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1. Enhancing catalytic epoxide ring-opening selectivity using surface-modified Ti ₃ C ₂ T _x MXenes

   https://doi.org/10.1088/2053-1583/abe951  

   Slot, Thierry K.; Natu, Varun; Ramos-Fernandez, Enrique V.; Sepúlveda-Escribano, Antonio; Barsoum, Michel; Rothenberg, Gadi; Shiju, N. Raveendran (March 2021, 2D Materials)

   Abstract MXenes are a new family of two-dimensional carbides and/or nitrides. Their 2D surfaces are typically terminated by O, OH and/or F atoms. Here we show that Ti₃C₂T_x—the most studied compound of the MXene family—is a good acid catalyst, thanks to the surface acid functionalities. We demonstrate this by applying Ti₃C₂T_xin the epoxide ring-opening reaction of styrene oxide (SO) and its isomerization in the liquid phase. Modifying the MXene surface changes the catalytic activity and selectivity. By oxidizing the surface, we succeeded in controlling the type and number of acid sites and thereby improving the yield of the mono-alkylated product to >80%. Characterisation studies show that a thin oxide layer, which forms directly on the Ti₃C₂T_xsurface, is essential for catalysing the SO ring-opening. We hypothesize that two kinds of acid sites are responsible for this catalysis: In the MXene, strong acid sites (both Lewis and Brønsted) catalyse both the ring-opening and the isomerization reactions, while in the Mxene–TiO₂composite weaker acid sites catalyse only the ring-opening reaction, increasing the selectivity to the mono-alkylated product. 

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2. Interstellar Detection of 2-cyanocyclopentadiene, C ₅ H ₅ CN, a Second Five-membered Ring toward TMC-1

   https://doi.org/10.3847/2041-8213/abe764  

   Kelvin Lee, Kin Long; Changala, P. Bryan; Loomis, Ryan A.; Burkhardt, Andrew M.; Xue, Ci; Cordiner, Martin A.; Charnley, Steven B.; McCarthy, Michael C.; McGuire, Brett A. (March 2021, The Astrophysical Journal Letters)

   null (Ed.)
3. Design and implementation of floating field ring edge termination on vertical geometry β-Ga ₂ O ₃ rectifiers

   https://doi.org/10.1116/6.0000693  

   Sharma, Ribhu; Xian, Minghan; Law, Mark E.; Tadjer, Marko; Ren, Fan; Pearton, Stephen J. (December 2020, Journal of Vacuum Science & Technology A)
4. Discovery of the Seven-ring Polycyclic Aromatic Hydrocarbon Cyanocoronene (C ₂₄ H ₁₁ CN) in GOTHAM Observations of TMC-1

   https://doi.org/10.3847/2041-8213/adc911  

   Wenzel, Gabi; Gong, Siyuan; Xue, Ci; Changala, P Bryan; Holdren, Martin S; Speak, Thomas H; Stewart, D Archie; Fried, Zachary_T P; Willis, Reace_H J; Bergin, Edwin A; et al (April 2025, The Astrophysical Journal Letters)

   Abstract We present the synthesis and laboratory rotational spectroscopy of the seven-ring polycyclic aromatic hydrocarbon (PAH) cyanocoronene (C₂₄H₁₁CN) using a laser-ablation-assisted cavity-enhanced Fourier transform microwave spectrometer. A total of 71 transitions were measured and assigned between 6.8 and 10.6 GHz. Using these assignments, we searched for emission from cyanocoronene in the Green Bank Telescope (GBT) Observations of TMC-1: Hunting Aromatic Molecules project observations of the cold dark molecular cloud TMC-1 using the 100 m GBT. We detect a number of individually resolved transitions in ultrasensitiveX-band observations and perform a Markov Chain Monte Carlo analysis to derive best-fit parameters, including a total column density of $N\left({\mathrm{C}}_{24}{\mathrm{H}}_{11}\mathrm{CN}\right)=2.69_{-0.23}^{+0.26}\times 10^{12}{\mathrm{cm}}^{-2}$at a temperature of $6.05_{-0.37}^{+0.38}$K. A spectral stacking and matched filtering analysis provides a robust 17.3σsignificance to the overall detection. The derived column density is comparable to that of cyano-substituted naphthalene, acenaphthylene, and pyrene, defying the trend of decreasing abundance with increasing molecular size and complexity found for carbon chains. We discuss the implications of the detection for our understanding of interstellar PAH chemistry and highlight major open questions and next steps. 

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5. Heterolytic Cleavage of L _n Pd–SiR ₃ ⁺ Bonds Enable the Ring-Opening C–C Functionalization of Nonstrained Ethers

   https://doi.org/10.1021/jacs.5c12528  

   Owen, Bradley A; Basemann, Kevin; Hearne, William A; Gagné, Michel R (August 2025, Journal of the American Chemical Society)

   Silyl palladium cations (R3P)2Pd–SiR3+ catalyze the ring opening, C–C bond forming, and functionalization of 5- and 6-membered cyclic allyl ethers with O-silyl nucleophiles. Conditions for high regio-control are achieved by adjustments in the phosphine electronics, with the identity of the 2-substituent also influencing the functionalization location in unsymmetrical furans. Allyl alcohols are obtained with a regio-preference for terminal addition with unsubstituted ethers with E-products being obtained with XantPhos and Z- with (4-CF3–Ar)3 ligation. Styrenes dominate with phenyl-substituted dihydrofurans, and for 2-alkyl-substituted, secondary alcohols result from an allyl migration pathway. Mechanistic studies demonstrate the feasibility of Pd–Si+ bonds to facilitate C–O activation to yield π-allyl intermediates, and for one substrate class to also sequence π-allyl migration prior to nucleophilic addition. DFT calculations demonstrated the viability of silylium-activated ether as a competent ligand for Pd(0). 

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