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A new cooperative photoredox catalytic system, [Ru^II(trpy)(bpy)(H₂O)][3,3′-Co(8,9,12-Cl₃-1,2-C₂B₉H₈)₂]₂, 5, has been synthesized and fully characterized for the first time. In this system, the photoredox catalyst [3,3′-Co(8,9,12-Cl₃-1,2-C₂B₉H₈)₂]⁻ [Cl₆-1]⁻, a metallacarborane, and the oxidation catalyst [Ru^II(trpy)(bpy)(H₂O)]²⁺, 2 are linked by non-covalent interactions. This compound, along with the one previously synthesized by us, [Ru^II(trpy)(bpy)(H₂O)][(3,3′-Co(1,2-C₂B₉H₁₁)₂]₂, 4, are the only examples of cooperative molecular photocatalysts in which the catalyst and photosensitizer are not linked by covalent bonds. Both cooperative systems have proven to be efficient photocatalysts for the oxidation of alkenes in water through Proton Coupled Electron Transfer processes (PCETs). Using 0.05 mol% of catalyst 4, total conversion values were achieved after 15 min with moderate selectivity for the corresponding epoxides, which decreases with reaction time, along with the TON values. However, with 0.005 mol% of catalyst, the conversion values are lower, but the selectivity and TON values are higher. This occurs simultaneously with an increase in the amount of the corresponding diol for most of the substrates studied. Photocatalyst 4 acts as a photocatalyst in both the epoxidation of alkenes and their hydroxylation in aqueous medium. The hybrid system 5 shows generally higher conversion values at low loads compared to those obtained with 4 for most of the substrates studied. However, the selectivity values for the corresponding epoxides are lower even after 15 min of reaction. This is likely due to the enhanced oxidizing capacity of Co^IV in catalyst 5, resulting from the presence of more electron-withdrawing substituents on the metallacarborane platform. Full article

Transient potential receptor (TRP) channels are conserved cation channels found in most eukaryotes, known to sense a variety of chemical, thermal or mechanical stimuli. The Saccharomyces cerevisiae TRPY1 is a TRP channel with vacuolar localization involved in the cellular response to hyperosmotic shock and oxidative stress. In this study, we found that S. cerevisiae diploid cells with heterozygous deletion in TRPY1 gene are haploinsufficient when grown in synthetic media deficient in essential metal ions and that this growth defect is alleviated by non-toxic Mn²⁺ surplus. Using cells expressing the Ca²⁺-sensitive photoprotein aequorin we found that Mn²⁺ augmented the Ca²⁺ flux into the cytosol under oxidative stress, but not under hyperosmotic shock, a trait that was absent in the diploid cells with homozygous deletion of TRPY1 gene. TRPY1 activation under oxidative stress was diminished in cells devoid of Smf1 (the Mn²⁺-high-affinity plasma membrane transporter) but it was clearly augmented in cells lacking Pmr1 (the endoplasmic reticulum (ER)/Golgi located ATPase responsible for Mn²⁺ detoxification via excretory pathway). Taken together, these observations lead to the conclusion that increased levels of intracytosolic Mn²⁺ activate TRPY1 in the response to oxidative stress. Full article