One-dimensional potential energy curves for the isomerization of protonated Schiff base of retinal (PSBR) in bacteriorhodopsin (bR), i.e., isomerization from all-trans- to 13-cis-forms, have been calculated by means of time-dependent density functional theory (TD-DFT) calculations, in order to elucidate the mechanism of initial step in photo-absorption. The transition state of the isomerization in the first excited state is located at theta(13-14)=58 degrees , where theta(13-14) means twist angle around the C(13)=C(14) double bond of PSBR The potential barrier is formed by the avoided crossing between S(1) (B(u)-like) and S(2) (A(g)-like) states. The mechanism of the isomerization was discussed on the basis of theoretical results.
Download full-text PDF |
Source |
|---|---|
| http://dx.doi.org/10.1016/j.jphotobiol.2004.07.005 | DOI Listing |
Publication Analysis
Top Keywords
Similar Publications
Mechanisms and Origins of Regioselectivity in Rare-Earth-Catalyzed C-H Functionalization of Anisoles and Thioanisoles.
Inorg Chem
March 2025
Institutes of Physical Science and Information Technology, Anhui University, Hefei 230601, China.
The direct catalytic C-H functionalization of aromatic compounds such as anisoles and thioanisoles is of great interest and significance. However, achieving precise regioselectivity remains a major challenge. In this study, we conducted comprehensive density functional theory calculations to explore the mechanisms of rare-earth-catalyzed regioselective C-H alkylation, borylation, and silylation of anisole and thioanisole.
View Article and Find Full Text PDFHigh-performance magnesium organic batteries using renewable biomolecule-based cathode.
Chemistry
March 2025
Chongqing University, College of Materials Science and Engineering, CHINA.
Rechargeable magnesium batteries (RMBs) exhibit significant potential in large-scale energy storage due to their features of high volumetric capacity, resistance to dendrite formation, and abundant magnesium resources. However, the high polarity of divalent Mg2+ ions results in sluggish diffusion kinetics in conventional inorganic cathode materials, adversely affecting reversible capacity and rate performance. Organic materials such as pyrene-4,5,9,10-tetrone (PTO) and 3,4,9,10-perylenetetracarboxylic dianhydride (PTCDA), achieve rapid and reversible intercalation of magnesium ions through carbonyl enolization, but these materials are challenged by high cost, complex preparation, and poor environmental friendliness.
View Article and Find Full Text PDFRevealed Preferential Short-Range Anion Ordering in Disordered RbMOF (M = Nb, Ta) Pyrochlore-Type Oxyfluorides.
Inorg Chem
March 2025
Institut des Molécules et Matériaux du Mans (IMMM)─UMR 6283 CNRS, Le Mans Université, Avenue Olivier Messiaen, 72085 Le Mans Cedex 9, France.
Describing the crystal structure of disordered materials with mixed-occupancy crystallographic sites is essential for understanding their physicochemical properties and designing new materials tuned to their targeted functionalities. Here, we investigate the structure of RbMOF (M = Nb, Ta) pyrochlore-type oxyfluorides using a multimodal approach that combines experimental and computational techniques. Rietveld structural refinement of powder X-ray powder diffraction (PXRD) data confirmed that these oxyfluorides are isostructural, and their average crystal structure is disordered.
View Article and Find Full Text PDFMechanistic Insights into Regioselectivity and Its Evolution in On-Surface Polymerization.
J Am Chem Soc
March 2025
CAS Key Laboratory of Molecular Nanostructure and Nanotechnology, CAS Research/Education Center for Excellence in Molecular Sciences, Beijing National Laboratory for Molecular Sciences (BNLMS), Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China.
Surface-catalyzed polymerization is crucial in both chemical science and industrial manufacturing, yet achieving regioselective radical polymerization on the surface remains challenging. Here, we demonstrate the regioselective Ullmann polymerization of nonsymmetrical 2,8-dibromoquinoline (DBQ) on an Au(111) surface. By combining scanning tunneling microscopy, density functional theory calculations, and kinetic modeling, we reveal the regioselectivity and its evolution with surface temperature at the molecular level.
View Article and Find Full Text PDFAre resting-state network alterations in late-life depression related to synaptic density? Findings of a combined 11C-UCB-J PET and fMRI study.
Cereb Cortex
March 2025
Neuropsychiatry, Department of Neurosciences, Leuven Brain Institute, KU Leuven, Herestraat 49, B-3000 Leuven, Belgium.
This study investigates the relationship between resting-state functional magnetic resonance imaging (rs-fMRI) topological properties and synaptic vesicle glycoprotein 2A (SV2A) positron emission tomography (PET) synaptic density (SD) in late-life depression (LLD). 18 LLD patients and 33 healthy controls underwent rs-fMRI, 3D T1-weighted MRI, and 11C-UCB-J PET scans to assess SD. The rs-fMRI data were utilized to construct weighted networks for calculating four global topological metrics, including clustering coefficient, characteristic path length, global efficiency, and small-worldness, and six nodal metrics, including nodal clustering coefficient, nodal characteristic path length, nodal degree, nodal strength, local efficiency, and betweenness centrality.
View Article and Find Full Text PDFWant AI Summaries of new PubMed Abstracts delivered to your In-box?
Enter search terms and have AI summaries delivered each week - change queries or unsubscribe any time!