Bulletin of the Korean Chemical Society最新文献

One-pot synthesis of spirooxindoles bearing α-metylene-γ-butyrolactone moiety has been carried out by the reaction of Morita–Baylis–Hillman (MBH) carbonates of isatins and paraformaldehyde in the presence of 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) in refluxing 1,2-dichloroethane in moderate yields. The reaction proceeded via (i) the formation of resonance-stabilized N-ylide from DBU and the MBH carbonate of isatin, (ii) a selective γ-attack of N-ylide to formaldehyde, (iii) lactonization to liberate methoxide ion, (iv) addition of methoxide ion to the iminium part of DBU, (v) intramolecular hydride transfer via a six-membered transition state, and finally (vi) elimination of DBU.

Zinc finger (ZF) proteins are well-known for their regulatory functions in the central dogma, and their structural domains serve as promising scaffolds for the study of neurodegenerative diseases. These proteins often contain multiple ZF domains, enabling interactions with target molecules that regulate transcription and translation. The Cys₂His₂ (C₂H₂) type ZF domains, found in the brain, are associated with long- and short-term memory, neuronal differentiation and development, and other physiological processes. The classical C-X₂-C-X₁₂-H-X₃-H type ZF domains have been detected in studies of Parkinson's disease (PD) and are closely linked to biological pathways involved in a wide range of neurodegenerative diseases. In this review, we introduce three ZF proteins expressed in the brain: Parkin-interacting substrate (PARIS), zinc finger and BTB domain-containing 20 (ZBTB20), and zinc finger protein 18 (ZNF18). We explore the structural and functional roles of these ZF proteins in the brain. Each of these proteins contains more than four ZF domains, as well as functional domains such as KRAB, BTB, and SCAN, which perform modular roles independently of the ZF domains. Biophysical studies of PARIS have demonstrated that its classical three-ZF domain, PARIS(ZF2–4), forms hydrogen bonds with insulin response sequences (IRSs) with high specificity (K_d = 38.9 ± 2.4 nM). Metal coordination studies showed that PARIS binds Co²⁺ with high affinity (K_d = 49.1 ± 7.7 nM), more strongly than other ZF domains, and it also coordinates with other xenobiotic metal ions such as Fe²⁺ and Ni²⁺. Although Zn²⁺–PARIS(ZF2–4) binds specifically to IRSs, Fe²⁺–, Fe³⁺– or Co²⁺–PARIS(ZF2–4) cannot, due to distortions in the ZF domain structure that disrupt hydrogen bonding. These brain-specific ZF domains exhibit common patterns, with similar numbers of ZF domains and sequence homology at the C-terminus, whereas both the ZF domains and N-terminal protein–protein interaction domains contribute to their functional versatility. Elucidating the structure and function of these classical ZF proteins offers promising avenues for the treatment of diverse brain disorders, including Alzheimer's disease, PD, and autism spectrum disorder.

Dry-gel conversion (DGC), which directly converts zeolite gel into crystals by vapor, is considered a promising method for reducing amounts of zeolite precursors and easily controlling crystallization. Synthesis of MFI zeolites employing the DGC method with different amounts of tetrapropylammonium bromide (TPABr) and sodium hydroxide (NaOH) was studied to investigate the effect of TPABr and NaOH on the crystallization of MFI zeolite, with the optimal condition for synthesis found to be 0.05625 for both NaOH/SiO₂ and TPABr/SiO₂. Additionally, carbon black (CB) was added onto the MFI zeolite precursor gel as a hard template to generate mesopores into zeolite frameworks. The resultant MFI zeolite with CB synthesized by the DGC method showed mesoporosity, with pore size distribution similar to the particle size of CB. However, the conventional hydrothermal method could not generate mesopores in MFI zeolite due to the separation of zeolite crystals from CB templates during crystallization.

This study explores the use of a cost-effective laser-induced breakdown spectroscopy (LIBS) instrument for analyzing magnesium (Mg) in fermented soybean pastes. Composed of soybeans and salts, these pastes are rich in proteins and minerals. A low-power diode-pumped solid-state laser and a miniature low-resolution spectrometer were used to analyze nine products, with Mg concentrations previously determined via inductively-coupled plasma optical emission spectroscopy. The LIBS spectra showed Mg II and Mg I emission peaks at 279.8 and 285.2 nm, respectively, used to create univariate calibration models. Additionally, a partial-least-squares regression (PLS-R) model showed superior accuracy. Mg concentrations correlated with the types of salts used. The study demonstrates the feasibility of using real products as calibration standards for LIBS, supported by other methods. The compact, low-cost LIBS instrument offers an alternative for quantitative mineral analysis and raw material identification in fermented soybean pastes.

The cover image depicts the Pt nanoparticles collision on an Ag ultramicroelectrode and the delicate oxide layer formed on the Ag electrode surface. When a single nanoparticle collides with the electrode surface, a current signal related to the catalytic reaction appears, and then the current returns to its original level due to the oxide layer of the electrode. More details are available in the article by Seong Jung Kwon, Seongkyeong Yoon, Jaedo Na, Sun Gyu Moon, Heewon Kim, and Ki Jun Kim.

This study evaluated the fog-collection efficiency of wrinkle-based multilayer surfaces using hydrophilic and hydrophobic treatments. The wrinkle structures were fabricated by leveraging the elastic modulus and Poisson's ratio of polydimethylsiloxane (PDMS) and ultraviolet (UV) resin. The optimal wrinkle periodicity for fog collection was determined by varying the spin-coating rate of the UV resin. Chemical surface treatments were examined by applying hydrophilic (hyaluronic acid [HA]) and hydrophobic (perfluoropolyether [PFPE] and TiO₂-PFPE) agents. Surfaces with perpendicular wrinkles treated with TiO₂-PFPE demonstrated the highest fog-collection efficiency due to increased surface roughness that promoted droplet nucleation and growth. These wrinkles further optimized efficiency by facilitating the rapid downward flow of water droplets through the combined effects of gravity and capillary action. The study highlights the significant impact of wrinkle structures and surface treatments on fog collection, with the TiO₂-PFPE treatment showing particular effectiveness and potential for applications in arid regions.

Indium–salen complexes with electron-donating 9,9-dimethyl-9,10-dihydroacridine (DMAC) groups at positions 4 (DMACIn1) and 4 and 6 (DMACIn2) were synthesized and characterized to investigate the effect of the substituents number and structural rigidity on photophysical properties. The single crystal structure of DMACIn1 revealed highly twisted arrays (83–89°) between the DMAC groups and salen moieties and a nearly square-pyramidal geometry around the indium center. Both complexes exhibited green fluorescence in toluene at 298 K and in rigid states (in toluene at 77 K and in a film), which originates from intramolecular charge transfer (ICT) transitions. The absolute photoluminescence quantum yields (PLQYs) of DMACIn1 and DMACIn2 were low in solution but high in the rigid states. The film-state PLQY of DMACIn2 (59.5%) was more than five-fold higher than that of DMACIn1 (11.1%). A similar result was observed in toluene at 77 K. These findings were rationalized in terms of the beneficial effects of structural rigidity and higher number of DMAC donors on ICT-based radiative decay. The experimental results agreed with those of computational studies.

This study introduces a novel nanogap-enhanced plasmonic absorber (NEPA) structure generated using the Gray–Scott algorithm. Finite-difference time-domain simulations analyzed NEPA's optical properties, varying top pattern thickness from 10 to 300 nm. The simulation results demonstrate exceptional broadband absorption, with rates exceeding 60% across the 90–300 nm thickness range and reaching a peak of 96.73% at 160 nm. The nanogap-mediated plasmonic nanomaze array exhibits multiple resonance features and complex electric field distributions due to various plasmonic modes. The nearly uniform spacing of the nanomaze pattern maintains consistent plasmonic properties. This innovative approach shows great potential for enhancing plasmonic devices, with applications in solar cells, photodetectors, surface-enhanced Raman spectroscopy, metamaterials, imaging, energy harvesting, and nanoantennas. Our research advances nanophotonics, offering new possibilities for high-efficiency optical and optoelectronic devices across various applications.

Helical peptides, as well as proteins composed of helical peptides, play essential roles in various biological processes, including their functions as components of cell membranes and their interactions with biological membranes. Therefore, it is crucial to predict the propensity and structural characteristics of helices formed in solution or lipid environments for specific peptide sequences. Melittin and pexiganan are antimicrobial peptides (AMPs) that possess distinct sequence characteristics but exhibit similar structural properties in both solution and lipid environments. In this study, we conducted molecular dynamics simulations to investigate how the presence of counter ions creates differences in structural characteristics between these two peptides in solution. By analyzing the structures formed for each AMP using extended helical projections, we aimed to uncover the underlying principles governing the interaction between counter ions and peptide sequences, leading to the formation of stable structures. It was found that the coordination of counter ions effectively extends the helical surface and stabilizes the extended helix by reducing the electrostatic repulsion between charged residues. Our results demonstrate how sequence specificity influences helical structure formation in solution and provide an explanation for the varying degrees of synergistic effects exhibited by different helical AMPs.

This review covers the visible light induced reactions of quinones such as benzoquinone, naphthoquinone, and anthraquinone. These quinones are distinguished by their fully conjugated structures, which feature minimal energy gaps, and nonbonding electron pairs on the oxygen atoms. Such structural attributes facilitate n_p → π* transition, allowing for easy access to excited states and rendering quinones highly reactive under visible-light irradiation. We describe three primary types of reactions facilitated by these electronic characteristics: Paternò–Büchi (PB) reactions, which entail [2 + 2] photocycloaddition between the carbonyl groups of quinones and alkenes or alkynes; CH activation processes, which showcase quinones' versatility in functionalizing hydrocarbons; and the formation of electron donor–acceptor complexes, demonstrating quinones' capability to engage in charge transfer interactions. Through this review, we highlight the critical role quinones play in photochemistry, their unique electronic properties, and their broad applicability in synthetic organic chemistry.