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The reaction of ebselen and its derivatives with peroxynitrite anion (PN) is studied in the gas and aqueous phases. It is observed that ebselen reacts with PN to exhibit glutatione peroxidase activity.

Using the density functional (B3LYP), coupled cluster (CCSD(T)), and polarizable continuum model (PCM) methods the reaction mechanism of a model compound of ebselen, 2, [1,2-benziodelenazol-3(2H)-one] with peroxynitrous acid (HOONO) was investigated. The B3LYP and CCSD(T) calculations with a number of basis sets indicate that the B3LYP methods is not a reliable method for studying the energies and stability of the weakly bound .OH...ONO structure and could lead to wrong calculations.

Anomalous enhancement of stimulated Raman scattering (SRS) of the aromatic CH stretching band was observed when the laser-induced plasma was generated in benzene-toluene mixed solvents. Time-resolved spectra of the SRS revealed that the strong excitation condition that led to generation of ionized molecules was an important factor for anomalous enhancement.

The study shows how the proposed 'two-in-one' model di-enol intermediate successfully represents the 'less-substituted' and 'more substituted' enol intermediates generated from an unsymmetrical ketone. When 'local softness' based reactivity descriptors are used to evaluate the reactivities of the relevant atoms (the less-substituted and the more-substituted alpha-carbon atoms which take part in the aldol addition reaction) in the proposed model, it could successfully predict the predominant aldol product (the more substituted one).

High level ab initio calculations are performed to examine the mechanism of NO decomposition by NH3 (super +) and NH4 (super +) in a gas phase. Maximum activation energies for the various reactions are estimated at 55.3 and 77.3 kcal/mol.

The alkaline hydrolysis of DNA proceeds in one step without producing any intermediate. Data suggest that acid catalysts mediating the removal of the leaving group from the P atom are of primary importance for DNA hydrolysis under alkaline conditions.

Binding energies and electronic structures of Li+ and Cu+ in their interaction with small ligands of the type HX has been studied by using B3LYP and CCSD(T) calculations. It was established that the second ligand in Cu+ complexes has higher binding energies than the first one.

A study was conducted to investigate the formation of carbon-carbon bond in methanol to gasoline processes. The formation was analyzed using density functional theory and indicated a new mechanism involving the reaction of methane and formaldehyde. Results showed that the new mechanism is the most energetically preferable route of all new mechanism. Findings also indicated that methane is not a byproduct in the methanol-to-gasoline process.

The redox switching of doped 1,5‐azulenequinones/hydroquinones wired between gold electrodes is investigated using density functional theory and the nonequilibrium Green's function. Their electronic transport properties when separately doped with nitrogen and boron as well as co‐doping of these atoms are examined. The results illustrate a significant enhancement of the current at low bias voltage in some of the 12 doped studied systems, leading to "switching on" the transmission, where the greatest switching ratio is 18. These systems also exhibit a modest rectification in which the greatest rectification ratio is 4. The significance of the position of the doped atom and the functional group on the switching behavior is analyzed through the transmission spectra and molecular orbitals. The present study broadens knowledge of organic redox switching bringing in potential diverse options for future molecular electronic circuit components. [ABSTRACT FROM AUTHOR]

Integrable singularity in the exact exchange calculations in hybrid functionals is an old and well-known problem in plane-wave basis. Recently, we developed a hybrid functional named Gaussian-attenuating Perdew-Burke-Ernzerhof (Gau-PBE), which uses a Gaussian function as a modified Coulomb potential for the exact exchange. We found that the modified Coulomb potential of Gaussian function enables the exact exchange calculation in plane-wave basis to be singularity-free and, as a result, the Gau-PBE functional shows faster energy convergence on k and q grids for the exact exchange calculations. Also, a tight comparison (same k and q meshes) between Gau-PBE and two other hybrid functionals, i.e., PBE0 and HSE06, indicates Gau-PBE functional as the least computational time consuming. The Gau-PBE functional employed in conjunction with a plane wave basis provides bandgaps with higher accuracy than the PBE0 and HSE06 in agreement with bandgaps previously calculated using Gaussian-type-orbitals. [ABSTRACT FROM AUTHOR]

Recently, we developed a Gaussian attenuation (Gau) scheme for solid-state bandgap calculation that uses a two-electron Gaussian function operator to include short-range Hartree-Fock exchange and combined it with the long-range Perdew-Burke-Ernzerhof (PBE) exchange correlation functional (Gau-PBE). Here, we apply the Ernzerhof-Perdew exchange hole (EP) model of PBE (PBEh) as a long-range density functional theory (DFT) exchange part to the Gau scheme (Gau-PBEh). We found that applying the EP model to the Gau scheme improves atomization energies and solid-state lattice constants and that the exact exchange included using the Gau scheme plays a critical role in simultaneously reproducing solid-state bandgaps and barrier heights. In addition, Gau-PBEh takes nearly the same computation time for bandgap calculations as Gau-PBE, implying less than 60% of the time taken in Heyd-Scuseria-Ernzerhof hybrid DFT functional calculations. [ABSTRACT FROM AUTHOR]