A cobaloxime H evolution catalyst with a hydroxo-functionalized pyridine ligand, Co(dmgH)(4-HEP)Cl [dmgH = dimethylglyoxime, 4-HEP = 4-(2-hydroxyethyl)pyridine] was immobilized on a chromium terephthalate metal-organic framework (MOF), MIL-101(Cr), to construct a MOF-catalyst hybrid which displays good photocatalytic H evolution activity. The longevity of the cobaloxime catalyst is increased by MOF incorporation, but limited by the stability of the cobalt-pyridine bond under turnover conditions.
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http://dx.doi.org/10.1039/c8se00072g | DOI Listing |
Org Lett
January 2025
Leibniz Institute for Catalysis e.V., Albert-Einstein-Str. 29a, 18059 Rostock, Germany.
Herein we present photoinduced cobaloxime-catalyzed selective remote desaturation of aliphatic alcohols. This transformation, which proceeds efficiently at room temperature, facilitates the synthesis of valuable cyclic and acyclic allylic and homoallylic alcohols from readily available saturated aliphatic alcohols. Remarkably, this method obviates the need for external oxidants, noble metal catalysts, and phosphine ligands.
View Article and Find Full Text PDFAdv Mater
January 2025
Department of Chemical Sciences, University of Padova, Via F. Marzolo 1, Padova, 35131, Italy.
The semi-hydrogenation of acetylene in ethylene-rich gas streams is a high-priority industrial chemical reaction for producing polymer-grade ethylene. Traditional thermocatalytic routes for acetylene reduction to ethylene, despite progress, still require high temperatures and high H consumption, possess relatively low selectivity, and use a noble metal catalyst. Light-powered strategies are starting to emerge, given that they have the potential to use directly the abundant and sustainable solar irradiation, but are ineffective.
View Article and Find Full Text PDFDalton Trans
October 2024
Department of Chemistry, Institute of Science, Banaras Hindu University, Varanasi 221005, India.
Three new molecular cobaloxime complexes with the general formula [ClCo(dpgH)L] (1-3), where L1 = -(4-pyridylmethyl)-1,8-naphthalimide, L2 = 4-bromo--(4-pyridylmethyl)-1,8-naphthalimide, L3 = 4-piperidin--(4-pyridylmethyl)-1,8-naphthalimide, have been synthesized and characterized by UV-Vis, multinuclear NMR, FT-IR and PXRD spectroscopic techniques. The crystal structures of all complexes have also been reported. The electrocatalytic activity of complexes is investigated under two catalysis conditions: (i) homogeneous conditions in acetonitrile using acetic acid (AcOH) as a proton source and (ii) heterogeneous conditions upon immobilization onto the surface of activated carbon cloth (CC).
View Article and Find Full Text PDFJ Am Chem Soc
October 2024
School of Chemistry, Chemical Engineering and Biotechnology, Nanyang Technological University, 21 Nanyang Link, Singapore 637371, Singapore.
The low immunogenicity of tumors, along with the abnormal structural and biochemical barriers of tumor-associated vasculature, impedes the infiltration and function of effector T cells at the tumor site, severely inhibiting the efficacy of antitumor immunotherapy. In this study, a cobaloxime catalyst and STING agonist (MSA-2)-coloaded Wurster-type covalent organic framework (Co-TB COF-M) with internal electron transfer-enhanced catalytic capacity was developed as a COF-based immune activator. The covalently anchored cobaloxime adjusts the energy band structure of TB COF and provides it with good substrate adsorption sites, enabling it to act as an electron transmission bridge between the COF and substrate in proton reduction catalytic reactions.
View Article and Find Full Text PDFACS Catal
April 2024
Department of Chemistry, Binghamton University, Binghamton, New York 13902, United States.
A combination of inter- and intramolecular C kinetic isotope effects and density functional theory analysis is used to evaluate the key mechanistic events of sequentially operating catalytic cycles in the dual photoredox-cobalt-catalyzed elimination of alkyl bromides. The results point to a mechanism proceeding via irreversible halogen-atom transfer (XAT) from the alkyl halide, resulting in an alkyl radical, which undergoes hydrogen-atom transfer (HAT) to a Co(II) intermediate to deliver the product olefin. Alternative pathways involving nucleophilic substitution by a Co(I) species and by -hydride elimination are discounted based on the poor agreement of experimental and predicted C KIEs.
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