Calculated electrostatic potentials and local surface ionization energies of para-substituted anilines as measures of substituent effects

1992 ◽  
Vol 70 (8) ◽  
pp. 2209-2214 ◽  
Author(s):  
Markus Haeberlein ◽  
Jane S. Murray ◽  
Tore Brinck ◽  
Peter Politzer
Keyword(s):  
Substituent Effects ◽  
Correlation Coefficients ◽  
Electrostatic Potentials ◽  
Surface Ionization ◽  
Local Surface ◽  
Substituted Anilines ◽  
Amine Nitrogen ◽  
Ionization Energies ◽  
Linear Relationships ◽  
Self Consistent Field

Using an abinitio self-consistent-field molecular orbital approach, we computed 3-21G//STO-3G* and STO-5G//STO-3G* electrostatic potentials and average local ionization energies for 17 para-substituted anilines. Our results demonstrate that the most negative potentials (Vmin) and the local surface ionization energy minima (ĪS,min) associated with the amine nitrogen lone pairs are highly sensitive indicators of the electron-donating and electron-attracting tendencies of the para substituents. We find excellent linear relationships between the 3-21G//STO-3G* amine nitrogen Vmin and ĪS,min and the σp0 Hammett constants of the substituent X; the correlation coefficients are 0.99. Correlations of slightly lesser quality are shown to exist between Vmin, ĪS,min, and σp−, σp, and pKa. Estimates of previously unknown σp0 and pKa values are given. The presence of ring carbon ĪS,minmeta to the substituent X also provides a predictive capability for determining σm values.

scholarly journals Proton transfer equilibria, temperature and substituent effects on hydrogen bonded complexes between chloranilic acid and anilines

2000 ◽  
Vol 14 (3) ◽  
pp. 99-107 ◽  
Author(s):  
Gamal A. Gohar ◽  
Moustafa M. Habeeb
Keyword(s):  
Hydrogen Bond ◽  
Complex Formation ◽  
Proton Transfer ◽  
Equilibrium Constants ◽  
Bond Formation ◽  
Substituent Effects ◽  
Substituted Anilines ◽  
Chloranilic Acid ◽  
Hydrogen Bond Formation ◽  
Linear Relationships

The proton transfer equilibrium constants (KPT) for 1 : 1 complex formation between Chloranilic Acid (CA) and a series ofp- andm‒substituted anilines have been measured in 1,4-dioxane spectrophotometrically. The results supported the concept of amine-solvent hydrogen bond formation (short range solvation effect). Beside, this effect, theKPTvalues were apparently affected by the electron donation power of the aniline ring substituent, which was transmitted to the interaction center via resonance and inductive effects. Linear relationships betweenKPTand σ-Hammett substituent constants, or pKvalues formandpanilines,were obtained verifying the above conclusions. The solute-solvent hydrogen bond formation might increase the reactivity of the aniline nitrogen than would the inductive effect of the alkyl group, in case of CA-N-alkyl aniline complexes. The thermodynamic parameters for the proton transfer complex formation were estimated and it was indicated that the solvent–aniline hydrogen bond formation was preferred in the case ofp-substituted aniline complexes more than in the case of the correspondingm‒isomer. It has been found that the proton transfer process was enthalpy and entropy controlled.

scholarly journals The Comorbidity of Psychopathy and Depression: Across Different Ethnic and Sex Groups

2017 ◽  
Vol 4 (3) ◽  
Author(s):  
Dr. Zlatko Šram
Keyword(s):  
Regression Analysis ◽  
Adult Population ◽  
Community Sample ◽  
Correlation Coefficients ◽  
Convenience Sample ◽  
Positive Direction ◽  
Demographic Groups ◽  
Secondary Psychopathy ◽  
Linear Relationships ◽  
Primary And Secondary Psychopathy

The aim of this research was to examine if comorbid relationships exist between psychopathy and depression in a community sample of different ethnic and sex groups. Based on some previous research, it was hypothesized that psychopathy and depression would be correlated and that secondary psychopathy would be the strongest predictor of depression regardless of different ethnic and sex belongings. The survey was carried out on the adult population in the region of Croatia populated by citizens of Croatian and Serbian minority ethnicity. The equalized convenience sample of 1100 participants, half of which were Croats and half of males. Pearson-product moment correlation coefficients were calculated as a measure of the strength and direction of linear relationships among primary and secondary and depression. In order to determine how well scores on depression could be predicted by primary and secondary psychopathy across different demographic groups, multiple regression analysis were used. It was found that both primary and secondary psychopathy were significantly correlated in a positive direction with depression in different ethnic and sex groups. However, secondary psychopathy was more correlated with depression across different ethnic and sex subsamples. The results of regression analysis revealed that secondary psychopathy was the strongest predictor of depression in all demographic subsamples. After age and school attainment were introduced into regression models, it was shown that a very small percentage of the variance is explained by the sociodemographic variables. The research suggested a significant role of secondary psychopathy in relation to a higher level of psychopathology.

Electrostatic Potentials and Local Ionization Energies in Nanomaterial Applications

2012 ◽  
pp. 233-256
Author(s):  
Peter Politzer ◽  
Felipe A. Bulat ◽  
James Burgess ◽  
Jeffrey W. Baldwin ◽  
Jane S. Murray
Keyword(s):  
Electrostatic Potentials ◽  
Ionization Energies

scholarly journals Quantification of one Prenylated Flavanone from Eysenhardtia platycarpa and four derivatives in Ex Vivo Human Skin Permeation Samples Applying a Validated HPLC Method

Biomolecules ◽  
2020 ◽  
Vol 10 (6) ◽  
pp. 889
Author(s):  
Paola Bustos-Salgado ◽  
Berenice Andrade-Carrera ◽  
María Luisa Garduño-Ramírez ◽  
Helen Alvarado ◽  
Ana Calpena-Campmany
Keyword(s):  
Human Skin ◽  
Ex Vivo ◽  
Skin Permeation ◽  
Correlation Coefficients ◽  
Biological Properties ◽  
Cell System ◽  
Hplc Method ◽  
Linear Relationships ◽  
Relative Standard ◽  
Instrumental System

Prenylated flavanones are polyphenols that have diverse biological properties. The present paper focuses on a HPLC method validation for the quantification of prenylated flavanones (2S)-5,7-dihydroxy-6-(3-methyl-2-buten-1-yl)-2-phenyl-2,3-dihydro-4H-1Benzopyran-4-one 1 and derivatives (2S)-5,7-bis(acetyloxy)-6-(3-methyl-2-buten-1-yl)-2-phenyl-2,3-dihydro-4H-1-Benzopyran-4-one A; (2S)-5-hydroxy-7-methoxy-6-(3-methyl-2-buten-1-yl)-2-phenyl-2,3-dihydro-4H-1-Benzopyran-4-one B; (8S)-5-hydroxy-2,2-dimethyl-8-phenyl-3,4,7,8-tetrahydro-2H,6H-Benzo[1,2-b:5,4-bˈ]dipyran-6-one C; and (8S)-5-hydroxy-2,2-dimethyl-8-phenyl-7,8-dihydro-2H,6H-Benzo[1,2-b:5,4-bˈ]dipyran-6-one D applied in biopharmaceutic studies. The linear relationships are proven with significant correlation coefficients (R2 ˃ 0.999) in the range of 1.56 to 200 μg/mL with low limits of detection and quantification, on average of 0.4 μg/mL and 1.2 μg/mL, respectively. The validation method used in this work is highly accurate and precise, with values lower than 15%. The relative standard deviation values of repeatability of the instrumental system are demonstrated with less than 0.6% for all studied flavanones. Therefore, the applicability method of the quantification of the prenylated flavanones was established using the permeation of human skin in the Franz cell system. During the method previously described, there was no interference observed from human skin components in ex vivo permeation studies.

scholarly journals Relationships between conformation traits and longevity of Holstein cows in the Czech Republic

2011 ◽  
Vol 51 (No. 8) ◽  
pp. 327-333 ◽  
Author(s):  
M. Vacek ◽  
M. Štípková ◽  
E. Němcová ◽  
J. Bouška
Keyword(s):  
Pearson Correlation ◽  
Correlation Coefficients ◽  
The Body ◽  
Holstein Cows ◽  
Body Depth ◽  
The Czech Republic ◽  
Productive Life ◽  
Linear Relationships ◽  
Type Traits ◽  
The Ideal

The relationships between conformation traits and longevity traits were analyzed in 41 489 Holstein cows born in the years 1994&ndash;1999 which were culled by 30<sup>th</sup> June 2005. Pearson correlation coefficients between type traits and the herd life or productive life of cows were calculated. The effects of type trait scoring level on the length of productive life were described by means of analyses of variance. The observed correlations between herd life or productive life and type traits are in the range of &ndash;0.061 to 0.160. Negative correlations were found for rump angle, rear leg set, udder depth, and teat length. Most of the body traits had slightly positive relationships to herd life, indicating that larger cows live longer. However, body depth and chest width did not have a linear relation to longevity traits. The longest productive life was found in cows undersized in chest width and body depth (P &lt; 0.01). A similar dependence was also found for rump width (P &lt; 0.01). The ideal rear leg set for longevity was scored as average or below average, i.e. moderately curved or slightly straight legs (P &lt; 0.05). Cows with well-attached fore udder, high attached rear udder, strong central ligament, close front teat placement, and with moderately long teats showed the longest functional productive life (P &lt; 0.05&ndash;0.001). Linear relationships between longevity traits and general conformation characteristics were found as well. &nbsp;

scholarly journals Spatial variation features description of soil available P, K, Mg and soil pH by proportional effect

2011 ◽  
Vol 52 (No. 1) ◽  
pp. 41-46 ◽  
Author(s):  
L. Brodský ◽  
J. Száková ◽  
M. Bazalová ◽  
V. Penížek
Keyword(s):  
Spatial Variation ◽  
Soil Ph ◽  
Correlation Coefficients ◽  
Available P ◽  
Relationship Strength ◽  
Soil P ◽  
Linear Relationships ◽  
Field Fluctuations ◽  
Proportional Effect ◽  
The Relationship

This paper investigates the proportional effect of selected soil properties &ndash; low spatial variation changes are related to their local magnitudes (here standard deviation vs. mean). Content of available P, K, and Mg, and soil pH were analysed on nine agricultural fields of the&nbsp;Xzech Republic. Firstly, strong direct within-field proportional effect based on Moving Window Statistics (MWS) was found for soil P and K, while Mg did not exhibit any clear proportionality. Soil pH showed indication of inverse proportional effect with high field-to-field fluctuations. The relationship strength of the effect was functionally related to the asymmetry (skewness) of distribution (r = 0.31 &times; skew 0.08). Secondly, between-field proportional effect of 9 surveyed fields, as a&nbsp;measure at different scale, showed generally parallel results with the MWS approach. Proportionality is therefore not scale dependent. However, slopes of linear relationships were different for the two scales. Finally, models for prediction of proportional variogram parameters were calculated. Correlation coefficients of relationship between semivariance parameters and mean proved that sill-nugget is more stable (r = 0.74 for P and 0.83 for K) than nugget (r = 0.30 for P and 0.53 for K).

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