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1. Relevance of Chemical vs. Electrochemical Oxidation of Tunable Carbene Iridium Complexes for Catalytic Water Oxidation: Relevance of Chemical vs. Electrochemical Oxidation of Tunable Carbene Iridium Complexes for Catalytic Water Oxidation

   https://doi.org/10.1002/ejic.202000090  

   Olivares, Marta ; van der Ham, Cornelis J. M. ; Mdluli, Velabo ; Schmidtendorf, Markus ; Müller-Bunz, Helge ; Verhoeven, Tiny W. G. M. ; Li, Mo ; Niemantsverdriet, J. W. Hans ; Hetterscheid, Dennis G. H. ; Bernhard, Stefan ; et al ( March 2020 , European Journal of Inorganic Chemistry)
2. Effect of water frustration on water oxidation catalysis in the nanoconfined interlayers of layered manganese oxides birnessite and buserite

   https://doi.org/10.1039/D0TA09635K  

   Bhullar, Ravneet K. ; Zdilla, Michael J. ; Klein, Michael L. ; Remsing, Richard C. ( March 2021 , Journal of Materials Chemistry A)

   null (Ed.)

   The role of geometric frustration of water molecules in the rate of water oxidation in the nanoconfined interlayer of manganese-oxide layered materials (birnessite, buserite) is examined in a well-controlled experiment. Calcium buserite is prepared, and used in a split-batch synthetic protocol to prepare calcium birnessite, sodium buserite, and sodium birnessite, and partially dehydrated sodium birnessite. Thus, four samples are prepared in which features effecting catalytic efficiency (defect density, average manganese oxidation state) are controlled, and the main difference is the degree of hydration of the interlayer (two layers of water in buserites vs. one layer of water in birnessite). Molecular dynamics simulations predict birnessite samples to exhibit geometric water frustration, which facilitates redox catalysis by lowering the Marcus reorganization energy of electron transfer, while buserite samples exhibit traditional intermolecular hydrogen bonding among the two-layer aqeuous region, leading to slower catalytic behavior akin to redox reactions in bulk water. Water oxdiation activity is investigated using chemical and electrochemical techniques, demonstrating and quantifying the role of water frustration in enhancing catalysis. Calculation and experiment demonstrate dehydrated sodium birnessite to be most effective, and calcium buserite the least effective, with a difference in electrocatlytic overpotential of ∼750 mV and a ∼20-fold difference in turnover number. 

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3. Effect of Oxidation Level on the Interfacial Water at the Graphene Oxide–Water Interface: From Spectroscopic Signatures to Hydrogen-Bonding Environment

   https://doi.org/10.1021/acs.jpcb.0c05282  

   David, Rolf ; Tuladhar, Aashish ; Zhang, Le ; Arges, Christopher ; Kumar, Revati ( September 2020 , The Journal of Physical Chemistry B)

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4. Water-Soluble Pd Nanoparticles for the Anti-Markovnikov Oxidation of Allyl Benzene in Water

   https://doi.org/10.3390/nano13020348  

   Avila, Edwin ; Nixarlidis, Christos ; Shon, Young-Seok ( January 2023 , Nanomaterials)

   The catalytic activity and selectivity of two different water-soluble palladium nanoparticles capped with 5-(trimethylammonio)pentanethiolate and 6-(carboxylate)hexanethiolate ligands are investigated using the catalytic reaction of allyl benzene. The results show that the regioselective transformation of allyl benzene to 3-phenylpropanal occurs at room temperature and under atmospheric pressure in neat water via a Tsuji–Wacker type oxidation. Conventionally, the Tsuji–Wacker oxidation promotes the Markovnikov oxidation of terminal alkenes to their respective ketones in the presence of dioxygen. Water-soluble Pd nanoparticles, however, catalyze the anti-Markovnikov oxidation of allyl benzene to 3-phenylpropanal in up to 83% yields. Catalytic results of other aromatic alkenes suggest that the presence of benzylic hydrogen is a key to the formation of a p-allyl Pd intermediate and the anti-Markovnikov addition of H2O. The subsequent b-H elimination and tautomerization contribute to the formation of aldehyde products. Water-soluble Pd nanoparticles are characterized using nuclear magnetic resonance (NMR), UV–vis spectroscopy, thermogravimetric analysis (TGA), and transmission electron microscopy (TEM). Catalysis results are examined using 1H NMR and/or GC-MS analyses of isolated reaction mixtures. 

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5. Probing the Hydrogen-Bonded Water Network at the Active Site of a Water Oxidation Catalyst: [Ru(bpy)(tpy)(H 2 O)] 2+ ·(H 2 O) 0–4

   https://doi.org/10.1021/acs.jpca.5b04778  

   Duffy, Erin M. ; Marsh, Brett M. ; Garand, Etienne ( June 2015 , The Journal of Physical Chemistry A)