共查询到20条相似文献,搜索用时 15 毫秒
1.
Ion Ghiviriga Florian Dulong William R. Dolbier 《Magnetic resonance in chemistry : MRC》2009,47(4):313-321
Complete assignment of the 1H and 19F chemical shifts in 4‐fluoro‐AF4 (1) were based on the nOes seen in its 19F‐1H HOESY spectrum. This allowed for identification of features which can further be applied to the assignment of the regiochemistry of substituted perfluoroparacyclophanes (PCPs) and AF4s: (i) an aromatic fluorine couples with the two fluorines in the closest bridge that are syn to it, with constants of ca. 20 Hz; (ii) an aromatic fluorine couples with the bridge fluorine five bonds away that is anti to it in the same paraphenylene moiety, with a constant of ca. 3.5 Hz; (iii) the geminal coupling of the bridge fluorines is 246 Hz if they have an ortho fluorine and 238 Hz if they do not; (iv) a bridge fluorine couples with those aromatic protons in the same paraphenylene moiety that are four or five bonds away and anti. These features have been used to assign the regiochemistry of the pseudo‐ortho, pseudo‐meta and pseudo‐para‐difluoro AF4s 2–4. It has also been demonstrated that SCS for the bridge fluorines can be used as well for this assignment. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
2.
Probing the interaction of the potassium channel modulating KCNE1 in lipid bilayers via solid‐state NMR spectroscopy
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Rongfu Zhang Indra D. Sahu Raven G. Comer Sergey Maltsev Carole Dabney‐Smith Gary A. Lorigan 《Magnetic resonance in chemistry : MRC》2017,55(8):754-758
KCNE1 is known to modulate the voltage‐gated potassium channel α subunit KCNQ1 to generate slowly activating potassium currents. This potassium channel is essential for the cardiac action potential that mediates a heartbeat as well as the potassium ion homeostasis in the inner ear. Therefore, it is important to know the structure and dynamics of KCNE1 to better understand its modulatory role. Previously, the Sanders group solved the three‐dimensional structure of KCNE1 in LMPG micelles, which yielded a better understanding of this KCNQ1/KCNE1 channel activity. However, research in the Lorigan group showed different structural properties of KCNE1 when incorporated into POPC/POPG lipid bilayers as opposed to LMPG micelles. It is hence necessary to study the structure of KCNE1 in a more native‐like environment such as multi‐lamellar vesicles. In this study, the dynamics of lipid bilayers upon incorporation of the membrane protein KCNE1 were investigated using 31P solid‐state nuclear magnetic resonance (NMR) spectroscopy. Specifically, the protein/lipid interaction was studied at varying molar ratios of protein to lipid content. The static 31P NMR and T1 relaxation time were investigated. The 31P NMR powder spectra indicated significant perturbations of KCNE1 on the phospholipid headgroups of multi‐lamellar vesicles as shown from the changes in the 31P spectral line shape and the chemical shift anisotropy line width. 31P T1 relaxation times were shown to be reversely proportional to the molar ratios of KCNE1 incorporated. The 31P NMR data clearly indicate that KCNE1 interacts with the membrane. Copyright © 2017 John Wiley & Sons, Ltd. 相似文献
3.
《Magnetic resonance in chemistry : MRC》2002,40(9):589-594
The 31P chemical shift (CS) tensors of the 1,3,2‐diazaphospholenium cation 1 and the P‐chloro‐1,3,2‐diazaphospholenes 2 and 3 and the 31P and 19F CS tensors of the P‐fluoro‐1,3,2‐diazaphospholene 4 were characterized by solid‐state 31P and 19F NMR studies and quantum chemical model calculations. The computed orientation of the principal axes system of the 31P and 19F CS tensors in the P‐fluoro compound was found to be in good agreement with experimentally derived values obtained from evaluation of P–F dipolar interactions. A comparison of the trends in the chemical shifts of 1 – 4 with further available literature data confirms that the unique high shielding of δ11 in the cation 1 can be related to the effective π‐conjugation in the five‐membered heterocycle, and that a further systematic decrease in δ11 for the P‐halogen derivatives 2 – 4 is attributable to the increased perturbation of the π‐electron distribution by interaction with the halide donor. Copyright © 2002 John Wiley & Sons, Ltd. 相似文献
4.
For asymmetric guest molecules in urea, the end‐groups of two adjacent guest molecules may arrange in three different ways: head–head, head–tail and tail–tail. Solid‐state 1H and 13C NMR spectroscopy is used to study the structural properties of 1‐bromodecane in urea. It is found that the end groups of the guest molecules are randomly arranged. The dynamic characteristics of 1‐bromodecane in urea inclusion compounds are probed by variable‐temperature solid‐state 2H NMR spectroscopy (line shapes, spin–spin relaxation: T2, spin‐lattice relaxation: T1Z and T1Q) between 120 K and room temperature. The comparison between the simulation and experimental data shows that the dynamic properties of the guest molecules can be described in a quantitative way using a non‐degenerate three‐site jump process in the low‐temperature phase and a degenerate three‐site jump in the high‐temperature phase, in combination with the small‐angle wobbling motion. The kinetic parameters can be derived from the simulation. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
5.
Raimund Marx Nikolas Pomplun Wolfgang Bermel Heinz Zeiger Frank Engelke Amr F. Fahmy Steffen J. Glaser 《Magnetic resonance in chemistry : MRC》2015,53(6):442-447
The realization of an all‐heteronuclear 5‐qubit nuclear magnetic resonance quantum computer is reported, from the design and synthesis of a suitable molecule through the engineering of a prototype 6‐channel probe head. Full control over the quantum computer is shown by a benchmark experiment. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
6.
Pseudo‐meta and pseudo‐para diamino‐octafluoro[2.2]paracyclophanes are challenging to separate either by chromatography or recrystallization, but through the use of a mixture of the two isomers, the 1H, 19F, and 13C NMR spectra of these compounds have been fully and unambiguously assigned using 1H COSY, 1H‐19F HOESY, 1H‐13C HSQC, 1H‐13C HMBC, and 19F‐13C HSQC techniques. This permits the easy identification of either of the individual isomers. In addition, the 13C spectrum of the pseudo‐ortho analogue is reported and assigned for the first time. The gem shift effect in this series of bridge‐fluorinated paracyclophanes serves to deshield 1H resonances and shield 13C. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
7.
Coordination Chemistry of P‐rich Phosphanes and Silylphosphanes XXI The Influence of the PR3 Ligands on Formation and Properties of the Phosphinophosphinidene Complexes [{η2‐tBu2P–P}Pt(PR3)2] and [{η2‐tBu2P1–P2}Pt(P3R3)(P4R′3)] (R3P)2PtCl2 and C2H4 yield the compounds [{η2‐C2H4}Pt(PR3)2] (PR3 = PMe3, PEt3, PPhEt2, PPh2Et, PPh2Me, PPh2iPr, PPh2tBu and P(p‐Tol)3); which react with tBu2P–P=PMetBu2 to give the phosphinophosphinidene complexes [{η2‐tBu2P–P}Pt(PMe3)2], [{η2‐tBu2P–P}Pt(PEt3)2], [{η2‐tBu2P–P}Pt(PPhEt2)2], [{η2‐tBu2P–P}Pt(PPh2Et)2], [{η2‐tBu2P–P}Pt(PPh2Me)2], [{η2‐tBu2P–P}Pt(PPh2iPr], [{η2‐tBu2P–P}Pt(PPh2tBu)2] and [{η2‐tBu2P–P}Pt(P(p‐Tol)3)2]. [{η2‐tBu2P–P}Pt(PPh3)2] reacts with PMe3 and PEt3 as well as with tBu2PMe, PiPr3 and P(c‐Hex)3 by substituting one PPh3 ligand to give [{η2‐tBu2P1–P2}Pt(P3Me3)(P4Ph3)], [{η2‐tBu2P1–P2}Pt(P3Ph3)(P4Me3)], [{η2‐tBu2P1–P2}Pt(P3Et3)(P4Ph3)], [{η2‐tBu2P1–P2}Pt(P3MetBu2)(P4Ph3)], [{η2‐tBu2P1–P2}Pt(P3iPr3)(P4Ph3)] and [{η2‐tBu2P1–P2}Pt(P3(c‐Hex)3)(P4Ph3)]. With tBu2PMe, [{η2‐tBu2P–P}Pt(P(p‐Tol)3)2] forms [{η2‐tBu2P1–P2}Pt(P3MetBu2)(P4(p‐Tol)3)]. The NMR data of the compounds are given and discussed with respect to the influence of the PR3 ligands. 相似文献
8.
Monitoring Conformational Changes in the NDM‐1 Metallo‐β‐lactamase by 19F NMR Spectroscopy
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Anna M. Rydzik Jürgen Brem Sander S. van Berkel Inga Pfeffer Anne Makena Dr. Timothy D. W. Claridge Prof. Christopher J. Schofield 《Angewandte Chemie (International ed. in English)》2014,53(12):3129-3133
The New Delhi metallo‐β‐lactamase (NDM‐1) is involved in the emerging antibiotic resistance problem. Development of metallo‐β‐lactamases (MBLs) inhibitors has proven challenging, due to their conformational flexibility. Here we report site‐selective labeling of NDM‐1 with 1,1,1‐trifluoro‐3‐bromo acetone (BFA), and its use to study binding events and conformational changes upon ligand–metal binding using 19F NMR spectroscopy. The results demonstrate different modes of binding of known NDM‐1 inhibitors, including L ‐ and D ‐captopril by monitoring the changing chemical environment of the active‐site loop of NDM‐1. The method described will be applicable to other MBLs and more generally to monitoring ligand‐induced conformational changes. 相似文献
9.
《Magnetic resonance in chemistry : MRC》2002,40(4):311-312
The complete analysis of the 1H NMR spectra of α‐pinene and myrtenol is reported and earlier results are corrected. Copyright © 2002 John Wiley & Sons, Ltd. 相似文献
10.
Christopher Sørum Nebojša Simić Eirik Sundby Bård Helge Hoff 《Magnetic resonance in chemistry : MRC》2010,48(3):244-248
Chemical shift assignment of seven N‐substituted 6‐(4‐methoxyphenyl)‐7H‐pyrrolo[2, 3‐d]pyrimidin‐4‐amines, six of which are fluorinated, have been performed based on 1H, 13C, 19F, and 2D COSY, HMBC and HSQC experiments. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
11.
《Magnetic resonance in chemistry : MRC》2003,41(12):1034-1037
The assignment of 1H and 13C NMR of the sesquiterpene (+)‐10β,14‐dihydroxy‐allo‐aromadendrane by means of two‐dimensional NMR is reported. Copyright © 2003 John Wiley & Sons, Ltd. 相似文献
12.
Daisuke Sawai Kazuyo Takahashi Toshiyuki Imamura Koh Nakamura Tetsuo Kanamoto Suong‐Hyu Hyon 《Journal of Polymer Science.Polymer Physics》2002,40(1):95-104
Melt‐crystallized, low molecular weight poly(L ‐lactic acid) (PLLA) consisting of α crystals was uniaxially drawn by solid‐state extrusion at an extrusion temperature (Text) of 130–170 °C. A series of extrusion‐drawn samples were prepared at an optimum Text value of 170 °C, slightly below the melting temperature (Tm) of α crystals (~180 °C). The drawn products were characterized by deformation flow profiles, differential scanning calorimetry (DSC) melting thermograms, wide‐angle X‐ray scattering (WAXD), and small‐angle X‐ray scattering as a function of the extrusion draw ratio (EDR). The deformation mode in the solid‐state extrusion of semicrystalline PLLA was more variable and complex than that in the extensional deformation expected in tensile drawing, which generally gave a mixture of α and β crystals. The deformation profile was extensional at a low EDR and transformed to a parabolic shear pattern at a higher EDR. At a given EDR, the central portion of an extrudate showed extensional deformation and the shear component became progressively more significant, moving from the center to the surface region. The WAXD intensities of the (0010)α and (003)β reflections on the meridian as well as the DSC melting thermograms showed that the crystal transformation from the initial α form to the oriented β form proceeded rapidly with increasing EDR at an EDR greater than 4. Furthermore, WAXD showed that the crystal transformation proceeded slightly more rapidly at the sheath region than at the core region. This fact, combined with the deformation profiles (shear at the sheath and extensional at the core), indicated that the crystal transformation was promoted by shear deformation under a high pressure rather than by extensional deformation. Thus, a highly oriented rod consisting of only β crystals was obtained by solid‐state extrusion of melt‐crystallized, low molecular weight PLLA slightly below Tm. The structure and properties of the α‐ and β‐form crystals were also studied. © 2001 John Wiley & Sons, Inc. J Polym Sci Part B: Polym Phys 40: 95–104, 2002 相似文献
13.
《Magnetic resonance in chemistry : MRC》2002,40(10):653-658
The Pd‐catalysed enantioselective allylic alkylation of a 1,3‐diphenylallyl substrate using a bulky phosphinooxazoline auxiliary leads to a relatively small enantiomeric excess of 66%. The ca 30% loss, relative to related P,N‐auxiliaries, is rationalized by (a) the presence of additional isomers, (b) a dynamic equilibrium between two of these as shown by exchange spectroscopy and (c) the identification of one exchanging diastereomer in which there is almost no difference between the two terminal allyl 13C chemical shifts, i.e. these P‐ and N‐donors reveal an almost identical trans influence. Copyright © 2002 John Wiley & Sons, Ltd. 相似文献
14.
研究了室温下间苯二酚和甲基乙烯基酮分别与β-环糊精( β-CD)形成包结物后的几种不同固相反应,结果表明包结物A(间苯二酚/β-CD)与包结物B(甲基乙烯基酮/β-CD)反应能够很好地得到目的产物,产率及ee值分别为82.8%和78.4%;间苯二酚与包结物B反应仅得到低光学活性产物(ee值为19.5%);包结物A与甲基乙烯基酮反应却没有得到手性目的产物。以熔点、X-粉末衍射、固相核磁碳谱及ROESY多种方法对所形成的包结物进行了表征,包结物中主客体的比例(1:1)通过1H NMR (400 MHz)得以确定,文章对固相环加成反应的机制也进行了初步探讨。 相似文献
15.
《Magnetic resonance in chemistry : MRC》2002,40(3):175-181
A 1H, 13C and 31P NMR study of monoethyl (HL1) and monobutyl (HL2) esters of (α‐anilinobenzyl)phosphonic acid and their metallocyclic dipalladium complexes (Pd2L4,L = L1, L2) in DMSO‐d6 was performed, based on 1D and 2D homo‐ and heteronuclear experiments including 1H,13C,31P,APT,1H–1H COSY, 1H–13C COSY, gs‐HMQC and gs‐HMBC NMR techniques. The results obtained are discussed with respect to those for some palladium(II) complexes reported for various anilinobenzylphosphonate derivatives. Copyright © 2002 John Wiley & Sons, Ltd. 相似文献
16.
Wei Liu Bing Zhao Yin‐Chao Li Hong‐Min Liu 《Magnetic resonance in chemistry : MRC》2011,49(9):611-615
Complexations between three oridonin derivatives and β‐cyclodextrin (βCD) were studied by nuclear magnetic resonance (NMR) method. Job's plots for complexes were depicted by 1H NMR spectra chemical shifts, which proved the 1:1 stoichiometry inclusion complex formation between each derivative and βCD. Two‐dimensional rotating frame overhauser effect spectroscopy (2D ROESY) support the above conclusion and also proved that ring A of each oridonin derivative deeply enters into hydrophobic cavity from the wider rim and the other parts are outside the cavity. Apparent formation constants (Ka) of complexes between three oridonin derivatives and two CDs are calculated according to Scott's equation. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
17.
《Magnetic resonance in chemistry : MRC》2002,40(3):219-224
An extensive study of both liquid‐ and solid‐state NMR spectroscopy was undertaken in order to elucidate the structural features of a phenyleneterephthalamide oligomer (OPTA) and of some related diarylamides. 1D‐ and 2D‐COSY measurements allowed us to assign completely the proton signals of the title compounds in solution, while 1D‐, 2D‐HETCOR and 2D‐COLOC measurements were used to assign 13C resonances. Solid‐state 13C NMR experiments, by conventional cross‐polarization (CP) at different contact times and with the dipolar dephased CP technique, were used to characterize these molecules in the solid state. Such techniques allowed us to differentiate among different carbon atoms; in the resulting spectra it was then possible to observe the selective appearance of signals from protonated and quaternary carbon atoms. It was also ascertained that the limited structural mobility of the insoluble OPTA, existing as a single monophasic species, can be explained in terms of hydrogen‐type bonds present in the solid state. Copyright © 2002 John Wiley & Sons, Ltd. 相似文献
18.
《Magnetic resonance in chemistry : MRC》2003,41(8):629-632
3α‐Acetyl‐20(29)‐lupene‐24‐oic acid ( 1 ) was isolated from the gum resin of Boswellia serrata. Its presence evidently suggests, that the oxidosqualene triterpene pathway of Boswellia serrata closely resembles the biosynthetic route already found in other plants. Complete 1H and 13C spectral assignments were derived from 1D and 2D NMR spectra. This is the first compound with the lupene backbone combining a 3α‐hydroxy or 3α‐acetyl group with the 24‐carboxyl group, a configuration which is typical of the classical boswellic acids. Copyright © 2003 John Wiley & Sons, Ltd. 相似文献
19.
Luísa R. Carvalho Marta C. Corvo Ramu Enugala M. Manuel B. Marques Eurico J. Cabrita 《Magnetic resonance in chemistry : MRC》2010,48(4):323-330
The solid‐phase synthesis (SPS) of a structurally complex glycopeptide, using Sieber amide resin, was monitored by high resolution magic angle spinning NMR, demonstrating the further application of this technique. A synthetic peptidoglycan derivative, a precursor of a biologically active PGN, known to be involved in the cellular recognition, was prepared by SPS. The synthesis involved the preparation of an N‐alloc glucosamine moiety and the synthesis of a simple amino acid sequence L ‐Ala‐D ‐Glu‐L ‐Lys‐D ‐Ala‐D ‐Ala. Last step consisted the coupling, on solid‐phase, of the protected muramyl unit to the peptide chain. Proton spectra with good suppression of the polystyrene signals in swollen resin samples were obtained in DMF‐d7 as a solvent and by using a nonselective 1D TOCSY/DIPSI‐2 scheme, thus allowing to follow the SPS without losses of compound and cleavage from the resin. The assignment of the proton spectra of the resin‐bound amino acid sequence and of the bound glycopeptide was achieved through the combination of MAS COSY, TOCSY and NOESY. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
20.
Teresa K. Zimmermann Stefan Haslinger Alexander Pthig Fritz E. Kühn 《Acta Crystallographica. Section C, Structural Chemistry》2014,70(4):384-387
The title compound, cis‐di‐μ‐perfluoroheptanoato‐κ4O:O′‐bis[dicarbonyl(dimethyl sulfoxide‐κS)ruthenium(I)](Ru—Ru), [Ru2(C7F13O2)2(C2H6OS)2(CO)4], is a sawhorse‐type dinuclear ruthenium complex with two bridging perfluoroheptanoate ligands, and with two dimethyl sulfoxide (DMSO) ligands in the axial positions coordinating via the S atoms. It is a new example of a compound with an aliphatic fluorinated carboxylate ligand. The Ru—Ru bond distance of 2.6908 (3) Å indicates a direct Ru—Ru interaction. The compound is an active catalyst in transvinylation of propionic acid with vinyl acetate. 相似文献