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1. Synthesis of 2,5-Dibutyl-3,6-dimethyl-1 H ,2 H ,4 H ,5 H -pyrrolo[3,4- c ]pyrrole-1,4-dione: A Diketopyrrolopyrrole Scaffold for the Formation of Alkenyldiketopyrrolopyrrole Compounds

   https://doi.org/10.1021/acs.orglett.9b00019  

   Feng, Daijun; Barton, George; Scott, Colleen N. (March 2019, Organic Letters)
2. Luminescent 1 H -1,3-benzazaphospholes

   https://doi.org/10.1039/d2ra07226b  

   Evariste, Sloane; Harrison, Alexandra M.; Sarkar, Sunandan; Rheingold, Arnold L.; Dunietz, Barry D.; Heinicke, Joachim W.; Delgado Rosario, Emalyn; Yoon, Sungwoon; Teets, Thomas S.; Protasiewicz, John D. (December 2022, RSC Advances)

   2-R-1 H -1,3-Benzazaphospholes (R-BAPs) are an interesting class of σ 2 P heterocycles containing PC bonds. While closely related 2-R-1,3-benzoxaphospholes (R-BOPs) have been shown to be highly photoluminescent materials depending on specific R substituents, photoluminescence of R-BAPs has been previously limited to an example having a fused carbazole ring system. Here we detail the synthesis and structural characterization of a new R-BAP (3c, R = 2,2′-dithiophene), and compare its photoluminescence against two previously reported R-BAPs (3a, R, R′ = Me and 3b, R = 2-thiophene). The significant fluorescence displayed by the thiophene derivatives 3b ( φ = 0.53) and 3c ( φ = 0.12) stands in contrast to the weakly emissive methyl substituted analogue 3a ( φ = 0.08). Comparative computational investigations of 3a–c offer insights into the interplay between structure–function relationships affecting excited state relaxation processes. 

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3. Precise equilibrium structures of 1 H - and 2 H -1,2,3-triazoles (C2H3N3) by millimeter-wave spectroscopy

   https://doi.org/10.1063/5.0097750  

   Zdanovskaia, Maria A.; Esselman, Brian J.; Kougias, Samuel M.; Amberger, Brent K.; Stanton, John F.; Woods, R. Claude; McMahon, Robert J. (August 2022, The Journal of Chemical Physics)

   The 1H- and 2H-1,2,3-triazoles are isomeric five-membered ring, aromatic heterocycles that may undergo chemical equilibration by virtue of intramolecular hydrogen migration (tautomerization). Using millimeter-wave spectroscopy in the 130–375 GHz frequency range, we measured the spectroscopic constants for thirteen 1H-1,2,3-triazole and sixteen 2H-1,2,3-triazole isotopologues. Herein, we provide highly accurate and highly precise semi-experimental equilibrium (reSE) structures for the two tautomers based on the spectroscopic constants of each set of isotopologues, together with vibration–rotation interaction and electron-mass distribution corrections calculated using coupled-cluster singles, doubles, and perturbative triples calculations [CCSD(T)/cc-pCVTZ]. The resultant structures are compared with a “best theoretical estimate” (BTE), which has recently been shown to be in exceptional agreement with the semi-experimental equilibrium structures of other aromatic molecules. Bond distances of the 1H tautomer are determined to <0.0008 Å and bond angles to <0.2°. For the 2H tautomer, bond angles are also determined to <0.2°, but bond distances are less precise (2σ ≤ 0.0015). Agreement between BTE and reSE values is discussed. 

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4. Mixed norm H ₂ / H _∞ and entropy covariance control: a convex optimisation approach

   https://doi.org/10.1080/00207179.2020.1833251  

   Haddad, Wassim M.; Lanchares, Manuel; Chen, Yongxin (January 2020, International Journal of Control)

   null (Ed.)
5. H β and H γ Absorption-line Profile Inconsistencies in Laboratory Experiments Performed at White Dwarf Photosphere Conditions

   https://doi.org/10.3847/1538-4357/ab479d  

   Schaeuble, M.-A.; Nagayama, T.; Bailey, J. E.; Gomez, T. A.; Montgomery, M. H.; Winget, D. E. (November 2019, The Astrophysical Journal)