1H NMR study of multiply charged anions of Ni-octaethylporphin

An analysis of¹H NMR spectra of reduced Ni-octaethylporphin (NiOEP)ⁿ⁻ n=2,3) complexes has allowed the conclusion that the first and third excess electrons are localized on orbitals of the porphyrin ligand, while the first excess electron is on the d_x ²-y²-orbital of Ni. This is a basis for thinking that in the course of NiOEP reduction the energy of the lowest unoccupied molecular orbital of the ligand becomes smaller than that of the d_x ²-y²-orbital of nickel. Institute of Molecular and Atomic Physics of the Academy of Sciences of Belarus, 70, F. Skorina Ave., Minsk, 220072, Belarus. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 64, No. 4, pp. 513–517, July–August, 1997.     

1H NMR study of ternary ammonia-alkali metal-graphite intercalation compounds

For the first-stage ternary ammonia-alkali metal-graphite intercalation compounds M(NH₃)_xC₂₄ (x ∼ 4, M = K, Rb, Cs), three sets of triplet ¹H NMR spectral lines have been observed at various temperatures and orientations due to the ¹H-¹H and ¹⁴N-¹H dipolar interactions. We have inferred the structures of these compounds as mobile (liquid-like) intercalant layers of planar M(NH₃)₄ ions in the between the carbon layers. For the intercalated ammonia molecules, the potential barrier is ∼ 0.2 eV and the molecular geometry is very close to the free NH₃ in gas phase.     

An NMR study of lithium responding manic depressive patients

Manic depressive patients on long-term prophylactic therapy with lithium carbonate are examined by nuclear magnetic resonance imaging of the brain. Their ventricular brain ratios and cerebral grey and white matter spin lattice relaxation times (T1) are within normal limits. The implication of these findings in the light of previous studies using other techniques is discussed.     

Homonuclear two-dimensional 1H NMR of proteins. Experimental procedures

Experimental techniques used for homonuclear 2D ¹H NMR studies of proteins are described. A brief survey of the general strategy for structural studies of proteins by 2D NMR is included. The main part of the paper discusses guidelines for the selection of experimental techniques, the elimination of artifacts and unwanted peaks in protein 2D ¹H NMR spectra, suppression of the solvent line in H₂O solutions, experimental parameters, numerical data processing before and after Fourier transformation, and suitable presentations of complex 2D NMR spectra.     

吉士脱酮的1H及13C NMR研究

Gestodene是避孕药物18甲基炔诺酮的衍生物,动物实验表明它的孕激素活性为18甲基炔诺酮的3~5倍.本文采用各种2D NMR技术,包括:¹H-¹H COSY,¹H-¹³C COSY和HMBC等,归属了它的¹H和¹³C的谱线,并得到了有关质子间的偶合常数.     

Double-quantum filtered 1H MAS NMR spectra

It is shown that straightforward double-quantum filtered (1)H MAS NMR experiments yield spectral lineshapes that permit to estimate the minimum number of (1)H spins in a cluster. The approach may offer an alternative to multiple-quantum experiments for the characterisation of (1)H spin clusters of moderate size. The duration of the double-quantum excitation period has to be chosen suitably, it is necessary to find a practical compromise between optimum double-quantum filtration efficiency and optimum information content of the spectral lineshapes. Some (1)H MAS NMR experiments on partially deuterated maleic acid are reported as well as numerical simulations.     

黄酮类化合物的1H NMR研究

报道了某些黄酮、黄烷酮及查耳酮的¹H NMR光潜特点及其规律以及取代基对化学位移的影响。     

Picoliter (1)H NMR spectroscopy

In this study, a 267-microm-diameter solenoid transceiver is used to acquire localized (1)H NMR spectra and the measured signal-to-noise ratio (SNR) at 500 MHz is shown to be within 20--30% of theoretical limits formulated by considering only its resistive losses. This is illustrated using a 100-microm-diameter globule of triacylglycerols (approximately 900mM) that may be an oocyte precursor in young Xenopus laevis frogs and a water sample containing choline at a concentration often found in live mammalian cells (approximately 33 mM). In chemical shift imaging (CSI) experiments performed using a few thousand total scans, the choline methyl line is shown to have an acceptable SNR in resolved volume elements containing only 50 pL of sample, and localized spectra are resolved from just 5 pL in the Xenopus globule. These findings demonstrate the feasibility of performing (1)H NMR on picoliter-scale sample volumes in biological cells and tissues and illustrate how the achieved SNR in spectroscopic images can be predicted with reasonable accuracy at microscopic spatial resolutions.     

Quantitative 2H NMR spectroscopy with 1H lock extender

An inexpensive external unit that allows the use of the commercial high-resolution NMR spectrometer for (2)H observation with an (1)H lock system is described. The external unit does not require any tuning, is extremely easy to use, and could be a cheaper and more straightforward alternative to the more expensive (19)F lock configuration. An application for the quantitative determination of the natural isotopic ratio (2)H/(1)H of ethanol and acetic acid is reported.     

1H NMR study of N(CH3)4H(ClF2CCOO)2

The proton spin–lattice relaxation times and ¹H NMR second moments were measured over a wide range of temperature. The results were compared with those of the ¹⁹F NMR relaxation that we obtained earlier. For both nuclear species, the evolution of the longitudinal magnetizations with time is observed to be strongly bi-exponential and were in good quantitative agreement with the cross-relaxation theory.     

含羟基的3-苯基-4(1H)-喹啉酮衍生物的1H NMR

在抗骨质疏松药物的设计中,根据电子等排原理和药物的构效关系理论,设计并同时合成了7-羟基-3-苯基-4(1H)-喹啉酮新衍生物以及其同分异构体5-羟基-3-苯基-4(1H)-喹啉酮新衍生物.本文报道上述新化合物的¹H NMR数据.     

Molecular dynamics in solid anhydrous beta-estradiol studied by 1H NMR.

Proton second moment and spin-lattice relaxation times T1 and T1p in solid anhydrous beta-estradiol are measured as a function of temperature. The results show that the C3 reorientation of the single methyl group provides the mechanism dominating relaxation at low temperatures and reveal the existence of a conformational motion of the carbon skeleton dominating relaxation at high temperatures. The activation energies of the respective motions are found to be 9.3 and 37.3 kJ/mol.     

1H NMR study of the hetero‐association of unsaturated alcohols with pyridine

The ¹H NMR titration method is used to investigate the association of some unsaturated alcohols with pyridine in benzene. The association constant for allyl alcohol (2‐propen‐1‐ol) is slightly higher than for alkanols, but putting one methylene group between the OH and vinyl group completely eliminates this enhancement. In alkynols both the OH and ≡CH protons associate with pyridine. Here, the effects of chain‐lengthening on the association constant are irregular. Values for alkynols and some alcohols with hetero‐atom substituents are lower than expected on the basis of a Taft polar constant (σ*) correlation of alkanol association constants and of a correlation with the pK_a’s of the corresponding carboxylic acids. It is suggested that stabilization of the ground state by OH/π interactions is responsible for these low association constants. Small increases in the NMR shifts of the OH protons in the 3‐carbon and 4‐carbon alkenols and alkynols can also be attributed to OH/π interactions, but the 5‐carbon analogues have shifts as low as alkanols. Copyright © 2011 John Wiley & Sons, Ltd.     

Characterisation of crosslinked elastomeric materials by 1H NMR relaxation time distributions.

One of the most critical structural parameters in elastomeric materials is the density of cross-linking between the polymeric chains. This chemical feature greatly affects chain motions and is determinant in controlling mechanical properties of the final product. NMR techniques are widely and efficiently applied to investigation of such materials. In this study we have measured both transverse and longitudinal 1H relaxation times of a series of polybutadiene rubber samples with increasing crosslink density induced by chemical treatment. This approach allowed the observation of T(1) and T(2) decrease with the increase of crosslink density in the samples examined. The data obtained have been analyzed and compared to theoretical models.     

1H NMR characterization of the product from single solid-phase resin beads using capillary NMR flow probes.

A capillary NMR flow probe was designed to generate high-resolution (1)H NMR spectra at 600 MHz from the cleaved product of individual 160-microm Tentagel combinatorial chemistry beads. By injecting a dissolved sample sandwiched between an immiscible, perfluorinated organic liquid directly into the probe, NMR spectra of the product cleaved from single beads were acquired in just 1 h of spectrometer time without diffusional dilution. Sample handling efficiency on the single bead scale was comparable to that obtained with a bulk sample. Using the relative intensity of the DMSO-d(5)H versus the analyte signals in a fully relaxed CPMG spectrum, the amount of product cleaved from a single bead was determined to be 540+/-170 pmol in one of the samples. Following the NMR data collection, the samples were examined with electrospray ionization mass spectrometry to provide additional structural information. By coupling with microliter-volume fluidic capabilities, the capillary flow probe described here will enable multidimensional characterization of single solid-phase resin products in an online manner.