The interaction of some substituted coumarin derivatives with the stable 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical was analysed by means of multivariate statistics using a variety of molecular descriptors. The compounds contain a conjugated double bond system, which was considered to be an essential structural characteristic for the free-radical scavenging activity. Partial least-square analysis led to an adequate two-component model based on bulk descriptors and the electronic properties concerning atoms involved or next to the double-bond system.
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http://dx.doi.org/10.1211/0022357044157 | DOI Listing |
Science
January 2025
Wolfson Catalysis Centre, Department of Chemistry, University of Oxford, Oxford, UK.
The distribution of substitutional aluminum (Al) atoms in zeolites affects molecular adsorbate geometry, catalytic activity, and shape and size selectivity. Accurately determining Al positions has been challenging. We used synchrotron resonant soft x-ray diffraction (RSXRD) at multiple energies near the Al K-edge combined with molecular adsorption techniques to precisely locate "single Al" and "Al pairs" in a commercial H-ZSM-5 zeolite.
View Article and Find Full Text PDFProc Natl Acad Sci U S A
January 2025
Department of Ecology and Evolution, University of Chicago, Chicago, IL 60637.
Many proteins form paralogous multimers-molecular complexes in which evolutionarily related proteins are arranged into specific quaternary structures. Little is known about the mechanisms by which they acquired their stoichiometry (the number of total subunits in the complex) and heterospecificity (the preference of subunits for their paralogs rather than other copies of the same protein). Here, we use ancestral protein reconstruction and biochemical experiments to study historical increases in stoichiometry and specificity during the evolution of vertebrate hemoglobin (Hb), an αβ heterotetramer that evolved from a homodimeric ancestor after a gene duplication.
View Article and Find Full Text PDFMethods Protoc
January 2025
Department of Pharmacy and Biomedical Sciences, University of Central Lancashire, Preston PR1 2HE, UK.
Multi-drug delivery systems have gained increasing interest from the pharmaceutical industry. Alongside this is the interest in amorphous solid dispersions as an approach to achieve effective oral delivery of compounds with solubility-limited bioavailability. Despite this, there is limited information regarding predicting the behavior of two or more drugs (in amorphous forms) in a polymeric carrier and whether molecular interactions between the compounds, between each compound, and if the polymer have any effect on the physical properties of the system.
View Article and Find Full Text PDFSmall
January 2025
Beijing Key Laboratory of Energy Conversion and Storage Materials, College of Chemistry, Beijing Normal University, Beijing, 100875, P. R. China.
Establishing the relationship between catalytic performance and material structure is crucial for developing design principles for highly active catalysts. Herein, a type of perovskite fluoride, NHMnF, which owns strong-field coordination including fluorine and ammonia, is in situ grown on carbon nanotubes (CNTs) and used as a model structure to study and improve the intrinsic catalytic activity through heteroatom doping strategies. This approach optimizes spin-dependent orbital interactions to alter the charge transfer between the catalyst and reactants.
View Article and Find Full Text PDFRSC Adv
January 2025
IMMM, Institut des Molécules et Matériaux du Mans Bd Charles Nicolle 72000 Le Mans France.
Samarium (Sm) modification is emerging as a powerful strategy to manipulate the electrical response of 0.8BiFeO-0.2BaTiO (BFBT) multiferroic ceramics.
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