Vertical Energy Values Research Articles

Understanding the Chemical Reactivity of Dihydroxyfumaric Acid and its Derivatives through Conceptual DFT

The chemical reactivity descriptors have been calculated through Molecular Electron Density Theory encompassing Conceptual DFT. The validity of �Koopmans� theorem in DFT� (KID) has been assessed by a comparison between the global descriptors (electronegativity, total hardness, and global electrophilicity) calculated through vertical energy values and those arising from the HOMO and LUMO values. These results suggest that the KID procedure is valid and may be used, in conjunction with the B3LYP/3-611G(d, p) level of theory in further studies of related compounds in the aqueous medium. The active sites for nucleophilic and electrophilic attacks have been identified and verified using the local reactivity descriptors: the dual descriptor, the electrophilic and nucleophilic Parr functions, the local reactivity difference index Rk and MEP maps. Obtained results suggest that the antioxidant/antiradical power of investigated compounds may be explained by the highest ambiphilic activation of the oxygen atoms of the hydroxyl groups in the ene-diol moiety.

Molecular modeling of anionic and cationic dyes adsorption on sludge derived activated carbon

Abstract The work deals with the adsorption of two dyes, namely Food Red 17 (FR17) and Methyl Violet (MV), onto a sludge derived activated carbon (SDAC). An experimental analysis of adsorbent properties is preliminary carried out, in order to determine its chemical and textural properties. Subsequently, a molecular simulation analysis based on the reviewed TPSS density functional is performed for the calculation of the molecular structure and properties of both SDAC and the two dyes, as well as for the determinations of their interaction parameters and chemical reactivity descriptors. The nucleophilic and electrophilic attacks within active sites are related to the Fukui function indices and the dual descriptor f (r). A comparison between the descriptors calculated through vertical energy values and those arising from the Koopmans' theorem approximation are performed in order to check for the validity of the procedure. The simulations results show that, although FR17 showed a better affinity with SDAC according to the interaction energy calculations, MV was adsorbed more efficiently than FR17 on SDAC, which was demonstrated by the HOMO–LUMO energies and by the retrieved optimized molecular conformation during adsorption of each dye on SDAC.

A conceptual DFT study of the molecular properties of glycating carbonyl compounds

Several glycating carbonyl compounds have been studied by resorting to the latest Minnesota family of density functional with the objective of determinating their molecular properties. In particular, the chemical reactivity descriptors that arise from conceptual density functional theory and chemical reactivity theory have been calculated through a DeltaSCF protocol. The validity of the KID (Koopmans’ in DFT) procedure has been checked by comparing the reactivity descriptors obtained from the values of the HOMO and LUMO with those calculated through vertical energy values. The reactivity sites have been determined by means of the calculation of the Fukui function indices, the condensed dual descriptor Delta {f}(mathbf {r}) and the electrophilic and nucleophilic Parr functions. The glycating power of the studied compounds have been compared with the same property for simple carbohydrates.Graphical abstractSeveral glycating carbonyl compounds have been studied by resorting to the latest Minnesota family of density functional with the objective of determinating their molecular properties, the chemical reactivity descriptors and the validity of the KID (Koopmans’ in DFT) procedure

A Molecular Electron Density Theory Study of the Chemical Reactivity of Cis- and Trans-Resveratrol.

The chemical reactivity of resveratrol isomers with the potential to play a role as inhibitors of the nonenzymatic glycation of amino acids and proteins, both acting as antioxidants and as chelating agents for metallic ions such as Cu, Al and Fe, have been studied by resorting to the latest family of Minnesota density functionals. The chemical reactivity descriptors have been calculated through Molecular Electron Density Theory encompassing Conceptual DFT. The active sites for nucleophilic and electrophilic attacks have been chosen by relating them to the Fukui function indices, the dual descriptor and the electrophilic and nucleophilic Parr functions. The validity of “Koopmans’ theorem in DFT” has been assessed by means of a comparison between the descriptors calculated through vertical energy values and those arising from the HOMO and LUMO values.

A comparison of the chemical reactivity of naringenin calculated with the M06 family of density functionals

BackgroundChemicals generically referred to as flavonoids belong to the group of phenolic compounds and constitute an important group of secondary metabolites due to their applications as well as their biochemical properties. Flavonoids, which share a common benzo- γ-pyrone structure, constitute a kind of compound which are highly ubiquitous in the plant kingdom.FindingsThe M06 family of density functionals has been assessed for the calculation of the molecular structure and properties of the Naringenin flavonoid. The chemical reactivity descriptors have been calculated through Conceptual DFT. The active sites for nucleophilic and electrophilic attacks have been chosen by relating them to the Fukui function indices and the dual descriptor f(2)(r). A comparison between the descriptors calculated through vertical energy values and those arising from the Koopmans’ theorem approximation have been performed in order to check for the validity of the last procedure.ConclusionsThe M06 family of density functionals (M06, M06L, M06-2X and M06-HF) used in the present work leads to the same qualitatively and quantitatively similar description of the chemistry and reactivity of the Naringenin molecule, yielding reasonable results. However, for the case of the M06-2X and M06-HF density functionals, which include a large portion of HF exchange, the calculations considering the validity of the Koopmans’ theorem lead to negative electron affinities.

Computational nanochemistry study of the molecular structure and properties of ethambutol

The M06 family of density functionals was employed to calculate the molecular structure and properties of the ethambutol molecule. Besides determination of molecular structures, UV-vis spectra were computed using TD-DFT in the presence of a solvent and the results compared with available experimental data. The chemical reactivity descriptors were calculated through conceptual DFT. The active sites for nucleophilic and electrophilic attacks have been chosen by relating them to Fukui function indices. A comparison between the descriptors calculated through vertical energy values and those arising from Koopmans' theorem approximation were performed in order to check the validity of the latter procedure.

Computational Nutraceutics: Chemical Reactivity Properties of the Flavonoid Naringin by Means of Conceptual DFT

The M06 family of density functionals has been assessed for the calculation of the molecular structure and properties of the Naringin molecule. The chemical reactivity descriptors have been calculated through Conceptual DFT. The active sites for nucleophilic and electrophilic attacks have been chosen by relating them to the Fukui function indices and the dual descriptor f(2)(r). A comparison between the descriptors calculated through vertical energy values and those arising from the Koopmans′ theorem approximation has been performed in order to check for the validity of the last procedure.

Computational Study of the Chemical Reactivity Properties of the Rhodamine B Molecule

The M06 family of density functionals has been assessed for the calculation of the molecular structure and properties of the Rhodamine B molecule. The chemical reactivity descriptors have been calculated through Conceptual DFT. The active sites for nucleophilic and electrophilic attacks have been chosen by relating them to the Fukui function indices and the dual descriptor f(2)(r). A comparison between the descriptors calculated through vertical energy values and those arising from the Koopmans’ theorem approximation have been performed in order to check for the validity of the last procedure.

Computational Nanochemistry Study of the Molecular Structure and Properties of Chlorophyll a

The M06 family of density functionals has been assessed for the calculation of the molecular structure and properties of the chlorophyll a molecule. Besides the determination of the molecular structures, the UV-Vis spectra have been computed using TD-DFT in the presence of a solvent, and the results were compared with the experimental data available. The chemical reactivity descriptors have been calculated through conceptual DFT. The active sites for nucleophilic and electrophilic attacks have been chosen by relating them to the Fukui function indices. A comparison between the descriptors calculated through vertical energy values and those arising from the Koopmans' theorem approximation have been performed in order to check for the validity of the last procedure.