Flavin mononucleotide (FMN) is a ubiquitous blue-light pigment due to its ability to drive one- and two-electron transfer reactions. In both light-oxygen-voltage (LOV) domains of phototropin from the green algae , FMN is noncovalently bound. In the LOV1 cysteine-to-serine mutant (C57S), light-induced electron transfer from a nearby tryptophan occurs, and a transient spin-correlated radical pair (SCRP) is formed. Within this photocycle, nuclear hyperpolarization is created by the solid-state photochemically induced dynamic nuclear polarization (photo-CIDNP) effect. In a side reaction, a stable protonated semiquinone radical (FMNH) forms undergoing a significant bathochromic shift of the first electronic transition from 445 to 591 nm. The incorporation of phototropin LOV1-C57S into an amorphous trehalose matrix, stabilizing the radical, allows for application of various magnetic resonance experiments at ambient temperatures, which are combined with quantum-chemical calculations. As a result, the bathochromic shift of the first absorption band is explained by lifting the degeneracy of the molecular orbital energy levels for electrons with alpha and beta spins in FMNH due to the additional electron.
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http://dx.doi.org/10.1021/acs.jpcb.4c00397 | DOI Listing |
Chem Sci
December 2024
National Key Laboratory of Green Pesticide, International Joint Research Center for Intelligent Biosensor Technology and Health, College of Chemistry, Central China Normal University Wuhan 430079 P. R. China
Developing dithienylethene (DTE)-based fluorescence switches triggered by biocompatible visible light has always been a long-term goal in view of their potential in numerous biological scenarios. However, their practical availability is severely limited by the short visible light (generally less than 500 nm) required for photocyclization, their inability to achieve red or near-infrared emission, and their short fluorescence lifetimes. Herein, we present a novel DTE derivative featuring a dimethylamine-functionalized BF-curcuminoid moiety (NBDC) by using an "acceptor synergistic conjugation system" strategy.
View Article and Find Full Text PDFNanoscale Adv
December 2024
Institute of Science and Technology, TNU-University of Sciences Thai Nguyen Vietnam
This article studies the synthesis, as well as the structural, vibrational, and optical properties of Eu-doped ZnO quantum dots (QDs) and investigates the energy transfer mechanism from the ZnO host to Eu ions using Reisfeld's approximation. Eu-doped ZnO QDs at varying concentrations (0-7%) were successfully prepared using a wet chemical method. The successful doping of Eu ions into the ZnO host lattice, as well as the composition and valence states of the elements present in the sample, were confirmed through X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) analyses.
View Article and Find Full Text PDFNanoscale
December 2024
Department of Radiology, Second Affiliated Hospital of Chongqing Medical University, Chongqing 400010, China.
As a nonlinear optical phenomenon, upconversion (UC) occurs when two or more low-energy excitation photons are sequentially absorbed and emitted. Upconversion nanomaterials exhibit superior photostability, non-invasiveness, a unique near-infrared anti-Stokes shift, and enhanced tissue penetration capability. However, general upconversion nanomaterials typically utilize visible light (400-700 nm) for excitation, leading to limited tissue penetration, background signal interference, limited excitation efficiency and imaging quality issues due to tissue absorption and scattering.
View Article and Find Full Text PDFBeilstein J Org Chem
December 2024
Institut de Physique et Chimie des Matériaux de Strasbourg (IPCMS), CNRS-Université de Strasbourg (UMR 7504), F-67034 Strasbourg, France.
The high potential of non-covalent arene-fluoroarene intermolecular interactions in the design of liquid crystals lies in their ability to strongly promote self-assembly, improve the order and stability of the supramolecular mesophases, and enable tuneability of the optical and electronic properties, which can potentially be exploited for advanced applications in display technologies, photonic devices, sensors, and organic electronics. We recently successfully reported the straightforward synthesis of several mesogens containing four lateral aliphatic chains and derived from the classical triphenylene core self-assembling in columnar mesophases based on this paradigm. These mesogenic compounds were simply obtained in good yields by the nucleophilic substitution (SFAr) of various types of commercially available fluoroarenes with the electrophilic organolithium derivatives 2,2'-dilithio-4,4',5,5'-tetraalkoxy-1,1'-biphenyl (2Li- ).
View Article and Find Full Text PDFSci Rep
December 2024
Department of Physics, Faculty of Science, Menoufia University, Shebin El-Koom, Menoufia, 32511, Egypt.
Barium fluoride borosilicate glass samples reinforced with varying amounts of GdO (BSBLG0-BSBLG4) have been manufactured using the conventional melt quenching procedure in order to provide additional research on the type of borosilicate glass. Structural, physical, and linear optical characteristics as well as γ-ray attenuation capacity of barium fluoride borosilicate doped with GdO was investigated. X-ray diffraction pattern proving the amorphous nature of the glass samples due to the absence of a distinctive crystalline characteristic peak.
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