Antioxidant and UV-radiation absorption activity of aaptamine derivatives - potential application for natural organic sunscreens.

Antioxidant and UV absorption activities of three aaptamine derivatives including piperidine[3,2-]demethyl(oxy)aaptamine (C1), 9-amino-2-ethoxy-8-methoxy-3-benzo[de][1,6]naphthyridine-3-one (C2), and 2-(-butyl)-7,8-dimethoxybenzo[de]imidazo[4,5,1-][1,6]-naphthyridin-10(9)-one (C3) were theoretically studied by density functional theory (DFT). Direct antioxidant activities of C1-C3 were firstly evaluated their intrinsic thermochemical properties and the radical scavenging activity of the potential antioxidants with the HOO˙/HO˙ radicals four mechanisms, including: hydrogen atom transfer (HAT), single electron transfer (SET), proton loss (PL) and radical adduct formation (RAF). Kinetic calculation reveals that HOO˙ scavenging in water occurs HAT mechanism with C1 ( , 7.

New insights into the competition between antioxidant activities and pro-oxidant risks of rosmarinic acid.

Direct and indirect antioxidant activities of rosmarinic acid (RA) based on HOO˙/CHOO˙ radical scavenging and Fe(iii)/Fe(ii) ion chelation were theoretically studied using density functional theory at the M05-2X/6-311++G(2df,2p) level of theory. First, four antioxidant mechanisms including hydrogen atom transfer (HAT), radical adduct formation (RAF), proton loss (PL) and single electron transfer (SET) were investigated in water and pentyl ethanoate (PEA) phases. Regarding the free radical scavenging mechanism, HAT plays a decisive role with overall rate coefficients of 1.

Theoretical Investigation of the Reaction of Pyrene Formation from Fluoranthene.

This paper has investigated the reaction process concerning pyrene formation from fluoranthene in their electronic ground states. Both aromatic compounds are considered as direct soot precursors. The geometrical parameters, the vibrational frequencies, and the zero-point energies have been calculated using the BMK (Boese-Martin for kinetics) method and the 6-311++G(d,p) basis set.

Microhydration of caesium metaborate: structural and thermochemical properties of CsBO + n HO (n = 1-4) aggregates.

The structures and thermodynamic properties of microhydrates of caesium metaborate (CsBO) of nuclear safety interest are reported in this work. CsBO + n HO (n = 1-4) molecular complexes were identified on the potential energy surface. The structures were optimized using the ωB97XD DFT method and the aug-cc-pVTZ basis set.

Theoretical Study of the Reactions of H Atoms with CHI and CHI.

High level ab initio methods have been used to provide reliable kinetic data for the H + CHI and H + CHI gas-phase reactions. The (H, I)-abstraction and I-substitution reaction pathways were identified. The structures were determined on the potential energy surface at the MP2/aug-cc-pVTZ level of theory.

Reactivity of Hydrogen Peroxide with Br and I Atoms.

The reaction mechanisms of Br and I atoms with HO have been investigated using DFT and high-level ab initio calculations. The H-abstraction and OH-abstraction channels were highlighted. The geometries of the stationary points were optimized at the B3LYP/aug-cc-pVTZ level of theory, and the energetics were recalculated with the coupled cluster theory.