Interfacial Hydrogen Atom Transfer by nanohybrids based on Humic Acid Like Polycondensates

Effects of Sorption on Redox Properties of Natural Organic Matter

“…Given the absence of electron transfer between the HA and the redox-inert aluminum oxide, these results can be rationalized by each of the following hypotheses or a combination of them: Conformational re-arrangements of HA moieties might take place on the Al 2 O 3 surface; an opening of the HA supramolecular folding might render the electron-donor groups (e.g., phenols, hydroquinones) more accessible to electron exchange with the electron mediator ABTS as compared to HA in solution, and thus the apparent EDC of adsorbed HA might be enhanced. This interpretation is in line with a massive increase (300%) of interfacial hydrogen atom transfer found for a HA like poly-condensate (HALP) coated on SiO 2 nanoparticles compared to HALP in solution . Conformational re-arrangements of HA supramolecular structures are known to depend on various environmental conditions (such as HA concentration, solution pH, ionic strength, etc.…”

“…This interpretation is in line with a massive increase (300%) of interfacial hydrogen atom transfer found for a HA like polycondensate (HALP) coated on SiO 2 nanoparticles compared to HALP in solution. 22 Conformational rearrangements of HA supramolecular structures are known to depend on various environmental conditions (such as HA concentration, solution pH, ionic strength, etc.). 85−87 At our experimental conditions [pH 7, 0.1 M background electrolyte and low (<500 mg C/L) HA concentrations], HAs are expected to behave as a permeable polyelectrolyte 85 either in aqueous phase or in adsorbed state.…”

“…Natural organic matter (NOM) is ubiquitously present in terrestrial and aquatic systems and is made up by a heterogeneous mixture comprising organic compounds originating from the decay of biomass. − The chemical composition, structure, and physicochemical properties of NOM are closely linked to its origin (terrestrial or aquatic), the type of biomass such as plants or microorganisms, as well as the climatic and environmental conditions such as light exposure. − Important biogeochemical and environmental functions of NOM include carbon and energy source for heterotrophic organisms, electron shuttling in microbial processes, , reactant for redox transformation of pollutants, absorbent for nutrients, metals, and organic pollutants affecting their mobility and bioavailability in soils, sediments, and aquifers. − Given its inherent heterogeneity, the standard reduction potential ( E H 0′ ) of a NOM sample is not a discrete value but covers a range of reduction potentials as demonstrated for terrestrial and aquatic humic substances (HSs). − Whereas quinone moieties are the major electron-acceptor functional groups within HSs, − polyphenols and hydroquinone moieties make up for most of their electron-donor capacity. − The presence of various electroactive moieties in NOM gives rise to a wide distribution of potential redox states of the very same NOM sample as a function of the prevailing redox potential. As a given NOM sample may be more or less oxidized, other physicochemical properties such as polarity, 3D-conformation, or aggregation state may also alter with its redox state.…”

Control of Tyrosyl Radical Stabilization by {SiO2@Oligopeptide} Hybrid Biomimetic Materials

“…That is, the solid nanomatrix could allow spatial control of the macromolecule, as we have shown for a humic-like polymer grafted on SiO 2 nanoparticles. 43,44 The synthesized peptides and hybrid NPs, and their abbreviations are shown in Table 1.…”

Διεργασίες Μεταφοράς Ηλεκτρονίων Σε Νανο - Υβριδικά Υλικά

“…τον Πίνακα 1.1 παρατίκενται οι τιμζσ BDE για τα γνωςτότερα αντιοξειδωτικά. (i) Θ μζκοδοσ «DPPH • » (2,2-diphenyl-1-picrylhydrazyl), θ οποία βαςίηεται ςτο αποχρωματιςμό τθσ ρίηασ DPPH • όταν αλλθλεπιδράςει με αντιοξειδωτικά 63,[77][78][79][80] .…”