Reconsideration of solvent effects calculated by semiempirical quantum chemical methods

Szafran, M.; Karelson, Mati; Katritzky, Alan R.; Koput, Jacek; Zerner, Michael C.

doi:10.1002/jcc.540140312

Cited by 148 publications

(80 citation statements)

References 36 publications

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“…The effects of aqueous solvation on the relative energetics were estimated by using a simple self-consistent reaction field (SCRF) 51 model. Since this model relies on the interaction between the dipole moment of the solute and the dielectric of the solvent (in this case, water), and since the dipole moments of the tautomers are all rather small, the predicted SCRF solvent effects on the relative energies are negligible and are not discussed further.…”

Section: Methodsmentioning

confidence: 99%

Structure and Energetics of Ground-State Hypericin: Comparison of Experiment and Theory

1998

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Calculations of the energies of the ground-state un-ionized tautomers of hypericin have been performed at the RMP2/6-31G(d) level of theory, using geometries obtained with the 3-21G basis set and Hartree−Fock wave functions. It is found that only the so-called normal form is likely to be populated at room temperature and that only two of the three possible double tautomers correspond to minima on the potential energy surface. The effect of continuum aqueous solvation on the tautomer energies is negligible. The O---O distances between which the proton is transferred are reported and are consistent with that required for an adiabatic proton transfer, i.e., ∼2.5 Å. All 156 vibrational frequencies are tabulated and may be viewed at www.msg.ameslab.gov. For example, the vibrations in the range 320−660 cm-1 are coupled with O---O vibrations. The vibrations that are most clearly O---O vibrations occur in the range 400−500 cm-1. Twisting of the backbone occurs in a wide range of frequencies, from 230 to 1150 cm-1, while the motion corresponding to an inversion of the (nonplanar) backbone occur at very low frequencies, 80−150 cm-1. The results of these calculations are discussed in terms of ground-state heterogeneity of hypericin that has been invoked to explain its spectra and excited-state kinetics. Disciplines Chemistry CommentsReprinted ( 24, 1997; In Final Form: December 10, 1997 Calculations of the energies of the ground-state un-ionized tautomers of hypericin have been performed at the RMP2/6-31G(d) level of theory, using geometries obtained with the 3-21G basis set and Hartree-Fock wave functions. It is found that only the so-called normal form is likely to be populated at room temperature and that only two of the three possible double tautomers correspond to minima on the potential energy surface. The effect of continuum aqueous solvation on the tautomer energies is negligible. The O---O distances between which the proton is transferred are reported and are consistent with that required for an adiabatic proton transfer, i.e., ∼2.5 Å. All 156 vibrational frequencies are tabulated and may be viewed at www.msg.ameslab-.gov. For example, the vibrations in the range 320-660 cm -1 are coupled with O---O vibrations. The vibrations that are most clearly O---O vibrations occur in the range 400-500 cm -1 . Twisting of the backbone occurs in a wide range of frequencies, from 230 to 1150 cm -1 , while the motion corresponding to an inversion of the (nonplanar) backbone occur at very low frequencies, 80-150 cm -1 . The results of these calculations are discussed in terms of ground-state heterogeneity of hypericin that has been invoked to explain its spectra and excited-state kinetics. IntroductionThe naturally occurring polycyclic quinone hypericin (Scheme 1) is of current interest because of its light-induced 1 antiviral (especially anti-HIV) and antitumor activity. [2][3][4][5][6][7][8][9][10][11] In addition, hypericin has attracted attention for its antidepressant activity. [12][13][14][15] The interaction of...

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Section: Methodsmentioning

confidence: 99%

Structure and Energetics of Ground-State Hypericin: Comparison of Experiment and Theory

1998

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“…[9][10][11] Nucleus-independent chemical shift (NICS) calculations 23 are obtained using the gauge-independent atomic orbital (GIAO/B3LYP/6-311++G * * //B3LYP/6-311+G * ) method. 24 The NBO population analysis on fully optimized structures are calculated at the B3LYP/6-311++G * * // B3LYP/6-311+G * level.…”

Section: Methodsmentioning

confidence: 99%

“…This theory has been applied to many problems using both semi-empirical and/or ab initio methods. 10,11 To date, however, nothing has been done to study the solvent effect on (E)-3-X-indoline-2-thione derivatives via theoretical methods. In this manuscript, we have used the DFT SCRF theory to study the effects of different solvents (polar and/or nonpolar) on the structure and properties of some of (E)-3-X-indoline-2-thione derivatives at 25 C and 1 atm.…”

Section: Introductionmentioning

confidence: 99%

Computational Study of Solvent Effects on Characterizations of (E)‐3‐X‐Indoline‐2‐thiones Derivatives as Antivirus and Anticancer Compounds

Sayyed-Alangi

Koohi

Sajjadi-Ghotabadi

2015

Bulletin Korean Chem Soc

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(E)-3-X-Indoline-2-thione derivatives (X = phenyl, furan-2-yl, 1H-pyrrole-2-yl, and thiophene-2-yl, I-IV, respectively) are considered as potent and selective inhibitors against different receptor tyrosine kinases. A particularly interesting issue for these biologically active compounds is how their stability is affected by solvation. Here we have tackled this issue using the self-consistent reaction field theory for I-IV, in the gas phase as well as solution including: toluene, CH 2 Cl 2 , MeOH, and H 2 O. The highest observed total free energy difference between liquid (l) and gas (g) phase (ΔE l-g ) relates to structure III in water, whereas the lowest ΔE l-g is associated with II in toluene. Thus, III is the most solvent sensitive and enjoys maximum stabilization in water. On the other extreme, II is the least solvent sensitive and its stability is least affected by solvation in toluene. Moreover, stability of each solute (I-IV) depends on the dielectric constant of the solvent and the possibility of the hydrogen bonding. In going from gas phase to different solvents, considerable changes of nucleophilicity as well as electrophilicity occur for scrutinized structures. The six-and fivemembered rings in indoline skeleton for all species show aromatic and nonaromatic property, respectively. Finally, the substituent rings appear the most aromatic property. These phenomena are confirmed by the succeeding geometrical parameters.

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“…Currently, the most widely used methods employ a continuum treatment of the bulk solvent through the quantum mechanical implementation of Onsager's reaction field model 1 via a modified molecular Hamiltonian that couples the electric field of the solute molecule to the bulk polarizability of the solvent. [2][3][4][5] The quantum mechanical implementation commonly involves a bulk dielectric constant for the solvent and a spherical or elipsoidal cavity surrounding the solute molecule. More sophisticated methods use more complex cavity shapes.…”

Section: Introductionmentioning

confidence: 99%

An effective fragment method for modeling solvent effects in quantum mechanical calculations

Day

Jensen

Gordon

et al. 1996

The Journal of Chemical Physics

596

404

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An effective fragment model is developed to treat solvent effects on chemical properties andreactions. The solvent, which might consist of discrete water molecules, protein, or othermaterial, is treated explicitly using a model potential that incorporates electrostatics,polarization, and exchange repulsion effects. The solute, which one can most generally envision as including some number of solvent molecules as well, is treated in a fully ab initio manner, using an appropriate level of electronic structure theory. In addition to the fragment model itself, formulae are presented that permit the determination of analytic energy gradients and, therefore, numerically determined energy second derivatives (hessians) for the complete system. Initial tests of the model for the water dimer and water-formamide are in good agreement with fully abinitio calculations. An effective fragment model is developed to treat solvent effects on chemical properties and reactions. The solvent, which might consist of discrete water molecules, protein, or other material, is treated explicitly using a model potential that incorporates electrostatics, polarization, and exchange repulsion effects. The solute, which one can most generally envision as including some number of solvent molecules as well, is treated in a fully ab initio manner, using an appropriate level of electronic structure theory. In addition to the fragment model itself, formulae are presented that permit the determination of analytic energy gradients and, therefore, numerically determined energy second derivatives ͑hessians͒ for the complete system. Initial tests of the model for the water dimer and water-formamide are in good agreement with fully ab initio calculations.

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Reconsideration of solvent effects calculated by semiempirical quantum chemical methods

Cited by 148 publications

References 36 publications

Structure and Energetics of Ground-State Hypericin: Comparison of Experiment and Theory

Structure and Energetics of Ground-State Hypericin: Comparison of Experiment and Theory

Computational Study of Solvent Effects on Characterizations of (E)‐3‐X‐Indoline‐2‐thiones Derivatives as Antivirus and Anticancer Compounds

An effective fragment method for modeling solvent effects in quantum mechanical calculations

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