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Which Flavor of 9,10-Bis(phenylethynyl)anthracene is Best for Perovskite-Sensitized Triplet-Triplet Annihilation?
No full textThe lack of viable solid-state annihilators is the greatest hurdle in perovskite-sensitized triplet-triplet annihilation upconversion (UC). Unfavorable singlet and triplet energy surfaces in the solid state have limited successful the implementation of many conventional solution-based annihilators. To date, rubrene is still the best performing annihilator; however, this comes at the cost of a small apparent anti-Stokes shift. To this point, anthracene derivatives are promising candidates to increase the apparent anti-Stokes shift. The well-known green glowstick dye 9,10-(bisphenylethynyl) anthracene (BPEA) and its chlorinated derivatives have already shown great promise in solution-based UC applications. Due to favorable band alignment of the perovskite and triplet energy levels of BPEA, it is conceivable that a wide variety of BPEA derivatives could be compatible with the perovskite-based UC system. Here, we investigate the properties of the parent molecule BPEA and its derivatives 1-chloro-9,10-(bisphenylethynyl)anthracene and 2-chloro-9,10-(bisphenylethynyl) anthracene. Despite similar optical properties in solution, the different molecules exhibit vastly different properties in thin films. UC studies in lead halide perovskite/BPEA bilayer devices demonstrate the importance of intermolecular coupling on the resulting properties of the upconverted emission
Deoxygenative Z-selective olefination of aliphatic alcohols
No full textAlcohols are one of the most abundant functional groups in commercially available materials and biologically active compounds. Herein, we report a mild photocatalytic method for the unprecedent deoxygenative Z-selective olefination of aliphatic alcohols. Key to this methodology is the dual role of a phenothiazine photocatalyst, which enables the desired cross-coupling and promotes in-situ E to Z isomerization of the cross-coupled olefin product. This protocol is distin-guished by its wide substrate scope and broad applicability, even in the context of pharmaceuticals and saccharides. Given the mild and water-compatible conditions, our chemistry can also be utilized to functionalize DNA headpieces with saccharides for DELs applications
Residue interactions guide translational diffusion of proteins
No full textDiffusion at the molecular level involves random collisions between particles, the structure of local microscopic environments, and interactions between the molecules involved. Sampling all these aspects, along with correcting for finite-size effects, can make calculation of infinitely dilute diffusion coefficients computationally difficult. We present a new approach for estimating the translational diffusion coefficient of biomolecular structures by encapsulating these driving forces of diffusion through piece-wise assembly of the component residues of protein structure. By linking the local chemistry of a solvent-exposed patch of a molecule to its contribution to the overall hydrodynamic radius, an accurate prediction of the computationally and experimentally comparable diffusion coefficients can be constructed following a solvent-excluded surface area calculation. We demonstrate that the resulting predictions for diffusion coefficients from peptides through to protein structures are comparable to explicit molecular simulations and improve on statistical mass-based predictions, which tend to rely on limited training data. As this approach uses the chemical identity of molecular structures, we find that it is able to predict and identify differences in diffusivity for structures that would be indistinguishable by mass information alone
Balancing Act: Environmental, Social, and Economic Impacts of PFAS Removal from Water
No full textPer- and polyfluoroalkyl substances (PFAS) are emerging water contaminants with significant environmental and health impacts, posing challenges in water treatment due to their degradation resistance. This study reviews 10 papers on the sustainability of technologies for PFAS removal, revealing a critical literature gap as regulations emerge. Our review shows sustainability varies across technologies and contexts. Specifically, single-use ion exchange (IX) demonstrates cost-effectiveness and environmental favorability for long-chain PFAS removal from groundwater and aqueous film-forming foam impacted water, while granular activated carbon (GAC) appears costlier due to rapid breakthroughs. These limited findings underscore the need for more comprehensive research to validate results across contexts and understand the full sustainability profile of PFAS treatment technologies, including removal and destruction. Current literature often overlooks key considerations like the ultimate fate of PFAS. To address these gaps, we propose a framework for future sustainability studies, enabling clearer technology evaluations under specific conditions. While IX shows broad applicability, treatment choice should consider water type, system boundary, functional unit, PFAS concentration, and ultimate fate of PFAS for a more holistic view of sustainability
Cyclopalladation of a Covalent Organic Framework for Near-Infrared Light-Driven Photocatalytic Hydrogen Peroxide Production
No full textCovalent organic frameworks (COFs) have been extensively developed as photosensitizers for photocatalytic energy conversion over the past decade. However, current COF photocatalysts have yet to demonstrate the capability to harvest near-infrared (NIR) light (above 760 nm), which constitutes approximately 53% of the solar spectrum, for fuel or chemical conversion. In this work, we introduce a novel post-synthetic functionalization strategy for COFs by incorporating a palladacycle directly into the COF backbone, extending the light absorption of an azobenzene-based COF into the NIR region. This approach enables homogeneous, atomically-distributed Pd functionalization with a high loading amount of 12 wt% and without noticeable formation of Pd nanoparticles. The cyclopalladated COF, TpAzo-CPd, was utilized as a catalyst for photocatalytic hydrogen peroxide production under 810 nm illumination. This study represents the first implementation of COFs for NIR photocatalysis and opens the door to Pd-single-site COF catalysts for a wide range of organic transformations
Multisite λ Dynamics for Protein-DNA Binding Affinity Prediction
No full textTranscription factors (TFs) regulate gene expression by binding to specific DNA sequences, playing a critical role in various cellular processes and diseases. Computational methods, particularly λ Dynamics, offer a promising approach for predicting TF binding affinities. This study evaluates the effectiveness of different λ Dynamics perturbation schemes in determining the binding free energy changes (ΔΔGb) of the WRKY transcription factor upon mutating its W-box binding site (GGTCAA) to a nonspecific sequence (GATAAA). Among the schemes tested, the single λ per base pair protocol demonstrated the fastest convergence and highest precision. Applying this protocol to additional mutations yielded ΔΔGb values that successfully ranked binding affinities, demonstrating a strong potential for high-throughput screening of DNA binding sites
Atomic-Resolution Cinematography of Catalytic Intermediates over a Single-Site Heterogeneous Catalyst
No full textHeterogeneous catalysts dominate the chemical industry but typically feature diverse, incompletely defined active sites. Thus, describing structure-activity relationships, unlike homogeneous catalysts, remains challenging. In contrast, molecularly defined single-site heterogeneous catalysts (SSHCs), using appropriate tools, are poised to address these challenges and provide new avenues for catalysis research and development. The present study explores eco-friendly H2 production mediated by discrete MO2 sites supported on carbon nanohorns (CNHs) and active for alcohol dehydrogenation. While informative, detailed ensemble EXAFS/XANES, XPS, kinetic measurements, and DFT analysis alone cannot provide a full molecular picture of the reaction pathway. Here, using single-molecule atomic-resolution time-resolved electron microscopy (SMART-EM), we identify four key catalytic intermediates anchored to the CNHs and uncover a new reaction pathway involving alkoxide/hemiacetal equilibration and acetal oligomerization. These intermediates are identified solely by theory and SMART-EM, and this advance highlights the potential of SMART-EM to establish and verify mechanistic hypotheses in catalysis
Spin-forbidden excitation of [Ru(bpy)3]2+ enables red light driven photocatalysis
No full textRed light driven catalysis presents a promising alternative to conventional blue light photocatalysis, offeringenhanced light penetration, functional group tolerance, and energy efficiency. However, its widespread application remains underdeveloped, partly due to the lack of readily accessible photocatalysts. [Ru(bpy)3]2+ is one of the most frequently used blue light photocatalysts. Here, we demonstrate the application of [Ru(bpy)₃]²⁺ in various red light-induced transformations and investigate the underlying photophysical properties, revealing a direct singlet-to-triplet excitation under red light irradiation. Our findings suggest that red light driven photocatalysis could be possible with many other photocatalysts not considered for this purpose until now
Fluorescence Lifetime Imaging Microscopy (FLIM) as a Tool to Understand Chemical Reactions and Catalysis
No full textFluorescence lifetime imaging microscopy (FLIM) is an emerging tool to characterize ongoing chemical reactions in synthetic chemistry and catalysis. Initially applied to biological systems, FLIM now reveals spatially resolved chemical reaction species and system-wide physiochemical changes that accompany ongoing reactions. FLIM combines the advantage of environmental sensitivity with high signal sensitivity (as sensitive as single molecules) and has the key ability to operate under synthetic conditions (e.g., high concentrations of reagents, in organic solvents, under ambient temperature and pressure, in opaque mixtures, and in multiphasic systems). Chemical reactions inherently induce changes in the reaction medium, neighboring compounds, surface compositions, and/or the bonding structure of the compounds involved, resulting in environmental changes. The FLIM methods recently developed harness and interpret these changes in ways that lead to characterizing compounds and enhancing mechanistic understanding. Here, current advantages and limitations of FLIM method are considered, common factors influencing fluorescence lifetime in chemical systems are discussed in a tutorial format, and seven research case studies are strategically analyzed—chosen to highlight how FLIM provided complementary information to understand chemical reaction mechanisms, intermediates, product distributions, partitioning, roles of reagents, and catalyst behaviors. These data and insights obtained from FLIM assist the rational design and optimization of synthetic and catalytic methods
Integrating time since deposition estimation of bloodstains into a DNA profiling workflow: A novel approach using fluorescence spectroscopy
No full textDetermining the time since deposition (TSD) of bloodstains is important to establish a timeline and contextualize physical evidence in forensic investigations, while DNA profiling addresses questions of identity and source attribution. Traditionally treated as separate processes, this study integrates TSD estimation into routine DNA profiling by analyzing typically discarded cell lysate (eluates) from spin-column-based DNA extractions. Fluorescence spectroscopy was used to analyze eluates from bloodstains deposited up to 23 months (99 weeks). Two excitation-emission matrices (EEMs) were acquired for each sample and deconvoluted using parallel factor analysis (PARAFAC) to identify individual fluorophores. We identified tryptophan and noted a time-dependent decrease in its corresponding fluorescence. An increase in fluorescence was observed between 400-500 nm as TSD progressed, attributed to an increase in fluorescent oxidation products (FOX) and advanced glycation end products (AGEs). Different chemometric models were then used to estimate TSD from EEM fluorescence data. Boruta feature selection coupled with random forest regression outperformed all other models and achieved high accuracy, with an R2 of 0.993 and root mean square error of prediction (RMSEP) of 2.83 weeks for the full 99-week period, and an R2 of 0.987 and RMSEP of 2.06 weeks for the 1-year timeframe. Comparisons were also made between anticoagulant-free (AC-free) and anticoagulant-treated (AC-treated) bloodstains deposited up to 3 months. We noted differences in fluorescence based on AC treatment, with AC-free blood exhibiting higher FOX and lower AGE fluorescence than AC-treated blood. A temperature study was also performed using bloodstains deposited at -18 ºC, 4 ºC and 21 ºC, with the strongest FOX and AGE fluorescence recorded at 21 ºC. Our findings demonstrate the effectiveness and feasibility of integrating TSD estimation into routine forensic DNA analyses while maintaining high prediction accuracies