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NMR Spectroscopic Data (nmr + spectroscopic_data)
Selected AbstractsThe Conformation of Alkyl Benzyl Alcohols Studied by ab initio MO Calculations , A Comparison with IR and NMR Spectroscopic DataEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 11 2004Osamu Takahashi Abstract Ab initio MO calculations were carried out for the conformations of a series of alkyl-substituted benzyl alcohols C6H5CH2CHOH,R (R = CH3, C2H5, iPr, tBu) at the MP2/6-311G(d,p)//MP2/6-31G(d) level. It was found that the conformation where the OH group is gauche to the phenyl group is the most stable. The geometry where both the OH and R groups are close to phenyl is the second most stable. This finding has been interpreted on the grounds of the attractive OH/, and CH/, hydrogen bonds and a repulsive van der Waals interaction between vicinal CH groups. NMR nuclear Overhauser effects, spin-coupling data, and IR spectroscopic data are consistent with the conclusion given by the MO calculations. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004) [source] Synthesis and Structure Determination of Selenium(IV) CyanidesEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 30 2008Stefanie Fritz Abstract The reaction of SeF4 with Me3SiCN did not result in thepreparation of the designated Se(CN)4 but Se(CN)F3 and Se(CN)2F2 were obtained as first known selenium(IV)cyanide compounds and characterized by their NMR spectra. Se(CN)2F2 was crystallized as 1,2-dimethoxyethane solvate as well as the corresponding tellurium compound Te(CN)2F2 with very similar structures. NMR spectroscopic data of some more miscellaneous tellurium cyanides and the crystal structures of solvates of Se(CN)2 and oxygen-bridged TeO(CN)2 are presented. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008) [source] Solvent-Mediated Redox Transformations of Ytterbium Bis(indenyl)diazabutadiene ComplexesEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 14 2005Alexander A. Trifonov Abstract The reactions of diamagnetic [(C9H7)2Yb(THF)2] (2) and [rac -(CH2 -1-C9H6)2Yb(THF)2] (3) with tBuN=CH,CH=NtBu (DAD) in toluene result in the formation of the paramagnetic complexes [(C9H7)2Yb(DAD)] (4) and [rac- (CH2 -1-C9H6)2Yb(DAD)] (5), respectively. The IR, UV/Vis, and 1H NMR spectroscopic data, the magnetic properties, and the single-crystal X-ray diffraction studies of 4 and 5 indicate that in the solid state and in noncoordinating media both complexes are ytterbium(III) derivatives containing the DAD radical-anion, whereas the 1H NMR and UV/Vis spectra of solutions of 4 and 5 in the coordinating solvent THF give evidence for divalent ytterbium. Recrystallization of 4 and 5 from THF/hexane results in the recovery of the starting ytterbium complexes 2 and 3 due to an unusual redox substitution of the radical anion of diazabutadiene by THF in the coordination sphere of ytterbium. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005) [source] Characterization by NMR Spectroscopy, X-ray Analysis and Cytotoxic Activity of the Ruthenium(II) Compounds [RuL3](PF6)2(L = 2-Phenylazopyridine or o -Tolylazopyridine) and [RuL'2L"](PF6)2(L', L" = 2-Phenylazopyridine, 2,2'-Bipyridine)EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 13 2005Anna C. G. Hotze Abstract Tris(ligand) complexes [RuL3](PF6)2 (L = 2-phenylazopyridine or o -tolylazopyridine) and mixed ligand [RuL'2L"](PF6)2 (L' and L" are 2-phenylazopyridine or 2,2'-bipyridine) have been synthesized, structurally characterized and investigated for cytotoxic activity. These complexes are important to study the hypothesis that the compound ,-[Ru(azpy)2Cl2] (azpy = 2-phenylazopyridine) exhibits a high cytotoxicity due to its two cis chloride ligands, which might be exchanged for biological targets as DNA. Molecular structures of mer -[Ru(azpy)3](PF6)2 (1) and mer -[Ru(tazpy)3](PF6)2 (5) (tazpy = o -tolylazopyridine) have been determined by X-ray diffraction. Series of complexes [RuL3](PF6)2 and [RuL'2L"](PF6)2 show interesting NMR spectroscopic data; e.g. the spectrum of mer -[Ru(azpy)3](PF6)2 (1) shows extremely broadened resonances at room temp. but sharpened resonances at low temperature. In the 1H NMR spectra of compounds [Ru(azpy)2(bpy)]2+ and [Ru(bpy)2(azpy)]2+ (bpy = 2,2-bipyridine), respectively, less broadened (room temp.) or completely sharp resonances (room temp.) occur in comparison to 1 (under same conditions). By selecting the right temperature and/or concentration, NMR spectra of these series of compounds have been resolved using 2D COSY and NOESY NMR spectroscopy. Remarkably, the cytotoxicity data against a series of human tumor cell lines (A498, EVSA-T, H226, IGROV, M19, MCF-7 and WIDR) show a moderate cytotoxicity for these series of tris(ligand) complexes. So, even though no chloride ligands are present in these tris(ligand) complexes, a considerable cytotoxic activity is observed. This would imply that the 2-phenylazopyridine ruthenium(II) complexes act by a completely different mechanism than the well-known cisplatin. This finding is important, because an anticancer compound acting via a different mechanism is a prerequisite in designing new anticancer drugs. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005) [source] Structural Studies of Lithium Telluro- and Seleno-Phosphorus CompoundsEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 18 2003Robert P. Davies Abstract Lithium tellurophosphinite [Ph2PTe][Li(TMEDA)1.33(THF)1.33] (4), ditellurophosphinate, [Ph2PTe2][Li(THF)3.5(TMEDA)0.25] (5), and selenotellurophosphinate [Ph2P(Se)Te][Li(THF)2(TMEDA)] (6) complexes have been prepared from the insertion/oxidation reactions of lithiated secondary phosphanes with elemental chalcogens and characterised by X-ray crystallography. Compounds 4,6 contain no tellurium,lithium bonding interactions in the solid state, instead existing as ion-separated species with THF/TMEDA-solvated lithium cations. Reaction of dilithiated primary phosphanes with more than three equivalents of elemental selenium gives [{(c -C6H11)P(Se)(SeLi)}2·2TMEDA] (7) via a phosphorus-phosphorus coupling reaction. Solid state characterisation of 7 reveals the organo groups in the tetradentate tetraselenohypodisphosphinate ligand to be in an anti conformation to one another and each lithium atom to be coordinated by two selenium atoms, one from each of the diselenophosphinate groups. Multinuclear NMR spectroscopic data are consistent with retention of the solid-state structures of 4,7 in solution. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003) [source] Enol Forms of 1,3-Indanedione, Their Stabilization by Strong Hydrogen Bonding, and Zwitterion-Assisted InterconversionEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 14 2010Mark Sigalov Abstract By analyzing NMR spectroscopic data, and supported by IR, UV/Vis, Raman, dielectrometry, and DFT techniques, a comprehensive study of the 1:2 adducts of picolinaldehyde and 1,3-indanediones is presented. The parent indanedione derivative 5 exists in an equilibrium between all-keto and enol forms, the latter being stabilized by an intramolecularO,H···N hydrogen bond. Only the all-keto form was observed in the 5,6-dimethoxy compound 6, whereas solely the enol tautomer was observed with its 5,6-dichloro analogue 7. Polar solvents and low temperatures shift the equilibrium towards the enol tautomer in 5. The structure of adduct 8, formed with isonicotinaldehyde, prevents the formation of intramolecular O,H···N hydrogen bonds and thus it exists in the all-keto form in low polar solvents. However, in DMSO solutions it adopts a zwitterionic form with a strong anionic O,···H···O hydrogen bond. Thus, the enol form in indanedione adducts was unequivocally characterized in solution and the factors that determine the keto,enol tautomerism, namely electronic effects, solvent, temperature, and intramolecular hydrogen bonds, have been methodically studied by spectroscopic and quantum mechanical methods. [source] J -Based Analysis and DFT,NMR Assignments of Natural Complex Molecules: Application to 3,,7-Dihydroxy-5,6-epoxycholestanesEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 23 2008Jesús Javier Poza Abstract In order to reproduce the stereochemical dispositions of the epoxy and hydroxy functionalities, four 3,,7-hydroxy-5,6-epoxycholestanes were easily prepared from cholesterol, and their NMR spectroscopic data were experimentally obtained from 1D and 2D NMR experiments. An exhaustive QM- J -based analysis was then performed to replicate the experimental H,H and C,H coupling constants as well as the 13C NMR chemical shifts. The B3LYP GIAO methodology with the 6-311-G(d,p) basis set was chosen and showed that the data obtained from rings A and B were sufficient to calculate the correct stereochemistry of the 5,6-epoxy and 7-hydroxy groups. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008) [source] Synthesis and Absolute Configuration of (+)-Pseudodeflectusin: Structural Revision of Aspergione BEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 21 2006Fumiyo Saito Abstract We report herein the total synthesis and determination of the absolute configuration of (+)-pseudodeflectusin. The total synthesis of (+)-pseudodeflectusin starting from o -anisic aid was achieved in 11 total steps with an overall yield of 2.0,%. The 1H- and 13C NMR spectroscopic data of our synthetic pseudodeflectusin was identical to that of the natural compound. The absolute configuration of (+)-pseudodeflectusin was determined by chiral HPLC and X-ray crystallographic analyses. We also synthesized the proposed structure of aspergione B, whose 1H- and 13C NMR spectroscopic data is identical to that of pseudodeflectusin. The 1H- and 13C NMR spectra of our synthetic aspergione B were different from those of the natural compound reported by Proksch et al. Our results confirm that aspergione B and pseudodeflectusin are, in fact, the same compound.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006) [source] Synthesis and Characterization of PY2- and TPA-Appended Diphenylglycoluril Receptors and Their Bis-CuI ComplexesEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 10 2006Vera S. I. Sprakel Abstract A number of metallohosts mimicking dinuclear copper oxygenases have been designed and synthesized. These metallohosts combine a substrate binding site, i.e. the diphenylglycoluril basket receptor, with two types of metal-binding ligands, viz. tri-coordinating bis(2-ethylpyridine)amine (PY2) and tetra-coordinating tris(2-methylpyridine)amine (TPA). The preparation of the bis-CuI complexes of the ligand-appended receptors and their characterization by NMR are reported. NMR spectroscopic data provide evidence for a dynamic inclusion behavior of some of the pyridine moieties in the receptor of both the metal-free ligands and the CuI complexes. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006) [source] Solid-State Structure and Tautomerism of 2-Aminotroponimines Studied by X-ray Crystallography and Multinuclear NMR SpectroscopyEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 21 2004Rosa M. Claramunt Abstract Structural studies in the solid state by X-ray crystallography and by 13C and 15N CPMAS NMR spectroscopy carried out on a series of 2-aminotroponimine derivatives 2,5 has allowed to establish the existence of hydrogen bonding and to determine the most stable tautomer. Almost all the structures reflect the classical double-well potential function for the N,H···N hydrogen bonds. Only in the case of the compound N -(pyrrol-1-yl)-2-(pyrrol-1-ylamino)troponimine (5) the crystal structure shows two independent molecules, one with a classical hydrogen bond and another with either a single-well or a low-barrier hydrogen bond. The structure of this compound is discussed with the use of the solid-state NMR spectroscopic data. 2-Aminotropones, as intermediates to the 2-aminotroponimines, show the oxo-tautomer as the stable form. B3LYP/6-31G* calculations are used to rationalise the experimental results. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004) [source] Synthesis and Electrochemical Studies of New Antimalarial EndoperoxidesEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 17 2003Fadia Najjar Abstract Structural analogues of endoperoxides belonging to the family of G factors have been synthesized under Mannich-type conditions. The structures of the different diastereoisomers have been established from NMR spectroscopic data. Their cathodic peak potentials have been determined by thin layer electrochemistry under potentiostatic conditions, and compared to artemisinin. These endoperoxides were evaluated in vitro against Plasmodium falciparum and showed moderate to good activity. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003) [source] Chondrochloren A and B, New ,-Amino Styrenes from Chondromyces crocatus (Myxobacteria)EUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 14 2003Rolf Jansen Abstract In a screening for biologically active metabolites of the genus Chondromyces, two novel metabolites, chondrochloren A (1) and B (2), were isolated from several strains of C. crocatus. Compounds 1 and 2 are unique chloro-hydroxy-styryl amides of a highly modified C14 carboxylic acid, which comprises an unsaturated ketone, two hydroxy, two methoxy and three methyl groups. After assignment of the absolute configuration of both carbinol stereocenters by Mosher's method, NMR spectroscopic data combined with MM2 calculations allowed the prediction of the preferred conformation in solution. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003) [source] 5-Chloro-3-methylthio-1,2,4-thiadiazol-2-ium chlorides as useful synthetic precursors to a variety of 6a,4 -thiapentalene systemsHETEROATOM CHEMISTRY, Issue 1 2003Georges Morel Title salts 3 were easily obtained by treatment of formimidoyl isothiocyanates 1 with a twofold excess of methanesulfenyl chloride. They showed interesting chemical behavior toward several nitrogen and carbon nucleophiles. Substitution reactions with isothioureas and acetamide in the presence of triethylamine gave the 1H, 6H -6a,4 -thia-1,3,4,6-tetraazapentalenes 7 and 6H -6a,4 -thia-1-oxa-3,4,6-triazapentalene 9, respectively. Addition of p -toluidine furnished the 5-imino-thiadiazole derivatives 10, which reacted further with diverse heterocumulenes to yield the corresponding thiatriaza- and tetraazapentalene species 11. The N,N,-bis(1,2,4-thiadiazol-5-ylidene)diaminobenzenes 13 were also prepared and reacted with phenyl isothiocyanate. Two stable rotational isomers were separated for the 1,2-phenylene product 14b. Other ,-hypervalent sulfur compounds 16 were synthesized under similar conditions from salts 3 and methyl cyanoacetate or dimethyl malonate. The structural assignments were discussed on the basis of IR and NMR spectroscopic data and received additional support from X-ray analysis of substrate 16a. © 2003 Wiley Periodicals, Inc. Heteroatom Chem 14:95,105, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.10106 [source] 1H-HRMAS NMR study of smoked Atlantic salmon (Salmo salar)MAGNETIC RESONANCE IN CHEMISTRY, Issue 9 2010David Castejón Abstract High-resolution magic angle spinning (HRMAS) NMR spectroscopic data of smoked Atlantic salmon (Salmo salar) were fully assigned by combination of one- and two-dimensional-HRMAS experiments. Complete representative spectra, obtained after few minutes of analysis time, revealed a large number of minor and major compounds in the sample. The methodology is limited by the low sensitivity of NMR, and therefore HRMAS only enables the determination of the most relevant components. These were fatty acids (FAs), carbohydrates, nucleoside derivatives, osmolytes, amino acids, dipeptides and organic acids. For the first time, spectra were resolved sufficiently to allow semiquantitative determination in intact muscle of the highly polyunsaturated FA 22:6 ,-3. Additionally, the feasibility of 1H-HRMAS NMR metabolite profiling was tested to identify some bioactive compounds during storage. This profiling was carried out by the non-destructive and direct analysis (i.e. without requiring sample preparation and multiple step procedures) of intact salmon muscle. The proposed procedure can be applied to a large number of samples with high throughput due to the short time of analysis and quick evaluation of the data. Copyright © 2010 John Wiley & Sons, Ltd. [source] Structure determination of selaginellins G and H from Selaginella pulvinata by NMR spectroscopyMAGNETIC RESONANCE IN CHEMISTRY, Issue 8 2010Yuan Cao Abstract Selaginellins G (1) and H (2), two new selaginellin derivatives, were isolated from the whole plant of Selaginella pulvinata. Their structures were elucidated, and complete assignments of the 1H and 13C NMR spectroscopic data were achieved by 1D and 2D NMR experiments (HSQC, HMBC, COSY and ROESY). Compound 1 displayed good antifungal activity against Candida albicans with an IC50 value of 5.3 µg/ml. Copyright © 2010 John Wiley & Sons, Ltd. [source] Complete assignments of 1H and 13C NMR spectral data for three new triterpenoid saponins from Ilex hainanensis Merr.MAGNETIC RESONANCE IN CHEMISTRY, Issue 2 2009Xiao-Qing Chen Abstract Three new oleanane-type triterpenoid saponins, ilexhainanoside C, D and E, all with 24, 28-dioic acid groups, were isolated from the leaves of Ilex hainanensis. They were 3,-hydroxyolean-12-ene-24, 28-dioic acid-28- O -,- D -glucopyranoside(1), 3,, 19,-dihydroxyolean-12-ene-24, 28-dioic acid-28- O -,- D -glucopyranoside(2) and 3,, 29-dihydroxyolean-12-ene-24, 28-dioic acid-28- O -,- D -glucopyranoside(3). The structures of these three new compounds were elucidated and complete assignments of the 1H and 13C NMR spectroscopic data were achieved by 1D and 2D NMR experiments [heteronuclear single quantum coherence (HSQC), HMBC and rotational nuclear Overhauser effect spectroscopy (ROESY)]. Copyright © 2008 John Wiley & Sons, Ltd. [source] 1H and 13C NMR assignments for two new angular furanocoumarin glycosides from Peucedanum praeruptorumMAGNETIC RESONANCE IN CHEMISTRY, Issue 7 2007Haitao Chang Abstract Two novel angular-type furanocoumarin glycosides, peucedanoside A (1) and peucedanoside B (2), along with a known compound apterin (3), were isolated from the roots of Peucedanum praeruptorum Dunn. Their chemical structures were determined by MS, NMR spectroscopy and chemical analysis. Complete assignments of the 1H and 13C NMR spectroscopic data were achieved by 1D and 2D NMR experiments including DEPT, HSQC, HMBC and ROESY. Copyright © 2007 John Wiley & Sons, Ltd. [source] Complete assignments of 1H and 13C NMR spectroscopic data for two new triterpenoid saponins from Ilex hainanensisMAGNETIC RESONANCE IN CHEMISTRY, Issue 2 2007Sixiang Zhou Abstract Two novel unsaturated E-ring pentacyclic triterpenoid saponins, ilexhainanoside A and ilexhainanoside B, were isolated from the leaves of Ilex hainanensis. Their chemical structures were determined by MS, NMR spectroscopy and chemical analysis. Complete assignments of the 1H and 13C NMR spectroscopic data were achieved by 1D and 2D NMR experiments (HSQC, HMBC, ROESY and 1H,1H COSY). Copyright © 2006 John Wiley & Sons, Ltd. [source] Complete assignments of 1H and 13C NMR spectral data for benzylidenebenzyl butyrolactone lignansMAGNETIC RESONANCE IN CHEMISTRY, Issue 11 2005Rosangela da Silva Abstract The structures of three benzylidenebenzyl butyrolactone lignans (gossypifan, carthamogenin, and savinin) have been established on basis of 1H NMR and 13C NMR spectroscopic data. The 1H NMR and 13C NMR spectra of these lignans have been fully assigned by the use of techniques such as gCOSY, non-edited gHSQC, and gHMBC. Complete assignment and most homonuclear hydrogen coupling constant measurements were performed, also providing enough data for the determination of the relative stereochemistry. Copyright © 2005 John Wiley & Sons, Ltd. [source] Conformational Consequences of Regio- and Stereoselective Disulfide Bridge Oxidation in a Cyclic PeptideCHEMBIOCHEM, Issue 1 2008Miroslav Male Synthesis of thiosulfinates. A thiosulfinate moiety was introduced into a cyclic peptide by regio- and stereoselective disulfide-bridge oxidation of S2,S6 -cyclo(H-Gly-Cys-Ser-Pro-Ala-Cys-Gly-OH). The CD, FTIR and NMR spectroscopic data demonstrated drastic changes in the peptide secondary structure upon oxidation of the Cys6 sulfur atom, while oxidation of the Cys2 sulfur atom caused only minor structure perturbations. [source] Cisplatin Adducts on a GGG Sequence within a DNA Duplex Studied by NMR Spectroscopy and Molecular Dynamics SimulationsCHEMISTRY - A EUROPEAN JOURNAL, Issue 45 2009Stéphane Téletchéa Dr. Abstract The antitumor drug cisplatin (cis -[PtCl2(NH3)2]) reacts with cellular DNA to form GG intrastrand adducts between adjacent guanines as predominant lesions. GGG sites have been shown to be hotspots of platination. To study the structural perturbation induced by binding of cisplatin to two adjacent guanines of a GGG trinucleotide, we examined here the decanucleotide duplex d[(G1C2C3G6T7 - C8G9C10),d(G11C12G13A14C15C16C17G18 - G19C20)] (dsCG*G*G) intrastrand cross-linked at the G* guanines by cis -{Pt(NH3)2}2+ using NMR spectroscopy and molecular dynamics (MD) simulations. The NMR spectra of dsCG*G*G were found to be similar to those of previously characterized DNA duplexes cross-linked by cisplatin at a pyG*G*X site (py=pyrimidine; X=C, T, A). This similarity of NMR spectra indicates that the base at the 3,-side of the G*G*,Pt cross-link does not affect the structure to a large extent. An unprecedented reversible isomerization between the duplex dsCG*G*G (bearing a ,Pt chelate) and duplex dsGG*G*T (bearing a ,Pt chelate) was observed, which yielded a 40:60 equilibrium between the two intrastrand GG,Pt cross-links. No formation of interstrand cross-links was observed. NMR spectroscopic data of dsCG*G*G indicated that the deoxyribose of the 5,-G* adopts an N-type conformation, and the cytidines C3, C15, and C16 have average phase angles intermediate between S and N. The NMR spectroscopic chemical shifts of dsGG*G*T showed some fundamental differences to those of pyG*G*,platinum adducts but were in agreement with the NMR spectra reported previously for the DNA duplexes cross-linked at an AG*G*C sequence by cisplatin or oxaliplatin. The presence of a purine instead of a pyrimidine at the 5,-side of the G*G* cross-link seems therefore to affect the structure of the XG* step significantly. [source] | ||||||||||