Search results for "Nuclear magnetic resonance crystallography"
showing 10 items of 17 documents
A community resource of experimental data for NMR / X-ray crystal structure pairs
2015
We have developed an online NMR / X-ray Structure Pair Data Repository. The NIGMS Protein Structure Initiative (PSI) has provided many valuable reagents, 3D structures, and technologies for structural biology. The Northeast Structural Genomics Consortium was one of several PSI centers. NESG used both X-ray crystallography and NMR spectroscopy for protein structure determination. A key goal of the PSI was to provide experimental structures for at least one representative of each of hundreds of targeted protein domain families. In some cases, structures for identical (or nearly identical) constructs were determined by both NMR and X-ray crystallography. NMR spectroscopy and X-ray diffraction …
Solid state structural studies of five bile acid derivatives
2008
Five synthetically important bile acid derivatives have been characterized by 13 C CP-MAS, X-ray diffraction (both single crystal and powder), FTIR, and thermoanalytical (DSC and TG) methods. The crystallinity of all these derivatives is high, which can be deducted from the 13 C CP-MAS and powder X-ray diffraction data. Two of the compounds showed polymorphism, and one polymorph was structurally elucidated for both by comparing single crystal and powder X-ray diffraction data.
Synthesis, characterization and thermal properties of nine quaternary dialkyldiaralkylammonium chlorides
2006
Abstract Nine R 2 R 2 ′ N + Cl − (R=benzyl, 2-methylbenzyl, 3-methylbenzyl, 4-methylbenzyl, 2-phenylethyl or 3-phenylpropyl; R′=ethyl or methyl) quaternary dialkyldiaralkylammonium chlorides were synthesized by treating dimethylformamide or diethylformamide with non-substituted or substituted arylalkyl (aralkyl) halide in the presence of sodium carbonate. The 1H NMR, 13C NMR spectroscopy, mass spectroscopy and elemental analysis were used to characterize the synthesized products. The crystal structures of six compounds were determined by X-ray single crystal diffraction. Four of the compounds crystallized in monoclinic space groups C2/c and P21/c (or P21/n), one in triclinic space group P−1…
Solid state NMR studies of gels derived from low molecular mass gelators
2016
The emergence of NMR crystallography provides a unique opportunity to study solids, gels and xerogels, thereby providing ample information to elucidate molecular packing in the native gel. This review details the importance as well as the application of solid state NMR spectroscopy combined with other analytical tools to study gels derived from low molecular mass organo- and hydrogelators.
15N NMR studies of tautomerism
2012
The literature related to 15N NMR studies of tautomerism is updated and discussed. The 15N NMR data show that the technique is applicable for both liquid and solid state (both crystalline and amorphous) materials. Modern computational methods combined with experimental NMR data can aid in the chemical shift assignments especially in case of crystalline materials (so-called NMR crystallography). This review article is divided into chapters based on the different classes of compounds and a brief description of experimental and computational NMR techniques is also included.
X-ray structures of five variably tert-butoxycarbonyl-substituted adenines and their liquid and solid state NMR investigations
2009
Abstract Adenine reacts selectively with di- tert -butyldicarbonate in THF in the presence of NaOH to give N 9-monoBoc-adenine 1 . The molecular structure and crystal packing of this and four other variably substituted Boc-derivatives of adenine were determined in solid state by means of X-ray diffraction and CP/MAS NMR experiments and characterized in liquid state by 1 H, 13 C, and 15 N NMR spectroscopy as well. Additionally, crystal structure of inclusion compound between N 6 -monoBoc-adenine 5 and CHCl 3 is reported. Tautomeric equilibria of mono- and disubstituted derivatives 4 and 5 in liquid state were studied by VT NMR experiments.
1H, 13C and 17O NMR spectral study of chlorinated 3,4-dihydroxybenzaldehydes (protocatechualdehydes)
1995
Abstract Chlorinated 3,4-dihydroxybenzaldehydes have been studied by means of 1 H, 13 C and 17 O NMR spectroscopy. The 1 H and 13 C NMR spectral assignments are based on 2-dimensional 13 C- 1 H chemical shift correlation spectroscopy (COSY). The 17 O NMR measurements at natural isotope content in organic solvents are problematic owing to the poor solubility of the compounds and/or broadness of the resonance lines. In aqueous alkaline solutions, however, all protocatechualdehydes exhibit “easy-to-detect” 17 O NMR spectral characteristics. The 17 O NMR chemical shifts in the range of 140–480 p.p.m. are interpreted as arising from the different canonical structures of formyl substituted phenol…
3-Diazopyrroles—IV. Structure determination using 13C NMR spectroscopy
1990
Abstract On the basis of the 13 C NMR chemical shifts, it is proposed that, although b is the major canonical structure, structure c , in which a negative charge resides at C-3, provides an important contribution to the resonance stabilization of the 3-diazopyrroles, 1–4 .
Nuclear Magnetic Resonance and Electron Spin Resonance Spectroscopy
2001
The article contains sections titled: 1. Introduction 2. Principles of Magnetic Resonance 2.1. Nuclear and Electronic Properties 2.2. Nuclei and Electrons in a Stationary Magnetic Field 2.3. Basic Principles of the NMR and ESR Experiments 2.4. Relaxation 3. High-Resolution Solution NMR Spectroscopy 3.1. The NMR Experiment 3.1.1. Continuous Wave Methodology 3.1.2. Fourier Transform Methodology 3.2. Spectral Parameters 3.2.1. Chemical Shift 3.2.2. Spin - Spin Coupling 3.2.3. Signal Intensity 3.2.4. Relaxation Times 3.3. NMR and Structure 3.3.1. Hydrogen (1H and 2H) 3.3.2. Carbon (13C) 3.3.3. Fluorine (19F) 3.3.4. Phosphorus (31P) 3.3.5. Nitrogen (14N and 15N) 3.3.6. Oxygen (17O) 3.3.7. Silico…
H-bonding schemes of di- and tri-p-benzamides assessed by a combination of electron diffraction, X-ray powder diffraction and solid-state NMR
2010
The crystal structures of di- and tri-p-benzamides are solved by a combination of single crystal, electron and powder X-ray diffraction. Different hydrogen-bonding schemes observed in the two structures are described and classified. The hydrogen-bonding networks are correlated to complementary data obtained from multinuclear solid-state NMR.