1. (2RS,5'RS)-3',4'-Bis(4-chloro-phen-yl)-3,4-dihydro-spiro-[acridine-2,5'(4'H)-[1,2]oxazol]-1(2H)-one
Ponmudisettu Narayanan, Shanmugavel Uma Maheswari, Krishnan Sethusankar Acta Crystallogr Sect E Struct Rep Online. 2012 Dec 1;68(Pt 12):o3289. doi: 10.1107/S1600536812045084. Epub 2012 Nov 7.
The title compound, C27H18Cl2N2O2, represents a racemic mixture of the corresponding R,R and S,S diastereomers. The isoxazoline ring adopts an envelope conformation with the spiro C atom deviating by 0.093 (2) Å from the rest of the ring. The six-membered keto-substituted carbocycle has a sofa conformation with the methyl-ene C atom adjacent to the spiro center deviating by 0.289 (2) Å from the mean plane of the remaining atoms. In the crystal, mol-ecules are linked via C-H⋯Cl inter-actions and C-Cl⋯O halogen bonds [2.958 (2) Å, 171.39 (7)°], which generate bifurcated R2(1)(6) ring motifs resulting in C2(1)[R2(1)(6)] chains running parallel to [010].
2. Selectively Enhanced 1H-1H Correlations in Proton-Detected Solid-State NMR under Ultrafast MAS Conditions
Zhengfeng Zhang, Andres Oss, Mai-Liis Org, Ago Samoson, Mingyue Li, Huan Tan, Yongchao Su, Jun Yang J Phys Chem Lett. 2020 Oct 1;11(19):8077-8083. doi: 10.1021/acs.jpclett.0c02412. Epub 2020 Sep 14.
Proton-detected solid-state NMR has emerged as a powerful analytical technique in structural elucidation via 1H-1H correlations, which are mostly established by broadband methods. We propose a new class of frequency-selective homonuclear recoupling methods to selectively enhance 1H-1H correlations of interest under ultrafast magic-angle spinning (MAS). These methods, dubbed as selective phase-optimized recoupling (SPR), can provide a sensitivity enhancement by a factor of ~3 over the widely used radio-frequency-driven recoupling (RFDR) to observe 1HN-1HN contacts in a protonated tripeptide N-formyl-Met-Leu-Phe (fMLF) under 150 kHz MAS and are successfully utilized to probe a long-range 1H-1H contact in a pharmaceutical molecule, the hydrochloride form of pioglitazone (PIO-HCl). SPR is not only highly efficient in frequency-selective recoupling but also easy to implement, imparting to it great potential to probe 1H-1H contacts for the structural elucidation of organic solids such as proteins and pharmaceuticals under ultrafast MAS conditions.
3. Tin-sulfur based catalysts for acetylene hydrochlorination
Yibo Wu, et al. Turk J Chem. 2021 Jun 30;45(3):566-576. doi: 10.3906/kim-2010-36. eCollection 2021.
In the present work, tin-sulfur based catalysts were prepared using Na2SO3 and (CH3SO3)2Sn and were tested in acetylene hydrochlorination. Based on the analysis of experiments results, the acetylene conversion of (CH3SO3)2Sn/S@AC is still over 90%after a 50 h reaction, at the reaction conditions of T = 200 oC, VHCl/VC2H2 = 1.1:1.0 and C2H2-GSHV = 15 h-1. According to the results of X-ray photoelectron spectroscopy (XPS), HCl adsorption experiments, and acetylene temperature programmed desorption (C2H2-TPD), it is reasonable to conclude that the interaction between Sn and S not only can retard the oxidation of Sn2+ in catalysts but also strengthen the reactant adsorption capacity of tin-based catalysts. Furthermore, results obtained from nitrogen adsorption/desorption and XPS proved that the CH3SO3- can effectively decrease the coke deposition of (CH3SO3)2Sn/AC and thus prolong the lifetime of (CH3SO3)2Sn/AC.
