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1. Metallacyclobuta‐(2,3)‐diene: A Bidentate Ligand for Stream‐line Synthesis of First Row Transition Metal Catalysts for Cyclic Polymerization of Phenylacetylene

   https://doi.org/10.1002/anie.202318956  

   Russell, John B; Konar, Debabrata; Keller, Taylor M; Gau, Michael R; Carroll, Patrick J; Telser, Joshua; Lester, Daniel W; Veige, Adam S; Sumerlin, Brent S; Mindiola, Daniel J (February 2024, Angewandte Chemie International Edition)

   Not, available (Ed.)

   Abstract Described here is a direct entry to two examples of 3d transition metal catalysts that are active for the cyclic polymerization of phenylacetylene, namely, [(BDI)M{κ²‐C,C‐(Me₃SiC₃SiMe₃)}] (2‐M) (BDI=[ArNC(CH₃)]₂CH⁻, Ar=2,6‐ⁱPr₂C₆H₃;M=Ti, V). Catalysts are prepared in one step by the treatment of [(BDI)MCl₂] (1‐M,M=Ti,V) with 1,3‐dilithioallene [Li₂(Me₃SiC₃SiMe₃)]. Complexes2‐Mhave been spectroscopically and structurally characterized and the polymers that are catalytically formed from phenylacetylene were verified to have a cyclic topology based on a combination of size‐exclusion chromatography (SEC) and intrinsic viscosity studies. Two‐electron oxidation of2‐Vwith nitrous oxide (N₂O) cleanly yields a [V^V] alkylidene‐alkynyl oxo complex [(BDI)V(=O){κ¹‐C‐(=C(SiMe₃)CC(SiMe₃))}] (3), which lends support for how this scaffold in2‐Mmight be operating in the polymerization of the terminal alkyne. This work demonstrates how alkylidynes can be circumvented using 1,3‐dianionic allene as a segue into M−C multiple bonds. 

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2. Lewis Acidity of the SbCl ₃ / o ‐chloranil System

   https://doi.org/10.1002/anie.202505893  

   Şit, Ferit; Hunter, Nathanael H; Maltz, Logan T; Gabbaï, François P (July 2025, Angewandte Chemie International Edition)

   Abstract While SbCl₃is typically inert toward oxidation byortho‐quinones, we useo‐chloranil to show that the outcome of such reactions may be altered by the presence of a donor such as triphenylphosphine oxide, which readily traps the SbCl₃(cat^Cl) synthon (cat^Cl = tetrachlorocatecholate) in the form of the corresponding adduct Ph₃PO→SbCl₃(cat^Cl). The same reaction in the presence of a chloride salt affords the corresponding antimonate anion [Cl₄Sb(cat^Cl)]⁻. Computational studies indicate that the putative SbCl₃(cat^Cl) synthon has a higher chloride ion affinity than SbCl₅, suggesting significant Lewis acidity. This property is further demonstrated by the use of the SbCl₃/o‐chloranil system for both THF polymerization and a Friedel–Crafts‐type alkylation of benzene using 1‐fluorooctane. Finally, the reaction ofE‐stilbene witho‐chloranil in the presence of SbCl₃affords the corresponding benzodioxene, suggesting that SbCl₃may also operate as a redox‐active catalyst. 

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3. Riboflavin‐Catalyzed Photoinduced Atom Transfer Radical Polymerization

   https://doi.org/10.1002/macp.202400323  

   Coskun, Halil Ibrahim; Votruba‐Drzal, Thomas; Wu, Hanshu; Jockusch, Steffen; Yilmaz, Gorkem; Matyjaszewski, Krzysztof (April 2025, Macromolecular Chemistry and Physics)

   Abstract The photoATRP of methyl acrylate (MA) is investigated using riboflavin (RF) and CuBr₂/Me₆TREN as a dual catalyst system under green LED irradiation (λ ≈ 525 nm). Both RF and CuBr₂/Me₆TREN enhanced oxygen tolerance, enabling effective ATRP in the presence of residual oxygen. High molar mass polymers (up toM_n ≈ 129 000 g·mol⁻¹) with low dispersity (Đ≤ 1.16) are prepared, and chain‐end fidelity is confirmed through successful chain extension. The molecular masses of the obtained polymer increased linearly with conversion and showed high initiation efficiency. Mechanistic studies by laser flash photolysis reveal that the predominant activator generation mechanism is reductive quenching of RF by Me₆TREN (83%, under [CuBr₂]/[Me₆TREN] = 1/3 condition), supported by polymerization kinetics and thermodynamic calculations. 

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4. Quaternary Ammonium‐Containing Polyelectrolyte Brush Particles for Removal of Perrhenate Anion From Water: Effect of N ‐Substituents

   https://doi.org/10.1002/marc.202401087  

   Ojima, Kingsley O; Dayarathne, Sachini H; Kelly, Michael T; Zhao, Bin (February 2025, Macromolecular Rapid Communications)

   Abstract Radioactive pertechnetate (TcO₄⁻) from the nuclear fuel cycle presents a severe risk to the environment due to its large solubility in water and non‐complexing nature. By utilizing the chaotropic properties of TcO₄⁻and its nonradioactive surrogate perrhenate (ReO₄⁻) and the principle of chaotropic interactions, a series of quaternary ammonium‐containing polyelectrolyte brush‐grafted silica particles are designed and applied to remove ReO₄⁻from water. These cationic hairy particles (HPs) are synthesized by surface‐initiated atom transfer radical polymerization of 2‐(N,N‐dimethylamino)ethyl methacrylate and subsequent quaternization with various halogen compounds. Dynamic light scattering (DLS) studies showed that the HPs with sufficiently longN‐alkyl andN‐benzyl substituents underwent sharp size reduction transitions in water when titrated with a KReO₄solution, indicating strong chaotropic interactions between the brushes and ReO₄⁻. All the HPs exhibited fast adsorption kinetics; the HPs with longerN‐alkyl andN‐benzyl substituents showed higher capabilities of removing ReO₄⁻than those with shorterN‐alkyls. Moreover, the brush particles with longerN‐substituents displayed a significantly stronger ability in selective adsorption of ReO₄⁻than the particles with shorterN‐substituents in the presence of competing anions, such as F⁻, Cl⁻, NO₃⁻, and SO₄²⁻. This work opens a new avenue to design high‐performance adsorbent materials for TcO₄⁻and ReO₄⁻. 

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5. Production and cross-feeding of nitrite within Prochlorococcus populations

   https://doi.org/10.1128/mbio.01236-23  

   Berube, Paul M.; O'Keefe, Tyler J.; Rasmussen, Anna; LeMaster, Trent; Chisholm, Sallie W. (July 2023, mBio)

   Dubilier, Nicole (Ed.)

   ABSTRACT Prochlorococcusis an abundant photosynthetic bacterium in the open ocean, where nitrogen (N) often limits phytoplankton growth. In the low-light-adapted LLI clade ofProchlorococcus, nearly all cells can assimilate nitrite (NO₂⁻), with a subset capable of assimilating nitrate (NO₃⁻). LLI cells are maximally abundant near the primary NO₂⁻maximum layer, an oceanographic feature that may, in part, be due to incomplete assimilatory NO₃⁻reduction and subsequent NO₂⁻release by phytoplankton. We hypothesized that someProchlorococcusexhibit incomplete assimilatory NO₃⁻reduction and examined NO₂⁻accumulation in cultures of threeProchlorococcusstrains (MIT0915, MIT0917, and SB) and twoSynechococcusstrains (WH8102 and WH7803). Only MIT0917 and SB accumulated external NO₂⁻during growth on NO₃⁻. Approximately 20–30% of the NO₃⁻transported into the cell by MIT0917 was released as NO₂⁻, with the rest assimilated into biomass. We further observed that co-cultures using NO₃⁻as the sole N source could be established for MIT0917 andProchlorococcusstrain MIT1214 that can assimilate NO₂⁻but not NO₃⁻. In these co-cultures, the NO₂⁻released by MIT0917 is efficiently consumed by its partner strain, MIT1214. Our findings highlight the potential for emergent metabolic partnerships that are mediated by the production and consumption of N cycle intermediates withinProchlorococcuspopulations. IMPORTANCEEarth’s biogeochemical cycles are substantially driven by microorganisms and their interactions. Given that N often limits marine photosynthesis, we investigated the potential for N cross-feeding within populations ofProchlorococcus, the numerically dominant photosynthetic cell in the subtropical open ocean. In laboratory cultures, someProchlorococcuscells release extracellular NO₂⁻during growth on NO₃⁻. In the wild,Prochlorococcuspopulations are composed of multiple functional types, including those that cannot use NO₃⁻but can still assimilate NO₂⁻. We show that metabolic dependencies arise whenProchlorococcusstrains with complementary NO₂⁻production and consumption phenotypes are grown together on NO₃⁻. These findings demonstrate the potential for emergent metabolic partnerships, possibly modulating ocean nutrient gradients, that are mediated by cross-feeding of N cycle intermediates. 

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