Predicting the Congener-Specific Environmental Behaviour of Perfluorinated Acid Contaminants Using Semi-Empirical Computational Methods

2014 ◽

Vol 22 (22) ◽

pp. 53-60

Author(s):

I. A. ADEJORO ◽

R. O. Ogede ◽

C. U. Ibeji ◽

O. O. Adeboye

Keyword(s):

Free Radical ◽

Rapid Method ◽

Computational Methods ◽

Theoretical Studies ◽

Hartree Fock ◽

Radical Bromination ◽

Total Energies ◽

Pyridazine Derivatives ◽

Semi Empirical

Theoretical studies on free radical bromination by N-bromosuccinimide were carried out on a range of ethyl-3-methoxy-pyridazine derivatives. The investigations of these reactions performed, in order to develop a convenient and rapid theoretical means of predicting selectivity. The geometry optimizations of the total energies of the reactants and the products were calculated using Semi-empirical; AMI, MNDO, PM3 e Hartree Fock, HF3- 21 G computational methods. The calculation performed using PM3 Hamiltonian gave the best qualitative predictions, thus providing a rapid method for the selectivity of the reactions used in the synthesis of novel heterocyclic analogs of neurotransmitters.

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Computational methods for the study of enzymic reaction mechanisms. II. An overlapping mechanically embedded method for hybrid semi-empirical-QM/MM calculations

Journal of Molecular Structure THEOCHEM ◽

10.1016/s0166-1280(03)00303-8 ◽

2003 ◽

Vol 632 (1-3) ◽

pp. 247-257 ◽

Cited By ~ 3

Author(s):

Peter L. Cummins ◽

Jill E. Gready

Keyword(s):

Computational Methods ◽

Reaction Mechanisms ◽

Enzymic Reaction ◽

Embedded Method ◽

Semi Empirical

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A computational study on heterodimerization of charged porphyrins

Journal of Porphyrins and Phthalocyanines ◽

10.1002/jpp.355 ◽

2001 ◽

Vol 05 (06) ◽

pp. 512-522 ◽

Cited By ~ 1

Author(s):

SAFİYE SAǦ ERDEM

Keyword(s):

Computational Methods ◽

Ground State ◽

Computational Study ◽

Electrostatic Attraction ◽

Quantum Mechanical ◽

Quantum Mechanical Calculations ◽

Face To Face ◽

Ground State Structures ◽

Semi Empirical ◽

Porphyrin Rings

The structures of the charged porphyrins and their dimers have been investigated with computational methods. Dimers have been formed based on electrostatic attraction of the opposite charges on two different porphyrin monomers, tetra ammonium porphyrin (TAP) and tetra carboxy porphyrin (TCP). Semi-empirical quantum mechanical calculations have been employed to explore the most stable ground-state structures of TCP, TAP and their hetero-dimers. Dimeric structures analyzed are all in face-to-face fashion indicating the strong electrostatic attraction between the two porphyrin rings. Calculations have also predicted that the protons transfer from [Formula: see text]; groups to -COO- groups when the interplanar separation is shorter than 3.7 Å.

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Comparison of different computational methods for water structure optimisation

Acta Facultatis Pharmaceuticae Universitatis Comenianae ◽

10.2478/v10219-012-0019-3 ◽

2012 ◽

Vol 59 (1) ◽

pp. 55-66

Author(s):

R. Staník ◽

P. Ballo ◽

I. Benkovský

Keyword(s):

Ab Initio ◽

Computational Methods ◽

Molecular Mechanic ◽

Water Structure ◽

Empirical Method ◽

Computational Techniques ◽

Exact Methods ◽

X Ray Scattering ◽

Good Characterization ◽

Semi Empirical

Comparison of different computational methods for water structure optimisationWe have compared several computational techniques with the aim to compute the radial distribution function (RDF) as a good characterization of water structure. In particular, we have used molecular mechanic (AMBER99), semi-empirical (AM1, PM3, PM6) and ab initio (DFT) technique. It has been shown that molecular mechanic gives very poor results in the case of water RDF. Ab initio techniques which are in general accepted as very exact methods, in the case of water underestimate intermolecular interaction. Unexpectedly, the semi-empirical method with PM6 parameterisation gives the best results in comparison with RDF measured by X-ray scattering experiment.

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