The vibrational spectra of 4,6-dimethyl-2-mercaptopyrimidine (DMMP) in acetonitrile, methanol, and water were assigned by resonance Raman spectroscopy through a combination of Fourier-transform infrared spectroscopy (FT-IR), FT-Raman UV-vis spectroscopy, and density functional theoretical (DFT) calculations. The FT-Raman spectra show that the neat solid DMMP is formed as a dimer due to intermolecular hydrogen bonding. In methanol and water, however, the majority of the Raman spectra were assigned to the vibrational modes of DMMP(solvent) ( n = 1-4) clusters containing NH···O hydrogen bonds. The intermolecular NH···O hydrogen bond interactions, which are key constituents of the stable DMMP thione structure, revealed significant structural differences in acetonitrile, methanol, and water. In addition, UV-induced hydrogen transfer isomeric reactions between the thione and thiol forms of DMMP were detected in water and acetonitrile. DFT calculations indicate that the observed thione → thiol tautomerization should occur easily in lower excited states in acetonitrile and water.
Download full-text PDF |
Source |
---|---|
http://dx.doi.org/10.1021/acs.jpca.8b04525 | DOI Listing |
Anal Chem
January 2025
Instrumental Analytical Chemistry, University of Duisburg-Essen, Universitätsstraße 5, 45141 Essen, Germany.
Compound-specific stable isotope analysis (CSIA) using liquid chromatography-isotope ratio mass spectrometry (LC-IRMS) is a powerful tool for determining the isotopic composition of carbon in analytes from complex mixtures. However, LC-IRMS methods are constrained to fully aqueous eluents. Previous efforts to overcome this limitation were unsuccessful, as the use of organic eluents in LC-IRMS was deemed impossible.
View Article and Find Full Text PDFAngew Chem Int Ed Engl
January 2025
Karlsruhe Institute of Technology KIT, Institute for Chemical Technology and Polymer Chemistry, Kaiserstr. 12, Fakultät für Chemie, 76131, Karlsruhe, GERMANY.
In the frame of developing a sustainable chemical industry, heterogeneously catalyzed CO2 hydrogenation to methanol has attracted considerable interest. However, the Cu-Zn based catalyst system employed in this process is very dynamic, especially in the presence of the products methanol and water. Deactivation needs to be prevented, but its origin and mechanism are hardly investigated at high conversion where product condensation is possible.
View Article and Find Full Text PDFAngew Chem Int Ed Engl
January 2025
Guangdong University of Technology, No. 100 Waihuan Xi Road, Guangzhou Higher Education Mega Center, Panyu District, 510006, Guangzhou, CHINA.
To enable highly efficient in situ hydrogen release from methanol/water reforming at lower temperature, the integration of solar-energy offers a promising approach to activate methanol/water and substantially lower the activation energy of this reaction. Herein, we present a novel dual-vacancy defective hollow heterostructure derived from Metal-Organic Frameworks, featuring abundant surface hydroxyl groups and S/O vacancies, for photothermal-promoted methanol solution reforming into hydrogen. The [In2S3-x/In2O3-x](OH)y exhibits exceptional photothermal H2 evolution activity, achieving a production rate of 215.
View Article and Find Full Text PDFTalanta
January 2025
Center for Multiplatform Metabolomics Studies (CEMM) at the Institute of Chemistry, University of Sao Paulo, Sao Paulo, SP, 05508-000, Brazil. Electronic address:
There is no consensus in the literature regarding the ideal protocol for obtaining and preparing cell samples for untargeted metabolomics. Nevertheless, the procedures must be carefully evaluated for proper and reliable results for each organism under study. This work proposes a novel protocol for determining intracellular metabolites in Leishmania promastigotes and is fully optimized for application in conjunction with gas chromatography-mass spectrometry platforms.
View Article and Find Full Text PDFPharmaceuticals (Basel)
January 2025
Institute for Medicinal Plants Research "Dr. Josif Pančić", Tadeuša Košćuška 1, 11000 Belgrade, Serbia.
Background/objectives: Scop. is traditionally used for treatment of various gastrointestinal ailments. In this study, we investigated the phytochemical profile and biological activities of leaves, bark and flowers extracts of Methods: Phytochemical analysis was performed using HPLC.
View Article and Find Full Text PDFEnter search terms and have AI summaries delivered each week - change queries or unsubscribe any time!