2D NMR Investigations of the Rotation of Axial Ligands in Six-Coordinate Low-Spin Iron(III) and Cobalt(III) Tetraphenylporphyrinates Having 2,6-Disubstituted Phenyl Rings:  Quantitation of Rate Constants from1H EXSY Cross-Peak Intensities

1997 ◽  
Vol 101 (15) ◽  
pp. 2778-2786 ◽  
Author(s):  
Nikolai V. Shokhirev ◽  
Tatjana Kh. Shokhireva ◽  
Jayapal Reddy Polam ◽  
C. Todd Watson ◽  
Kamran Raffii ◽  
...  
Keyword(s):  
Rate Constants ◽  
2D Nmr ◽  
Cross Peak ◽  
Axial Ligands ◽  
Phenyl Rings

Dramatic Enhancement of Hyperpolarized Xenon-129 2D-NMR Exchange Cross-Peak Signals in Nanotubes by Interruption of the Gas Flow

2008 ◽  
Vol 130 (8) ◽  
pp. 2390-2391 ◽  
Author(s):  
Chi-Yuan Cheng ◽  
Jessica Pfeilsticker ◽  
Clifford R. Bowers
Keyword(s):  
Gas Flow ◽  
2D Nmr ◽  
Cross Peak ◽  
Hyperpolarized Xenon

Assignment of13C Resonances in the Phencyclone-Norbornadiene Adduct Via 2D NMR.13C Evidence for Hindered Rotation of Unsubstituted Bridgehead Phenyl Rings

1993 ◽  
Vol 26 (1) ◽  
pp. 179-196 ◽  
Author(s):  
Yangdong Xu ◽  
Laurine A. LaPlanche ◽  
Robert Rothchild
Keyword(s):  
2D Nmr ◽  
Hindered Rotation ◽  
Phenyl Rings

Long-range CH correlation 2D NMR spectroscopy 3—long-rangeJ modulation of cross-peak intensities

1988 ◽  
Vol 26 (5) ◽  
pp. 367-372 ◽  
Author(s):  
V. V. Krishnamurthy ◽  
John E. Casida
Keyword(s):  
Nmr Spectroscopy ◽  
Long Range ◽  
2D Nmr ◽  
Cross Peak ◽  
2D Nmr Spectroscopy

Two Kinds of Cross-Peak Orientations in a Single 2D NMR Contour Plot of Organofluorines

1994 ◽  
Vol 48 (3) ◽  
pp. 412-413
Author(s):  
A. L. Cholli
Keyword(s):  
2D Nmr ◽  
Cross Peak ◽  
Contour Plot

Investigation of axial ligand effects on catalytic activity of manganese porphyrin, evidence for the importance of hydrogen bonding in cytochrome-P450 model reactions

2014 ◽  
Vol 18 (05) ◽  
pp. 354-365 ◽  
Author(s):  
Elnaz Mesbahi ◽  
Nasser Safari ◽  
Mahin Gheidi
Keyword(s):  
Hydrogen Bonding ◽  
Catalytic Activity ◽  
Product Formation ◽  
Axial Ligand ◽  
Active Species ◽  
Manganese Porphyrin ◽  
Axial Ligands ◽  
Epoxidation Reaction ◽  
Phenyl Rings ◽  
Hydroxy Groups

Various nitrogenous bases, such as imidazoles, pyridines and amines were employed as axial ligands in epoxidation reaction of cyclooctene bytetra-n-butylammonium hydrogen monopersulfate (n- Bu 4 NHSO 5), in the presence of Mn ( III )-tetrakis(2,3-dimethoxyphenyl)porphyrin-acetate ( T (2,3- OMeP ) PorMnOAc ). T (2,3- OMeP ) PorMnOAc is a fairly stable catalyst, with the ability of producing hydrogen bonding. High epoxidation yield of 85 ± 6% was obtained in the presence of imidazole axial ligand with 100% selectivity in 30 min. Higher conversion of around 100% was obtained by pyridine axial base, while selectivity was reduced to 69%. Further epoxidation reactions were also performed using Mn ( III )-Tetrakis(2,3-dihydroxyphenyl)porphyrin-acetate ( T (2,3- OHP ) PorMnOAc ) as catalyst. In addition to the usual electronic and steric effects, it is proposed that the catalytic activity depends on the existence and kind of hydrogen bonding between the axial base and the ortho-methoxy or hydroxy groups on the phenyl rings of manganese porphyrin. The cis to trans ratio of cis-stilbene oxide formed by imidazole and pyridine axial bases were obtained as 7.5 and 2.5 respectively. In addition GC-Ms and UV-vis studies were employed to find the nature of active species and product formation. Our DFT calculations disclosed that pyridine hydrogen bonding with moiety of the macrocycle rings strongly affects the relative energies of S/Q spin states in [ T (2,3- OMeP ) PorMn V ( O )( Py )]+, in that it results in the longer Mn – O bond and reactivity toward substrates.

Variances of rate constants estimated from 2D NMR exchange spectra

1988 ◽  
Vol 76 (1) ◽  
pp. 136-142
Author(s):  
Philip W Kuchel ◽  
Brian T Bulliman ◽  
Bogdan E Chapman ◽  
George L Mendz
Keyword(s):  
Rate Constants ◽  
2D Nmr

scholarly journals Metabolomic Profiling and Cytotoxic Tetrahydrofurofuran Lignans Investigations from Premna odorata Blanco

Metabolites ◽  
2019 ◽  
Vol 9 (10) ◽  
pp. 223 ◽  
Author(s):  
Abeer H. Elmaidomy ◽  
Rabab Mohammed ◽  
Hossam M. Hassan ◽  
Asmaa I. Owis ◽  
Mostafa E. Rateb ◽  
...  
Keyword(s):  
Hydrogen Bond ◽  
2D Nmr ◽  
Hydroxyl Group ◽  
Hydrogen Bond Donor ◽  
Hydrogen Bond Acceptor ◽  
Metabolomic Profiling ◽  
Phytochemical Investigation ◽  
Phenyl Rings ◽  
Ic50 Values ◽  
Mcf 7

Metabolomic profiling of different Premna odorata Blanco (Lamiaceae) organs, bark, wood, young stems, flowers, and fruits dereplicated 20, 20, 10, 20, and 20 compounds, respectively, using LC–HRESIMS. The identified metabolites (1–34) belonged to different chemical classes, including iridoids, flavones, phenyl ethanoids, and lignans. A phytochemical investigation of P. odorata bark afforded one new tetrahydrofurofuran lignan, 4β-hydroxyasarinin 35, along with fourteen known compounds. The structure of the new compound was confirmed using extensive 1D and 2D NMR, and HRESIMS analyses. A cytotoxic investigation of compounds 35–38 against the HL-60, HT-29, and MCF-7 cancer cell lines, using the MTT assay showed that compound 35 had cytotoxic effects against HL-60 and MCF-7 with IC50 values of 2.7 and 4.2 µg/mL, respectively. A pharmacophore map of compounds 35 showed two hydrogen bond acceptor (HBA) aligning the phenoxy oxygen atoms of benzodioxole moieties, two aromatic ring features vectored on the two phenyl rings, one hydrogen bond donor (HBD) feature aligning the central hydroxyl group and thirteen exclusion spheres which limit the boundaries of sterically inaccessible regions of the target’s active site.

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