Structure and ESR features of glycine radical in its zwitterionic form

Barone, Vincenzo; Adamo, Carlo; Grand, André; Subra, R.

doi:10.1016/0009-2614(95)00752-p

Cited by 43 publications

(58 citation statements)

References 19 publications

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“…This was for the first time mentioned by Tomasi 58 for glycine and later by others. 59,60 Except for the different character of the product, the transfer from NH 3 to NH 4 ϩ does not change the position of the remote particle substantially. As it is demonstrated in Table 1 and in Figure 2b, the remote particle remains in very similar position in both the gas phase and COSMO models.…”

Section: Structure Of the Pt(ii) Complexesmentioning

confidence: 93%

Hydration process as an activation of trans‐ and cisplatin complexes in anticancer treatment. DFT and ab initio computational study of thermodynamic and kinetic parameters

2005

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The thermodynamic and kinetic aspects of hydration reactions of cis-/transplatin were explored. The polarizable continuum model was used for estimation of solvent effects. Using the B3LYP/6-31+G(d) method, the structures were optimized and vibrational frequencies estimated. Interaction energies and activation barriers were determined at the CCSD(T)/6-31++G(d,p) level within the COSMO approach. An associative mechanism was assumed with a trigonal-bipyramidal structure of the transition state. Within the applied model, all the hydration reactions are slightly endothermic. The Gibbs energies of cisplatin hydration amount to 7.0 and 14.2 kcal/mol for the chloride and ammonium replacement, respectively. Analogous values for the transplatin reactions are 6.8 and 11.9 kcal/mol. The determined rate constants are by several (three to four) orders of magnitude larger for the dechlorination process than for deammination. The cisplatin dechlorination rate constant was established as 1.3 x 10(-4) s(-1) in excellent accord with the experiment.

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Section: Structure Of the Pt(ii) Complexesmentioning

confidence: 93%

Hydration process as an activation of trans‐ and cisplatin complexes in anticancer treatment. DFT and ab initio computational study of thermodynamic and kinetic parameters

2005

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“…Upon irradiation, zwitterionic radicals are formed. Various ab initio studies have shown that the zwitterionic form is not the energetically most favored structure in vacuo 17, 30. Consequently, the study of amino acids such as alanine or glycine and their derived radicals requires incorporation of intermolecular environmental forces in the model.…”

Section: Radical Defects In Amino Acidsmentioning

confidence: 99%

“…Moreover, the latter approach also gives the opportunity to perform finite‐temperature simulations on the radicals. This may be important, because various suggestions in the literature indicate that not only is an accurate modeling of the environment necessary for a good reproduction of experimental magnetic resonance data but also the effect of temperature on the radical structures must be examined 17, 18.…”

Section: Introductionmentioning

confidence: 99%

Study of radical defects in crystalline lattices from first‐principles molecular dynamics simulations

Speybroeck¹,

Pauwels²,

Stevens³

et al. 2004

Int J of Quantum Chemistry

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ABSTRACT:Theoretical calculations are presented to determine the structure of radical defects in crystalline lattices. The applications are concentrated on radical defects as they are induced by irradiation in organic crystals and paramagnetic molecular ions embedded in alkali halide lattices. Various approaches are possible to model the molecular environment: the single-molecule approach, the cluster approach, and periodic calculations. The latter are based on a Car-Parrinello formalism in which the molecular orbitals are expanded in a plane-wave basis set and in which the optimized structures at 0 K are obtained by a simulated annealing technique. The pros and cons of the various approaches are highlighted, and where possible comparison with experimental electron paramagnetic resonance data are given. Due to the different natures of ionic and organic crystals, specific computational procedures are needed to get good correspondence with the experimental data. In various cases there is experimental evidence that some radical structures are submitted to noticeable changes with increasing temperature. These effects were theoretically reproduced by performing molecular dynamics calculations at elevated temperatures.

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“…To test our procedure on open shell systems, we optimized the geometry of the zwitterionic form of 74 Ž . the glycine radical Fig.…”

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confidence: 99%

Geometry optimization of molecular structures in solution by the polarizable continuum model

1998

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Structure and ESR features of glycine radical in its zwitterionic form

Cited by 43 publications

References 19 publications

Hydration process as an activation of trans‐ and cisplatin complexes in anticancer treatment. DFT and ab initio computational study of thermodynamic and kinetic parameters

Hydration process as an activation of trans‐ and cisplatin complexes in anticancer treatment. DFT and ab initio computational study of thermodynamic and kinetic parameters

Study of radical defects in crystalline lattices from first‐principles molecular dynamics simulations

Geometry optimization of molecular structures in solution by the polarizable continuum model

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