Bulletin of the Korean Chemical Society最新文献

The cover image illustrates the catalytic potential of manganese oxides with varying oxidation states, highlighting Mn2O3 as the most efficient catalyst for aerobic HMF oxidation. Key factors contributing to this performance, including the oxidation state of metal moieties, oxygen mobility, and surface basicity, are visually represented to emphasize the synergetic effects driving the enhanced catalytic activity. More details are available in the article by Hyejin Yu, Yeonkyeong Ryu, Younghoon Kim, Hyun Sung Kim, Hyun Gil Cha

Targeted protein degradation (TPD) is a relatively novel drug discovery strategy that could help break through the limitations of traditional small molecule inhibitors. While TPD mostly utilizes diverse E3 ligases to incorporate the ubiquitin-proteasome system (UPS), cereblon (CRBN) could be considered one of the most successfully adopted E3 ligases. Thus, expanding the scope of CRBN ligands has received tremendous attention to overcome related issues, such as selectivity and druggability. In this study, design and synthesis of novel benzosultam-based CRBN ligands have been explored by replacement of lactam in lenalidomide with sultam. The sultam-based ligands showed CRBN binding affinities 2-20 times stronger than lenalidomide, presumably from additional hydrogen bonds generated from the extra oxygen atom in the sultam group, as supported by docking studies. This research highlights the potential of novel benzosultam CRBN ligands as a new tool for CRBN-mediated TPD strategies.

Solid-state NMR spectroscopy has gained increasing attention as a probe to investigate structures and dynamics of various solid materials, in particular, materials for rechargeable batteries. Cathodes and anodes for rechargeable batteries contain unpaired electrons (paramagnetic), which generate localized magnetic fields at molecules. Owing to this paramagnetic interaction, it is often complicated to measure and interpret the NMR spectra of the paramagnetic systems. Thus, understanding the effect of the interaction between unpaired electrons and nuclei is important. NMR spectroscopy at higher magnetic fields has been perceived as beneficial since this can provide higher sensitivity and resolution. However, the response to the magnetic field strength varies depending on the nuclei of interest and material properties because various factors affect NMR characteristics. In this work, we performed a systematic study of the effect of the field strength on the magic angle spinning (MAS) NMR characteristics by comparing diamagnetic and paramagnetic systems at two different magnetic fields. As diamagnetic materials, LiCoO₂ (LCO) and Li₂O are examined. As paramagnetic materials, LiFePO₄(LFP) and lithium nickel manganese cobalt oxides (LiNi_xMn_yCo_1–x–yO₂) with different compositions are investigated. We have demonstrated that higher signal intensity and narrower linewidths can be obtained at higher magnetic fields for diamagnetic systems, whereas higher signal intensity and better resolution are obtained at lower magnetic fields for paramagnetic systems. Our research will provide systematic and experimental evidence about the field strength dependence of paramagnetic systems and rationalized grounds for choosing proper NMR spectrometers for each material.

Vibrational relaxation in a hydrogen-bonded adenosine monophosphate has been studied in classical dynamics procedures. The initial excitation stored in the phosphate OH vibration is shown to mainly redistribute in the ribose moiety through efficient energy pumping by the phosphoester bond. The efficiency is due to the phosphoester bond couples with neighboring bonds and transports the initial excitation to the ribose in a series of small steps. In the ribose unit, energy travels the carbon–carbon pathway and distributes mainly in the C–O–H side chains. Energy distribution in the phosphate unit is minor, but the extent is significantly higher than the amount distributed in the adenine moiety, which shares only about 10% of the initial excitation due to the inefficient energy pumping of the ribose-to-adenine bond. The numerical procedures are repeated to prevent the leakage of zero-point energies by modifying the kinetic energy for each bond.

To develop an adsorbent for Li⁺ recovery from seawater and/or spent lithium batteries, a benzo-12-crown-4 ether (B12C4) moiety was immobilized with silica (immobilization yield: 0.70 meq g⁻¹). Compared to pure silica, the resulting adsorbent (FB12C4-SG) had a reduced Brunauer–Emmett–Teller surface area (500 vs. 180 m² g⁻¹) and pore volume (0.75 vs. 0.26 cm³ g⁻¹). The Li⁺ adsorption reached equilibrium at 31 mg g⁻¹ after 2 h (1000 ppm Li⁺ solution). The adsorption behavior was well explained by pseudo-second-order kinetics and the Langmuir adsorption model (maximum adsorption capacity: 33 mg g⁻¹). The material exhibited a Li⁺/Na⁺ adsorption selectivity factor of 4.2 and high chemical stability under acidic regeneration conditions (1.0 N HCl solution).

The cover image depicts a DMAC-functionalized salen–In complex exhibiting intense green emission in the rigid matrix. This feature is attributed to the synergistic effects of enhanced structural rigidity and higher number of DMAC-donors on ICT-based radiative decay. This result will greatly contribute to the future development of highly efficient indium luminescent materials.

This study presents a comprehensive computational pipeline to identify and evaluate potential stabilizing mutations for the coiled-coil protein–protein interaction between methyl-CpG-binding domain protein 2 (MBD2) and transcriptional repressor p66-alpha (p66α). The pipeline begins with the BeAtMuSiC program, which employs statistical potentials derived from known structures to predict candidate stabilizing mutations at the protein–protein interface. Out of 565 potential mutations, 10 single-point mutations (K149I, K163I, A237F, K149L, K149M, K163L, R166M, R166W, K163F, and E155L) with the highest binding affinity were selected for further evaluation using rigorous alchemical free energy calculations. These alchemical simulations conducted using the double-system/single-box method, predicted changes in binding free energy (ΔΔG) upon mutation while maintaining charge neutrality. The Crooks–Gaussian intersection technique was employed to analyze the results, identifying K149I, K149L, and K163L as potentially enhancing binding affinity the most, while mutations like K163F, A237F, and E155L were predicted to destabilize the interaction significantly. Complementary conventional Molecular Dynamics Simulations provided further support for the alchemical predictions, revealing decreased flexibility, increased contacts, and more compact structures for the predicted stabilizing mutants compared with the wild-type complex. Additionally, Molecular Mechanics Poisson–Boltzmann Surface Area (MM/PBSA) binding free energy calculations were performed, and their results were consistent with the direction of free energy change predicted by the alchemical approach. This multifaceted computational pipeline, combining predictive methods, alchemical simulations, and conventional analyses, offers valuable insights into modulating the binding affinity of the MBD2–p66α coiled-coil interaction. The identified stabilizing mutations can create numerous opportunities across biotechnology, biomedical research, and synthetic biology.

The aerobic oxidation of 5-hydroxymethylfurfural (HMF) into 2,5-furandicarboxylic acid (FDCA), a bio-based plastic monomer, is an important process for the valorization of biomass. Here, manganese oxides of various oxidation states with identical morphologies and similar surface areas were synthesized by introducing oxygen vacancy sites, and they were investigated as heterogeneous catalysts for HMF oxidation. Mn₂O₃ exhibited a remarkable catalytic efficiency due to synergistic effect of the oxidation state of metal moieties, the basicity of the catalyst, and oxygen mobility of the oxide materials under basic condition.

Nucleic acid-templated reactions are chemical processes driven by the increased effective concentration of reactants on nucleic acids through the sequence-specific hybridization of nucleic acids. Because these reactions translate the signals of target nucleic acids to detectable specific outputs, such as fluorescence, they can be applied for nucleic acid sensing and imaging. Owing to their advantageous features, such as signal amplification, isothermal nonenzymatic operation, and diverse reaction outputs and designs, the templated reactions have considerable potential for designing next-generation nucleic acid sensors with high sensitivity, selectivity, rapidity, and user-friendliness. Thus, over the past two decades, numerous templated reactions have been developed for more efficient nucleic acid detection. This review highlights recent advances in nucleic acid-templated reactions since 2020, focusing on the newly developed reactions and strategies for designing highly sensitive, selective, and accurate nucleic acid sensing systems. We also summarize templated reaction research since 2015 and explore how integrating these reactions with other signal amplification systems and readout methods has led to the development of practical nucleic acid sensors with improved properties. According to the analysis of each type of templated reactions (ligation, releasing, and transformation), design trends are discussed that inform the outlook for the future development of nucleic acid sensors utilizing templated reactions.

Photoredox catalysis has attracted increasing attention because of wide range of synthetic transformations and solar energy conversion applications. Reviews on photoredox catalysis have so far focused predominantly on the synthetic applications. This review highlights how organic photoredox catalysts were developed and how they function as efficient photocatalysts in mechanistic point of views. In particular, 9-mesityl-10-methylactidinium (Acr⁺–Mes) has been highlighted as one of the best organic photoredox catalysts. Acr⁺–Mes was originally developed as a model compound of the photosynthetic reaction center to mimic the long lifetime of the charge-separated state in which the energy is converted to chemical energy in photosynthesis. The reason why Acr⁺–Mes acts as one of the most efficient photoredox catalyst is clarified in terms of the one-electron redox potentials and long lifetimes of the electron-transfer state (Acr^•–Mes^•+) produced upon photoexcitation of Acr⁺–Mes in different solvents. The reason why the mesityl substituent at the 9-position of the Acr⁺ moiety is essential for the efficient photoredox catalysis is discussed in comparison with acridinium ions with different substituents R (Acr⁺–R) including 10-methylacridinium ion with no substituent (AcrH⁺). The mechanisms of photoredox catalysis of Acr⁺–Mes are discussed in various synthetic transformations and solar energy conversion reactions mimicking photosynthesis. Photoredox catalysis of quinolinium ion and its derivatives is also discussed in comparison with that of Acr⁺–Mes. Finally, immobilization of Acr⁺–Mes and quinolinium ions to form the composite catalysts with redox catalyst is discussed to improve the photoredox catalytic activity and stability.