Thermochemical Properties and Structure of Phenol−(H 2 O) 1-6 and Phenoxy−(H 2 O) 1-4 by Density Functional Theory (original) (raw)
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Computational Chemistry
It is experimentally well established that the phenolic systems such as phenol and diphenols undergo strong hydrogen bonding interaction with water molecule. But, the possible mode hydrogen bonding in phenol-water systems may be of different types. Although, the experimental methods are not always well enough to give the proper hydrogen bonding conformations in the phenol-water complexes. The hydrogen bonding ability in phenol-water systems can directly be influenced by changing the interacting sites in the given molecular systems, which could be investigated by theoretical studies. Generally, in phenol-water system, the hydrogen bonding is taking place through −OH group of phenol with water molecule, and this kind of interactions between phenol-water and diphenol-water complexes have been extensively investigated in electronic ground state by Quantum Mechanical MP4 calculations. It is also very important to study the stability of different phenol-water complexes and to find out the proper phenol-water complexes with minimized interaction energy. This study will also be helpful for understanding the effect of hydrogen bonding interaction in a better way on other aromatic systems.
Int. J. Quantum Chem., 2008
The O–H and S–H homolytic bond dissociation enthalpies of a set of disubstituted phenols and thiophenols (NH2, OH, CH3, Cl, CF3, and NO2) have been computed by a density functional theory procedure with the 6-311++G(d,p) basis set. A very good agreement between our results and available experimental ones is observed. The effect of substituents on structure, charges and BDEs are investigated and their correlation with Hammett parameters is studied.
The Journal of Physical Chemistry B, 2003
Monte Carlo simulations and thermodynamic perturbation theory calculations have been carried out to analyze the differential hydration of phenol (PhOH) and phenoxy radical (PhO • ). The hydration enthalpy of phenol predicted by different phenol-water interaction models is in good agreement with experimental data. On the basis of the difference in the hydration enthalpy of phenol and phenoxy radical, we find that the O-H bond dissociation enthalpy in water is above the recommended experimental value for the gas phase by ca. 7 kcal/mol. This result is in agreement with photoacoustic calorimetry measurements for phenol in other polar solvents. Thermodynamic perturbation theory results for the relative hydration Gibbs energy of phenol and phenoxy radical are also reported. The structure of the solutions suggests that the differential solvation of phenol and phenoxy radical can be related to the strong character of phenol as a hydrogen bond donor in comparison with the role played by phenoxy radical as a hydrogen bond acceptor.
Chemical Physics Letters, 2002
A B3LYP and mPW1PW91/6-31++G(d; p) study of phenol-benzene(+) radical cation was performed, revealing an existence of T-shaped O-H Á Á Á p hydrogen bonded minima at both PES-s, with center-of-mass separation of 5.087 A A (B3LYP) and 4.970 A A (mPW1PW91) and the interplanar angle between monomeric units of 89.9°and 89.4°(at B3LYP and mPW1PW91 levels correspondingly). Calculated anharmonic O-H vibrational frequencies on the basis of onedimensional DFT vibrational potentials reproduce excellently the experimentally measured m(OH) frequency shift upon this interaction. According to CFP-like calculations, most of the interaction energy (47.09 and 49.64 kJ mol À1 at B3LYP and mPW1PW91 levels correspondingly) is of electrostatic origin. Ó
Phenol O-H bond dissociation energy in water clusters
We are reporting ab initio and density functional theory (DFT) calculations for the phenol O-H bond dissociation energy in the gas phase and in phenol-water clusters. We have tested a series of recently proposed functionals and verified that DFT systematically underestimates the O-H bond dissociation energy of phenol. However, O-H bond dissociation energies in water clusters are in reasonable agreement with experimental data for phenol in solution. We. have evaluated electronic difference densities in phenol-water, phenoxy-water, and water, and we are suggesting that the representation of this quantity gives an interesting picture of the electronic density rearrangement induced by hydrogen bond interactions in phenol-water clusters.
Redox Report, 2004
We report here on calculations at the hybrid DFT/HF (B3-LYP/6-31G(d,p)) level of the O-H bond dissociation enthalpy (O-H BDE) of phenylpropenoic acids (caffeic, ferulic, p-coumaric and cinnamic) and phenolic acids and related compounds (gallic, methylgallate, vanillic and gentisic) in order to gain insight into the understanding of structure-antioxidant activity relationships. The results were correlated and discussed mainly on the basis of experimental data in a companion work (Galato D, Giacomelli C, Ckless K, Susin MF, Vale RMR, Spinelli A. Antioxidant capacity of phenolic and related compounds: correlation among electrochemical, visible spectroscopy methods and structure-antioxidant activity. Redox Report 2001; 6: 243-250). The O-H BDE values showed remarkable dependence on the hydroxyl position in the benzene ring and the existence of additional interaction due to hydrogen bonding. For parent molecules, the experimental antioxidant activity (AA) order was properly obeyed only when intramolecular hydrogen bonding was present in the radicalized structures of o-dihydroxyl moieties. In structurally related compounds, excellent correlation with experimental data was in general observed (0.64 < ρ < 0.99). However, it is shown that excellent correlation can also be obtained for this series of compounds considering p-radicalized structures which were not stabilized by intramolecular hydrogen bonding, but this had no physical meaning. These findings suggested that the antioxidant activity evaluation of phenolic and related compounds must take into consideration the characteristics of each particular compound.
Theoretical study of neutral and cationic complexes involving phenol
International Journal of Quantum Chemistry, 2005
CH 3 F) involving neutral or cationic phenol were determined using the density functional theory formalism based on the minimization of the total energy bifunctional and gradient-dependent approximations for its exchangecorrelation and nonadditive kinetic-energy parts. For the neutral complexes the calculated interaction energies range from 1 kcal/mol for the Ph-Ar complex to about 10 kcal/mol for Ph-NH 3. The interactions are stronger if the cationic phenol is involved (up to 25 kcal/mol). It is found, except for neutral Ph-Ar, that the hydrogen-bonded structure is more stable than the-bound one. Calculated interaction energies (D e) correlate well with the experimental dissociation energies (D 0).
Physical Chemistry Chemical Physics, 2017
The torsional potential of OH and SH rotations in 2-hydroxy thiophenol is systematically studied using the MP2 ab initio method. The outcome of state-of-the-art calculations is used in the investigation of the structures and conformational preferences of 2-hydroxy thiophenol and aims at further interaction studies with a gas phase water molecule. SCS-MP2 and CCSD(T) complete basis set (CBS) limit interaction energies for these complexes are presented. The SCS-MP2/CBS limit is achieved using various two-point extrapolation methods with aug-cc-pVDZ and aug-cc-pVTZ basis sets. The CCSD(T) correction term is determined as the difference between CCSD(T) and SCS-MP2 interaction energies calculated using a smaller basis set. The effect of counterpoise correction on the extrapolation to the CBS limit is discussed. The performance of DFT based wB97XD, M06-2X and B3LYP-D3 functionals is tested against the benchmark energy from ab initio calculations. Hydrogen bond interactions are characterized by carrying out QTAIM, NCIPLOT, NBO and SAPT analyses.