On the dielectric continuum solvent model for theoretical estimates of the conformational equilibrium of molecules with an intramolecular hydrogen bond

Yasuda, Toshio; Ikawa, Shun‐ichi

doi:10.1016/s0301-0104(98)00314-0

Cited by 10 publications

(5 citation statements)

References 9 publications

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“…Consequently, it can be concluded that the SCRF model is too crude to be successfully adopted for such chemical species as studied here, substituted pyridines and their conjugated cations. Similar conclusions regarding the use of the SCRF model have been reached previously 19 in our studies of the substituted pyridine N -oxide systems, as well as by other authors. , …”

Section: Resultssupporting

confidence: 92%

Ab Initio Study of the Energetics of Protonation and Homocomplexed Cation Formation in Systems with Pyridine and Its Derivatives

et al. 2001

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The energetics of protonation of pyridine and a series of its derivatives, as well as the energetics of formation of hydrogen-bonded N...H...N homocomplexed cations in systems involving substituted pyridines and conjugate cationic acids were investigated by means of restricted Hartree-Fock (RHF) and Møller-Plesset (MP2) ab initio calculations. The Gaussian functional basis set 6-31G* was employed to calculate energy and Gibbs free energy of protonation and cationic homoconjugation in the gas phase. The proton potential of a homocomplexed pyridine cation exhibits a double minimum with a 5.7 kcal/mol energy barrier, which could be reduced to 2.7 kcal/mol by accounting for a thermodynamic correction factor. The calculated protonation energies, ∆E prot , and Gibbs free energies, ∆G prot , have been found to correlate well with the acid dissociation constants (expressed as pK a values) in acetonitrile. On the contrary, the calculated energies, ∆E BHB + , and Gibbs free energies, ∆G BHB + , of formation of the homocomplexes do not correlate with the cationic homoconjugation constant values (expressed as log 10 K BHB + ) determined in acetonitrile.

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Section: Resultssupporting

confidence: 92%

Ab Initio Study of the Energetics of Protonation and Homocomplexed Cation Formation in Systems with Pyridine and Its Derivatives

et al. 2001

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“…Second, the differences between the protonation and homoconjugation energies in the series of compounds studied are relatively small and probably a more refined solvent model is required to reproduce them correctly. The drawbacks of continuum electrostatic solvation models were also reported by other authors. , A correct way to evaluate the solvation free energy could be Monte Carlo or molecular dynamics simulations with explicit solvent molecules and effective potential energy surface of intrasolute, solute−solvent, and solvent−solvent interaction derived from ab initio calculations. These studies are now being carried out in our laboratory.…”

Section: Resultsmentioning

confidence: 83%

Ab Initio Study of Energetics of Protonation and Hydrogen Bonding of Pyridine N-Oxide and Its Derivatives

et al. 1999

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The energetics of protonation and hydrogen-bonded complex formation between the base and its conjugated acid (homoconjugation) of pyridine N-oxide and its selected derivatives was investigated by means of Restricted Hartree-Fock (RHF) and Møller-Plesset (MP2) ab initio calculations. It has been found that introducing the d polarization functions (the 6-31G* basis set) is required to reproduce correctly the geometry of the N−O bond. The proton-transfer energy surface in the homoconjugated cations exhibits a double minimum, with 2.4 kcal/mol energy barrier for the pyridine N-oxide homocomplex; this barrier vanishes when the thermodynamic correction is included. The protonation and homoconjugation Gibbs free energies computed in vacuo correlate well with the acid dissociation and cationic homoconjugation constants determined in acetonitrile.

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“…Another interesting viewpoint is that the solvent effect may be responsible for drastic changes in several molecular properties, e.g., geometrical deformations; increase in the reaction rate; control of products along the reaction paths, for instance [32][33]. If we consider that intramolecular hydrogen bonds can be formed in the minimum structure of benznidazole, the specialized literature informs us that the application of the Polarized Continuum Model (PCM) [34] to evaluate the solvent effect is recommended [35][36][37][38][39]. By taking into account the importance of drug action in human organisms, that are predominantly aqueous, this article also presents a theoretical investigation of the solvent effect on the benznidazole structure through the application of PCM protocol, demonstrating the importance of solvation in the conformational study of this bioactive molecule [40].…”

Section: Computational Proceduresmentioning

confidence: 99%

Comparisons between Crystallography Data and Theoretical Parameters and the Formation of Intramolecular Hydrogen Bonds: Benznidazole

2016

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Abstract:The conformational preferences of benznidazole were examined through the application of DFT, PCM and QTAIM calculations, whose results were compared with crystallography data. The geometries were fully optimized with minimum potential energy surface by means of the Relaxed Potential Energy Surface Scan (RPESS) at AM1, followed by the B3LYP/6-311++G(d,p) theoretical level. As a result, the s-cis conformation (1C) was shown to be more stable (4.78 kcal¨mol´1) than s-trans (1T). The Quantum Theory Atoms in Molecules (QTAIM) was applied in order to characterize the (N-H¨¨¨O=N) and (C-H¨¨¨=N) intramolecular hydrogen bonds. The simulation of solvent effect performed by means of the implicit Polarized Continuum Model (PCM) revealed great results, such as, for instance, that the conformation 1W is more stable (23.17 kcal¨mol´1) in comparison to 1C. Our main goal was stressed in the topological description of intramolecular hydrogen bonds in light of the QTAIM approach, as well as in the solvent simulation to accurately obtain an important conformation of benznidazole.

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On the dielectric continuum solvent model for theoretical estimates of the conformational equilibrium of molecules with an intramolecular hydrogen bond

Cited by 10 publications

References 9 publications

Ab Initio Study of the Energetics of Protonation and Homocomplexed Cation Formation in Systems with Pyridine and Its Derivatives

Ab Initio Study of the Energetics of Protonation and Homocomplexed Cation Formation in Systems with Pyridine and Its Derivatives

Ab Initio Study of Energetics of Protonation and Hydrogen Bonding of Pyridine N-Oxide and Its Derivatives

Comparisons between Crystallography Data and Theoretical Parameters and the Formation of Intramolecular Hydrogen Bonds: Benznidazole

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