A series of novel hetero­[n]­circulenes of the first, second, and the third generation including S and Se heteroatoms for n = 6, 7, 8, and 9 were theoretically designed. Their chemical and electronic structures were investigated using B3LYP-based computational method. The interaction energies and electric drift mobilities were evaluated for model parallel-stacked and parallel-slipped dimer configurations at the room temperature using the Marcus theory and the Einstein relation. On the basis of the calculated properties, the second and third generation of sunflower molecules containing the six-membered central ring are suggested to be perspective candidates for the construction of organic p- and n-type semiconductors, respectively. The obtained results were also compared with the theoretical and published experimental results for reference α-sexithiophene, [6]­circulene (coronene), and octathio[8]­circulene (sulflower) molecules.

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Ferulic acid (FA) is used in skin formulations for protection against the damaging actions of the reactive oxygen species (ROS) produced by UVA radiation. Possible underlying protective mechanisms are not fully elucidated. By considering the kinetics of proton-coupled electron transfer (PCET) and radical-radical coupling (RRC) mechanisms, it appears that direct scavenging could be operative, providing that a high local concentration of FA is present at the place of •OH generation. The resulting FA phenoxyl radical, after the scavenging of a second •OH and keto-enol tautomerization of the intermediate, produces 5-hydroxyferulic acid (5OHFA). Inhibition of the lipoxygenase (LOX) enzyme, one of the enzymes that catalyse free radical production, by FA and 5OHFA were analysed. Results of molecular docking calculations indicate favourable binding interactions of FA and 5OHFA with the LOX active site. The exergonicity of chelation reactions of the catalytic Fe2+ ion with FA and 5OHFA indicate the potency of these chelators to prevent the formation of •OH radicals via Fenton-like reactions. The inhibition of the prooxidant LOX enzyme could be more relevant mechanism of skin protection against UVA induced oxidative stress than iron chelation and assumed direct scavenging of ROS.

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