Bulletin of the Korean Chemical Society最新文献

Among various strategies to enhance electrocatalytic activity, nanoporous structured electrodes have been widely utilized owing to their improved performance. Along with enlarged electrode surface, modified crystalline facets, and surface defects of nanoporous electrodes, recent studies have reported their unique electrocatalytic characteristics originating from the nanoconfined space, denoted as the nanoconfinement effect. Introducing nanoporous electrodes with controllable thickness made of indium tin oxide, an electrochemically inert material, has provided an optimal platform for analyzing the contribution of nanoporous structures to the catalytic effects. Nevertheless, the scope of reactants that has been studied based on this system so far is mostly limited to ferric/ferrous redox species in sulfate anion environment. Here, using the nanoporous indium tin oxide electrodes, we demonstrate the nanoconfinement effect toward the ferric/ferrous reaction in a different chemical environment that alters its electrokinetic characteristics compared to the previous studies. Furthermore, a complex multi-electron transfer reaction of oxygen reduction is employed to explore the effects of nanoporous structure toward inner-sphere reactions. Our work suggests that the nanoconfinement effects can be applied to a wider range of electrochemical reactions taking place in nanoporous electrodes.

Single-entity electrochemistry (SEE) has transformed the study of electrochemical processes, allowing for the observation of discrete electrochemical events at the level of individual entities such as nanoparticles (NPs) and biomolecules. This review categorizes SEE signals ranging from typical staircase, spike, and blip signals to more complex combined responses based on their shape, each providing insight into the reaction mechanism. Papers exploring reaction mechanisms based on changes in SEE signals under varying experimental conditions, such as applied potential or pH, are also discussed. By analyzing the experimental systems that generate these signals, a better understanding of electrocatalytic reactions mediated by single entities, such as NPs and biomolecules, can be achieved. This review offers insight into interpreting new signal types and paves the way for further research into electrochemical processes and the applications of SEE in sensing, catalysis, and diagnostics.

Efforts are underway to develop highly active catalysts to reduce the high overpotential of the oxygen evolution reaction (OER). Metal–organic frameworks or coordination polymers are promising candidates because of their tunable structures and high surface areas. In this study, Nickel and Cobalt trans-cinnamate (t-ca) were synthesized via a hydrothermal method. Their structures were analyzed and found to be isostructural. Both complexes exhibited superior electrocatalytic properties in the OER compared to those of IrO₂, with overpotentials of 373 and 390 mV and Tafel slopes of 58 and 66 mV/dec. These excellent characteristics were attributed to the electron delocalization of the metal centers via interactions with π-π delocalized organic ligands. Ni t-ca, with stronger ligand interactions, displayed an enhanced OER catalytic performance, emphasizing the importance of metal–ligand interactions and suggesting that further exploration of diverse π–π delocalized organic ligands and metal centers may lead to further advancements in electrocatalytic activity.

In this study, tocopherol-derived ionizable lipids were synthesized to create functional lipid nanoparticles for mRNA delivery. Tocopherol succinate is considered a biocompatible material because it has anti-cancer effects and degrades into vitamin E in the body. Two types of new ionizable tocopherol derivative lipids (DMT and AIT) were synthesized by introducing ionizable functional groups. The synthesized tocopherol lipids were used to make lipid nanoparticles with helper lipid, cholesterol, and PEG-DMG. The DMT LNP showed high mRNA encapsulation efficiency. Using HeLa cell lines, it was confirmed that gene transfection efficiency was increased approximately 2-fold in DMT LNP-treated cells compared to that of MC3 LNP. The two types of tocopherol derivative lipids exhibited high cell viability of over 90%, confirming very low levels of toxicity. The results of this study confirmed that lipid nanoparticles using newly developed ionizable tocopherol derivatives have potential as biocompatible and effective mRNA delivery vehicles.

Over the past century, biomimetic synthesis has significantly enhanced our understanding of the biosynthetic pathways involved in the formation of natural products. In this article, we present a two-step biomimetic synthesis of fluvirosaone A from 2,3-dehydroallosecurinine, featuring a Nazarov-type cyclization as the key step. Based on our synthetic results and computational analysis, we propose an alternative biosynthetic route for fluvirosaone A, identifying pyruvaldehyde as the likely source of the extraneous three carbons incorporated into the securinega skeleton.

PEDOT:PSS, an ionic polymer mixture of positively-charged poly-3,4-ethylenedioxythiophene (PEDOT⁺) and negatively-charged poly-styrenesulfonate (PSS⁻), is a water-processable and environmentally-benign organic semiconductor and electrochemical transistor, which plays a key role in organic (bio)electronic devices. However, pristine PEDOT:PSS films form 10-to-30-nm granular domains, where conducting-but-hydrophobic PEDOT-rich cores are surrounded by hydrophilic-but-insulating PSS-rich shells. Such morphology makes PEDOT:PSS water-soluble and thermally stable but very poor in conductivity. A tremendous amount of effort has been made to enhance the conductivity of PEDOT:PSS by restoring the extended conduction network of PEDOT. Recently, remarkable ~5000-fold improvements of conductivity have been achieved by mixing PEDOT:PSS with proper ionic liquids (ILs). In a series of free energy estimations using density functional theory calculation and molecular dynamics simulation, we have demonstrated that the classic hard-soft acid–base (or cation-anion) principle of chemistry plays an important role in such improvements. Ion exchange between PEDOT⁺:PSS⁻ and A⁺:X⁻ ILs helps PEDOT⁺ to decouple from PSS⁻ and to grow into large-scale conducting domains of π-stacked PEDOT⁺ decorated by IL anions X⁻. Thus, the most spontaneous decoupling between soft (hydrophobic) PEDOT⁺ and hard (hydrophilic) PSS⁻ would be induced by strong interaction with soft anions X⁻ and hard cations A⁺, respectively. Such hard-cation-soft-anion principles have led us to design ILs containing extremely hydrophilic (i.e., protic) cations and hydrophobic anions. Not only they indeed improve the conductivity of PEDOT:PSS but also enhance its stretchability as well. In summary, our modeling offered molecular-level insights on the morphological, electrical, and mechanical properties of PEDOT:PSS and a molecular-interaction-based enhancement strategy for intrinsically stretchable conductive polymers.

The single-entity electrochemistry (SEE) of electrocatalytic platinum (Pt) single nanoparticles (NPs) on a less electrocatalytic silver (Ag) ultramicroelectrode (UME) surface was investigated using the electrocatalytic amplification method. Two characteristic types of current responses—current staircases and blips (or spikes)—were observed during single NP collision experiments, depending on the applied potential at the Ag UME. Notably, at applied potentials of 0.13 and 0.17 V, the Ag UME becomes passive due to the formation of a delicate oxide layer, resulting in a highly stable background current. This leads to an enhanced signal-to-noise (S/N) ratio, attributed to the low background current, when using Ag UME compared to commonly used UMEs such as Au, C, Ni, and Hg for the SEE of Pt NPs. The exceptionally low background current can provide a significant advantage for detailed observation of SEE signals and further mechanistic studies based on the current response.

Recent advancements in the utilization of naturally derived nanocellulose and nanochitin/chitosan have opened new avenues for self-cleaning and purification applications to address environmental challenges. This review highlights the unique structural properties of bio-based nanofibers, which are typically rich in hydroxyl groups that enhance their functionality in various industrial sectors. Through appropriate chemical modification, they can perform specific functions facilitated by carboxylic acids or amine groups. We explored the mechanisms by which these materials facilitate oil/water separation, ultrafiltration, and self-cleaning processes, including the incorporation of inorganic nanoparticles, such as TiO₂, to improve hydrophilicity and oleophobicity. Furthermore, this review discusses innovative fabrication techniques, such as spray-assisted layer-by-layer assembly, which enhance the performance of nanofiber-based coatings. We examined the potential of these materials for diverse applications, including food packaging, wastewater treatment, and personal protective equipment, emphasizing their role in promoting sustainable industrial practices. As the global emphasis on eco-friendly solutions intensifies, continued research and development of nanocellulose and nanochitin is expected to drive significant advancements in materials science, paving the way for greener technologies.

The cover image depicts the synthesis of cyclic carbonates from carbon dioxide and epoxides using a ferrocene-based catalyst in which two dimethylamino groups were introduced in the same Cp ring. The new catalyst does not need halide-based additives or tethered salts attached to ligands when used for this coupling reaction. More details are available in the article by Jienu Lee, Wooram Lee, Yoseph Kim, Mujin Choi, Seol Ryu, Joonkyung Jang, Youngjo Kim.

1,2,4,5-Tetrazines serve as versatile two-carbon synthons, essential for synthesizing a variety of (hetero)aromatic compounds. Their specific reactivity with certain dienophiles, without interfering with biochemical processes, makes them ideal for bioorthogonal ligation. Despite their broad utility, current synthetic methods are costly and raise safety concerns, particularly during scale-up. This study introduces safer and more cost-effective synthetic strategies utilizing zinc chloride or boron trifluoride diethyl etherate as catalysts. These alternatives significantly reduce costs and enhance safety, potentially expanding the applicability of tetrazine synthesis across broader research domains.