Bulletin of the Korean Chemical Society最新文献

Postpolymerization modification (PPM) offers a powerful strategy for diversifying polymer structures beyond the limitations of conventional polymerization. In this study, we present a selective decarbonylation-based PPM approach that partially converts ester bonds in polycaprolactone to ether bonds using a mild InBr₃/triethylsilane system at room temperature. This transition enables the development of previously inaccessible polyester–polyether copolymers, with controllable composition and properties. These results demonstrate the utility of reductive framework modification as a versatile method for designing structurally and thermally tunable flexible materials.

The increased use of fossil fuels has resulted in elevated concentrations of atmospheric carbon dioxide, which contributes to the greenhouse effect and other climate-related challenges. CO₂ emissions and research seeking solutions have been discussed across various fields for decades. Among proposed solutions, converting atmospheric CO₂ into valuable fuels and chemicals using catalysts represents a promising approach for reducing CO₂ concentrations. The electrocatalytic CO₂ reduction reaction (eCO₂RR) has attracted considerable attention due to its eco-friendly process compared to other conversion reactions. However, owing to the challenges of producing numerous by-products and the difficulty of controlling selectivity, recent research has focused on overcoming these problems. Metal–organic frameworks (MOFs) represent promising candidate materials for eCO₂RR applications due to their ability to capture CO₂ through pore size adjustment and accessibility to open metal sites, as well as their engineering versatility. Recent advances have demonstrated the development of MOF-based catalysts through diverse strategies that increase activity and selectivity for target products. MOF-based materials offer easier structural modification compared to other pure metal-based catalysts. In this review, we examine MOF-based materials from the perspective of engineering strategies and performance in eCO₂RR, focusing on morphology control as a means of modifying the electronic structure and the distance between active sites within the framework.

The cover illustration shows the solvent-dependent amphiphilic assembly of Pluronic® F127 in ethanol and water. In ethanol, F127 forms reversed micelle-like structures with a PEO core and PPO corona, whereas in water, conventional micelles are formed with a PPO core and PEO corona. This structural difference of F127 assemblies leads to polyphenol-induced aggregation of F127 assemblies specifically in ethanol, highlighting the solvent-driven tunability of polymer-polyphenol interactions. Details are in the article by Woongrak Choi, Eunu Kim, Helen H. Ju, Haeshin Lee.

Messenger RNA (mRNA) therapeutics have substantial potential in modern medicine, such as brain disorder treatment, following the success of mRNA vaccines against coronavirus disease 2019 (COVID-19). Their ability to drive endogenous protein production makes them highly versatile, but clinical translation for brain disorders faces major obstacles. The blood–brain barrier (BBB), rapid enzymatic degradation, and inefficient cellular uptake still remain key challenges preventing efficient delivery of mRNA therapeutics. To overcome these hurdles, diverse carrier systems were used. Lipid nanoparticles, polymeric carriers, and exosome-based carriers provide mRNA protection from enzymatic degradation and facilitate efficient uptake into target cells. Furthermore, conjugation with brain-targeting ligands is under development to enhance BBB penetration and brain selectivity. This review summarizes the delivery of RNA therapeutics for the treatment of brain disorders published over the past 5 years, categorized by administration route. Direct injection bypasses the BBB and ensures local delivery but is invasive and clinically limited. Systemic administration offers a less invasive option, leveraging passive, and active delivery mechanism. Immune cell-mediated brain cancer treatment is also promising, enabling engineered immune cells to cross or circumvent the BBB. In parallel, peripheral delivery routes, including intranasal and intratympanic injections, are being explored to exploit alternative pathways to the brain. Although no mRNA therapeutics for brain disorders have been approved, preclinical and early clinical studies demonstrate considerable potential. Continued innovation in carrier design, administration routes, and molecular engineering is expected to reveal safe and effective mRNA therapeutics for previously untreatable brain disorders. We hope that this review will offer valuable insights into the development of next-generation mRNA delivery platforms for brain disorders by summarizing current brain-targeted mRNA delivery strategies.

We report transparent and soluble poly(amide-imide)s with high glass transition temperature (T_g) synthesized from alicyclic diacid monomer containing trifluoromethyl groups. The good solubility of the polymers in polar aprotic solvents allows solvent casting of transparent polymer films having good transparency. We found that the alicyclic units, together with trifluoromethyl groups, between imide and amide bonds in the polymer main chains were critical for improving the optical properties of aromatic polymers. The transparent films exhibit good thermal properties, even with alicyclic units, due to hydrogen bonding along the main chain.

Alzheimer's disease (AD) is a complex neurodegenerative disorder marked by progressive cognitive decline and neuronal loss. A key pathological hallmark of AD is the accumulation and aberrant aggregation of amyloid-β (Aβ) peptides, which contributes to synaptic dysfunction and neurotoxicity. While the aggregation behavior of Aβ has been extensively studied, it can be altered by various factors, particularly metal ions, such as Fe(II/III), Cu(I/II), and Zn(II). These metal ions directly interact with specific amino acid residues in Aβ, influencing its oligomerization, fibrillization, and capacity to generate reactive oxygen species, thereby exacerbating oxidative stress and accelerating disease progression. Understanding the coordination chemistry between metal ions and Aβ is critical for deciphering their pathological impact in AD. This review provides a comprehensive overview of metal-bound Aβ (metal–Aβ) coordination at the molecular level, with a focus on insights gained from advanced spectroscopic methods. Nuclear magnetic resonance, electron paramagnetic resonance, and x-ray absorption spectroscopies collectively illuminate metal-binding sites, coordination geometries, and dynamic structural behavior of metal–Aβ complexes. These complementary approaches enable detailed structural characterization and mechanistic understanding of metal-induced Aβ aggregation and toxicity. By integrating spectroscopic findings on Fe(II/III), Cu(I/II), and Zn(II) coordination to Aβ, we highlight their distinct roles in AD pathogenesis as well as the broader significance of metal–peptide interactions underlying the mechanisms of neurodegenerative diseases.

DIYETDYYR is a tryptic peptide from the regulatory loop of insulin receptor, which has the three tyrosine residues need for activation of the protein. In order to spectroscopically differentiate the tyrosine residues, singly protonated DIYETDYYR and its phenylalanine-substituted analogs were studied by cryogenic ion spectroscopy. By comparing the UV absorption of the peptide at room temperature with those of phenylalanine-substituted ones, the second and the third tyrosine residues showed UV absorption between 35 000 and 35 200 cm⁻¹, while the first tyrosine residue did not. Comparing the infrared (IR) spectra of the peptides at cryogenic temperature, the second tyrosine residue was found to have a hydrogen-bonded phenolic OH. The IR spectra were explained by density-functional-based tight-binding calculations. The structure of DIYETDYYR was tentatively assigned to the one with a hydrogen bond between the second tyrosine and the C-terminus.

The transition metal dichalcogenides (TMDs) are an important class of two-dimensional materials due to their tunable band gap, high carrier mobility, and adjustable carrier concentration. Owing to these advantages, TMD can be utilized in a wide range of applications. In this work, we discuss the role of TMDs and their modifications on semiconductor materials for photocatalytic activity studies. Several modification strategies of MoS₂ have been explored to enhance its photocatalytic activity. These include: (i) deposition of few-layered MoS₂ on CdS to increase surface-active site density (FMC), (ii) activating basal plane sites in addition to edge sites via Cu doping (Cu-FMC), and (iii) coupling with conductive reduced graphene oxide to facilitate charge transport while retaining catalytic edge sites (RGO-FMC). Comparative photocatalytic studies under solar light irradiation with lactic acid as a hole scavenger reveal that Cu doping enhances the intrinsic activity of MoS₂, while reduced graphene oxide suppresses electron–hole recombination, and their combined structural modifications significantly boost hydrogen evolution performance, providing valuable insights into the rational design of transition metal sulfide-based heterostructures for solar fuel production.

This work demonstrates efficient selective adsorption of CO₂ from N₂ using two Zn-based BDP MOFs functionalized with imidazole and zwitterionic groups. In the single-component gas adsorption isotherms, both N-ZnMOF and Z-ZnMOF show the selective adsorption of CO₂ over N₂ and CH₄. Zn(BDP) with imidazole integration demonstrated the same behavior in adsorption isotherms; however, the imidazole-functionalized Zn(BDP) (N-ZnMOF) exhibits similar adsorption behavior to the parent Zn(BDP) framework, whereas incorporating a zwitterionic group (Z-ZnMOF) leads to a notably different adsorption behavior. Both MOFs exhibited high selectivity for CO₂ over N₂ at room temperature and 25 bar in power plant and direct air condition. This work suggests a new potential application for gas selective adsorption and storage using BDP-based MOFs integrated with imidazole and zwitterionic groups.

The kinetic resolution of 2-substituted tetrahydro-4-quinolone derivatives (N-tosyl azaflavones) has been accomplished by Ru(II)-TsDPEN-catalyzed asymmetric transfer hydrogenation (ATH). Employing HCO₂Na in the presence of a phase transfer catalyst as the hydrogen source, this methodology proceeds under mild and operationally convenient conditions. The process provides access to enantiomerically enriched 2-substituted-N-tosyl-2,3-dihydroquinolin-4(1H)-ones with excellent levels of enantioselectivity, frequently exceeding 99% ee. In parallel, the corresponding 2-substituted-1-tosyl-1,2,3,4-tetrahydroquinolin-4-ols are obtained in high conversion, also with superior enantioselectivity up to >99% ee. Both product classes are of considerable synthetic utility, and the high selectivity factors observed underscore the efficiency of this ATH approach. Overall, these results demonstrate the value of Ru(II)-TsDPEN catalysis combined with HCO₂Na/PTC as a practical strategy for the enantioselective synthesis of structurally diverse azaflavone derivatives.