Antioxidant Activities of Hydroxylated Naphthalenes: The Role of Aryloxyl Radicals.

Herein is delineated a first systematic framework for the definition of structure-antioxidant property relationships in the dihydroxynaphthalene (DHN) series. The results obtained by a combined experimental and theoretical approach revealed that 1,8-DHN is the best performing antioxidant platform, with its unique hydrogen-bonded peri-hydroxylation pattern contributing to a fast H atom transfer process. Moreover, the comparative analysis of the antioxidant properties of DHNs carried out by performing DPPH and FRAP assays and laser flash photolysis experiments, revealed the higher antioxidant power associated with an α-substitution pattern (i.

The interplay of chemical structure, physical properties, and structural design as a tool to modulate the properties of melanins within mesopores.

The design of modern devices that can fulfil the requirements for sustainability and renewable energy applications calls for both new materials and a better understanding of the mixing of existing materials. Among those, surely organic-inorganic hybrids are gaining increasing attention due to the wide possibility to tailor their properties by accurate structural design and materials choice. In this work, we'll describe the tight interplay between porous Si and two melanic polymers permeating the pores.

Non-covalent small molecule partnership for redox-active films: Beyond polydopamine technology.

Hypothesis: The possibility to use hexamethylenediamine (HMDA) to impart film forming ability to natural polymers including eumelanins and plant polyphenols endowed with biological activity and functional properties has been recently explored with the aim to broaden the potential of polydopamine (PDA)-based films overcoming their inherent limitations. 5,6-dihydroxyindole-2-carboxylic acid, its methyl ester (MeDHICA) and eumelanins thereof were shown to exhibit potent reducing activity.

Experiments: MeDHICA and HMDA were reacted in aqueous buffer, pH 9.

Disentangling the Puzzling Regiochemistry of Thiol Addition to -Quinones.

The addition of thiol compounds to -quinones, as exemplified by the biologically relevant conjugation of cysteine to dopaquinone, displays an anomalous 1,6-type regiochemistry compared to the usual 1,4-nucleophilic addition, for example, by amines, which has so far eluded intensive investigations. By means of an integrated experimental and computational approach, herein, we provide evidence that the addition of glutathione, cysteine, or benzenethiol to 4-methyl--benzoquinone, modeling dopaquinone, proceeds by a free radical chain mechanism triggered by the addition of thiyl radicals to the -quinone. In support of this conclusion, DFT calculations consistently predicted the correct regiochemistry only for the proposed thiyl radical-quinone addition pathway.