Noble gas hydrides: theoretical prediction of the first group of anionic species.

The first group of anionic noble-gas hydrides with the general formula HNgBeO- (Ng = Ar, Kr, Xe, Rn) is predicted through MP2, Coupled-Cluster, and Density Functional Theory computations employing correlation-consistent atomic basis sets. We derive that these species are stable with respect to the loss of H, H-, BeO, and BeO-, but unstable with respect to Ng + HBeO-. The energy barriers of the latter process are, however, high enough to suggest the conceivable existence of the heaviest HNgBeO- species as metastable in nature. Their stability arises from the interaction of the H- moiety with the positively-charged Ng atoms, particularly with the σ-hole ensuing from their ligation to BeO. This actually promotes relatively tight Ng-H bonds featuring a partially-covalent character, whose degree progressively increases when going from HArBeO- to HRnBeO-. The HNgBeO- compounds are also briefly compared with other noble-gas anions observed in the gas phase or isolated in crystal lattices.

Complexes of the noble gases with H3O+: a theoretical investigation on Ng(H3O+) (Ng = He-Xe).

The geometries, harmonic vibrational frequencies, and binding energies (Bes) of the Ng(H(3)O(+)) complexes (Ng = He-Xe) were investigated at the coupled cluster level of theory, and their bonding situation was assayed by various methods of bonding analysis. The effects of Ng on H(3)O(+) progressively increase from He to Xe, and only He can be regarded as an essentially "innocent" ligand. The binding energies also increase in the same periodic order, and are by far dominated by the "noncovalent" ion-induced dipole interaction arising from the H(3)O(+)-induced polarization of Ng. For Ne, Ar, Kr, and Xe, this term has a larger contribution from the p orbital lying on the bond axis, and two smaller contributions from the p orbitals perpendicular to the bond axis. For the heaviest Ar(H(3)O(+)), Kr(H(3)O(+)), and Xe(H(3)O(+)), BE also has a "covalent" component, which is ascribed to the relatively-appreciable charge transfer from Ng to H(3)O(+).

The first quantitative rating system of the antioxidant capacity of beauty creams via the Briggs-Rauscher reaction: a crucial step towards evidence-based cosmetics.

Oxidative damage is the primary cause of skin aging. Skin care products are numerous and overwhelming, yet there is certain similarity among different formulations. Moisturizers are ubiquitous and the presence of particular added ingredients supports specific marketing claims. The antioxidant effects of botanical polyphenols possess tremendous marketing appeal, because oxidative stress is caused by an imbalance between the production of reactive oxygen species (ROS) and the skin ability to neutralize them. The concept of evidence-based cosmetics lacks a widely accepted method to estimate the antioxidant capacity of the beauty cream. This was the motive force of the present study: for the first time we put forth a quantitative rating system of skin care products. The overall antioxidant power of 75 widely used and advertised beauty creams was comparatively measured via the oscillating Briggs-Rauscher (BR) reaction. Many dermocosmetic products confirmed their ability to ensure protection against free radicals, even if differences among various creams are striking and often not correlated with the their price. The method we developed is simple and cheap and it can allow dermatologists and consumers to compare and choose effectively; on the other hand, producers can used this method to select the most active antioxidant cosmetic agent to optimise the product performance.

Noble gas anions: a theoretical investigation of FNgBN- (Ng = He-Xe).

Noble gas anions of general formula FNgBN- (Ng = He-Xe) have been investigated by MP2, coupled-cluster, and multireference-CI calculations with correlation-consistent basis sets. These species reside in deep wells on the singlet potential energy surface and are thermodynamically stable with respect to the loss of F, F-, BN, and BN-. They are unstable with respect to Ng + FBN-, but at least for Ng = Ar, Kr, and Xe, the involved energy barriers are high enough to suggest their conceivable existence as metastable species. The stability of FNgBN- arises from the strong F--stabilization of the elusive NgBN. The character of the boron-noble gas bond passes from purely ionic for FHeBN- and FNeBN- to covalent for FXeBN-.