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Nanowire Morphology Control in Sb Metal-derived Antimony Selenide Photocathodes for Solar Water Splitting
No full textWe report a facile method to enhance the photoelectrochemical (PEC) performance of Sb2Se3 photocathodes by controlling the growth of bilayer Sb2Se3 consisting of vertically oriented nanorods on a compact Sb2Se3 layer. Sb2Se3 thin films with controllable nanorod diameters were achieved by manipulating the substrate temperature during metallic Sb thin film deposition. The lower temperature-derived Sb2Se3 photocathode, with a larger nanorod diameter (202 ± 48 nm), demonstrated a photocurrent density of -15.2 mA cm−2 at 0 VRHE and an onset potential of 0.21 VRHE. In contrast, the higher temperature-derived Sb2Se3 photocathode, with a smaller nanorod diameter (124 ± 28 nm), exhibited an improved photocurrent density of -22.1 mA cm−2 at 0 VRHE and an onset potential of 0.31 VRHE. The enhanced PEC performance is attributed to reduced charge recombination facilitated by a shorter charge transport path in the [hk0] direction. This study highlights the significance of morphology control in optimizing Sb2Se3 photocathodes, providing insights for future material and device design
Machine Learning Approaches for Determining Molecular Packing of Organic Semiconductors: Toward Accurate Crystal Structure Prediction
No full textOrganic semiconductors (OSCs) with π-electron skeletons (π-cores) have attracted much attention. The creation of more innovative new molecules with high carrier mobility requires the strategic molecular design.
One of the most important properties affecting the carrier mobility of π-conjugated OSCs is the molecular arrangement, especially the two-dimensional (2D) molecular packing of the π-cores which exhibit 1D or 2D carrier conductivity as follows: π-stacking, herringbone (HB) packing, and brickwork (BW).
Since two molecular packing structures, HB and BW, have not been predicted theoretically, chemists have typically designed new OSC molecules based on their previous knowledge so far. Therefore, the use of computational science and informatics science is eagerly needed to strategically design an OSC molecule with unprecedented properties and functions.
In this study, we introduce machine learning method to determine whether an OSC forms 2D HB or BW molecular packing with a high accuracy. We further present the computational method to predict the crystal structure of an OSC only from its chemical structure using molecular mechanics calculation and molecular dynamics simulation coupled with our proposed machine learning model to classify the type of 2D molecular packing. The combination of molecular simulations with the machine learning model has the potential to predict the crystal structure of organic molecules
An Automated Electrochemical Flow Platform to Accelerate Library Synthesis and Reaction Optimization
No full textAutomated batch and flow reactors are well-established for high throughput experimentation in both thermal chemistry and photochemistry. However, the development of automated electrochemical platforms is hindered by cell miniaturization challenges in batch and difficulties in designing effective single-pass flow systems. In order to address these issues, we have designed and implemented a new, slug-based automated electrochemical flow platform. This platform was successfully demonstrated for electrochemical C-N cross-couplings of E3 ligase binders with diverse amines (44 examples), which were subsequently transferred to a continuous-flow mode for confirmation and isolation. To further validate the versatility of the platform, Design of Experiments (DoE) optimization was performed for an unsuccessful library target. This optimization process, fully automated by the platform, resulted in a remarkable 5-fold increase in reaction yield
Guiding the rational design of biocompatible metal-organic frameworks for drug delivery
No full textIn drug delivery, metal-organic frameworks (MOFs) have emerged as an interesting paradigm owing to their tuneable porosity, structural diversity, and ease of external surface functionalization. Compared to other drug delivery systems, state-of-the-art MOFs can encapsulate up to 50 times higher quantities of drugs per unit of mass while showing very long release times. Nevertheless, for their translation into clinical applications, concerns regarding MOF biocompatibility necessitate comprehensive mitigation. Unfortunately, experiments are resource and time-intensive, while modeling approaches fail to capture the behavior of MOFs in intricate biological systems. Herein, we report a novel computational pipeline guided by machine learning (ML) for probing the biocompatibility of MOFs. The pipeline is designed to expedite the assessment of potential MOF toxicity based on the chemical properties of their precursors. Interpretable ML models were built on a database of over 35,000 organic molecules, predicting the potential toxicity of MOF linkers with 83% accuracy. Additionally, we established a comprehensive database cataloging the toxicity of MOF metallic centers. Leveraging these, we have screened the Cambridge Structural Database (CSD) containing 86,000 non-disordered MOFs, identifying existing and future promising candidates with minimal toxicity profiles for drug delivery applications. Beyond high-throughput screening, the developed models shed light on the chemical landscape associated with high biocompatibility precursor molecules, enabling the derivation of guidelines for the rational design of biocompatible MOFs. This framework thus expedites the identification of biocompatible materials, while facilitating deeper insights into their underlying chemistry
Exploiting thiolate/disulfide redox couples toward large-scale electrochemical carbon dioxide capture and release
No full textReducing global carbon dioxide emissions is a critical issue that requires sustainable, energy-efficient and scalable solutions. Electrochemical carbon dioxide capture and release with redox active molecule has drawn an intense amount of interest, owing to its mild operation condition, low energy consumption and high flexibility compared with traditional CO2 capture technologies. Here, we demonstrate a series of thiolate/ disulfide redox couples, with high practical solubility and weak protonation ability, which are able to reversibly capture and release CO¬2. The mechanism of CO2 capture and release using such redox couples is elucidated via combining cyclic voltammetric and Fourier transform infrared spectroscopic measurements. Further, we show the redox performance of such materials can be significantly improved by functional group tuning and electrolyte engineering. Among them, the 4-fluorophenyl thiolate/4-fluorophenyl disulfide redox couple shows an initial CO2 capacity utilization efficiency and average release/capture efficiency of ~100% and ~90%, respectively, under simulated flue gas (20% CO2) in a flow system. Besides, it exhibits a good cycling stability against moisture. This work opens new opportunity to future works in developing thiolate/disulfide redox couples for large-scale electrochemical carbon dioxide capture and release applications
NQO1-responsive Prodrug for in Cellulo Release of Cytochalasin B as Cancer Cell-targeted Migrastatic
No full textMigrastatic drugs targeting cell motility and thereby suppress invasiveness of solid cancer cells, including their ability to metastasize and establish secondary tumors, are of high interest and have the potential to bring about a paradigm shift in the treatment of solid cancer. Cytochalasans, such as cytochalasin B, are known to disrupt cytoskeletal dynamics by inhibiting actin polymerization and have attracted considerable attention as potential migrastatics over the last decades, but are limited by selectivity issues so far. We herein report on the design, synthesis and evaluation of a bioresponsive prodrug BQTML-CB cleavable by the quinone-oxidoreductase NQO1, discussed as therapeutic target for the treatment of cancer
Enhanced Electrochemical Oxygen Evolution Reaction Enabled by Ni Cavity-Arrayed Electrodes
No full textThe water electrolysis is mostly limited by the slow kinetics of the oxygen evolution reaction (OER) including the interfacial electron and mass transfer and autoionization reactions. Especially in the neutral pH condition, slow rate of the autoionization reaction of water molecules also limits the electrolysis. The vibrational strong coupling, where the matter excitation is coupled to the cavity vacuum field mediated by a virtual photon, can be expected to modulate the physicochemical properties of water. Here, we utilized the cavity-arrayed electrode for the promotion of the OER. The OER activities of Ni cavity-array electrodes were evaluated from the oxygen bubble growth behavior. The Tafel slopes from the bubble analyses were modulated from 120 mV per decade to 30 mV per decade and the OER activity was enhanced by the cavity-arrayed electrode. This enhancement was explained with regards to the acceleration of autoionization of water molecules under the vibrational strong coupling. This study demonstrates that the cavity systems modulate the thermodynamic equilibrium of water autoionization under the vibrational strong coupling of liquid water at room temperature, leading to enhanced OER
N-Heterocyclic Silylene-Copper(I)-Aryl Complex: Multitasking Cu(I) Synthon
No full textIn this work, we have prepared [PhC{N(tBu)}2SiN(SiMe3)2] (1) coordinated organocopper(I) complexes (2 and 3) and utilized them as a useful synthon for the aryl group transfer and cleavage of a variety of homolytic and heterolytic bonds. Complex 2 was used as a mesityl transfer reagent in the C–C cross-coupling reaction that led to the formation of the coupled products in excellent yields. Further, we have demonstrated the reaction of 2 with compounds having B–B and Se–Se bonds, which led to the formation of dimeric µ-boryl bound Cu(I) complex (6) and a new class of unprecedented NHSi-supported copper-selenides (8 and 9). Finally, this new synthetic methodology smoothly afforded several elusive NHSi-copper amide complexes (10-14)
Overriding Cage Effect in Electron Donor-Acceptor Photoactivation of Diaryliodonium Reagents: Synthesis of Chalcogenides
No full textIn recent times, diaryliodonium reagents (DAIRs) have witnessed a resurgence as an arylating agent, especially under photoinduced conditions. However, reactions proceeding through electron donor-acceptor (EDA) complex formation with DAIRs are restricted to electron-rich reacting partners serving as donors due to the well-known cage effect. We discovered a visible-light-induced convenient and practical EDA platform to activate DAIRs for generating and concomitant utilization of resulting aryl radicals for synthesizing organic chalcogenides that are prevalent in natural products and biologically active compounds. In this process, an array of DAIRs and dichalcogenides react in the presence of 1,4 diazabicyclo[2.2.2]octane (DABCO) as a cheap and readily available donor, furnishing a diverse variety of di(hetero)aryl and aryl/alkyl chalcogenides in good yields. The method is scalable, features a broad scope with good yields, and operates under open-to-air conditions. The photoinduced chalcogenation technology is suitable for late-stage functionalizations and disulfide bioconjugations and facilitates access to biologically relevant thioesters, dithiocarbamates, sulfoximines, and sulfones. Moreover, the discovered method applies to synthesizing diverse pharmaceuticals, such as vortioxetine, promazine, mequitazine, and dapsone, under amenable conditions
Synthesis and Reactivity of Di(9-anthly)methyl Radical
No full textThe di(9-anthryl)methyl (DAntM) radical was synthesized and investigated to elucidate its optical, electrical properties, and reactivity. The generation of the DAntM radical was confirmed by its ESR spectrum, which showed two broad signals. The unpaired electron is primarily localized on the central sp2 carbon and slightly delocalized over the two anthryl moieties. Although the DAntM radical undergoes dimerization in solution, the radical still remains even at 190 K due to the bulky nature of the two anthryl group. Interestingly, upon exposure to air, the purple color of the radical solution quickly fades to orange, resulting in decomposition to give 9-anthryl aldehyde and anthroxyl radical derivatives