Carbon-13 nmr spectra and excess positive charge densities for mesitylenonium ion

1968 ◽  
Vol 9 (37) ◽  
pp. 4009-4012 ◽  
Author(s):  
V. Koptyug ◽  
A. Rezvukhin ◽  
E. Lippmaa ◽  
T. Pehk
Keyword(s):  
Nmr Spectra ◽  
Positive Charge ◽  
Charge Densities ◽  
Excess Positive Charge

Charge density studies on methylene blue – a potential anti-Alzheimer agent

2018 ◽  
Vol 73 (2) ◽  
pp. 99-108 ◽  
Author(s):  
Peter Luger ◽  
Birger Dittrich ◽  
Leonard Benecke ◽  
Hannes Sterzel
Keyword(s):  
Methylene Blue ◽  
Charge Density ◽  
Molecular Electrostatic Potential ◽  
Positive Charge ◽  
Atomic Charges ◽  
Charge Densities ◽  
Density Distributions ◽  
Atomic Properties ◽  
Counter Ions ◽  
Medical Interest

AbstractMotivated by the medical interest in methylene blue as potential anti-Alzheimer agent, the charge densities of three salt structures containing the methylene blue cation with nitrate (as dihydrate), chloride (as pentahydrate) and thiocyanate counter-ions were generated by application of the invariom formalism and examined. The so-obtained charge density distributions were analyzed using the QTAIM formalism to yield bond topological and atomic properties. The atomic charges on the methylene blue cation indicate a delocalized charge distribution; only a small positive charge on the sulfur atom was found. Electrostatic potentials mapped onto iso-surfaces of electron density for the cations, and for the methylene blue cations with anions, were compared. The effect of hydrogen disorder on the molecular electrostatic potential was investigated for the thiocyanate structure.

Induction of oxidative stress and sensitization of cancer cells to paclitaxel by gold nanoparticles with different charge densities and hydrophobicities

2018 ◽  
Vol 6 (11) ◽  
pp. 1633-1639 ◽  
Author(s):  
Hainan Sun ◽  
Yin Liu ◽  
Xue Bai ◽  
Xiaofei Zhou ◽  
Hongyu Zhou ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Gold Nanoparticles ◽  
Cancer Cells ◽  
Positive Charge ◽  
Charge Densities

Gold nanoparticles with various positive charge densities and hydrophobicities induce cellular oxidative stress differently and sensitize cancer cells to paclitaxel.

Why is the capacity hump almost always at positive charge densities?

1984 ◽  
Vol 176 (1-2) ◽  
pp. 383-387 ◽  
Author(s):  
Wolfgang Schmickler ◽  
Douglas Henderson
Keyword(s):  
Positive Charge ◽  
Charge Densities

scholarly journals Reaction of substituted 6-oxocyclohexane- 1,3-dicarboxamides with hydroxylamine

2020 ◽  
Vol 63 (9) ◽  
pp. 31-34
Author(s):  
Natalia V. Nosova ◽  
◽  
Daria D. Lezhnina ◽  
Daria D. Rubtsova ◽  
Vladimir L. Gein ◽  
...  
Keyword(s):  
Carbon Atom ◽  
1H Nmr ◽  
13C Nmr ◽  
Nmr Spectra ◽  
Positive Charge ◽  
Hydroxylamine Hydrochloride ◽  
13C Nmr Spectroscopy ◽  
Amide Group ◽  
New Compounds ◽  
Proton Singlet

Functionalized cyclohexanones are multifunctional highly reactive available substrates. They are convenient for the synthesis of new compounds, including practically significant ones. The presence of a 1,3-dicarbonyl fragment in their composition makes it possible to obtain various heterocyclic systems in reactions with binucleophilic reagents: indazoles, benzisoxazoles, and diazepines. The interaction of cyclohexanones functionalized with acetyl or alkoxycarbonyl substituents with hydroxylamine was previously studied. It was shown that, depending on the nature of the substituents, the reaction can proceed with the formation of the corresponding oximes, or give products of heterocyclization – benzisoxazoles. The interaction of cyclohexanones containing amide groups in an alicycle with hydroxylamine has not been studied. We studied the reaction of unsubstituted 2-aryl-4-hydroxy-4-methyl-6-oxocyclohexane-1,3-dicarboxamides with hydroxylamine hydrochloride in the presence of an equivalent amount of alkali. When boiling in ethanol in the absence of a catalyst, new 2-aryl-4-hydroxy-6-(hydroxyimino)-4-methylcyclohexane-1,3-dicarboxamides were obtained. Cyclization with the formation of benzisoxazoles does not occur in this case due to a lower positive charge on the carbon atom of the amide group compared to the carbon atom of the acetyl or alkoxycarbonyl groups. The structure of the synthesized compounds was established based on the data of IR, 1H NMR and 13C NMR spectroscopy. The IR spectra of the obtained oximes contain bands of valence vibrations of the OH, NH, and CON groups. The 1H NMR spectra contain four NH-proton singlets of two amide groups, the proton singlet =N-OH group. The 13C NMR spectra of solutions of compounds contain signals of two carbon atoms of amide groups and a carbon atom of the C=N-OH group, which fully confirm the assumed structure.

The entropy of formation of the mercury/methanol interface

1982 ◽  
Vol 60 (14) ◽  
pp. 1787-1792 ◽  
Author(s):  
Z. Borkowska ◽  
W. R. Fawcett
Keyword(s):  
Negative Charge ◽  
Positive Charge ◽  
Charge Densities ◽  
Mercury Surface ◽  
Carbonate Solutions ◽  
Excess Surface ◽  
Double Layer Capacity ◽  
Charge Dependence ◽  
Entropy Of Formation ◽  
Three State Model

The entropy of formation of the mercury/methanol interface has been calculated from double layer capacity and interfacial tension measurements. In contrast to results for aqueous and propylene carbonate solutions, the plot of entropy against electrode charge density passes through a minimum at negative charge densities and a maximum at positive charge densities in the same regions where a minimum and maximum are found on the capacity curve. The excess surface entropy of methanol is negative for all charge densities, indicating that the solvent is more structured at the mercury surface than in the bulk. The results have been discussed in terms of the three state model in which the charge dependence of the entropy is attributed to reorientation of solvent dipoles at the interface.

Notizen: 13C NMR Spectra of Alkyl Substituted Pyrylium Salts

1975 ◽  
Vol 30 (7-8) ◽  
pp. 654-655 ◽  
Author(s):  
A. T. Balaban ◽  
V. Wray
Keyword(s):  
Nmr Spectra ◽  
Chemical Shifts ◽  
13C Nmr Spectra ◽  
Charge Densities ◽  
Ring Carbon ◽  
Pyridinium Cation ◽  
Pyrylium Salts ◽  
Isoelectronic Series ◽  
Alkyl Substitution ◽  
Alkyl Benzenes

The 13C chemical shifts of several alkylsubstituted pyrylium salts are presented. Charge densities in the isoelectronic series benzene, pyridine, pyridinium cation and pyrylium cation, calculated from INDO M. O. theory, are shown to correlate well with the ring carbon 13C chemical shifts. The effect of alkyl substitution on ring carbon 13C chemical shifts in the pyrylium salts are shown to correlate with those of the alkyl benzenes.

scholarly journals Measurements of vertical electric field in a thunderstorm in a Chinese inland plateau

2018 ◽  
Vol 36 (4) ◽  
pp. 979-986 ◽  
Author(s):  
Tinglong Zhang ◽  
Hai Yu ◽  
Fangcong Zhou ◽  
Jie Chen ◽  
Maohua Zhang
Keyword(s):  
Electric Field ◽  
Positive Charge ◽  
Atmospheric Electricity ◽  
Early Period ◽  
Vertical Direction ◽  
Mature Stage ◽  
Weak Charge ◽  
Charge Densities ◽  
Vertical Electric Field ◽  
Mean Charge

Abstract. A balloon-borne instrument was designed to measure the electric field in thunderstorms. One case of thunderstorm was observed in the Pingliang region (35.57∘ N, 106.59∘ E; and 1620 m above sea level, a.s.l.) of a Chinese inland plateau, through penetration by the balloon-borne sounding in the early period of the mature stage. Results showed that the sounding passed through seven predominant charge regions. A negative charge region with a depth of 800 m located near the surface, and a positive charge region appeared in the warm cloud region; their mean charge densities were −0.44 ± 0.136 and 0.43 ± 0.103 nC m−3, respectively. Five charge regions existed in the region colder than 0 ∘C, and charge polarity alternated in a vertical direction with a positive charge at the lowest region. The mean charge densities for these five regions were 0.40±0.037 nC m−3 (−9.5 to −4 ∘C), -0.63±0.0107 nC m−3 (−18 to −14 ∘C), 0.35±0.063 nC m−3 (−27 to −18 ∘C), -0.36±0.057 nC m−3 (−34 to −27 ∘C), and 0.24±0.06 nC m−3 (−38 to −34 ∘C). We speculated that the two independent positive charge regions in the lower portion are the same charge region with a weak charge density layer in the middle. The analysis showed that the real charge structure of the thunderstorm is more complex than the tripole model, and the lower dipole is the most intensive charge region in the thunderstorm. Keywords. Meteorology and atmospheric dynamics (atmospheric electricity)

Carrier Accumulation in Silicon-On-Insulator Structures Containing Ge Nanocrystals in the Burried SiO2 Layer

2005 ◽  
Vol 108-109 ◽  
pp. 77-82
Author(s):  
Ida E. Tyschenko ◽  
A.A. Frantsuzov ◽  
O.V. Naumova ◽  
B.I. Fomin ◽  
D.V. Nikolaev ◽  
...  
Keyword(s):  
Physical Properties ◽  
Positive Charge ◽  
Silicon Layer ◽  
Silicon On Insulator ◽  
Electron Trapping ◽  
Mos Transistors ◽  
Electrical Field ◽  
Excess Positive Charge ◽  
Mos Structures ◽  
Ge Nanocrystals

Electro-physical properties of metal-oxide-silicon (MOS) structures and MOS transistors, prepared in the top silicon layer of silicon-on-insulator (SOI) structures containing Ge nanocrystals in the buried SiO2 layers, have been studied. It was obtained that carrier accumulation in MOS structures depend on the direction of built-in electrical field in MOS structures. Accumulation of the excess negative charges in the case of p-channel transistors is associated with electron trapping on Ge nanocrystals synthesized in the buried dielectric. In the case of n-channel transistor, positive charge related to the Si/SiO2 interface or to the charged oxide is accumulated. The Ge atoms diffused to the SiO2/Si interface can stimulate the formation of the excess positive charge.

Structural studies on 6-ethoxytetrahydropyrylium cations; stereoelectronic control in the reactions of lactonium salts

1991 ◽  
Vol 69 (12) ◽  
pp. 2024-2032 ◽  
Author(s):  
Ronald F. Childs ◽  
Marianne D. Kostyk ◽  
Colin J. L. Lock ◽  
Mailivaganam Mahendran
Keyword(s):  
Nmr Spectra ◽  
Positive Charge ◽  
Nucleophilic Attack ◽  
Structural Studies ◽  
Narrow Line ◽  
Crystal Lattices ◽  
X Ray ◽  
X Ray Crystallography ◽  
Stereoelectronic Control ◽  
C Nmr

The structures of 6-ethoxy-2,3,4,5-tetrahydropyrylium, 1, 6-ethoxy-2-methyl-2,3,4,5-tetrahydropyrylium, 2, and 2-ethoxy-3,4,4a,5,6,7,8,8a-octahydro-1-benzopyrylium, 3, hexachloroantimonates have been determined by X-ray crystallography. In each case the tetrahydropyrylium rings exist in shallow half-chair conformations with the cationic centers C(6), C(5), O(1), and O(6) having a planar arrangement. The cations all have a Z conformation about the O(6)—C(7) bonds and it is shown that this conformation is also preferred in solution by comparison of narrow-line 13C NMR spectra in the solid state and solution. The O(1)—C(2) and O(6)—C(7) bond distances in 1–3 are significantly longer than those of comparable bonds in neutral esters. The length of the O(1)—C(2) bond is very dependent on substitution at C(2) suggesting a considerable fraction of the positive charge resides on this carbon as well as C(7). The closest cation/anion interactions present in the crystal lattices of these salts are between the chlorine atoms of the anion and the cationic center, C(6). These interactions provide information on the origin of the stereoselectivity observed in nucleophilic attack on these cations. The conformations, details of the C—O bonding, and closest contacts between cation and anion are discussed in terms of the concept of stereoelectronic control. Key words: 6-ethoxytetrahydropyrylium cations, lactonium salts, structure, X-ray, stereoelectronic control.

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