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1. Synthesis and characterization of modular polyphosphonate homopolymers and copolymers

   https://doi.org/10.1002/pol.20200066  

   Totsch, Timothy R.; Stanford, Victoria L.; Klep, Oleksander; Burdette, Mary K.; Grant, Benjamin; Foulger, Stephen H.; Gray, Gary M. (June 2020, Journal of Polymer Science)

   Abstract Linear polyphosphonates with the generic formula –[P(Ph)(X)OR′O]_n– (X = S or Se) have been synthesized by polycondensations of P(Ph)(NEt₂)₂and a diol (HOR′OH = 1,4‐cyclohexanedimethanol, 1,4‐benzenedimethanol, tetraethylene glycol, or 1,12‐dodecanediol) followed by reaction with a chalcogen. Random copolymers have been synthesized by polycondensations of P(Ph)(NEt₂)₂and mixture of two of the diols in a 2:1:1 mol ratio followed by reaction with a chalcogen. Block copolymers with the generic formula –[P(Ph)(X)OR′O]_(x + 2)–[P(Ph)(X)OR′O]_(x + 3)– (X = S or Se) have been synthesized by the polycondensations of Et₂N[P(Ph)(X)OR′O]_(x + 2)P(Ph)NEt₂oligomers with HOR′O[P(Ph)(X)OR′O]_(x + 3)H oligomers followed by reaction with a chalcogen. The Et₂N[P(Ph)(X)OR′O]_(x + 2)P(Ph)NEt₂oligomers are prepared by the reaction of an excess of P(Ph)(NEt₂)₂with a diol while the HOR′O[P(Ph)(X)OR′O]_(x + 3)H oligomers are prepared by the reaction of P(Ph)(NEt₂)₂with an excess of the diol. In each case the excess, x is the same and determines the average block sizes. All of the polymers were characterized using¹H,¹³C{¹H}, and³¹P{¹H} NMR spectroscopy, TGA, DSC, and SEC.³¹P{¹H} NMR spectroscopy demonstrates that the random and block copolymers have the expected arrangements of monomers and, in the case of block copolymers, verifies the block sizes. All polymers are thermally stable up to ~300°C, and the arrangements of monomers in the copolymers (block vs. random) affect their degradation temperatures andT_gprofiles. The polymers have weight average MWs of up to 3.8 × 10⁴ Da. 

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2. Cooperative Bond Activation and Facile Intramolecular Aryl Transfer of Nickel–Aluminum Pincer‐type Complexes

   https://doi.org/10.1002/anie.202104050  

   Graziano, Brendan J.; Vollmer, Matthew V.; Lu, Connie C. (June 2021, Angewandte Chemie International Edition)

   Abstract Pincer‐type nickel–aluminum complexes were synthesized using two equivalents of the phosphinoamide, [PhNCH₂PⁱPr₂]⁻. The Ni⁰–Al^IIIcomplexes, {(^MesPAlP)Ni}₂(μ‐N₂) and {(^MesPAlP)Ni}₂(μ‐COD), where^MesPAlP is (Mes)Al(NPhCH₂PⁱPr₂)₂, were structurally characterized. The (PAlP)Ni system exhibited cooperative bond cleavage mediated by the two‐site Ni–Al unit, including oxidative addition of aryl halides, H₂activation, and ortho‐directed C−H bond activation of pyridine N‐oxide. One intriguing reaction is the reversible intramolecular transfer of the mesityl ring from the Al to the Ni site, which is evocative of the transmetalation step during cross‐coupling catalysis. The aryl‐transfer product,(THF)Al(NPhCH₂PⁱPr₂)₂Ni(Mes), is the first example of a first‐row transition metal–aluminyl pincer complex. The addition of a judicious donor enables the Al metalloligand to convert reversibly between the alane and aluminyl forms via aryl group transfer to and from Ni, respectively. Theoretical calculations support a zwitterionic Ni^δ−–Al^δ+electronic structure in the nickel–aluminyl complex. 

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3. Mixed Signals From the Stable Isotope Composition of Precipitation and Plant Waxes in the Northern Tropical Andes

   https://doi.org/10.1029/2022JG006932  

   Pérez‐Angel, Lina C.; Sepúlveda, Julio; Montes, Camilo; Smith, Jamila J.; Molnar, Peter; González‐Arango, Catalina; Snell, Kathryn E.; Dildar, Nadia (December 2022, Journal of Geophysical Research: Biogeosciences)

   Abstract We evaluate the efficacy of the stable isotope composition of precipitation and plant waxes as proxies for paleoaltimetry and paleohydrology in the northern tropical Andes. We report monthly hydrogen (δ²H_p) and oxygen (δ¹⁸O_p) isotope values of precipitation for an annual cycle, and hydrogen isotope values of plant waxes (δ²H_wax) obtained from modern soils along the eastern and western flanks of the Eastern Cordillera of Colombia. δ²H_p, δ¹⁸O_p, as well as the unweighted mean δ²H_waxvalues ofn‐C₂₉,n‐C₃₁, andn‐C₃₃n‐alkanes in the eastern flank show a dependence on elevation (R² = 0.90, 0.82, and 0.65, respectively). In stark contrast, the stable isotope compositions of neither precipitation nor plant waxes from the western flank correlate with elevation (R² < 0.23), on top of a negligible (p‐value >0.05) correlation between δ²H_waxand δ²H_p. In general, δ²H_waxvalues along the eastern flank of the Eastern Cordillera seem to follow the trend of a simple Rayleigh distillation process that is consistent with studies elsewhere on the eastern side of the Andes in South America. Neither δ²H_pnor δ¹⁸O_p, and therefore δ²H_wax, offer reliable estimates of past elevations in the western flank, due perhaps to water vapor source mixing, evaporation overprint, contrasting plant communities, and/or differences in evapotranspiration. Thus, δ²H_waxis only reliable for paleohydrology and paleoaltimetry reconstructions on the eastern flank of the Andes, whereas interpretations based on δ²H_pand/or δ¹⁸O_pwest of the highest point of the Eastern Cordillera need to consider mixing of moisture sources in addition to precipitation amount. 

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4. Syntheses and crystal structures of three triphenylsulfonium halometallate salts of zinc, cadmium and mercury

   https://doi.org/10.1107/S2056989025002245  

   Artis, Rylan; Heyward, Elizabeth; Reyes, Naomi; Van_Ostenbridge, Kaitlyn; Lynch, Will E; Padgett, Clifford W (April 2025, Acta Crystallographica Section E Crystallographic Communications)

   Bis(triphenylsulfonium) tetrachloridozinc(II), (C₁₈H₁₅S)₂[ZnCl₄] (I), bis(triphenylsulfonium) tetrachloridocadmium(II), (C₁₈H₁₅S)₂[CdCl₄] (II), and bis(triphenylsulfonium) tetrachloridomercury(II) methanol monosolvate, (C₁₈H₁₅S)₂[HgCl₄]·CH₃OH (III), each crystallize in the monoclinic space groupP2₁/n. In all three structures, there are two crystallographically independent triphenylsulfonium (TPS) cations per asymmetric unit, each adopting a distorted trigonal–pyramidal geometry about the S atom (S—C bond lengths in the 1.77–1.80 Å range and C—S—C angles of 100–107°). The [MCl₄]^2–anions (M= Zn²⁺, Cd²⁺, Hg²⁺) are tetrahedral; their M—Cl bond lengths systematically increase from Zn²⁺to Hg²⁺, consistent with the larger ionic radius of the heavier metal. Hirshfeld surface analyses show that H...H and H...C contacts dominate the TPS cation environments, whereas H...Cl and S...Minteractions anchor each [MCl₄]^2–anion to two surrounding TPS cations. Weak C—H...Cl hydrogen bonds, as well as inversion-centered π–π stacking, generate layers in (I) and (II) and dimeric [(TPS)₂–HgCl₄]₂assemblies in (III). 

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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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