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1. A zinc-based oxysulfide photocatalyst SrZn ₂ S ₂ O capable of reducing and oxidizing water

   https://doi.org/10.1039/c9dt03699g  

   Nishioka, Shunta; Kanazawa, Tomoki; Shibata, Kengo; Tsujimoto, Yoshihiro; zur Loye, Hans-Conrad; Maeda, Kazuhiko (October 2019, Dalton Transactions)

   Although Zn-based binary semiconductors such as ZnO and ZnS are photocatalytically unstable toward water oxidation, we found that mixed-anionization successfully addressed this issue. This report shows that an oxysulfide SrZn 2 S 2 O functions as a photocatalyst to reduce and oxidize water under band-gap irradiation without noticeable decomposition of the material. 

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2. Trifluoromethyl substitution enhances photoinduced activity against breast cancer cells but reduces ligand exchange in Ru( ii ) complex

   https://doi.org/10.1039/d1sc03213e  

   Lanquist, Austin P.; Gupta, Sayak; Al-Afyouni, Kathlyn F.; Al-Afyouni, Malik; Kodanko, Jeremy J.; Turro, Claudia (September 2021, Chemical Science)

   A series of five ruthenium complexes containing triphenyl phosphine groups known to enhance both cellular penetration and photoinduced ligand exchange, cis -[Ru(bpy) 2 (P( p -R-Ph) 3 )(CH 3 CN)] 2+ , where bpy = 2,2′-bipyridine and P( p -R-Ph) 3 represent para -substituted triphenylphosphine ligands with R = –OCH 3 (1), –CH 3 (2) –H (3), –F (4), and –CF 3 (5), were synthesized and characterized. The photolysis of 1–5 in water with visible light ( λ irr ≥ 395 nm) results in the substitution of the coordinated acetonitrile with a solvent molecule, generating the corresponding aqua complex as the single photoproduct. A 3-fold variation in quantum yield was measured with 400 nm irradiation, Φ 400 , where 1 is the most efficient with a Φ 400 = 0.076(2), and 5 the least photoactive complex, with Φ 400 = 0.026(2). This trend is unexpected based on the red-shifted metal-to-ligand charge transfer (MLCT) absorption of 1 as compared to that of 5, but can be correlated to the substituent Hammett para parameters and p K a values of the ancillary phosphine ligands. Complexes 1–5 are not toxic towards the triple negative breast cancer cell line MDA-MB-231 in the dark, but 3 and 5 are >4.2 and >19-fold more cytotoxic upon irradiation with blue light, respectively. A number of experiments point to apoptosis, and not to necrosis or necroptosis, as the mechanism of cell death by 5 upon irradiation. These findings provide a foundation for understanding the role of phosphine ligands on photoinduced ligand substitution and show the enhancement afforded by –CF 3 groups on photochemotherapy, which will aid the future design of photocages for photochemotherapeutic drug delivery. 

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3. In vitro oxidations of low-density lipoprotein and RAW 264.7 cells with lipophilic O( ³ P)-precursors

   https://doi.org/10.1039/D0RA01517B  

   Petroff, John T.; Isor, Ankita; Chintala, Satyanarayana M.; Albert, Carolyn J.; Franke, Jacob D.; Weinstein, David; Omlid, Sara M.; Arnatt, Christopher K.; Ford, David A.; McCulla, Ryan D. (July 2020, RSC Advances)

   A beneficial property of photogenerated reactive oxygen species (ROS) is the capability of oxidant generation within a specific location or organelle inside a cell. Dibenzothiophene S -oxide ( DBTO ), which is known to undergo a photodeoxygenation reaction to generate ground state atomic oxygen [O( 3 P)] upon irradiation, was functionalized to afford localization within the plasma membrane of cells. The photochemistry, as it relates to oxidant generation, was studied and demonstrated that the functionalized DBTO derivatives generated O( 3 P). Irradiation of these lipophilic O( 3 P)-precursors in the presence of LDL and within RAW 264.7 cells afforded several oxidized lipid products (oxLP) in the form of aldehydes. The generation of a 2-hexadecenal ( 2-HDEA ) was markedly increased in irradiations where O( 3 P) was putatively produced. The substantial generation of 2-HDEA is not known to accompany the production of other ROS. These cellular irradiation experiments demonstrate the potential of inducing oxidation with O( 3 P) in cells. 

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4. In situ aerobic methane oxidation rates in a stratified lake

   https://doi.org/10.1002/lno.12583  

   Hudspeth, Zachary W; Morningstar, Joshua L; Mendlovitz, Howard P; Baily, Jennifer A; Lloyd, Karen G; Martens, Christopher S (May 2024, Limnology and Oceanography)

   Abstract Microbial aerobic methane oxidation is an important sink for aquatic methane worldwide. Despite its importance to global methane fluxes, few aerobic methane oxidation rates have been obtained in freshwater or marine environments without imposing changes to the microbial community through use of ex situ methods. A novel in situ incubation method for continuous time‐series measurements was used in Jordan Lake, North Carolina, during 2020–2021, to determine reaction kinetics for aerobic methane oxidation rates across a wide range of naturally varying methane (55–1833 nM) and dissolved oxygen (DO; 28–366 μM) concentrations and temperatures (17–30°C). Methane oxidation began immediately at the start of each of 21 incubations and methane oxidation rates were 1^storder with respect to methane. The data density allowed for accurate calculation of 1^st‐order rate constants,k, that ranged from 0.018 to 0.462 h⁻¹(R² > 0.967). Addition of ammonium (20–45 μM) to natural concentrations ranging from 0.057 to 2.4 μM did not change aerobic methane oxidation rate kinetics, suggesting that the natural population of aerobic methane oxidizers in this eutrophic lake was not nitrogen limited. Values ofkinversely correlated most strongly with initial DO concentrations (R² = 0.82) rather than temperature. Values forkincreased with Julian day throughout our sampling period, suggesting seasonal influences on methane oxidation via responses to geochemical changes or shifts in microbial community abundance and composition. These experiments demonstrate a high variability in the enzymatic capacity for 1^st‐order methane oxidation rates in this eutrophic lake that is tightly and inversely coupled to oxygen concentrations. Measurements of in situ aerobic methane oxidation rate constants allow for the direct quantification and modeling of the microbial community's capacity for methane oxidation over a wide range of natural methane concentrations. 

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5. Cu( i )–O ₂ oxidation reactions in a fluorinated all-O-donor ligand environment

   https://doi.org/10.1039/C8DT05028G  

   Brazeau, Sarah E.; Doerrer, Linda H. (April 2019, Dalton Transactions)

   Investigation of Cu–O 2 oxidation reactivity is important in biological and anthropogenic chemistry. Zeolites are one of the most promising Cu/O based oxidation catalysts for development of industrial-scale CH 4 to CH 3 OH conversion. Their oxidation mechanisms are not well understood, however, highlighting the importance of the investigation of molecular Cu( i )–O 2 reactivity with O-donor complexes. Herein, we give an overview of the synthesis, structural properties, and O 2 reactivity of three different series of O-donor fluorinated Cu( i ) alkoxides: K[Cu(OR) 2 ], [(Ph 3 P)Cu(μ-OR) 2 Cu(PPh 3 )], and K[(R 3 P)Cu(pin F )], in which OR = fluorinated monodentate alkoxide ligands and pin F = perfluoropinacolate. This breadth allowed for the exploration of the influence of the denticity of the ligand, coordination number, the presence of phosphine, and K⋯F/O interactions on their O 2 reactivity. K⋯F/O interactions were required to activate O 2 in the monodentate-ligand-only family, whereas these connections did not affect O 2 activation in the bidentate complexes, potentially due to the presence of phosphine. Both families formed trisanionic, trinuclear cores of the form {Cu 3 (μ 3 -O) 2 } 3− . Intramolecular and intermolecular substrate oxidation were also explored and found to be influenced by the fluorinated ligand. Namely, {Cu 3 (μ 3 -O) 2 } 3− from K[Cu(OR) 2 ] could perform both monooxygenase reactivity and oxidase catalysis, whereas those from K[(R 3 P)Cu(pin F )] could only perform oxidase catalysis. 

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