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Amyloid fibrils are exceptionally stable oligomeric structures with extensive, highly cooperative H-bonding networks whose physical origin remains elusive. While nonpolar systems benefit from both H-bonds and hydrophobic interactions, we found that highly polar sequences containing glutamine and asparagine amino acid residues form hyperpolarized H-bonds. This feature, observed by density functional theory calculations, encodes the origin of these polar oligomers' high stability. These results are explained in a theoretical model for complex amyloid assembly based on two different types of cooperative effects resulting from highly delocalized electrons, one of which is always present in both polar and hydrophobic systems. Experimental electric conductivity measurements, ThT fluorescence enhancement, and NMR spectroscopy support this proposal and reveal the conditions for disassembly.
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http://dx.doi.org/10.1021/acs.jpclett.6b00699 | DOI Listing |
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September 2025
Institute of New Energy Materials, School of Materials Science and Engineering, Tianjin University, Tianjin, 300072, China.
Copper (Cu) catalysts with abundant defects are pivotal for converting CO into valuable multi-carbon products. However, the practical application of Cu catalysts is challenged by the thermodynamic instability of the defects, often leading to surface reconstruction during catalytic processes. Here, it is found that particle size and COO-containing intermediates are key factors driving reconstruction, as the defect stability is size-dependent and can be amplified by leveraging the highly reactive intermediates as the initial reactant.
View Article and Find Full Text PDFDelocalization insights into inorganic lead halide perovskites of the form CsPbBrI ( = 0, 1, 2, 3), obtained a DFT based tight-binding method, are presented. Compared to first principles studies like DFT (physically accurate and computationally expensive), the tight-binding approach allows the disentanglement of the region of interest, namely, the Fermi level. Further adjustment of the hopping norm and maximum distance leads to a simplified, highly interpretable but chemically grounded, reduced model which regenerates the broad features of the band structure with a fraction of the parameters.
View Article and Find Full Text PDFPhys Chem Chem Phys
September 2025
Fukui Institute for Fundamental Chemistry, Kyoto University, 606-8103 Kyoto, Japan.
To elucidate the molecular electronic energy variation and to simultaneously track the topography of a potential energy surface (PES) such as the potential basin, transition states, and potential barriers in the study of chemical bond formation and relevant chemical reactions, we devise ENOX as an extension of the ENO (energy natural orbital). The total sum of the ENOX orbital energies exactly matches the PES energy, that is, the sum of the electronic energy and nuclear-nuclear repulsion energy. ENOX gives a one-electron (orbital) energy representation, enabling to track the potential energy surface with the ENOX orbital energies alone.
View Article and Find Full Text PDFACS Appl Mater Interfaces
August 2025
Laboratory of Advanced Materials and Energy Electrochemistry, Institute of New Carbon Materials, College of Material Science and Engineering, Taiyuan University of Technology, Taiyuan 030024, China.
Bimetallic single-atom catalysts have garnered considerable interest in the field of the oxygen reduction reaction due to their unique electronic configurations and synergistic catalytic effects. However, precise modulation of d-orbital electron distribution at single-atom sites and comprehensive elucidation of the underlying catalytic mechanisms continue to present significant challenges. Herein, the FeCo(mlm)-N-C catalyst, integrating atomically dispersed Fe-Co dual-metal sites and FeC nanoparticles, was synthesized by using an encapsulation and ligand exchange strategy.
View Article and Find Full Text PDFJ Am Chem Soc
August 2025
Department of Chemistry, University of California, Davis, California 95616, United States.
[FeFe] hydrogenases are highly efficient metalloenzymes that catalyze hydrogen conversion via a sophisticated active site cofactor known as the H-cluster. Biosynthesis of its [2Fe] subcluster, which contains CO, CN, and azadithiolate ligands, requires the action of several dedicated enzymes, including the radical -adenosyl-l-methionine (rSAM) enzyme HydE. HydE has been proposed to convert a mononuclear [Fe(II)(cysteinate)(CO)(CN)] precursor into a dimeric [Fe(SH)(CO)(CN)] complex, yet direct characterization of this product species has remained elusive.
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