Comparisons of butyrylcholinesterase inhibitory potencies of selected 3-substituted-1-decylpiperidines with their electron charge densities

1971 ◽  
Vol 14 (11) ◽  
pp. 1134-1136 ◽  
Author(s):  
O. Elmo Millner ◽  
William P. Purcell
Keyword(s):  
Electron Charge ◽  
Charge Densities ◽  
Substituted 1

Erratum: Electron charge densities at conduction-band edges of semiconductors

1987 ◽  
Vol 35 (17) ◽  
pp. 9308-9309
Author(s):  
Steven L. Richardson ◽  
Marvin L. Cohen ◽  
Steven G. Louie ◽  
James R. Chelikowsky
Keyword(s):  
Conduction Band ◽  
Electron Charge ◽  
Charge Densities

Electron charge densities at conduction-band edges of semiconductors

1986 ◽  
Vol 33 (2) ◽  
pp. 1177-1182 ◽  
Author(s):  
Steven L. Richardson ◽  
Marvin L. Cohen ◽  
Steven G. Louie ◽  
James R. Chelikowsky
Keyword(s):  
Conduction Band ◽  
Electron Charge ◽  
Charge Densities

Site Occupation of Excess Al Atoms in Off-Stoichiometric γ-Tial: Measurement of Debye-Waller Factors

1994 ◽  
Vol 364 ◽  
Author(s):  
S. Swaminathan ◽  
I. P. Jones ◽  
D. M. Maher ◽  
H. L. Fraser
Keyword(s):  
Site Occupancy ◽  
Diffraction Method ◽  
Electron Charge ◽  
X Ray Diffraction ◽  
Charge Density Distribution ◽  
Electron Charge Density ◽  
X Ray ◽  
Charge Densities ◽  
Structure Factors

AbstractIn recent years, the determination of x-ray structure factors and hence the electron charge density distribution in TiAl has received considerable attention. Experimental assessment of electron charge densities requires accurate values of the Debye-Waller (D-W) factors. This work attempts to determine the Debye-Waller factors from measurements of an Al rich off-stoichiometric single crystal of TiAl using the four circle x-ray diffraction method. The results suggest an ordered substitution of the excess Al atoms on the Ti-sublattice. This result is consistent with previous site occupancy studies.

Photochromic systems. Part 1. Structural and spectroscopic study of photochromically active products of Stobbe condensation. 2,3-Dibenzylidenesuccinic acid and its anhydride

1990 ◽  
Vol 68 (5) ◽  
pp. 741-746 ◽  
Author(s):  
P. Adriaan Davidse ◽  
Jan L. M. Dillen ◽  
Anton M. Heyns ◽  
Tomasz A. Modro ◽  
Petrus H. van Rooyen
Keyword(s):  
Cinnamic Acid ◽  
Structural Changes ◽  
Chemical Shifts ◽  
Spectroscopic Properties ◽  
Shielding Effect ◽  
Electron Charge ◽  
Hydrogen Atoms ◽  
Steric Strain ◽  
Space Group ◽  
Charge Densities

E,E-2,3-Dibenzylidenesuccinic acid (2) and its anhydride (1) were synthesized, their crystal structures and 1H and 13C nuclear magnetic resonance spectra were determined, and electron charge densities of carbon atoms were calculated. These results were related to the corresponding data available for E-cinnamic acid (3) in order to evaluate the effect of structural changes in a series 3 → 2 → 1 on the molecular parameters and spectroscopic properties of the cinnamic system. In the molecule of 2 most of the steric strain is released by the rotation about the C(α)—C(α′) bond giving rise to a structure consisting of two, approximately independent, cinnamic acid moieties. In 1, severe steric strain is introduced, as demonstrated by the unusually large values of the CCC bond angles exocyclic with respect to the anhydride ring, as well as by significant deviations from the plane of the cinnamic skeleton. The geometry of 1 results in an intramolecular shielding of the aromatic hydrogen atoms due to the proximity of the two benzene rings; this shielding effect for the ortho, meta, and para hydrogen atoms correlates well with the intramolecular distances between the corresponding positions of both rings. The common linear relationship between 13C chemical shifts and the electron charge densities on the given carbon atom has been obtained for compounds 1, 2, and 3.Crystal data. Anhydride (1): space group P21/c with a = 13.536(3), b = 14.391(3), c = 7.159(1) Å; β = 98.69(1)°; Rw = 0.029 and R = 0.055. Succinic acid (2): space group [Formula: see text] with a = 8.881(3), b = 9.786(1), c = 11.355(3) Å; α = 85.56(1), β = 88.76(2), γ = 69.46(2)°; Rw = 0.048 and R = 0.081. This compound cocrystallizes with one molecule of the solvent (acetic acid). Keywords: photochromic, cinnamic, succinic.

scholarly journals Interpretation of Substituent Angular Parameters of Monosubstituted Benzenes by Means of ab initio STO-3G Fully Optimized Molecular Structures and Charges Densities. Part VI of the Series: “Crystallographic Studies and Physicochemical Properties of π-Electron Systems”

1986 ◽  
Vol 41 (7) ◽  
pp. 895-903 ◽  
Author(s):  
Tadeusz Marek Krygowski ◽  
Günter Häfelinger ◽  
Josef Schüle
Keyword(s):  
Ab Initio ◽  
Linear Regression Analysis ◽  
Multiple Linear Regression Analysis ◽  
Molecular Structures ◽  
Steric Effects ◽  
Electron Charge ◽  
Charge Densities ◽  
Dual Regression ◽  
Monosubstituted Benzenes ◽  
Electron Effects

AbstractThe angular variations of molecular structures calculated for 17 monosubstituted derivatives of benzene by use of ab initio analytical gradient optimization at the STO -3G level have been correlated by multiple linear regression analysis with Mulliken σ- and π-electron charge densities at corresponding ring carbon atoms. Variations of angles γ at meta positions are solely due to π-electron effects (R = 0.961). Changes in angles β at ortho positions are independent of σ- or π-electron effects but may be related to steric effects (R = 0.719) alone or additionally to charge densities on ortho protons (for dual regression R = 0.846). Angles a at ipso atom s depend significantly on both, σ- and π-electron charge densities in the ratio of 70% to 21% with R = 0.974 for dual regression. Variations of angles δ para-positions depend on all three effects considered (with correlation coefficient for a triple regression R = 0.951) in the ratio 37.6% :2 8 .3% : 34.1% for steric effects, σ- and π-electron charge densities, respectively.

Topological analysis of CeMIn5 (M = Co, Rh) electron charge densities

2019 ◽  
Vol 164 ◽  
pp. 205-217 ◽  
Author(s):  
M. Yazdani-Kachoei ◽  
S. Jalali-Asadabadi ◽  
Negar Arianmehr
Keyword(s):  
Topological Analysis ◽  
Electron Charge ◽  
Charge Densities

Fast calculation of π-electron charge densities in organic molecules: Non-condensed compounds

1995 ◽  
Vol 314 (1-2) ◽  
pp. 101-110 ◽  
Author(s):  
Ivan P. Bangov ◽  
Kimito Funatsu ◽  
Carlos A.Del Carpio ◽  
Shin-ichi Sasaki
Keyword(s):  
Organic Molecules ◽  
Electron Charge ◽  
Fast Calculation ◽  
Charge Densities

THE PROTON RESONANCE SPECTRA AND STRUCTURES OF SUBSTITUTED AZULENES IN TRIFLUOROACETIC ACID

1962 ◽  
Vol 40 (9) ◽  
pp. 1777-1785 ◽  
Author(s):  
S. S. Danyluk ◽  
W. G. Schneider
Keyword(s):  
Trifluoroacetic Acid ◽  
Membered Ring ◽  
Coupling Constants ◽  
Electron Charge ◽  
Proton Resonance ◽  
Charge Densities ◽  
Electron Deficiency

The proton resonance spectra for a number of substituted azulenes and their conjugate acids are reported at 22 °C. From the spectra for the conjugate acids it is confirmed that monoprotonation occurs in the five-membered ring in each case. The unit electron deficiency is shown to be mainly localized in the seven-membered ring of the ion.Chemical shift changes on protonation are interpreted qualitatively in terms of changes in local π electron charge densities on the carbon atoms.Unusually large values are noted for the coupling constants between protons on the five-membered ring of the cations and are attributed in part to hyperconjugative effects.

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