Chemical Constituents from Bombacopsis glabra (Pasq.) A. Robyns: Complete ¹H and 13C NMR Assignments and X Ray Structure of 5-Hydroxy-3,6,7,8,4'-pentamethoxyflavone

To enlarge the chemical diversity of Eurotium sp. SCSIO F452, a talented marine-derived fungus, we further investigated its chemical constituents from a large-scale fermentation with modified culture. Four pairs of new salicylaldehyde derivative enantiomers, euroticins F-I (1–4), as well as a known one eurotirumin (5) were isolated and characterized. Compound 1 features an unprecedented constructed 6/6/6/5 tetracyclic structures, while 2 and 3 represent two new types of 6/6/5 scaffolds. Their structures were established by comprehensive spectroscopic analyses, X-ray diffraction, 13C NMR, and electronic circular dichroism calculations. Selected compounds showed significant inhibitory activity against α-glucosidase and moderate cytotoxic activities against SF-268, MCF-7, HepG2, and A549 cell lines.

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Chemical constituents from Ouratea floribunda: complete¹H and 13C NMR assignments of atranorin and its new acetyl derivative

Journal of the Brazilian Chemical Society ◽

10.1590/s0103-50532000000200007 ◽

2000 ◽

Vol 11 (2) ◽

pp. 143-147 ◽

Cited By ~ 15

Author(s):

Mário G. de Carvalho ◽

Geizi J. A. de Carvalho ◽

Raimundo Braz-Filho

Keyword(s):

13C Nmr ◽

Nmr Assignments ◽

Chemical Constituents ◽

Acetyl Derivative

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Sem and X-Ray Analysis of Renal and Biliary Calculi

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100091512 ◽

1976 ◽

Vol 34 ◽

pp. 306-307

Author(s):

R. J. Narconis ◽

G. L. Johnson

Keyword(s):

Chemical Constituents ◽

Natural State ◽

X Ray Diffraction ◽

Chemical Methods ◽

X Ray ◽

Additional Dimension ◽

Biliary Calculi ◽

Calculus Formation ◽

Scanning Electron

Analysis of the constituents of renal and biliary calculi may be of help in the management of patients with calculous disease. Several methods of analysis are available for identifying these constituents. Most common are chemical methods, optical crystallography, x-ray diffraction, and infrared spectroscopy. The application of a SEM with x-ray analysis capabilities should be considered as an additional alternative.A scanning electron microscope equipped with an x-ray “mapping” attachment offers an additional dimension in its ability to locate elemental constituents geographically, and thus, provide a clue in determination of possible metabolic etiology in calculus formation. The ability of this method to give an undisturbed view of adjacent layers of elements in their natural state is of advantage in determining the sequence of formation of subsequent layers of chemical constituents.

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The Electron Effect of Aromatic Group: Control Conformation of 2-Aromatic Cyclododecanone Derivatives

Current Organic Chemistry ◽

10.2174/1385272824999200607175514 ◽

2020 ◽

Vol 24 (10) ◽

pp. 1139-1147

Author(s):

Yang Mingyan ◽

Wang Daoquan ◽

Wang Mingan

Keyword(s):

1H Nmr ◽

13C Nmr ◽

Nmr Spectra ◽

Coupling Constants ◽

The Other ◽

Repulsive Interaction ◽

X Ray Diffraction ◽

X Ray ◽

Electron Effect ◽

Group Control

2-Phenylcyclododecanone and 2-cyclohexylcyclododecanone derivatives were synthesized and characterized by 1H NMR, 13C NMR, HR-ESI-MS and X-ray diffraction. Their preferred conformations were analyzed by the coupling constants in the 1H NMR spectra and X-ray diffraction, which showed the skeleton ring of these derivatives containing [3333]-2-one conformation, and the phenyl groups were located at the side-exo position of [3333]-2-one conformation due to the strong π-π repulsive interaction between the π- electron of benzene ring and π-electron of carbonyl group. The cyclohexyl groups were located at the corner-syn or the side-exo position of [3333]-2-one conformation depending on the hindrance of the other substituted groups. The π-π electron effect played a crucial role in efficiently controlling the preferred conformation of 2-aromatic cyclododecanone and the other 2-aromatic macrocyclic derivatives with the similar preferred square and rectangular conformations.

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Homopiperazine (Hexahydro-1,4-diazepine)

Molbank ◽

10.3390/m1200 ◽

2021 ◽

Vol 2021 (2) ◽

pp. M1200

Author(s):

R. Alan Aitken ◽

Dheirya K. Sonecha ◽

Alexandra M. Z. Slawin

Keyword(s):

13C Nmr ◽

Title Compound ◽

Coupling Constants ◽

15N Nmr ◽

Time Data ◽

Nmr Spectrum ◽

X Ray ◽

First Time

The X-ray structure of the title compound has been determined for the first time. Data on its 1H–13C-NMR coupling constants and 15N-NMR spectrum are also given.

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Tuning π-Acceptor/σ-Donor Ratio of the 2-Isocyanoazulene Ligand: Non-Fluorinated Rival of Pentafluorophenyl Isocyanide and Trifluorovinyl Isocyanide Discovered

Molecules ◽

10.3390/molecules26040981 ◽

2021 ◽

Vol 26 (4) ◽

pp. 981

Author(s):

Mason D. Hart ◽

John J. Meyers ◽

Zachary A. Wood ◽

Toshinori Nakakita ◽

Jason C. Applegate ◽

...

Keyword(s):

Charge Transfer ◽

Coordination Chemistry ◽

Single Crystal ◽

13C Nmr ◽

Quantitative Assessment ◽

X Ray ◽

New Class ◽

Linear Relationships ◽

Ligand Charge Transfer ◽

Donor Characteristics

Isocyanoazulenes (CNAz) constitute a relatively new class of isocyanoarenes that offers rich structural and electronic diversification of the organic isocyanide ligand platform. This article considers a series of 2-isocyano-1,3-X2-azulene ligands (X = H, Me, CO2Et, Br, and CN) and the corresponding zero-valent complexes thereof, [(OC)5Cr(2-isocyano-1,3-X2-azulene)]. Air- and thermally stable, X-ray structurally characterized 2-isocyano-1,3-dimethylazulene may be viewed as a non-benzenoid aromatic congener of 2,6-dimethyphenyl isocyanide (2,6-xylyl isocyanide), a longtime “workhorse” aryl isocyanide ligand in coordination chemistry. Single crystal X-ray crystallographic {Cr–CNAz bond distances}, cyclic voltametric {E1/2(Cr0/1+)}, 13C NMR {δ(13CN), δ(13CO)}, UV-vis {dπ(Cr) → pπ*(CNAz) Metal-to-Ligand Charge Transfer}, and FTIR {νN≡C, νC≡O, kC≡O} analyses of the [(OC)5Cr(2-isocyano-1,3-X2-azulene)] complexes provided a multifaceted, quantitative assessment of the π-acceptor/σ-donor characteristics of the above five 2-isocyanoazulenes. In particular, the following inverse linear relationships were documented: δ(13COtrans) vs. δ(13CN), δ(13COcis) vs. δ(13CN), and δ(13COtrans) vs. kC≡O,trans force constant. Remarkably, the net electron withdrawing capability of the 2-isocyano-1,3-dicyanoazulene ligand rivals those of perfluorinated isocyanides CNC6F5 and CNC2F3.

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ChemInform Abstract: Synthesis, 13C NMR, and X-Ray Crystal Structure of N6,N9- Octamethylenepurinecyclophane.

ChemInform ◽

10.1002/chin.199236197 ◽

2010 ◽

Vol 23 (36) ◽

pp. no-no

Author(s):

R. A. BELL ◽

R. FAGGIANI ◽

H. N. HUNTER ◽

C. J. L. LOCK

Keyword(s):

Crystal Structure ◽

13C Nmr ◽

X Ray

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Solid state stereochemistry of crown ethers: X-ray crystal structure and 13C NMR studies of the LiNCS complex of 1,4,7,11-tetraoxacyclotetradecane

Canadian Journal of Chemistry ◽

10.1139/v00-008 ◽

2000 ◽

Vol 78 (3) ◽

pp. 316-321

Author(s):

G W Buchanan ◽

A B Driega ◽

G PA Yap

Keyword(s):

Crystal Structure ◽

Solid State ◽

Crown Ether ◽

13C Nmr ◽

Title Complex ◽

Nmr Studies ◽

Nmr Spectrum ◽

X Ray ◽

Large Amplitude Motion ◽

C Nmr

The title complex is asymmetric in the crystal due to the spatial orientation of the NCS function. The space group has been determined to be P21 with a = 9.496(3), b = 8.736(3), c = 9.676(3) Å, β = 117.859(5)°, and Z = 2. The solid state 13C NMR spectrum is consistent with the lack of symmetry in the crystal and there is little evidence for large amplitude motion in the macrocycle as determined from the dipolar dephased spectrum.Key words: macrocyclic crown ether, lithium complex.

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