Configuration and Conformation Study of S-Allyl O-Methyl N-(2- and 4-Substituted Acridin-9-yl)thiocarbonimidates in Relation to Their [3,3] Sigmatropic Rearrangement

1998 ◽  
Vol 63 (3) ◽  
pp. 387-393 ◽  
Author(s):  
Ivan Danihel ◽  
Kalevi Pihlaja ◽  
Ján Imrich ◽  
Gejza Suchár ◽  
Pavol Kristian ◽  
...  
Keyword(s):  
Quantum Chemical Calculations ◽  
Quantum Chemical ◽  
Dipole Moments ◽  
Chair Conformation ◽  
Sigmatropic Rearrangement ◽  
Difference Spectra ◽  
Vector Addition ◽  
Chloro Derivatives ◽  
Experimental Values ◽  
Configuration And Conformation

Configuration and conformations of S-allyl O-methyl N-(2- and 4-substituted acridin-9-yl)thiocarbonimidates were studied by means of NMR spectroscopy, dipole moments and quantum chemical calculations. The E configuration was proved for the unsubstituted and 2-chloro derivatives from the NOE-difference spectra. Experimental values of dipole moments were related to those obtained from vector addition. Quantum chemical calculations pointed to the chair conformation of these compounds in transition state for above-mentioned rearrangement.

The Electronic and Non-linear Optical Properties of Oxo-titanium Phthalocyanines

1999 ◽  
Vol 03 (05) ◽  
pp. 331-338 ◽  
Author(s):  
FRYAD HENARI ◽  
ANDREW DAVEY ◽  
WERNER BLAU ◽  
P. HAISCH ◽  
M. HANACK
Keyword(s):  
Optical Properties ◽  
Electronic Properties ◽  
Quantum Chemical Calculations ◽  
Quantum Chemical ◽  
Dipole Moments ◽  
Non Linear ◽  
Linear Behaviour ◽  
Linear Optical Properties ◽  
Linear Optical ◽  
Semiempirical Quantum Chemical Calculations

The valence electronic properties of some unsubstituted and peripherally substituted oxo-titanium phthalocyanines are reported. Semiempirical quantum chemical calculations show that the nature of peripheral substituents has a strong bearing on the valence electronic properties, including the state dipole moments and absorption wavelength. The non-linear optical response was measured around the the Q-band resonance. The effect of different substituents and substitution patterns on the non-linear behaviour of the samples was determined. The combined results suggest that tuning of electronic and optical properties is effectively achieved by functionalization of the edges of the conjugated ring.

Principle of additivity of dipole moments: 1,3- and 1,3,5-derivatives of benzene

1985 ◽  
Vol 50 (1) ◽  
pp. 188-199 ◽  
Author(s):  
Juraj Koudelka ◽  
Otto Exner
Keyword(s):  
Dipole Moments ◽  
Bond Angles ◽  
Vector Addition ◽  
Inductive Interaction ◽  
Donor Acceptor ◽  
Experimental Values ◽  
Derivatives Of

Dipole moments of fourteen 1,3-derivatives and thirteen 1,3,5-derivatives of benzene, with axially symmetrical substituents only, were measured in two solvents. After excluding the compounds forming the donor-acceptor complexes with benzene, the experimental values are well reproduced by the vector addition of group moments, i.e. the accuracy achieved is sufficient for practical purposes. Nevertheless, small systematic deviations were observed: the experimental moments were as a rule less than additive in the case of 1,3-derivatives but greater in the case of 1,3,5-derivatives. These deviations cannot be accounted for by deformation of bond angles from the hexagonal geometry but they can be semiquantitatively interpreted by mutual inductive interaction of dipoles. The latter interpretation was supported by CNDO/2 calculations.

Principle of additivity of dipole moments: Halogen derivatives of adamantane

1985 ◽  
Vol 50 (1) ◽  
pp. 200-207 ◽  
Author(s):  
Otto Exner ◽  
Juraj Koudelka
Keyword(s):  
Dipole Moments ◽  
Tetrahedral Geometry ◽  
General Applicability ◽  
Smith Method ◽  
Vector Addition ◽  
Moment Approach ◽  
Experimental Values ◽  
Derivatives Of ◽  
Mutual Induction

Dipole moments of halogenated adamantanes II-IV were measured in two solvents using the Guggenheim-Smith method. The reliability of the method was checked on non-polar symmetrical compounds I, V. The dipole moments of 1,3-dihalogen and 1,3,5-trihalogen derivatives reveal small but real deviations from the additive behaviour: the experimental values are less than those calculated by vector addition from the moments of monoderivatives, assuming tetrahedral geometry. This fact can be explained by mutual induction of dipole rather than by angle deformation, although both effects can contribute. The deviations from the additive behaviour are qualitatively represented by CNDO/2 calculations with fixed geometry. However, even the greatest deviations observed amount only several percent in relative values and do not impair the general applicability of the bond moment approach.

Dielectric properties of hexafluoroacetone and hexachloroacetone

1969 ◽  
Vol 47 (12) ◽  
pp. 2253-2256 ◽  
Author(s):  
R. K. Chan
Keyword(s):  
Dipole Moment ◽  
Dielectric Properties ◽  
Liquid State ◽  
Dipole Moments ◽  
Dielectric Constants ◽  
Pure Liquid ◽  
Gaseous State ◽  
Vector Addition ◽  
Inductive Effects ◽  
Experimental Values

The dielectric constants of hexafluoro- and hexachloro-acetone are measured in the solid and liquid state. They show negligible association in the liquid state. The dipole moments are 0.648 D measured in the gaseous state and 0.63 D in pure liquid for hexafluoroacetone, and 1.24 D in carbon tetrachloride solution and 1.34 D in pure liquid for hexachloroacetone. If the differences between inductive effects due to CX3 and C=O groups can be ignored, the vector addition of bond moments gives values of dipole moment which are compatible with the experimental values.

Investigation of corona discharge ionization of barbituric acid using ion mobility spectrometry along with quantum chemical calculations

2021 ◽  
Vol 27 (1) ◽  
pp. 39-47
Author(s):  
Masoumeh Ghahremani ◽  
Hafezeh Salehabadi ◽  
Hamed Bahrami ◽  
Massoud Amanlou
Keyword(s):  
Corona Discharge ◽  
Quantum Chemical Calculations ◽  
Ion Mobility Spectrometry ◽  
Ion Mobility ◽  
Quantum Chemical ◽  
Barbituric Acid ◽  
Atmospheric Pressure Chemical Ionization ◽  
Dipole Moments ◽  
Injection Port ◽  
Acid Sample

This study aimed at examining atmospheric-pressure chemical ionization of barbituric acid through the corona discharge ion mobility spectrometry (CD-IMS) and the quantum chemical calculations. The results indicated two product ion peaks in the IMS spectrum of barbituric acid. The thermal decomposition of the barbituric acid sample was investigated by scanning the temperature of the injection port and analyzing the temporal evolution of the IMS peaks over elapsed time. It was found that the barbituric acid sample was not thermally decomposed in the injection port of the instrument. Experimental evidences were collected by changing the reactant ions, concentration of barbituric acid sample, and IMS cell temperature. The two observed peaks were then assigned to cationic form and oxygen protonated isomers of barbituric acid. The positions of the product ion peaks were explicated considering the dipole moments of the product ions.

Experimentelle und Quantenchemische Untersuchungen der Dipolmomente von Substituierten Stilbenen im Ersten Angercgten Singulettzustand / Experimental and Quantum Chemical Investigations of Dipole Moments of Substituted Stilbens in the First Excited Singlet State

1977 ◽  
Vol 32 (5) ◽  
pp. 420-425 ◽  
Author(s):  
A. Kawski ◽  
I. Gryczyński
Keyword(s):  
Dipole Moment ◽  
Excited States ◽  
Ground State ◽  
Quantum Chemical ◽  
Singlet State ◽  
Dipole Moments ◽  
Excited Singlet State ◽  
Excited Singlet ◽  
Fluorescent State ◽  
Experimental Values

Abstract The values a/a3 (α = polarizability), the Onsager cavity radii a and the dipole moments μe of six substituted stilbens in the fluorescent state have been determined. It is shown that if the dipole moment of the lowest excited singlet state μe is parallel to the dipole moment in the ground state μg, the values of μe and a can be determined from the solvent effects. Moreover, quantum chemical investigations of the dipole moments in the ground and excited states were carried out with the Pariser-Parr-Pople method and compared with the experimental values.

Quantum chemical study of sulfonium ylides: Structure, charge distribution and dipole moments

1980 ◽  
Vol 45 (4) ◽  
pp. 1236-1250 ◽  
Author(s):  
Vladimír Král ◽  
Zdeněk Arnold ◽  
Václav Jehlička ◽  
Otto Exner
Keyword(s):  
Ab Initio ◽  
Charge Distribution ◽  
Quantum Chemical ◽  
Dipole Moments ◽  
Quantum Chemical Study ◽  
Chemical Study ◽  
Quantum Chemical Methods ◽  
Sulfonium Ylide ◽  
Experimental Values ◽  
Sulfonium Ylides

The geometry, charge distribution and dipole moments of parent sulfonium ylide - dimethylsulfoniomethylide (I) - and a series of stabilized sulfonium ylides, including 2-dimethylsulfuranylidene-1,3-cyclopentanedione (VI) prepared in this study, was investigated using the CNDO/2, PCILO and ab initio methods. Values of dipole moments, calculated by quantum chemical methods (CNDO/2 with sp and spd bases, ab initio with the STO-3G basis) as well as by the method of empirical bond moments, are compared with the experimental values determined in dioxane or benzene. Dipole moments of several related ammonium ylides were also studied.

Semiempirical quantum chemical PM3 computations and evaluations of redox potentials, basicities, and dipole moments of the diphenylamine series as analytical reagents

1999 ◽  
Vol 77 (12) ◽  
pp. 2053-2058 ◽  
Author(s):  
Alexei N Pankratov ◽  
Andrew E Shchavlev
Keyword(s):  
Dipole Moment ◽  
Redox Potential ◽  
Quantum Chemical ◽  
Dipole Moments ◽  
Cooh Group ◽  
Redox Potentials ◽  
Proton Affinities ◽  
Chemical Evaluation ◽  
Analytical Reagents ◽  
Experimental Values

By evaluating the obtained results of PM3 computations, the following correlations were found: (i) the diarylamines redox potentials (E) with the first ionization potentials (I); (ii) the pKa values characterizing both the amines nitrogen protonation and the carboxy substituted reagents dissociation via the COOH group, with the proton affinities of the corresponding diphenylamines and COO--containing anions; (iii) the experimental values of the molecules dipole moments (μ) with the theoretical ones. The feasibility of the simple semiempirical quantum chemical evaluation of E, pKa, and μ of the diphenylamine series as redox reagents was determined.Key words: diphenylamine series, redox potential, pKa, dipole moment, semiempirical quantum chemical evaluation

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