Photofragmentation spectra of protonated vanillin produced under electrospray ionisation (ESI) conditions have been recorded in the 3000-3700 cm (vibrational) and 225-460 nm (electronic) ranges, using room temperature IRMPD (infrared multiphoton dissociation) and cryogenic UVPD (ultraviolet photodissociation) spectroscopies, respectively. The cold (∼50 K) electronic UVPD spectrum exhibits very well resolved vibrational structure for the S ← S and S ← S transitions, suggesting long excited state dynamics, similar to its simplest analogue, protonated benzaldehyde. The experimental data were combined with theoretical calculations to determine the protonation site and configurational isomer observed in the experiments.
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http://dx.doi.org/10.1039/d3cp05573f | DOI Listing |
Anal Chem
December 2024
Department of Electronic Science, Fujian Provincial Key Laboratory of Plasma and Magnetic Resonance, State Key Laboratory of Physical Chemistry of Solid Surfaces, Xiamen University, Siming South Road 422, Xiamen 361005, China.
Proton (H) NMR spectroscopy presents a powerful tool for biomass mixture studies by revealing the involved chemical compounds with identified ingredients and molecular structures. However, conventional H NMR generally suffers from spectral congestion when measuring biomass mixtures, particularly biomass carbohydrate samples, that contain various physically and chemically similar compounds. In this study, a targeted detection NMR approach, DREAMTIME, is exploited for studying biomass carbohydrate mixtures by spectroscopically targeting the desired compounds in separate 1D NMR spectra.
View Article and Find Full Text PDFJ Magn Reson
December 2024
Univ. Lille, CNRS, Centrale Lille, Univ. Artois, UMR 8181, UCCS - Unité de Catalyse et Chimie du Solide, F-59000 Lille, France. Electronic address:
The two-dimensional (2D) refocused INADEQUATE NMR experiment, which correlates double-quantum (DQ) and single-quantum (SQ) coherences, is widely used to probe the chemical connectivities in solids. Nevertheless, the multiplets along the F dimension reduce the resolution and sensitivity of this experiment. The Composite-Refocusing (CR) technique with two excitation pulses has been proposed to suppress these multiplets in 2D INADEQUATE spectra of liquids.
View Article and Find Full Text PDFAngew Chem Int Ed Engl
December 2024
Qingdao University of Science and Technology, State Key Laboratory Base of Eco-Chemical Engineering College of Chemical Engineering, Qingdao, CHINA.
Electrocatalytic reduction of NO3- is a green and sustainable method that not only helps to treat industrial pollutants in wastewater, but also produces valuable chemicals. However, the slow dynamics of the proton-coupled electron transfer process results in a high barrier and low conversion efficiency. In this work, the Se-deficient FeSe2/Fe3O4 heterojunction was synthesized, which showed excellent electrochemical performance in 0.
View Article and Find Full Text PDFJ Chem Phys
December 2024
Center for Advanced Materials Research, Beijing Normal University, Zhuhai 519087, China.
Proton transfer plays a crucial role in various chemical and biological processes. A major theoretical challenge in simulating proton transfer arises from the quantum nature of the proton. The constrained nuclear-electronic orbital (CNEO) framework was recently developed to efficiently and accurately account for nuclear quantum effects, particularly quantum nuclear delocalization effects, in quantum chemistry calculations and molecular dynamics simulations.
View Article and Find Full Text PDFNMR Biomed
February 2025
CIBM Center for Biomedical Imaging, Lausanne, Switzerland.
Magnetic resonance spectroscopic imaging (MRSI) enables the simultaneous noninvasive acquisition of MR spectra from multiple spatial locations inside the brain. Although H-MRSI is increasingly used in the human brain, it is not yet widely applied in the preclinical setting, mostly because of difficulties specifically related to very small nominal voxel size in the rat brain and low concentration of brain metabolites, resulting in low signal-to-noise ratio (SNR). In this context, we implemented a free induction decay H-MRSI sequence (H-FID-MRSI) in the rat brain at 14.
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