Heat capacities measured as a function of temperature for Al(115)(+), Al(116)(+), and Al(117)(+) show two well-resolved peaks, at around 450 and 600 K. After being annealed to 523 K (a temperature between the two peaks) or to 773 K (well above both peaks), the high temperature peak remains unchanged but the low temperature peak disappears. After considering the possible explanations, the low te...

To eludicate the role in conformational stability of Cys residues buried in the interior of a protein, the thermodynamic properties of denaturation of mutant alpha subunit of Escherichia coli tryptophan synthase, in which Ser, Ala, Val or Gly was substituted for each of the three Cys residues, were analyzed using calorimetry. The mutants were less stable than the wild type, indicating that Cys ...

A quantitative understanding of the thermochemistry of cyclohexadienyl radical and 1,4-cyclohexadiene is beneficial for diverse areas of chemistry. Given the interest in these two species, it is surprising that more detailed thermodynamic data concerning the homolytic C-H bond enthalpies of such entities have not been forthcoming. We thus undertook an experimental and computational evaluation o...

Microcalorimetry is an excellent method of determining the thermodynamics of ligand–protein binding in solution, because the signal being measured is the observed binding enthalpy (Db-obsH [Editors’ note: this term can also be written DHobs or DbHobs as seen elsewhere in this book]), which is free of any model assumptions. The affinity (DbG) can be computed from the shape of a binding curve, an...

The electrical conductivities of the dilute solutions containing ionic liquids (1-hexyl-3-methylimidazolium chloride [Hmim]Cl, 1-hexyl-3-methylimidazolium bromide [Hmim]Br, and iodide [Hmim]I) with water isopropanol were determined in temperature ranging from 293.15 to 313.15 K. liquid densities all binary mixtures further for model parameterization. In theoretical modeling, limiting molar Λ0(T...

In the current work, chemical reactivity of some trivalent phosphorus derivatives R2PR? towards polyhaloalkanes CCl3POR ? ?2 was studied by quantum method DFT/B3LYP/6-311G(d,p). The introduction substituents for derivative and polyhaloalkane allowed us to have more information on these reactions. On one hand, calculation indices derived from DFT/B3LYP/6-311G(d,p) gapLUMO ? HOMO show that organo...

AbstractThe present work deals with studying the effect of solvent and temperature on solvolysis process using both pH-metric conductometric measurements. The pH conductivity different concentrations phenyl hydrazine hydrochloride in water (H2O), ethanol (EtOH) (EtOH-H2O) mixtures percentages EtOH; 30%, 50%, 70%, 100% (v/v) at temperatures from 293.15 to 308.15 K a step 5 were measured experime...

Araticum (Annona crassiflora) seeds have relevant characteristics for industrialization due to the contents of phytosterols, carotenoids, phenolic compounds, fatty acids, and organic among other components responsible biological properties. The objective this study was fit different mathematical models experimental data, use criteria choose best model, evaluate effective diffusion coefficient, ...

Intermolecular interactions involving aromatic pi-electron density are widely believed to be governed by the aromatic molecular quadrupole moment, Theta(zz). Arene-cation binding is believed to occur primarily with negative Theta(zz) aromatics, and arene-anion binding is believed to occur largely with positive Theta(zz) aromatics. We have performed quantum mechanical computations that show the ...