Experimentally measured rate constants, , for the reductions of [Ni(III)tripeptides(HO)] with Fe(CN), Mo(CN), and W(CN) are 10 to 10 times faster than the calculated rate constants with the Marcus theory for outer-sphere electron-transfer processes, , even when work terms are considered. This gives rise to a kinetic advantage of / = 10-10, which is consistent with an inner-sphere electron-transfer mechanism via a bridged intermediate. In addition, values are nearly independent of the electrochemical driving force of the reactions. This is consistent with one of the two axial water ligands coordinated to [Ni(III)tripeptides(HO)] being substituted in the rate-limiting step to form bridged intermediates of the type [(CN)M-(CN)-Ni(tripeptide)(HO)] with M = Fe, Mo, or W. A limiting rate constant of HO replacement from [Ni(III)tripeptides(HO)] of (5 ± 2) × 10 M s at 25.0 °C is observed. Electron paramagnetic resonance spectra of Ni(III) peptide complexes in the presence of Fe(CN), Mo(CN), or IrCl provide evidence for the cyanide-bridged intermediates. Substitution-limited electron-transfer reactions could serve as an additional criterion for inner-sphere pathways when atom or group transfer does not occur during electron-transfer and when precursor and successor complexes cannot be observed directly.
Download full-text PDF |
Source |
|---|---|
| http://dx.doi.org/10.1021/acs.inorgchem.0c01582 | DOI Listing |
Publication Analysis
Top Keywords
Similar Publications
Modulating Built-In Electric Field Via N-Doped Carbon Dots for Robust Oxygen Evolution at Large Current Density.
Small
January 2025
School of Materials and Chemical Engineering, Xuzhou University of Technology, Xuzhou, 221018, P. R. China.
Constructing a built-in electric field (BIEF) within heterostructures has emerged as a compelling strategy for advancing electrocatalytic oxygen evolution reaction (OER) performance. Herein, the p-n type nanosheet array heterojunction NiP-NCDs-Co(OH)-NF are successfully prepared. The variation in interaction affinity between nitrogen within N-doped carbon dots (NCDs) and Ni/Co induces charge redistribution between Co and Ni in the NiP-NCDs-Co(OH)-NF-3 heterostructure, thereby enhancing the intensity of the BIEF, facilitating electron transfer, and markedly improving OER activity.
View Article and Find Full Text PDFSynthesis of Nonplanar Push-Pull Chromophores with Various Heterocyclic Moieties via [2 + 2] Cycloaddition-Retroelectrocyclization Reaction.
J Org Chem
January 2025
Department of Materials Science and Engineering, Institute of Science Tokyo, 2-12-1 Ookayama, Meguro-ku, Tokyo 152-8552, Japan.
A series of 1,1,4,4-tetracyanobuta-1,3-diene (TCBD) derivatives with various heterocyclic moieties, including pyridine, carbazole, indole, and benzothiadiazole, was newly synthesized through a [2 + 2] cycloaddition-retroelectrocyclization reaction. Symmetric electron-rich 1,3-butadiynes with end-capped heterocyclic substituents were reacted with tetracyanoethylene (TCNE), yielding the target TCBD products in 60-80% yields under ambient or mild heating conditions. The thermal stability and optical and electrochemical properties of both 1,3-butadiyne precursors and the corresponding TCBD derivatives were investigated by using thermogravimetric analysis (TGA), UV-vis spectroscopy, and cyclic voltammetry (CV).
View Article and Find Full Text PDFOxygen, light, and mechanical force mediated radical polymerization toward precision polymer synthesis.
Chem Commun (Camb)
January 2025
State Key Laboratory of Molecular Engineering of Polymers, Department of Macromolecular Science, Fudan University, Shanghai 200438, China.
The synthesis of polymers with well-defined composition, architecture, and functionality has long been a focal area of research in the field of polymer chemistry. The advancement of controlled radical polymerization (CRP) has facilitated the synthesis of precise polymers, which are endowed with new properties and functionalities, thereby exhibiting a wide range of applications. However, radical polymerization faces several challenges, such as oxygen intolerance, and common thermal initiation methods may lead to side reactions and depolymerization.
View Article and Find Full Text PDFSurface Composition Impacts Selectivity of ZnTe Photocathodes in Photoelectrochemical CO Reduction Reaction.
ACS Energy Lett
January 2025
Liquid Sunlight Alliance, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, California 94720, United States.
Light-driven reduction of CO into chemicals using a photoelectrochemical (PEC) approach is considered as a promising way to meet the carbon neutral target. The very top surface of the photoelectrode and semiconductor/electrolyte interface plays a pivotal role in defining the performance for PEC CO reduction. However, such impact remains poorly understood.
View Article and Find Full Text PDFEpigenetic Control of Redox Pathways in Cancer Progression.
Antioxid Redox Signal
January 2025
Department of Pharmacology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore.
Growing evidence indicates the importance of redox reactions homeostasis, mediated predominantly by reactive oxygen species (ROS) in influencing the development, differentiation, progression, metastasis, programmed cell death, tumor microenvironment, and therapeutic resistance of cancer. Therefore, reviewing the ROS-linked epigenetic changes in cancer is fundamental to understanding the progression and prevention of cancer. We review in depth the molecular mechanisms involved in ROS-mediated epigenetic changes that lead to alteration of gene expression by altering DNA, modifying histones, and remodeling chromatin and noncoding RNA.
View Article and Find Full Text PDFWant AI Summaries of new PubMed Abstracts delivered to your In-box?
Enter search terms and have AI summaries delivered each week - change queries or unsubscribe any time!