Mathisbeasley3243

In addition, the oxidized polystyrene polymer may play a role in the production of singlet oxygen under light.Aggregation-induced enhancement (AIE) in the photoluminescence quantum yield (PLQY) from 12.5 to 51% in the N,N-dimethylformamide (DMF)-stabilized Au nanocluster (AuNC) system is reported here. The self-assembling of AuNC has been achieved via hydrogen bonding interaction, which is further utilized in designing the AuNC_DCM system for realizing a Förster resonance energy transfer (FRET)-based white LED (WLED), having CIE coordinates of (0.35, 0.29). The solution-processed fabrication strategy used, has given us the liberty to optimize its components for optimal full-spectrum light output. The CIE coordinates of the designed WLED have been improved further to (0.33, 0.32), with a high color rendering index of 93 and correlated color temperature of 5620 K by incorporating a green emitter, namely nitrogen-doped graphene quantum dots (NGQD), in the AuNC_DCM system. The excellent spectral quality of the as-designed WLED and the repeatability of the proposed fabrication method will make the developed AuNCs_DCM FRET conjugate useful in practical photonic applications.The photophysical and electrochemical properties of a new class of fluorinated benzonitrile compounds substituted with mixed phenoxazine and carbazole units have been investigated. When absorbing in a large range of the UV-vis spectrum due to both localized and charge-transfer absorptions, these compounds show dual broad emission in solution and intense emission in PMMA films, with photoluminescence quantum yields changing from a few percent in solution to 18% in a more rigid environment. The compounds also exhibit thermally activated delayed fluorescence demonstrated by the role of oxygen in the quenching of delayed fluorescence and by time-resolved luminescence studies, with an efficiency directly related to the number of phenoxazine substituents. Electrochemistry reveals dramatic changes in the reduction mechanisms according to the number of remaining fluorine atoms on the benzonitrile core. All these results demonstrate how it is possible to tune the photophysical and electrochemical properties of easily synthesizable derivatives by controlling the nature and relative number of the substituents on a simple aromatic platform.Understanding how the complex interplay among excitonic interactions, vibronic couplings, and reorganization energy determines coherence-enabled transport mechanisms is a grand challenge with both foundational implications and potential payoffs for energy science. We use a combined experimental and theoretical approach to show how a modest change in structure may be used to modify the exciton delocalization, tune electronic and vibrational coherences, and alter the mechanism of exciton transfer in covalently linked cofacial Zn-porphyrin dimers (meso-beta linked ABm-β and meso-meso linked AAm-m). While both ABm-β and AAm-m feature zinc porphyrins linked by a 1,2-phenylene bridge, differences in the interporphyrin connectivity set the lateral shift between macrocycles, reducing electronic coupling in ABm-β and resulting in a localized exciton. Pump-probe experiments show that the exciton dynamics is faster by almost an order of magnitude in the strongly coupled AAm-m dimer, and two-dimensional electronic spectroscopy (2DES) identifies a vibronic coherence that is absent in ABm-β. Theoretical studies indicate how the interchromophore interactions in these structures, and their system-bath couplings, influence excitonic delocalization and vibronic coherence-enabled rapid exciton transport dynamics. Real-time path integral calculations reproduce the exciton transfer kinetics observed experimentally and find that the linking-modulated exciton delocalization strongly enhances the contribution of vibronic coherences to the exciton transfer mechanism, and that this coherence accelerates the exciton transfer dynamics. These benchmark molecular design, 2DES, and theoretical studies provide a foundation for directed explorations of nonclassical effects on exciton dynamics in multiporphyrin assemblies.Permanently charged and ionizable organic compounds (IOC) are a large and diverse group of compounds belonging to many contaminant classes, including pharmaceuticals, pesticides, industrial chemicals, and natural toxins. Sorption and mobility of IOCs are distinctively different from those of neutral compounds. Due to electrostatic interactions with natural sorbents, existing concepts for describing neutral organic contaminant sorption, and by extension mobility, are inadequate for IOC. Predictive models developed for neutral compounds are based on octanol-water partitioning of compounds (Kow) and organic-carbon content of soil/sediment, which is used to normalize sorption measurements (KOC). We revisit those concepts and their translation to IOC (Dow and DOC) and discuss compound and soil properties determining sorption of IOC under water saturated conditions. Highlighting possible complementary and/or alternative approaches to better assess IOC mobility, we discuss implications on their regulation and risk assessment. The development of better models for IOC mobility needs consistent and reliable sorption measurements at well-defined chemical conditions in natural porewater, better IOC-, as well as sorbent characterization. Such models should be complemented by monitoring data from the natural environment. The state of knowledge presented here may guide urgently needed future investigations in this field for researchers, engineers, and regulators.Coherent phonons generated through regulation of lattice oscillation via ultrafast laser pulses or X-rays have been desired in various fields, including optoelectronics, thermal and quantum information, and communications. Phonon coherence of two-dimensional (2D) materials is particularly attractive as it enables controllable information transmission but is challenging as the weak interplanar coupling makes phonon excitation extremely difficult. Herein we managed to generate size-dependent phonon coherence from bulk Bi to few-layer bismuthene by an ultrafast femtosecond laser pulse and made a systematic comparison thorough a combination of computation, transient absorption, and reflectance spectroscopic methods. The results witnessed the A1g phonon excitation in all of the three Bi materials with distinct thicknesses, and the quantum size effect of 2D materials caused phonon confinement and eventual bond softening manifested as a red-shifted vibration frequency and shortened decoherence time compared with those of their bulk counterpart. This study offers new perspectives for tailoring coherent phonons in 2D materials for quantum science and technology including quantum communication, computing, and design of novel quantum devices, etc.Nanozymes have emerged as a class of novel catalytic nanomaterials that show great potential to substitute natural enzymes in various applications. Nevertheless, spatial organization of multiple subunits in a nanozyme to rationally engineer its catalytic properties remains to be a grand challenge. Here, we report a DNA-based approach to encode the organization of gold nanoparticle clusters (GNCs) for the construction of programmable enzyme equivalents (PEEs). We find that single-stranded (ss-) DNA scaffolds can self-fold into nanostructures with prescribed poly-adenine (polyA) loops and double-stranded stems and that the polyA loops serve as specific sites for seed-free nucleation and growth of GNCs with well-defined particle numbers and interparticle spaces. A spectrum of GNCs, ranging from oligomers with discrete particle numbers (2-4) to polymer-like chains, are in situ synthesized in this manner. The polymeric GNCs with multiple spatially organized nanoparticles as subunits show programmable peroxidase-like catalytic activity that can be tuned by the scaffold size and the inter-polyA spacer length. This study thus opens new routes to the rational design of nanozymes for various biological and biomedical applications.A handful of molecular docking tools have been extended to enable a covalent docking. learn more However, all of them face the challenge brought by the covalent bond between proteins and ligands. Many covalent drug design scenarios still heavily rely on demanding crystallographic experiments for accurate binding structures. Aiming at filling the gap between covalent dockings and crystallographic experiments, we develop and validate a hybrid method, dubbed as Cov_DOX, in this work. Cov_DOX achieves an overall success rate of 81% with RMSD less then 2 Å for the Top 1 pose prediction in the validation against a test set including 405 crystal structures for covalent protein-ligand complexes, covering various types of the warhead chemistry and receptors. Such accuracy is not far from the much more demanding crystallographic experiments, in sharp contrast to the performance of the covalent docking front runners (success rate 40-60%).Single-molecule circuits with group 8 metallocenes are formed without additional linker groups in scanning tunneling microscope-based break junction (STMBJ) measurements at cryogenic and room-temperature conditions with gold (Au) electrodes. We investigate the nature of this direct gold-π binding motif and its effect on molecular conductance and persistence characteristics during junction evolution. The measurement technique under cryogenic conditions tracks molecular plateaus through the full cycle of extension and compression. Analysis reveals that junction persistence when the metal electrodes are pushed together correlates with whether electrodes are locally sharp or blunt, suggesting distinct scenarios for metallocene junction formation and evolution. The top and bottom surfaces of the "barrel"-shaped metallocenes present the electron-rich π system of cyclopentadienyl rings, which interacts with the gold electrodes in two distinct ways. An undercoordinated gold atom on a sharp tip forms a donor-acceptor bond to a specific carbon atom in the ring. However, a small, flat patch on a dull tip can bind more strongly to the ring as a whole through van der Waals interactions. Density functional theory (DFT)-based calculations of model electrode structures provide an atomic-scale picture of these scenarios, demonstrating the role of these bonding motifs during junction evolution and showing that the conductance is relatively independent of tip atomic-scale structure. The nonspecific interaction of the cyclopentadienyl rings with the electrodes enables extended conductance plateaus, a mechanism distinct from that identified for the more commonly studied, rod-shaped organic molecular wires.Protein biomolecules including enzymes, cagelike proteins, and specific peptides have been continuously exploited as functional biomaterials applied in catalysis, nutrient delivery, and food preservation in food-related areas. However, natural proteins usually function well in physiological conditions, not industrial conditions, or may possess undesirable physical and chemical properties. Currently, rational protein design as a valuable technology has attracted extensive attention for the rational engineering or fabrication of ideal protein biomaterials with novel properties and functionality. This article starts with the underlying knowledge of protein folding and assembly and is followed by the introduction of the principles and strategies for rational protein design. Basic strategies for rational protein engineering involving experienced protein tailoring, computational prediction, computation redesign, and de novo protein design are summarized. Then, we focus on the recent progress of rational protein engineering or design in the application of food science, and a comprehensive summary ranging from enzyme manufacturing to cagelike protein nanocarriers engineering and antimicrobial peptides preparation is given.