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1. Proline C−H Bonds as Loci for Proline Assembly via C−H/O Interactions

   https://doi.org/10.1002/cbic.202200409  

   Daniecki, Noah_J; Bhatt, Megh_R; Yap, Glenn_P_A; Zondlo, Neal_J (November 2022, ChemBioChem)

   Abstract Proline residues within proteins lack a traditional hydrogen bond donor. However, the hydrogens of the proline ring are all sterically accessible, with polarized C−H bonds at Hα and Hδ that exhibit greater partial positive character and can be utilized as alternative sites for molecular recognition. C−H/O interactions, between proline C−H bonds and oxygen lone pairs, have been previously identified as modes of recognition within protein structures and for higher‐order assembly of protein structures. In order to better understand intermolecular recognition of proline residues, a series of proline derivatives was synthesized, including 4R‐hydroxyproline nitrobenzoate methyl ester, acylated on the proline nitrogen with bromoacetyl and glycolyl groups, and Boc‐4S‐(4‐iodophenyl)hydroxyproline methyl amide. All three derivatives exhibited multiple close intermolecular C−H/O interactions in the crystallographic state, with H⋅⋅⋅O distances as close as 2.3 Å. These observed distances are well below the 2.72 Å sum of the van der Waals radii of H and O, and suggest that these interactions are particularly favorable. In order to generalize these results, we further analyzed the role of C−H/O interactions in all previously crystallized derivatives of these amino acids, and found that all 26 structures exhibited close intermolecular C−H/O interactions. Finally, we analyzed all proline residues in the Cambridge Structural Database of small‐molecule crystal structures. We found that the majority of these structures exhibited intermolecular C−H/O interactions at proline C−H bonds, suggesting that C−H/O interactions are an inherent and important mode for recognition of and higher‐order assembly at proline residues. Due to steric accessibility and multiple polarized C−H bonds, proline residues are uniquely positioned as sites for binding and recognition via C−H/O interactions. 

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2. Phosphine-Directed sp ³ C–H, C–O, and C–N Borylation

   https://doi.org/10.1021/acs.joc.0c01706  

   Morris, Kelsey C.; Wright, Shawn E.; Meyer, Gillian F.; Clark, Timothy B. (November 2020, The Journal of Organic Chemistry)

   null (Ed.)
3. Molecules with ALMA at Planet-forming Scales (MAPS). XII. Inferring the C/O and S/H Ratios in Protoplanetary Disks with Sulfur Molecules

   https://doi.org/10.3847/1538-4365/ac2583  

   Le Gal, Romane; Öberg, Karin I.; Teague, Richard; Loomis, Ryan A.; Law, Charles J.; Walsh, Catherine; Bergin, Edwin A.; Ménard, François; Wilner, David J.; Andrews, Sean M.; et al (November 2021, The Astrophysical Journal Supplement Series)
4. Top-induced contributions to H → $$ b\overline{b} $$ and H → $$ c\overline{c} $$ at $$ \mathcal{O}\left({\alpha}_s^3\right) $$

   https://doi.org/10.1007/JHEP12(2020)058  

   Mondini, Roberto; Schubert, Ulrich; Williams, Ciaran (December 2020, Journal of High Energy Physics)

   null (Ed.)

   A bstract In this paper we present a fully-differential calculation for the contributions to the partial widths H → $$ b\overline{b} $$ b b ¯ and H → $$ c\overline{c} $$ c c ¯ that are sensitive to the top quark Yukawa coupling y t to order $$ {\alpha}_s^3 $$ α s 3 . These contributions first enter at order $$ {\alpha}_s^2 $$ α s 2 through terms proportional to y t y q ( q = b, c ). At order $$ {\alpha}_s^3 $$ α s 3 corrections to the mixed terms are present as well as a new contribution proportional to $$ {y}_t^2 $$ y t 2 . Our results retain the mass of the final-state quarks throughout, while the top quark is integrated out resulting in an effective field theory (EFT). Our results are implemented into a Monte Carlo code allowing for the application of arbitrary final-state selection cuts. As an example we present differential distributions for observables in the Higgs boson rest frame using the Durham jet clustering algorithm. We find that the total impact of the top-induced (i.e. EFT) pieces is sensitive to the nature of the final-state cuts, particularly b -tagging and c -tagging requirements. For bottom quarks, the EFT pieces contribute to the total width (and differential distributions) at around the percent level. The impact is much bigger for the H → $$ c\overline{c} $$ c c ¯ channel, with effects as large as 15%. We show however that their impact can be significantly reduced by the application of jet-tagging selection cuts. 

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5. Development of a Charge-Implicit ReaxFF for C/H/O Systems

   https://doi.org/10.1021/acs.jpclett.1c03867  

   Kański, Michał; Hrabar, Sviatoslav; van Duin, Adri C.; Postawa, Zbigniew (January 2022, The Journal of Physical Chemistry Letters)