoretical explanations.
Synthesis of 13C, 15N‐enriched α‐dicarbonyl model adducts to determine the utility of 13c and 15N NMR for studying mechanism‐based inactivation of cytochromes P‐450 by substituted dichloroacetamides
Authors: Weiner Scott J. , Holl Susan M. , Covey Douglas F.
Published: May 2005

To determine the feasibility of using NMR to study the inactivation of cytochromes P‐450 by dichloroacetamide‐containing mechanism‐based inactivators, 13C, 15N‐enriched compounds were synthesized, modeling adducts between the nucleophilic side‐chains of cysteine, lysine, serine (threonine) and tyrosine and the α‐aminooxoacyl chloride that presumably results from enzymatic conversion of a dichloroacetamide‐containing inhibitor. 13C chemical shifts of the carbonyls attached to the nucleophiles easily distinguish the model cysteine adduct (δ 192.3) from the other adducts (δ 159.6–161.8). Although the other adducts cannot be distinguished at this carbon, the carbonyl attached to the 15N two bonds away can distinguish the lysine mimic (δ 161.2 or 161.3) from the serine (threonine) and tyrosine mimics (δ 156.1–158.1). These assignments were made by comparing 15N/13C J values and were confirmed by solid‐state rotational echo double resonance (REDOR) studies. Finally, aminooxo‐15N chemical shifts three bonds removed from the nucleophile can distinguish adducts formed to lysine (δ 108.3), cysteine (δ 104.8) and oxygen‐containing side‐chains (δ 112.8–113.9).
Structure of a feruloylated arabinoxylan tetrasaccharide that contains the β‐D‐Xylp‐(1 → 2)‐α‐L‐Araf element by 1H and 13C NMR spectrocopy
Authors: Himmelsbach David S. , Hartley Roy D. , Borneman William S. , Poppe Leszek , van Halbeek Herman
Published: May 2005

The determination of the structure of {[5‐O‐(E)‐feruloyl] [O‐β‐D ‐xylopyranosyl‐(1 → 2)]‐O‐α‐L arabinofuranosyl‐(1 → 3)}‐O‐β‐D‐xylopyranosyl‐(1 → 4)‐D‐xylopyranose, a compound isolated from the cell walls of Gramineae, is presented. Use is made of 1D HOHAHA and 2D 1H, 13C 1H‐detected HMQC to assign the 1H and 13C NMR spectra of the individual residues. The 2D 1H, 13C 1H‐detected HMBC and 1H, 1H ROESY, in comparison with 1H, 1H COSY, experiments are used to establish the inter‐residue linkages. This is the first report of a feruloylated arabinoxylan that contains the β‐D‐Xylp‐(1 rarr; 2)‐α‐L‐Araf element.
Lithium‐7 and lithium‐6 NMR studies of solid complexes of lithium tetrahydroborate
Authors: Espidel Joussef E. , Harris Robin K. , Wade Kenneth
Published: May 2005

Lithium‐7 and lithium‐6 spectra were obtained for four solid air‐sensitive complexes of LiBH4 under both magic angle spinning (MAS) and static conditions. The MAS experiments were carried out using a specially designed rotor insert to prevent degradation of the sample. The spectra yield semi‐quantitative information about the magnitude of the quadrupolar coupling constants, but some structure in the static spectra cannot be fully explained. Chemical shift variations are, as expected, modest. Only a single MAS centreband is seen in each case, suggesting that there is only one lithium atom in the asymmetric unit.
Complete 13C 1H chemical shift assignments for trifluoromethyl‐substituted naphthylidineanilines: Remote polar effects on the naphthyl π electron distribution
Authors: Fernandez‐G. Juan M. , Enriquez Raul G. , Reynolds William F. , Yu Margaret
Published: May 2005

13C and 1H chemical shifts are assigned, using 2D methods, for naphthylidineaniline derivatives with CF3 groups substituted in the phenyl group. The 13C chemical shifts for the naphthalene rings are interpreted in terms of remote π polarization effects.
Magnitudes and relative sign of J(119Sn,13C) and J(119Sn,H) coupling constants in some vinyltin(IV) compounds obtained by 2D NMR spectroscopy
Authors: Lyčka Antonín , Tkáč Ivan , Holeček Jaroslav , Pejchal Vladimír
Published: May 2005

Two‐dimensional H,C‐COSY spectra of some vinyltin(IV) compounds were measured. The relative signs of nJ(119Sn, 13C) and (n+1)J(119Sn, 1H) coupling constants were determined after analysis of the orientation of appropriate 119/117Sn satellites in H,C‐COSY spectra.
Structure elucidation and proton and carbon‐13 assignment of a pentasaccharide glycoside from Agave americana
Authors: Pant Geeta , Purohit Mahesh C. , Morris Gareth A. , Halstead Adam G. W. , Thompson Robert I. G.
Published: May 2005

A glycoside extracted from the rhizomes of Agave americana was identified as 3‐O‐[{{β‐D‐xylosyl(1 → 3)}{β‐D‐xylosyl(1 → 3) ‐ β ‐ D ‐ glucopyranosyl(1 → 2)} ‐ β ‐ D ‐ glucopyranosyl(1 → 4)} ‐ β ‐ D ‐ galactopyranosyl] ‐ (25R) ‐ 5α ‐ spirostan‐3β‐ol by concerted use of proton and carbon‐13 2D NMR methods. Complete assignments for the sugar resonances were obtained with standard methods, but the presence of chemical shift degeneracies prevented an unequivocal determination of two of the glycosidic linkage points by the HMBC experiment. Further two‐dimensional experiments failed to resolve the ambiguity, but a clear identification of the linkages was obtained using a selective reverse INEPT experiment with homonuclear double resonance.
NMR study of the solid‐state rearrangement of 3‐amino‐1‐ and ‐2‐(chloroacetyl)pyrazole to 3‐(chloroacetamido)pyrazole
Authors: Clarke David , Mares Richard W. , McNab Hamish , Riddell Frank G.
Published: May 2005

Reaction of 3‐aminopyrazole (1) with chloroacetyl chloride gives a mixture of 3‐amino‐1‐ and ‐2‐(chloroacetyl)pyrazole (2 and 3), both of which rearrange in the solid‐state to 3‐(chloroacetamido)pyrazole (4) over a period of a few days. The course of the rearrangements was monitored directly by CP/MAS NMR and indirectly by 1H NMR spectroscopy; the results suggest that the mechanism involves 3 → 2 → 4.
Quantitative treatment of the rotational dynamics of flexible‐chain molecules. 13C NMR relaxation study of hydrocarbon chains attached to the fluorene anchor
Authors: Pissas D. , Dais Photis , Mikros E.
Published: May 2005

13C spin‐lattice relaxation times (T1) and nuclear Overhauser enhancements (NOEs) were measured for individual carbons in flexible‐chain molecules consisting of a hydrocarbon chain attached to fluorene moiety at position 3 through an ester bond. Quantitative treatment of the relaxation data of the ring carbons revealed an anisotropic motion for all the molecules studied. The relaxation times of the chain carbons were analysed in terms of a correlation function describing multiple internal rotations about successive CC bonds. The results (rotational diffusion constants) were used to discuss features of the chain mobility as a function of chain length and chain unsaturation. The assumptions involved in the quantitative treatment were examined and the values were compared with those of n‐alkanes and lipid bilayers.
Multinuclear magnetic resonance study of some mesoionic 1,3‐diphenyltetrazoles with various exocyclic groups
Authors: Bocian Wojciech , Jaźwiński Jaroslaw , Koźmiński Wiktor , Stefaniak Lech , Webb Graham A.
Published: May 2005

1H, 13C, 14N and 15N NMR methods were applied to the study of some Type A mesoionic 1,3‐diphenyltetrazoles with various exocyclic groups. The ring structures of these tetrazoles are confirmed by the nitrogen NMR data. The shielding of N‐4 increases consecutively by amounts of ca 10 ppm as the bonded exocyclic atom changes from S to C to O.
Nuclear quadrupolar coupling constants in the cyanoborohydride ion: T1 measurements and ab initio molecular orbital calculations
Authors: Penner Glenn H. , Custodio Angela R.
Published: May 2005

The 11B and 2H spin–lattice relaxation times, T1, were measured for sodium cyanoborohydride (BH3CN−) and sodium cyanoborodeuteride (BD3CN−) in methanol–ethylene glycol solution as a function of temperature. Both 11B and 2H T1 minima were observed, yielding 11B and 2H nuclear quadrupolar coupling constants, χ, of 766 and 104 kHz, respectively. Measurement of the 14N T1 at 300 K gave a χ(14N) value of 2.8 MHz. Electric field gradients were calculated using ab initio molecular orbital theory, in order to obtain theoretical 11B, 14N and 2H χ values. The values of 847 kHz, −3.25 MHz and 141 kHz for 11B, 14N and 2H, respectively, are larger than those found in solution.
Selective restricted phenyl rotation in an η3‐Ph2CCHCHPh allyl sparteine complex of Pd(II). Variable‐temperature 13C and multinuclear exchange spectroscopy
Authors: Pregosin Paul S. , Rüegger Heinz
Published: May 2005

Variable‐temperature studies in addition to 2D exchange and NOE measurements on the chiral allyl complex [Pd(η3‐Ph2CCHCHPh){(−)‐sparteine}] [PF6] have revealed that there is restricted rotation about the ipso‐Callyl‐C bonds for the three Ph groups of the η3‐Ph2CCHCHPh ligand, with that for the anti Ph group having a much higher activation energy. Possible consequences for the reaction chemistry of 1,1‐diphenylallyl complexes due to the close proximity of this anti Ph to the chiral bidentate nitrogen ligand are discussed. Detailed 13C and 1H assignments, based on NOESY, TOCSY and C,H correlation measurements, are given.
Will the real β‐pinene please stand up
Authors: Smith William B.
Published: May 2005

In the past year, two complete analyses of the proton NMR spectrum of β‐pinene have appeared from different laboratories. The assignments of the chemical shifts to the protons on carbon‐3 were consistent in both studies although there was disagreement in the values assigned to the coupling constants associated with these protons. A molecular modeling study shows β‐pinene to exist in a single conformation. The proton spectrum has been re‐examined with the aid of the Ag(fod)–Yb(fod)3 reagent, and the coupling constants redetermined. The results are consistent with the modeling results and confirm that the existing assignments for the C‐3 protons should be reversed.
High‐field NMR studies on neo‐clerodane diterpenoids from Mexican Salvia species
Authors: Cárdenas J. , Esquivel B. , Rodríguez‐Hahn L. , Jankowski K. , Van Calsteren M. R.
Published: May 2005

High‐field 2D NMR studies were performed on nine neo‐clerodane diterpenoids. Unambiguous assignments of the 13C signals and proton chemical shifts were achieved which led to the revision of some previous assignments.
Regioselectivity studies by selective detection of long‐range heteronuclear couplings from the SDEPT‐1D method
Authors: Parella Teodor , Sánchez‐Ferrando Francisco , Virgili Albert
Published: May 2005

Some regiosomers formed by palladium(0)‐catalysed allylation of several ambident heterocyclic nucleophiles, among others, were easily distinguished in very short spectrometer times by selective polarization transfer via DEPT from well resolved protons to long‐range coupled carbons using the SDEPT‐1D experiment. This pulse sequence was also analysed in terms of the product operator formalism. These structural elucidations can provide useful information about the regioselectivity in these reactions.
Multinuclear NMR study of protonation in some indolizine systems
Authors: Wiench Jerzy W. , Stefaniak Lech , Webb Graham A.
Published: May 2005

1H, 13C and 15N NMR data are presented for seven indolizine derivatives in solutions of dimethyl sulphoxide and trifluoroacetic acid (TFA). The TFA solutions contain species protonated at position N‐1 in all cases. The most definitive evidence for the site of protonation is provided by the 15N results.
Extensive high‐resolution reverse 2D NMR analysis for the structural elucidation of procyanidin oligomers
Authors: Balas Laurence , Vercauteren Joseph
Published: May 2005

The structures of the procyanidin dimers catechin‐(4α–8)‐catechin and catechin‐(4α–6)‐catechin were proved by spectroscopic means. To distinguish between the two possible interflavanoid linkages, it is necessary to assign all the quaternary aromatic carbon signals. How these assignments can be made through two‐dimensional NMR spectroscopy is described.
Generalized relationship for calculation of nuclear spin—spin coupling constants between directly bonded carbon and hydrogen atoms
Authors: Zhan Chang‐Guo , Hu Zhen‐Min
Published: May 2005

A generalized relationship to describe bond coupling constants is introduced. This expression includes the contributions for hybrid orbitals and the net atomic charges. The resulting expression provides an excellent description of directly bonded CH coupling constants. This equation is suitable both for hydrocarbons and for molecules with I+ and I− substituents.
Analysis of the 13C and 1H spectra of mixtures of benzylidene derivatives
Authors: Bradley J. C. , Williams A. J.
Published: May 2005

The 1H and 13C NMR spectra of methyl (E)‐2,3,‐diphenylprop‐2‐enoate and methyl (E)‐2‐(2‐phenylethenyl) benzoate resulting from the electrocyclic ring opening of benzocyclobutenone starting materials have been assigned. A combination of direct detection 2D NMR techniques, COSY, HETCOR and FLOCK, provided the assignments of the 1H and 13C resonances.
Proton resonance spectra and substituent‐induced chemical shifts of 3‐halocamphors
Authors: Kaiser C. R. , Rittner R. , Basso E. A.
Published: May 2005

Complete signal assignments of high‐field 1H NMR spectra for 3‐halosubstituted camphors (endo and exo) are presented, allowing a refinement of a previous analysis for the chloro (endo and exo) and bromo (endo) derivatives. In addition, still unpublished data for the dichloro and exo‐fluoro derivatives and for three new compounds (endo‐fluoro, endo‐ and exo‐iodo), in addition to a revised assignment of the camphor parent molecule, are reported. The precise substituent‐induced chemical shifts (SCS) obtained for these difunctional systems are examined on the basis of well known transmission mechanisms aided by correlations with steric and electronic parameters, and taking into account SCS data from monohaloalkanes and the calculated molecular geometry data (using the AM1 method).
NMR studies of the luteinizing hormone‐releasing hormone (LH‐RH) decapeptide in DMSO solution
Authors: Calzolai Luigi , Gaggelli Elena , Valensin Gianni , Maccotta Antonella
Published: May 2005

The structure of LH‐RH in DMSO solution was studied using 2D NMR experiments at 600 MHz. The 13C NMR spectrum was completely assigned by the combined use of 1H‐detected heteronuclear multiple‐quantum coherence and 1H‐detected multiple‐bond heteronuclear multiple‐quantum coherence. Measured 1J(CH) values were used to obtain the possible sets of Φ and Ψ dihedral angles. These features, together with some relevant dipolar interactions observed in the ROESY spectrum, were interpreted to provide evidence of some degree of intramolecular structuring.
15N NMR chemical shifts for cyanamide, phenylcyanamide and a series of phenyl‐substituted derivatives
Authors: Buchanan G. W. , Crutchley R. J.
Published: May 2005

15N NMR chemical shifts are reported for cyanamide, phenylcyanamide and nine substituted phenylcyanamide derivatives. Results are discussed in terms of the degree of the π interaction between the cyanamide moiety and the aromatic ring and the stereoelectronic influence of the substituents.
13C NMR of some iodinated methoxy‐amphetamines
Authors: Dawson Brian A. , Black D. B. , Sy W.‐W. , Graham K.
Published: May 2005

13C NMR chemical shift assignments for 14 iodinated methoxyamphetamines were measured and interpreted. Chemical shift assignments for these compounds have not been reported previously. Data are based on a number of one‐ and two‐dimensional experiments performed at 9.4 T.
Hydroacridines. XIV—carbon‐13 NMR spectra of three perhydroacridine stereoisomers
Authors: Potmischil Francisc , Kalchhauser Hermann
Published: May 2005

The 13C NMR chemical shifts of (4aα,8aα, 9aβ, 10aα)‐, (4aα,8aα,9aα, 10aβ)‐ and (4aα,8aβ,9aα, 10aβ)‐tetradecahydroacridine were measured and fully assigned on the basis of APT, 13C, 1H shift correlation and 2D‐INADEQUATE spectra.
13C, 1H long‐range coupling constants in configuration assignment of some trisubstituted alkenes
Authors: Fischer Peter , Schweizer Eberhard , Langner Jörg , Schmidt Ulrich
Published: May 2005

Chemical shifts and long‐range 13C, 1H coupling constants to the two carbonyl C atoms were determined for a series of ethyl 2‐acyloxy‐2‐alkenoates. The 3J(C,H) coupling constant across the double bond is 9.5–10.1 Hz for the E‐ and 2.9–3.8 Hz for the Z‐isomer. 3J(C,H) values, therefore, may be used as a criterion for E/Z differentiation even if only one isomer is available. 13C chemical shift data, in contrast, cannot be employed for a straightforward differentiation.
Dependence of one‐bond deuterium isotope shifts in 13C NMR on CH bond lengths for substituted and unsubstituted aromatic compounds
Authors: Nakashima Yasuki , Teranishi Takashi , Suzuki Toshiya , Sone Tyo , Takahashi Kensuke
Published: May 2005

One‐bond deuterium‐induced isotope shifts of 13C NMR (1Δ) for 106 sp2‐hybridized carbons are discussed in terms of CH bond lengths. 1Δ correlates linearly with the related CH bond length calculated by the MNDO MO method by the equation 1Δ(ppb)=8350 rCH (Å) – 8824.
Ab initio IGLO calculations of 31P NMR shielding tensors of thiophosphoryl compounds. I—dithiadiphosphetanes and dithioxophosphoranes
Authors: Krüger Kerstin , Grossmann Gisbert , Fleischer Ulrich , Franke Robert , Kutzelnigg Werner
Published: May 2005

By means of the IGLO method the 31P NMR chemical shift, δiso, the principal values, σii, and the orientation of the principal axes of the shielding tensor were calculated for a number of dithiadiphosphetanes [RP(S)S]2 and of dithioxophosphoranes RPS2 with RH, CH3 or C6H5. The calculated compare well to the available experimental data from solid‐state NMR and can be taken as predictions where no experimental data are available. The dependence of the principal values σii on geometry changes and the substitution was studied. The shielding tensors were calculated as sums of contributions of localized molecular orbitals. These contributions were used to discuss the effects observed. They provide valuable insights into relationships between geometrical structure and the principal values of σ.
DNA–protein interaction in solution: NMR studies of the 13C‐site‐specifically labelled Lac operator–Lac repressor complex
Authors: Lancelot Gérard , Maurizot Jean‐Claude , Chassignol Marcel , Thuong Nguyeng T. , Chanteloup Luc , Beau Jean‐Marie
Published: May 2005

Carbon‐13 and proton resonance assignments for a DNA fragment complexed with its regulatory protein were obtain with the use of a selectively 13C‐labelled oligonucleotide. Data obtained on the Lac operator–Lac repressor complex from the HMQC–NOESY maps of the free and complexed Lac operator demonstrate that only minor conformational modifications are induced on complexation.
17O NMR spectroscopic investigation of steroids at natural abundance
Authors: Kählig H. , Robien W.
Published: May 2005

Natural abundance 17O NMR spectroscopic data, in toluene‐d8 at 90°C, were obtained for different classes of steroids, including androstanes, estranes, pregnanes, cholanes and cholestanes. Only routine acquisition parameters were used in combination with linear prediction methods during the processing for eliminating acoustic ringing artifacts. The results are discussed in terms of stereochemical effects on the 17O chemical shift of the various oxygen‐containing functionalities.
Gradient selection of coherences in experiments with carbon detection
Authors: Willker Wieland , Leibfritz Dieter
Published: May 2005

Coherence pathway selection with gradients in carbon‐detected experiments is demonstrated. Gradient selection (gs) offers excellent suppression of artifacts and unwanted magnetization, and in practice the signal‐to‐noise ratio is at least as good as for the equivalent phase cycled experiment. A selective gs‐1D‐13C‐COSY is used to correlate one carbon resonance with its neighbours. The gs‐INADEQUATE is used to select multi‐quantum coherences; this can be performed as a 1D or a 2D experiment. Complete elimination of t1 noise is obtained in the gs version only. Applications to labelled glucose, 3‐phenylpropan‐1‐ol and natural abundance menthol are presented. Interference from high‐frequency stray radiation in the gradient cable is removed by inserting a low‐pass filter between the gradient wiring and the probe.