The Effect of Phenolic Antioxidants on the Adsorption of the Antiwear Additive Dilinoleic Acid on Metals

Wheeler, Phillip A.; Dacre, B.; Savory, B.

doi:10.1080/05698198308981484

Cited by 4 publications

(4 citation statements)

References 2 publications

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“…was also supported by a University of Georgia Presidential Fellowship and would like to thank A. C. Simmonett for timely help with the computation of anharmonic ZPVEs. Figures −4 were generated using HFSmol …”

Section: Acknowledgmentsmentioning

confidence: 99%

Thermochemistry of Key Soot Formation Intermediates: C₃H₃ Isomers

Wheeler

Robertson²,

Allen³

et al. 2007

J. Phys. Chem. A

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Accurate standard enthalpies of formation for allene, propyne, and four C3H3 isomers involved in soot formation mechanisms have been determined through systematic focal point extrapolations of ab initio energies. Auxiliary corrections have been applied for anharmonic zero-point vibrational energy, core electron correlation, the diagonal Born-Oppenheimer correction (DBOC), and scalar relativistic effects. Electron correlation has been accounted for via second-order Z-averaged perturbation theory (ZAPT2) and primarily through coupled-cluster theory, including single, double, and triple excitations, as well as a perturbative treatment of connected quadruple excitations [ROCCSD, ROCCSD(T), ROCCSDT, and UCCSDT(Q)]. The correlation-consistent hierarchy of basis sets, cc-pVXZ (X = D, T, Q, 5, 6), was employed. The CCSDT(Q) corrections do not exceed 0.12 kcal mol(-)1 for the relative energies of the systems considered here, indicating a high degree of electron correlation convergence in the present results. Our recommended values for the enthalpies of formation are as follows: Delta(f)H(o)(0)(propargyl) = 84.76, Delta(f)H(o)(0) (1-propynyl) = 126.60, Delta(f)H(o)(0) (cycloprop-1-enyl) = 126.28, Delta(f)H(o)(0)(cycloprop-2-enyl) = 117.36, Delta(f)H(o)(0)(allene) = 47.41, and Delta(f)H(o)(0)(propyne) = 46.33 kcal mol(-1), with estimated errors no larger than 0.3 kcal mol(-1). The corresponding C3H3 isomerization energies are about 1 kcal mol(-1) larger than previous coupled-cluster results and several kcal mol(-1) below those previously obtained using density functional theory.

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Section: Acknowledgmentsmentioning

confidence: 99%

Thermochemistry of Key Soot Formation Intermediates: C₃H₃ Isomers

Wheeler

Robertson²,

Allen³

et al. 2007

J. Phys. Chem. A

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“…thanks the NIH (GM31186, CA06927) and NCI for financial support of this work, which was also supported by an appropriation from the Commonwealth of Pennsylvania. Figures were generated by Steven E. Wheeler using HFSmol …”

Section: Acknowledgmentsmentioning

confidence: 99%

“…Figures were generated by Steven E. Wheeler using HFSmol. 90 Supporting Information Available: Listing of the MP2-(FC)/aug-cc-pVTZ vibrational frequencies of the endo-exo conformer of the monomer and conformer 1 of the dimer (Table 1S), relative energies of the local minima identified during the B3LYP/6-31+G* initial conformer search (Table 2S), DFT/6-311++G** relative energies of the dimers (Table 3S), and xyz coordinates of the species studied (Table 4S). This material is available free of charge via the Internet at http://pubs.acs.org.…”

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confidence: 99%

Structure of the Boronic Acid Dimer and the Relative Stabilities of Its Conformers

et al. 2006

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Despite the widespread use of boronic acids in materials science and as pharmaceutical agents, many aspects of their structure and reactivity are not well understood. In this research the boronic acid dimer, [HB(OH)(2)](2), was studied by second-order Møller-Plesset (MP2) perturbation theory and coupled cluster methodology with single and double excitations (CCSD). Pople split-valence 6-31+G*, 6-311G**, and 6-311++G** and Dunning-Woon correlation-consistent cc-pVDZ, aug-cc-pVDZ, cc-pVTZ, and aug-cc-pVTZ basis sets were employed for the calculations. A doubly hydrogen-bonded conformer (1) of the dimer was consistently found to be lowest in energy; the structure of 1 was planar (C(2h)) at most computational levels employed but was significantly nonplanar (C(2)) at the MP2/6-311++G** and CCSD/6-311++G** levels, the result of an intrinsic problem with Pople-type sp-diffuse basis functions on heavy atoms. The dimerization energy, enthalpy, and free energy for the formation of (1) from the exo-endo conformer of the monomer were -10.8, -9.2, and +1.2 kcal/mol, respectively, at the MP2/aug-cc-pVTZ level. Several other hydrogen-bonded conformers of the dimer were local minima on the potential energy surface (PES) and ranged from 2 to 5 kcal/mol higher in energy than 1. Nine doubly OH-bridged conformers, in which the boron atoms were tetracoordinated, were also local minima on the PES, but they were all greater than 13 kcal/mol higher in energy than 1; doubly H-bridged structures proved to be transition states. MP2 and CCSD results were compared to those from the BLYP, B3LYP, OLYP, O3LYP, PBE1PBE, and TPSS functionals with the 6-311++G** and aug-cc-pVTZ basis sets; the PBE1PBE functional performed best relative to the MP2 and CCSD results. Self-consistent reaction field (SCRF) calculations predict that boronic acid dimerization is less favorable in solution than in vacuo.

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“…This research was supported by National Science Foundation under Grant CHE-0451445. Figures −4 were generated using HFSMOL …”

Section: Acknowledgmentsmentioning

confidence: 99%

Hydrogen-Abstracted Adenine−Thymine Radicals with Interesting Transferable Properties

et al. 2007

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The formation of radicals on DNA bases through various pathways can lead to harmful structural alterations. Such processes are of interest for preventing alteration of healthy DNA and, conversely, to develop more refined methods for inhibiting the replication of unwanted mutagenic DNA. In the present work, we explore theoretically the energetic and structural properties of the nine possible neutral radicals formed via hydrogen abstraction from the adenine-thymine base pair. The lowest energy radical is formed by loss of a hydrogen atom from the methyl group of thymine. The next lowest energy radicals, lying 8 and 9 kcal mol-1 higher than the global minimum, are those in which hydrogens are removed from the two nitrogens that would join the base pair to 2-deoxyribose in double-stranded DNA. The other six radicals lie between 16 and 32 kcal mol-1 higher in energy. Unlike the guanine-cytosine base pair, adenine-thymine (A-T) exhibits only minor structural changes upon hydrogen abstraction, with all A-T derived radicals maintaining planarity. Moreover, the energetic ordering for the radicals of the two isolated bases (adenine and thymine) is preserved upon formation of the base pair, though with a wider spread of energies. Even more significantly, the energetic interleaving of the (A-H)*-T and A-(T-H)* radicals is correctly predicted from the X-H bond dissociation energies of the isolated adenine and thymine. This suggests that the addition of the hydrogen-bonded complement base only marginally affects the bond energies.

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The Effect of Phenolic Antioxidants on the Adsorption of the Antiwear Additive Dilinoleic Acid on Metals

Cited by 4 publications

References 2 publications

Thermochemistry of Key Soot Formation Intermediates: C₃H₃ Isomers

Thermochemistry of Key Soot Formation Intermediates: C₃H₃ Isomers

Structure of the Boronic Acid Dimer and the Relative Stabilities of Its Conformers

Hydrogen-Abstracted Adenine−Thymine Radicals with Interesting Transferable Properties

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The Effect of Phenolic Antioxidants on the Adsorption of the Antiwear Additive Dilinoleic Acid on Metals

Cited by 4 publications

References 2 publications

Thermochemistry of Key Soot Formation Intermediates: C3H3 Isomers

Thermochemistry of Key Soot Formation Intermediates: C3H3 Isomers

Structure of the Boronic Acid Dimer and the Relative Stabilities of Its Conformers

Hydrogen-Abstracted Adenine−Thymine Radicals with Interesting Transferable Properties

Contact Info

Product

Resources

About

Thermochemistry of Key Soot Formation Intermediates: C₃H₃ Isomers

Thermochemistry of Key Soot Formation Intermediates: C₃H₃ Isomers