The gas-phase cyclopropanation and apparent metathesis reactivity of ligand-supported gold arylidenes with electron-rich olefins is explained by quantum-chemical calculations. A deep potential minimum corresponding to a metal-bound cyclopropane adduct is in agreement with the measured absolute energies of the cyclopropanation and metathesis channels and is also consistent with previously reported electronic effects of arylidenes and supporting phosphorus ylid ligands on the product ratios. In the gas phase, the rate-determining step for the cyclopropanation is dissociation of the Lewis-acidic metal fragment, whereas the metathesis pathway features several rate-limiting transition states that are close in energy to the final product dissociation and hence contribute to the overall reaction rate. Importantly, the presented potential energy surface also accounts for the recently reported gold-catalyzed solution-phase retro-cyclopropanation reactivity.
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Biomed Phys Eng Express
January 2025
Physics Department, University at Albany, 1400 Washington Ave, Albany, New York, 12222-0100, UNITED STATES.
Conventional x-ray radiography relies on attenuation differences in the object, which often results in poor contrast in soft tissues. X-ray phase imaging has the potential to produce higher contrast but can be difficult to utilize. Instead of grating-based techniques, analyzer-based imaging, also known as diffraction enhanced imaging (DEI), uses a monochromator crystal with an analyzer crystal after the object.
View Article and Find Full Text PDFNanotechnology
January 2025
Xidian University, Xi'an 710071, China, Xi'an, Xian, Shaanxi, 710126, CHINA.
Anti-ambipolar transistors (AAT) are considered as a breakthrough technology in the field of electronics and optoelectronics, which is not only widely used in diverse logic circuits, but also crucial for the realization of high-performance photodetectors. The anti-ambipolar characteristics arising from the gate-tunable energy band structure can produce high-performance photodetection at different gate voltages. As a result, this places higher demands on the parametric driving range (ΔVg) and peak-to-valley ratio (PVR) of the AAT.
View Article and Find Full Text PDFPLoS One
January 2025
Chemistry and Biochemistry, University of St. Thomas, Houston, TX, United States of America.
Cardiovascular disease (CVD) remains the leading cause of morbidity and mortality globally, with oxidative stress playing a pivotal role in its progression. Free radicals produced via oxidative stress contribute to lipid peroxidation, leading to subsequent inflammatory responses, which then result in atherosclerosis. Antioxidants inhibit these harmful effects through their reducing ability, thereby preventing oxidative damage.
View Article and Find Full Text PDFJ Phys Chem A
January 2025
Université Paris-Saclay, CNRS, Institut des Sciences Moléculaires d'Orsay UMR 8214, 91405 Orsay, France.
This study deals with the understanding of hydrogen atom scattering from graphene, a process critical for exploring C-H bond formation and energy transfer during atom surface collision. In our previous work [Shi, L.; 2023, 159, 194102], starting from a cell with 24 carbon atoms treated periodically, we have achieved quantum dynamics (QD) simulations with a reduced-dimensional model (15D) and a simulation in full dimensionality (75D).
View Article and Find Full Text PDFACS Nano
January 2025
WA School of Mines: Minerals, Energy and Chemical Engineering, Curtin University, Perth, WA 6102, Australia.
Quadruple perovskite oxides have received extensive attention in electronics and catalysis, owing to their cation-ordering structure and intriguing physical properties. However, their repertoires still remain limited. In particular, piezoelectricity from quadruple perovskites has been rarely reported due to the frustrated symmetry-breaking transition in A-site-ordered perovskite structures, disabling their piezoelectric applications.
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