Recombination of aromatic radicals with molecular oxygen

<p>Avoiding faradaic side reactions during the operation of electrochemical devices is important to enhance the device stability, to achieve low power consumption, and to prevent the formation of reactive side‑products. This is particularly important for bioelectronic devices which are designed to operate in biological systems. While redox‑active materials based on conducting and semiconducting polymers represent an exciting class of materials for bioelectronic devices, they are susceptible to electrochemical side‑reactions with molecular oxygen during device operation. We show that this electrochemical side reaction yields hydrogen peroxide (H<sub>2</sub>O<sub>2</sub>), a reactive side‑product, which may be harmful to the local biological environment and may also accelerate device degradation. We report a design strategy for the development of redox-active organic semiconductors based on donor-acceptor copolymers that prevent the formation of H<sub>2</sub>O<sub>2</sub> during device operation. This study elucidates the previously overlooked side-reactions between redox-active conjugated polymers and molecular oxygen in electrochemical devices for bioelectronics, which is critical for the operation of electrolyte‑gated devices in application-relevant environments.</p>

Download Full-text

Optical Properties of Photodynamic Therapy Drugs in Different Environments: The Paradigmatic Case of Temoporfin

10.26434/chemrxiv.12118917.v2 ◽

2020 ◽

Author(s):

busenur Aslanoglu ◽

Ilya Yakavets ◽

Vladimir Zorin ◽

Henri-Pierre Lassalle ◽

Francesca Ingrosso ◽

...

Keyword(s):

Drug Delivery ◽

Optical Properties ◽

Photodynamic Therapy ◽

Minimally Invasive ◽

Visible Light ◽

Cancer Treatment ◽

Singlet Oxygen ◽

Tumor Cells ◽

Molecular Oxygen ◽

Computational Tools

Computational tools have been used to study the photophysical and photochemical features of photosensitizers in photodynamic therapy (PDT) –a minimally invasive, less aggressive alternative for cancer treatment. PDT is mainly based by the activation of molecular oxygen through the action of a photoexcited sensitizer (photosensitizer). Temoporfin, widely known as mTHPC, is a second-generation photosensitizer, which produces the cytotoxic singlet oxygen when irradiated with visible light and hence destroys tumor cells. However, the bioavailability of the mostly hydrophobic photosensitizer, and hence its incorporation into the cells, is fundamental to achieve the desired effect on malignant tissues by PDT. In this study, we focus on the optical properties of the temoporfin chromophore in different environments –in <i>vacuo</i>, in solution, encapsulated in drug delivery agents, namely cyclodextrin, and interacting with a lipid bilayer.

Download Full-text

Reactivity Trends in the Gas Phase Addition of Acetylene to N-protonated Aryl Radical Cations

10.26434/chemrxiv.13078334 ◽

2020 ◽

Author(s):

Oisin Shiels ◽

P. D. Kelly ◽

Cameron C. Bright ◽

Berwyck L. J. Poad ◽

Stephen Blanksby ◽

...

Keyword(s):

Gas Phase ◽

Ion Trap ◽

Radical Cations ◽

Rate Coefficients ◽

Similar Process ◽

Ion Molecule Reactions ◽

Aromatic Radicals ◽

Polycyclic Aromatic ◽

Gas Phase Ion ◽

Type Radical

<div> <div> <div> <p>A key step in gas-phase polycyclic aromatic hydrocarbon (PAH) formation involves the addition of acetylene (or other alkyne) to σ-type aromatic radicals, with successive additions yielding more complex PAHs. A similar process can happen for N- containing aromatics. In cold diffuse environments, such as the interstellar medium, rates of radical addition may be enhanced when the σ-type radical is charged. This paper investigates the gas-phase ion-molecule reactions of acetylene with nine aromatic distonic σ-type radical cations derived from pyridinium (Pyr), anilinium (Anl) and benzonitrilium (Bzn) ions. Three isomers are studied in each case (radical sites at the ortho, meta and para positions). Using a room temperature ion trap, second-order rate coefficients, product branching ratios and reaction efficiencies are reported. </p> </div> </div> </div>

Download Full-text

OXIDATION OF CYCLOPENTADIENYL RADICAL WITH MOLECULAR OXYGEN: A THEORETICAL STUDY

8th International Symposium on Nonequilibrium Processes, Plasma, Combustion, and Atmospheric Phenomena held Том. Volum 1. Kinetics and plasma ◽

10.30826/nepcap2018-1-28 ◽

2018 ◽

Author(s):

A. D. OLEINIKOV ◽

◽

V. N. AZYAZOV ◽

A.M. MEBEL ◽

◽

...

Keyword(s):

Molecular Oxygen ◽

Theoretical Study ◽

Cyclopentadienyl Radical

Download Full-text

RuIII(edta) complexes as molecular redox catalysts in chemical and electrochemical reduction of dioxygen and hydrogen peroxide: inner-sphere versus outer-sphere mechanism

RSC Advances ◽

10.1039/d1ra03293c ◽

2021 ◽

Vol 11 (35) ◽

pp. 21359-21366

Author(s):

Debabrata Chatterjee ◽

Marta Chrzanowska ◽

Anna Katafias ◽

Maria Oszajca ◽

Rudi van Eldik

Keyword(s):

Hydrogen Peroxide ◽

Electron Transfer ◽

Electrochemical Reduction ◽

Molecular Oxygen ◽

Outer Sphere ◽

Transfer Processes ◽

Edta Complexes ◽

Inner Sphere ◽

Electron Transfer Processes ◽

Sphere Mechanism

[RuII(edta)(L)]2–, where edta4– =ethylenediaminetetraacetate; L = pyrazine (pz) and H2O, can reduce molecular oxygen sequentially to hydrogen peroxide and further to water by involving both outer-sphere and inner-sphere electron transfer processes.

Download Full-text