Benzoannelated quinone methides

1982 ◽  
Vol 47 (6) ◽  
pp. 1645-1653 ◽  
Author(s):  
Bohumír Koutek ◽  
Milena Píšová ◽  
Josef Krupička ◽  
Antonín Lyčka ◽  
Dobroslav Šnobl ◽  
...  
Keyword(s):  
Ground State ◽  
Charge Separation ◽  
Side Chain ◽  
Exocyclic Double Bond ◽  
Electronic Effects ◽  
Quinone Methides ◽  
Factors Influencing ◽  
Nmr Data ◽  
State Charge ◽  
C Nmr

On the basis of detailed study of UV, IR, 13C NMR and E1/2 data of quinone methides V-VII three dominant factors influencing the behaviour of benzoannelated compounds must be considered: 1) electronic effects of both the exocyclic carbon substituents and the fused rings, 2) the extent to which the substituents are displaced out of the plane of the exocyclic double bond through steric interference between the side-chain substituents and peri-hydrogens and 3) the extent of the angular distorsion of the quinone-like rings. The ground state charge separation (~0.2e) in nonannelated derivatives was found to be strongly minimized by annelation of two benzene units to the parent systems. Near parallelism with this phenomenon was also observed in both the carbonyl vibration frequency and 13C NMR data.

Zur Strukturchemie von 2-Methylenimidazolinen [1]

2005 ◽  
Vol 60 (3) ◽  
pp. 294-299 ◽  
Author(s):  
Norbert Kuhn ◽  
Ahmed Abu-Rayyan ◽  
Ahmed Al-Sheikh ◽  
Klaus Eichele ◽  
Cäcilia Maichle-Mößmer ◽  
...  
Keyword(s):  
Charge Separation ◽  
Structural Data ◽  
Imidazolium Salts ◽  
Electronic Effects ◽  
Olefinic Bond ◽  
Nmr Data ◽  
C Nmr

The 2-methylenimidazolines ImC(CN)2 (6a - c, Im = 1,3-dialkyl-4,5-dimethylimidazol-2-ylidene) are prepared by the reaction of the imidazolium salts [ImBr]Br (5) and malodinitrile while ImC{C(O)Ph}2 (7) is obtained from ImCH2 (2) and benzoic fluoride. Both the structural data of 6b, 6c, and 7 and the 13C NMR data demonstrate the influence of steric and electronic effects on the charge separation and the nonplanar arrangement of the substituents attached at the carbon atoms of the central olefinic bond

Collision induced charge separation in ground-state water splitting dynamics

2018 ◽  
Vol 20 (17) ◽  
pp. 12229-12240 ◽  
Author(s):  
Kentaro Yamamoto ◽  
Kazuo Takatsuka
Keyword(s):  
Water Splitting ◽  
Ground State ◽  
Charge Separation ◽  
Electron Hole ◽  
Hole Transfer ◽  
State Water ◽  
Induced Charge ◽  
State Charge

The pathway of one-way electron–hole transfer induced by proton reciprocating motions, thereby realizing the collision induced ground-state charge separation.

13C-nuclear magnetic resonance spectra of oxiranes. Configuration of 1,2-epoxypropyl side chains in fungal metabolites

1978 ◽  
Vol 56 (24) ◽  
pp. 3117-3120 ◽  
Author(s):  
Suzanne Lesage ◽  
Arthur S. Perlin
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Side Chain ◽  
Fungal Metabolites ◽  
Trans Isomers ◽  
Model Compounds ◽  
Nmr Data ◽  
Nuclear Magnetic Resonance Spectra ◽  
13C Nuclear Magnetic Resonance ◽  
Cis And Trans ◽  
C Nmr

13C nmr data indicate that the epoxypropyl side chain of 'asperlin' (1) has a trans configuration. This assignment follows from associated measurements on model compounds, showing that the 13C chemical shift of an epoxypropyl CH3 group is close to either 17 ppm (trans isomers) or 13 ppm (cis isomers). Synthesized as oxirane derivatives related to 1 are diastereomeric pairs of 8-deoxy-6,7-cis- and -trans-epoxy-1,2:3,4-di-O-isopropylidene-α-D-galacto-octopyranoses.

1H and 13C NMR study of some substituted 2-furyl- and 2-thienylethylene derivatives

1986 ◽  
Vol 51 (4) ◽  
pp. 889-898 ◽  
Author(s):  
Miloslava Dandárová ◽  
Daniel Végh ◽  
Jaroslav Kováč ◽  
Igor Goljer ◽  
Nadežda Prónayová ◽  
...  
Keyword(s):  
Double Bond ◽  
Heterocyclic Ring ◽  
Coupling Constants ◽  
Side Chain ◽  
1H And 13C Nmr ◽  
H Nmr ◽  
Nmr Data ◽  
Nmr Study ◽  
Thiophene Derivatives ◽  
C Nmr

The 1H and 13C NMR spectral data of 1-(5-nitro-2-furyl)-2-X-2-Y-ethylenes and some their thienyl analogues are presented. Geometrical arrangement of the trisubstituted ethylenes was adduced from vicinal coupling constants 3J(C, H) for the carbon atom at the functional group attached to the double bond and the ethylene proton. The orientation of the heterocyclic ring towards the double bond of the side chain was determined from the 1H NMR data. The preferred s-cis or s-trans conformations of 5-nitro-2-furylethylene derivatives is substituent at the double bond dependent; all thiophene derivatives under study were found in the s-trans conformation.

Glucan isolated from leaves of Althaea officinalis L.

1983 ◽  
Vol 48 (7) ◽  
pp. 2082-2087 ◽  
Author(s):  
Alžbeta Kardošová ◽  
Jozef Rosík ◽  
Rudolf Toman ◽  
Peter Capek
Keyword(s):  
Medicinal Plant ◽  
Periodate Oxidation ◽  
Linear Structure ◽  
Water Soluble ◽  
Partial Hydrolysis ◽  
Methylation Analysis ◽  
Glycosidic Bonds ◽  
Nmr Data ◽  
Althaea Officinalis ◽  
C Nmr

A water-soluble low-molecular D-glucan was isolated from leaves of the medicinal plant marsh-mallow (Althaea officinalis L.). The results of methylation analysis, partial hydrolysis, periodate oxidation, and 13C NMR data indicated a virtually linear structure with α-(1→6) glycosidic bonds.

Synthesis and characteristics of ethylenediamine-N,N'-di-S-α-isovalerate and isomers of its cobalt(III) complexes

1982 ◽  
Vol 47 (1) ◽  
pp. 210-216 ◽  
Author(s):  
Milan Strašák ◽  
František Bachratý ◽  
Jaroslav Majer
Keyword(s):  
Amino Acids ◽  
Absolute Configuration ◽  
Electronic Absorption ◽  
Electronic Absorption Spectra ◽  
Chemical Parameters ◽  
Methyl Group ◽  
Nmr Data ◽  
Physico Chemical ◽  
Natural Amino Acids ◽  
C Nmr

The synthesis and physico-chemical parameters are described of a new complexone based on natural amino acids, viz. ethylenediamine-N,N'-di-S-α-isovalerate (SS-EDDIV). 1H- and 13C-NMR data revealed that the methyl group in the substance are not equivalent. The isomers of the cobalt(III) complex with the asymmetric tetradentate SS-EDDIV ligand were prepared and separated; their characteristics are given. The absolute configuration of two of the five theoretically feasible isomers was determined based on their electronic absorption spectra and circular dichroism data.

scholarly journals Structural Investigations of C-Nitrosobenzenes. Part 3.1 Solid-state and Solution 13C NMR Studies, and Crystal Structure of E-(4-CIC6H4NO)2

1999 ◽  
Vol 23 (3) ◽  
pp. 202-203
Author(s):  
Daniel A. Fletcher ◽  
Brian G. Gowenlock ◽  
Keith G. Orrell ◽  
David C. Apperley ◽  
Michael B. Hursthouse ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Solid State ◽  
13C Nmr ◽  
Nmr Studies ◽  
Structural Investigations ◽  
Nmr Data ◽  
C Nmr

Solid-state and solution 13C NMR data for the monomers and dimers of 3- and 4-substituted nitrosobenzenes, and the crystal structure of E-(4-CIC6H4NO)2 are reported.

scholarly journals Anion-enhanced excited state charge separation in a spiro-locked N-heterocycle-fused push-pull zinc porphyrin

2021 ◽  
Author(s):  
Mandeep K. Chahal ◽  
Anuradha Liyanage ◽  
Ajyal Z. Alsaleh ◽  
Paul A. Karr ◽  
Jonathan P. Hill ◽  
...  
Keyword(s):  
Excited State ◽  
Charge Transfer ◽  
Charge Separation ◽  
Charge Transfer Complex ◽  
Zinc Porphyrin ◽  
New Type ◽  
State Charge

A new type of push–pull charge transfer complex, viz., a spiro-locked N-heterocycle-fused zinc porphyrin, ZnP-SQ, is shown to undergo excited state charge separation, which is enhanced by axial F− binding to the Zn center.

Stereospecific Association of C-20 Epimers of 3β-Hydroxy-16-oxo-24-nor-17-azachol-5-eno-23-nitryle

1997 ◽  
Vol 52 (6) ◽  
pp. 749-756
Author(s):  
Zofia Plesnar ◽  
Stanisław Malanowski ◽  
Zenon Lotowski ◽  
Jacek W. Morzycki ◽  
Jadwiga Frelek ◽  
...  
Keyword(s):  
Proton Nuclear Magnetic Resonance ◽  
Side Chain ◽  
Water Molecules ◽  
Carbonyl Groups ◽  
Nmr Data ◽  
Molecular Modelling Studies ◽  
Modelling Studies ◽  
Lactam Carbonyl ◽  
Self Association ◽  
Chain Conformations

Abstract The cryoscopic measurements show that title compounds are strongly associated in CHCl3 solutions. The association of the 20 R epimer is distinctly less pronounced than that of the 20 S epipmer. Self-association of the 20 S epimer leads to the formation of very large com­plexes. The 20 R epimer forms associates via water molecules. The dissimilarity may be ex­plained in terms of different accessibility of the lactam carbonyl groups in the two epimers for the association. It is proposed that the association process is controlled by the configura­tion at the carbon atom C(20) and conformation around the C(20)-C(22) bond. Populations of side chain conformations of both epimers were determined by means of proton nuclear magnetic resonance. It was found for the 20 R epimer that the t and the -g rotamers are almost equally populated, and the rotamer +g is excluded. For the 20 S epimer the +g rotamer predominates over the t one, and the -g rotamer is excluded. The NMR data are fully consistent with the results of the molecular modelling studies.

GROUND STATE CHARGE OF FERMION SOLITON SYSTEM IN 1+1 AND 3+1 DIMENSIONS

1993 ◽  
Vol 08 (04) ◽  
pp. 705-721
Author(s):  
M. RAVENDRANADHAN ◽  
M. SABIR
Keyword(s):  
Ground State ◽  
Energy State ◽  
Flow Analysis ◽  
Background Field ◽  
Bound State ◽  
Fermion Mass ◽  
Spectral Flow ◽  
Bound State Spectrum ◽  
Spectral Asymmetry ◽  
State Charge

Ground state charge of some fermion soliton system without C-invariance is calculated in 1+1 and 3+1 dimensions by a combination of adiabatic method and spectral flow analysis. Induced charge is calculated by evolving adiabatically the fields from a vacuum having a background field which has a zero energy state and spectral symmetry. The spectral flow is calculated by an analysis of the bound state spectrum. In 1+1 dimension our calculations are in agreement with the results already found in the literature. In 3+1 dimension we study the interaction of fermions with monopoles and dyons. In the case of monopoles, even though there is spectral asymmetry, ground state charge is found to be ±1/2. It is shown that ground state charge gets contribution only from the lowest angular momentum states and is discontinuous at the fermion mass.

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