More Like this

1. Crystal structures of (η ⁴ -cycloocta-1,5-diene)bis(1,3-dimethylimidazol-2-ylidene)iridium(I) iodide and (η ⁴ -cycloocta-1,5-diene)bis(1,3-diethylimidazol-2-ylidene)iridium(I) iodide

   https://doi.org/10.1107/S2056989020004235  

   Bernier, Chad M.; DuChane, Christine M.; Merola, Joseph S. (May 2020, Acta Crystallographica Section E Crystallographic Communications)

   null (Ed.)

   The title complexes, (η 4 -cycloocta-1,5-diene)bis(1,3-dimethylimidazol-2-ylidene)iridium(I) iodide, [Ir(C 5 H 8 N 2 ) 2 (C 8 H 12 )]I, ( 1 ) and (η 4 -cycloocta-1,5-diene)bis(1,3-diethylimidazol-2-ylidene)iridium(I) iodide, [Ir(C 7 H 12 N 2 ) 2 (C 8 H 12 )]I, ( 2 ), were prepared using a modified literature method. After carrying out the oxidative addition of the amino acid L-proline to [Ir(COD)(IMe) 2 ]I in water and slowly cooling the reaction to room temperature, a suitable crystal of 1 was obtained and analyzed by single-crystal X-ray diffraction at 100 K. Although this crystal structure has previously been reported in the Pbam space group, it was highly disordered and precise atomic coordinates were not calculated. A single crystal of 2 was also obtained by heating the complex in water and letting it slowly cool to room temperature. Complex 1 was found to crystallize in the monoclinic space group C 2/ m , while 2 crystallizes in the orthorhombic space group Pccn , both with Z = 4. 

   more » « less
2. Formation, Selective Encapsulation, and Tautomerization Control of Isoindolone Utilizing Guanidinium Sulfonate Frameworks

   https://doi.org/10.1002/chem.202400957  

   Chaudhry, Mohammad_T; Newman, Justin_A; Lee, Alfred_Y (May 2024, Chemistry – A European Journal)

   Abstract Herein we report the use of tetrakis (guanidinium) pyrenetetrasulfonate (G₄PYR) and bis (guanidinium) 1,5‐napthalene disulfonate (G₂NDS) to catalyze the cyclization of 2‐cyanobenzamide (1) to isoindolone (2). Moreover, we demonstrate the remarkable selectivity of these guanidinium organosulfonate hosts in encapsulating2over1. By thoroughly investigating the intramolecular cyclization reaction, we determined that guanidinium and the organosulfonate moiety acts as the catalyst in this process. Additionally,2is selectively encapsulated, even in mixtures of other structurally similar heterocycles like indole. Furthermore, the tautomeric state of2(amino isoindolone (2–A) and imino isoindolinone forms (2–I)) can be controlled by utilizing different guanidinium organosulfonate frameworks. 

   more » « less
3. Formation of All Three C ₂ H ₄ O Isomers—Ethylene Oxide ( c -C ₂ H ₄ O), Acetaldehyde (CH ₃ CHO), and Vinyl Alcohol (CH ₂ CHOH)—in Ethanol-containing Interstellar Analog Ices

   https://doi.org/10.3847/1538-4357/adc308  

   Wang, Jia; Zhang, Chaojiang; Marks, Joshua H; Kaiser, Ralf I (May 2025, The Astrophysical Journal)

   Abstract Oxygen-containing complex organic molecules are key precursors to biorelevant compounds fundamental for the origins of life. However, the untangling of their interstellar formation mechanisms has just scratched the surface, especially for oxygen-containing cyclic molecules. Here, we present the first laboratory simulation experiments featuring the formation of all three C₂H₄O isomers—ethylene oxide (c–C₂H₄O), acetaldehyde (CH₃CHO), and vinyl alcohol (CH₂CHOH)—in low-temperature model interstellar ices composed of carbon monoxide (CO) and ethanol (C₂H₅OH). Ice mixtures were exposed to galactic cosmic-ray proxies with an irradiation dose equivalent to a cold molecular cloud aged (7 ± 2) × 10⁵yr. These biorelevant species were detected in the gas phase through isomer-selective photoionization reflectron time-of-flight mass spectrometry during temperature-programmed desorption. Isotopic labeling experiments reveal that ethylene oxide is produced from ethanol alone, providing the first experimental evidence to support the hypothesis that ethanol serves as a precursor to the prototype epoxide in interstellar ices. These findings reveal feasible pathways for the formation of all three C₂H₄O isomers in ethanol-rich interstellar ices, offering valuable constraints on astrochemical models for their formation. Our results suggest that ethanol is a critical precursor to C₂H₄O isomers in interstellar environments, representing a critical step toward unraveling the formation mechanisms of oxygen-containing cyclic molecules, aldehydes, and their enol tautomers from alcohols in interstellar ices. 

   more » « less
4. Generalized symmetries in singularity-free nonlinear $\sigma$ models and their disordered phases

   https://doi.org/10.1103/PhysRevB.110.195149  

   Pace, Salvatore D; Zhu, Chenchang; Beaudry, Agnès; Wen, Xiao-Gang (November 2024, Physical Review B)

   We study the nonlinear $$\sigma$$-model in $${(d+1)}$$-dimensional spacetime with connected target space $$K$$ and show that, at energy scales below singular field comfigurations (such as vortices), it has an emergent non-invertible higher symmetry. The symmetry defects of the emergent symmetry are described by the $$d$$-representations of a discrete $$d$$-group $$\mathbb{G}^{(d)}$$ (i.e. the emergent symmetry is the dual of the invertible $$d$$-group $$\mathbb{G}^{(d)}$$ symmetry). The $$d$$-group $$\mathbb{G}^{(d)}$$ is determined such that its classifying space $$B\mathbb{G}^{(d)}$$ is given by the $$d$$-th Postnikov stage of $$K$$. In $(2+1)$D and for finite $$\mathbb{G}^{(2)}$$, this symmetry is always holo-equivalent to an invertible $${0}$$-form---ordinary---symmetry with potential 't Hooft anomaly. The singularity-free disordered phase of the nonlinear $$\sigma$$-model spontaneously breaks this symmetry, and when $$\mathbb{G}^{(d)}$$ is finite, it is described by the deconfined phase of $$\mathbb{G}^{(d)}$$ higher gauge theory. We consider examples of such disordered phases. We focus on a singularity-free $S^2$ nonlinear $$\sigma$$-model in $${(3+1)}$$D and show that it has an emergent non-invertible higher symmetry. As a result, its disordered phase is described by axion electrodynamics and has two gapless modes corresponding to a photon and a massless axion. Notably, this non-perturbative result is different from the results obtained using the $S^N$ and $$\mathbb{C}P^{N-1}$$ nonlinear $$\si$$-models in the large-$$N$$ limit. 

   more » « less
5. Revealing Coexisting Cu ⁰ –Cu ⁺ Sites in Cu ₃ N Nanoensembles for Selective CC Coupling of CO ₂ Under Low Overpotential

   https://doi.org/10.1002/cssc.202500003  

   Li, Junrui; Zhong, Hong; Hong_Lee, Soo; Li, Hui; Drisdell, Walter_S; Dun, Chaochao; Burciaga, Rihana; Ingram, Conrad; Beckman, Scott_P; Urban, Jeffrey_J; et al (June 2025, ChemSusChem)

   To address a long‐existing debate on what copper species are responsible for efficient CC coupling, especially ethanol formation, in electrochemical CO₂reduction reaction, herein, a comprehensive study using Cu₃N nanocubes with a uniform size and shape, alongside a single crystalline phase is reported. The Cu₃N nanoensemble electrode has a remarkable Faradaic efficiency (FE) of 64% for ethanol production at a relatively low potential of −0.6 V versus reversible hydrogen electrode. Throughin‐operandoX‐ray absorption spectroscopy study, a dynamic phase evolution that directly correlates with changes in FE across varying applied potentials is observed. Notably, the nanoensemble with a composition of ≈71% Cu⁺and 29% Cu⁰is identified as being selective for ethanol formation at the low overpotential. Conversely, a predominantly metallic Cu phase formed at potentials more negative than −0.6 V favors the hydrogen evolution reaction. Density functional theory calculations at the Cu₃N–Cu interface substantiate that the coexistence of Cu⁰–Cu⁺not only energetically favors the ethanol reaction pathway but also destabilizes the intermediates for ethylene pathway. 

   more » « less