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Surface Engineering for Enhanced Perovskite Solar Cells: Fullerene-Mediated Trap State Formation on CsPbI3 (001) Surface
No full textPhotovoltaic technology, particularly perovskite solar cell (PSC) materials, has emerged as a promising avenue due to their excellent light-absorbing properties. Despite significant progress in PSC technology, defects within the perovskite material continue to pose challenges, leading to reduced efficiency and stability of the devices. CsPbI3 perovskites have shown potential, but trap states induced by surface defects remain a challenge. The use of fullerene-derivatives, like C60 and PC61BM, has been highlighted to enhance the device stability eliminating/reducing hysteresis and passivating trap states. However, the mechanisms behind fullerene-induced passivation of trap states and their impact on surface energetics remain unclear. This study employs periodic density functional theory (DFT) simulations to explore the interaction between C60, PC61BM, and CsPbI3 (001) surface, with and without defects (cesium vacancy, lead vacancy, and I-antisite). The DFT simulations reveal that both C60 and PC61BM effectively passivate trap states induced by I-antisite defects by reorienting and reorganizing the iodine atoms that promote the presence of trap states. This work contributes to understanding the fundamental aspects of surface-defect interactions in CsPbI3 perovskites. Both C60 and PC61BM play a crucial role in passivating trap states, causing atomic reorganization and avoiding the nonradiative recombination. The findings provide valuable insights into mechanisms for trap state passivation by fullerene derivatives, paving the way for further research to enhance PSC performance
A Framework for Optimizing Continuous Methane Monitoring System Configuration for Minimal Blind Time: Application and Insights from over 100 Operational Oil & Gas Facilities
No full textContinuous monitoring systems (CMS) that utilize fixed-point sensors provide high temporal resolution point-in-space measurements of ambient methane concentration. This study introduces a modular framework for optimizing CMS configurations, encompassing sensor density (number of sensors) and near-optimal placement. By introducing a metric called ‘blind time’, this study attempts to capture periods where the network fails to make detections that could satisfy the regulatory requirement of quantifying emissions every 12 hours. This framework is then applied to 124 operational oil and gas production facilities with a wide variety of site characteristics and meteorological conditions. This study determines a representative blind time for near-optimum CMS configurations for operational facilities and then investigates the impact of different sensor network densities on the performance of the CMS. The results demonstrate that 3-sensor networks, when placed in near-optimum arrangements, can achieve blind time of less than 10% and a mean time to detection of approximately 82 minutes
A lanthanide MOF with nanostructured node disorder
No full textThe synthesis and structural characterization of a new metal organic framework, UoB-100(Dy), is reported. Average structure refinements indicate that the node is disordered between two orientations of the nonanuculear secondary building unit (SBU). By performing 3D diffuse scattering (DS) analysis and Monte Carlo (MC) simulations, we confirm the presence of strong correlations between the metal clusters of UoB-100(Dy). These nodes assemble into a complex and novel nanodomain structure. Quantum mechanical calculations identify linker strain as the driving force behind the nanodomain structure. The implications of such a nanodomain structure for the magnetic, gas storage, and mechanical properties of lanthanide MOFs are discussed
The effect of pyridinecarboxaldehyde functionalisation on reactivity and N-terminal protein modification
No full textThe site-selective modification of protein N-termini represents a powerful strategy for producing homogeneous bioconjugates. 2-Pyridinecarboxaldehydes have emerged as a leading reagent class in this area, but conjugation suffers from relatively slow rates and a degree of reversibility. In this work, we therefore studied the effects of pyridinecarboxaldehyde functionalisation on N-terminal modification, providing insight into the factors governing relative contributions from competing reaction pathways and design criteria for second generation reagents for protein labelling. Importantly, this insight allowed us to identify several candidate reagents which provide both accelerated and more stable protein labelling, enabling further applications of this powerful technology
Automated Multicolumn Screening Workflow in Ultra-High Pressure Hydrophilic Interaction Chromatography for Streamlined Method Development of Polar Analytes
No full textThe pharmaceutical industry is rapidly advancing toward new drug modalities, necessitating the development of advanced analytical strategies for effective, meaningful, and reliable assays. Hydrophilic Interaction Chromatography (HILIC) is a powerful technique for the analysis of polar analytes. Despite being a well-established technique, HILIC method development can be laborious owing to the multiple factors that affect the separation mechanism, such as the selection of stationary phase chemistry, mobile phase eluents, and optimization of column equilibration time. Herein, we introduce a new automated multicolumn and multi-eluent screening workflow that streamlines the development of new HILIC assays, circumventing the existing tedious ‘hit-or-miss’ approach. A total of 12 complementary columns packed with sub-2 µm fully porous and 2.7 µm superficially porous particles operated on readily available ultra-high pressure liquid chromatography (UHPLC) instrumentation across a diverse set of commercially available polar stationary phases were investigated. Different mobile phases with pH ranging from pH 3 to 9 were evaluated using different organic modifier. The gradient and column re-equilibration were judiciously set to ensure a reliable assay screening framework yielding straightforward separation conditions for subsequent optimization and method deployment in fast-paced laboratory settings. This UHPLC screening system is coupled with a diode array and charged aerosol detectors (DAD and CAD) to ensure versatile detection for a variety of compounds. This fast-screening platform lays the foundation for a convenient generic workflow, accelerating the pace of HILIC method development and transfer across both academic and industrial sectors
High Throughput Parallel Reaction Monitoring with Computer Vision
No full textWe report the development and applications of a computer vision based reaction monitoring method for high throughput experimentation (HTE). Whereas previous efforts reported methods to extract bulk kinetics from a single video, this new approach enables one video to capture bulk kinetics of multiple reactions running in parallel. Case studies in and beyond well-plate high throughput settings are described. Analysis of parallel dye-quenching hydroxylations, DMAP-catalysed esterification, solid-liquid sedimentation dynamics, metal catalyst degradation, and biologically-relevant sugar-mediated nitro reduction reactions have each provided insight into the scope and limitations of camera-enabled high throughput kinetics as a means of widening known analytical bottlenecks in HTE for reaction discovery, mechanistic understanding, and optimisation. It is envisaged that the nature of the multi-reaction time-resolved datasets made available by this analytical approach will later serve a broad range of downstream efforts in machine learning approaches towards exploring chemical space
Deuterated-Alkylation Reagents based on Sulfonium Salts as Cation and Radical Sources
No full textThe replacement of C-H bonds with more stable C-D bonds at the a-position of heteroatoms, which is the typical metabolic site for cytochrome P450, is important in drug discovery. Recently, we have developed dn (deuterated)-alkylated sulfonium salts (1a-dn), which were easily prepared by deuteration (H/D exchange reaction) with D2O of the corresponding alkyl diphenylsulfonium salts (1a), as electrophilic dn-alkylating reagents (cation sources). Herein, we newly report an improved preparation method of 1a and one-pot synthesis of dn-alkylated compounds via the deuteration of 1a with D2O and the subsequent nucleophilic substitution under basic conditions. Additionally, dn-alkyl thianthrenium salts (1b-dn) were also found to work as dn-alkylating reagents (cation sources). Furthermore, 1b-dn surved as radical sources under photo-induced reaction conditions with Ir photocatalyst, Hantzsch ester, or triphenylamine to obtain various regioselectively deuterium-incorporated alkyl compounds. These dn-alkylating reagents will contribute to advance the drug discovery
Berkelium–Carbon Bonding in a Tetravalent Berkelocene
No full textInterest in actinide–carbon bonds has persisted since actinide organometallics were first targeted for isotope separation during the Manhattan Project. Sandwich complexes with cyclooctatetraenide ligands have been used extensively to form tetravalent actinide compounds, “actinocenes,” from thorium through plutonium. These complexes have been pivotal in the development of electronic structure models used throughout inorganic chemistry. The isolation and structural characterization of transplutonium organometallics is extremely challenging due to limited isotope inventories, a scarcity of suitable laboratory infrastructure, and intrinsic difficulties with the anaerobic conditions required. Herein, we show that berkelium–carbon bonds can be stabilized in an organometallic “berkelocene” complex. Metal–ligand bonding involves the berkelium 5f orbitals in covalent overlap; however, charge transfer from the ligands is reduced to maximize contributions from the stable, half-filled 5f^7 configuration of tetravalent berkelium
Ring-to-Chain Transformation of Elemental Sulfur: Nonadiabatic Dynamics Simulations
No full textThe emergence of high-sulfur content polymeric materials and their diverse applications underscore the need for a comprehensive understanding of the ring-to-chain transformation of elemental sulfur. In this study, we delve into the ultra-fast transformation of the elemental sulfur S8 ring upon photoexcitation employing advanced non-adiabatic dynamics simulations. Our findings reveal that the bond breaking of the S8 ring occurs within tens of femtoseconds. At the time of bond breaking, most molecules are in the lowest singlet excited state S1. S1 survives for 40 to 450 fs before relaxing to the quasi-degenerate manifolds formed by the T1 and S0 states of the S8 chain. This suggests that upon photoexcitation the polymerization of the S8 chains might proceed before the chains relax to their lowest energy states. The derived temporal resolution provides a detailed perspective on the dynamics of S8 rings upon photoexcitation, shedding light on the intricate processes involved in its excited-state transformations
A Facile Access to Aliphatic Trifluoromethyl Ketones via Photocatalyzed Cross-Coupling of Bromotrifluoroacetone and Alkenes
No full textBiological molecules incorporating trifluoromethyl ketones (TFMKs) have emerged as reversible covalent inhibitors, aiding in the management and treatment of inflammatory diseases, cancer, and respiratory conditions. TFMKs, renowned for their versatile binding properties and adaptability, are pivotal in the rational design of novel drugs for diverse diseases. The photocatalytic insertion of alkenes, abundant feedstocks, into the α-carbon of trifluoromethylacetone represents a highly effective and atom-economical method for synthesizing valuable TFMKs. However, these processes typically necessitate high-energy photoirradiation (λ >300 nm, Hg lamp) and stoichiometric oxidants to generate the acetonyl radical from acetone. In our study, we demonstrate the visible-light photocatalytic radical addition into olefins using bromotrifluoroacetone as the trifluoroacetonyl radical precursor under mild conditions. Aliphatic trifluoromethyl ketones or the corresponding bromo-substituted products can be obtained by selecting an appropriate photocatalyst and solvent. Comprehensive experimental investigations, including cyclic voltammetry, Stern–Volmer quenching studies, and kinetic isotope effects, corroborate the synthesis of trifluoroacetonyl radical species from bromotrifluoroacetone under photoredox conditions. Further, we demonstrate the efficient synthesis of an oseltamivir derivative bearing a trifluoromethylketone moiety, which shows promising biological activity. Hence, this methodology will streamline the direct introduction of trifluoromethyl ketone into biological target molecules during drug discovery