We theoretically investigate the photon-echo spectroscopy of coupled electron-nuclear quantum dynamics. Two situations are treated. In the first case, the Born-Oppenheimer (adiabatic) approximation holds. It is then possible to interpret the two-dimensional (2D) spectra in terms of vibrational motion taking place in different electronic states. In particular, pure vibrational coherences which are related to oscillations in the time-dependent third-order polarization can be identified. This concept fails in the second case, where strong non-adiabatic coupling leads to the breakdown of the Born-Oppenheimer-approximation. Then, the 2D-spectra reveal a complicated vibronic structure and vibrational coherences cannot be disentangled from the electronic motion.
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JACS Au
January 2025
Department of Chemistry, University of Missouri, 601 South College Avenue, Columbia, Missouri 65211, United States.
Our newly developed AshPhos ligand represents a significant advancement in Buchwald-Hartwig aminations, overcoming many limitations of existing ligands. Created from affordable and accessible materials, AshPhos enhances catalytic performance, especially for extremely difficult substrates, by emphasizing the principles of ligand chelation and cooperativity. Its successful synthesis and application in catalytic aminations underscore its potential for use in the sustainable synthesis of compounds important to medicinal chemistry, materials, and energy.
View Article and Find Full Text PDFChem Sci
January 2025
School of Physical Science and Technology, ShanghaiTech University Shanghai 201210 China
The process of proton translocation in , triggered by light, is powered by the photoisomerization of all--retinal in bacteriorhodopsin (bR). The primary events in bR involving rapid structural changes upon light absorption occur within subpicoseconds to picoseconds. While the three-state model has received extensive support in describing the primary events between the H and K states, precise characterization of each excited state in the three-state model during photoisomerization remains elusive.
View Article and Find Full Text PDFNat Commun
January 2025
Institut de Chimie de Strasbourg (UMR 7177, CNRS-Unistra), Université de Strasbourg, 4 rue Blaise Pascal, CS 90032, F-, Strasbourg, France.
Electric fields represent an ideal means for controlling spins at the nanoscale and, more specifically, for manipulating protected degrees of freedom in multispin systems. Here we perform low-temperature magnetic far-IR spectroscopy on a molecular spin triangle (Fe) and provide initial experimental evidence suggesting spin-electric transitions in polynuclear complexes. The co-presence of electric- and magnetic-dipole transitions, allows us to estimate the spin-electric coupling.
View Article and Find Full Text PDFMethods Mol Biol
January 2025
College of Pharmacy, Yonsei Institute of Pharmaceutical Sciences, Yonsei University, Incheon, Republic of Korea.
Saponins represent specialized (secondary) metabolites primarily sourced from plants, typically characterized by an aglycone component of triterpenoids or steroids, often referred to as sapogenin, coupled with sugar moieties. Their structural intricacy and diversity, along with their manifold pharmacological properties, have garnered significant interest among researchers. Notwithstanding this interest, the study of saponins has been encumbered by challenges in their isolation, purification, and structural characterization.
View Article and Find Full Text PDFMethods Mol Biol
January 2025
Natural Products Laboratory, Institute of Biology Leiden, Leiden University, Leiden, The Netherlands.
Salicylic acid is a member of benzoic acid derivatives, a group of compounds which have a backbone of C6C1 consisting of one carboxyl group and one (or more) hydroxyl group(s) attached to the aromatic ring. Salicylic acid is a signaling compound in systemic acquired resistance (SAR). An increased level of salicylic acid is found in the plant after a fungi's attack, which further induces the accumulation of phytoalexins, low molecular weight defense compounds.
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