Quantum Chemical Calculations of Dipole Moments and Ionization Potentials of Triglycerides

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.

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Tautomerism in Five-membered Nitrogen Heterocycles. A Test of the Reliability of Semiempirical (AMI, PM3, MNDO) Quantum Chemical Methods

Zeitschrift für Naturforschung A ◽

10.1515/zna-1990-11-1216 ◽

1990 ◽

Vol 45 (11-12) ◽

pp. 1328-1334 ◽

Cited By ~ 29

Author(s):

Walter M. F. Fabian

Keyword(s):

Quantum Chemical ◽

Dipole Moments ◽

Nitrogen Heterocycles ◽

Ionization Potentials ◽

Semiempirical Methods ◽

Chemical Methods ◽

Pm3 Method ◽

Lone Pairs ◽

Quantum Chemical Methods ◽

The Stability

AbstractThe reliability of three popular semiempirical quantum chemical methods (AM1, PM3, MNDO) for the treatment of tautomeric equilibria is tested in a series of five-membered nitrogen heterocycles. The known flaw of MNDO to overestimate the stability of compounds with two or more adjacent pyridine-like lone pairs is also present in AM1 and to a somewhat lesser extent in PM3. Tautomeric species differing in the number of adjacent pyridine-like lone pairs, thus, cannot be adequately treated by these semiempirical methods. Both AM1 as well as PM3, however, represent major improvements over MNDO in the case of lactam-lactim tautomerism. The stability of N-oxides as compared to N-hydroxy tautomers seems to be overestimated by the PM3 method. All three semiempirical methods yield quite reliable ionization potentials and dipole moments.

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

European Journal of Mass Spectrometry ◽

10.1177/1469066721993745 ◽

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.

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The correlations and quantum chemical interpretations of some molecular properties of several p-phenylenediamines and related compounds

Collection of Czechoslovak Chemical Communications ◽

10.1135/cccc19870819 ◽

1987 ◽

Vol 52 (4) ◽

pp. 819-829 ◽

Cited By ~ 7

Author(s):

Günter Grampp ◽

Peter Pluschke

Keyword(s):

Exchange Rates ◽

Quantum Chemical Calculations ◽

Quantum Chemical ◽

Activation Energies ◽

Molecular Properties ◽

Ionization Potentials ◽

Related Compounds ◽

Good Agreement

Quantum chemical calculations of various p-phenylenediamines and related compounds are correlated with different molecular properties, such as electrochemical E1/2-values, ionization potentials, pK-values, UV-VIS spectra, the activation energies of the homogeneous electron self-exchange rates, and the synproportionation constants. All correlations are in good agreement with the predictions of simple HMO-theory.

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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

Collection of Czechoslovak Chemical Communications ◽

10.1135/cccc19980387 ◽

1998 ◽

Vol 63 (3) ◽

pp. 387-393 ◽

Cited By ~ 1

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.

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