Bulletin of the Korean Chemical Society最新文献

This paper reports the development of a universal antifouling coating based on a small molecule, tyrosine-conjugated diethylene glycol (Tyr-EG₂). Tyrosine, a natural precursor in melanin biosynthesis, undergoes tyrosinase-catalyzed oxidation to initiate film formation on various surfaces. Building on this principle, Tyr-EG₂ was designed to form a melanin-mimetic poly(Tyr-EG₂) film through enzymatic oxidation under mild aqueous conditions (pH 7.4). In contrast to polymeric systems composed of repeating ethylene glycol and catechol units, which often suffer from batch-to-batch variations owing to their high molecular weight and structural complexity, Tyr-EG₂ exhibits a well-defined, low molecular weight, which enables consistent synthesis. Moreover, compared with catechol, the phenol-based structure of Tyr-EG₂ provides enhanced resistance to auto-oxidation under ambient conditions. The resulting poly(Tyr-EG₂) films exhibited excellent coating capabilities on a wide range of substrates, as well as antifouling properties, reducing nonspecific protein adsorption and marine organism adhesion. This simple, mild, and versatile strategy offers a practical platform for achieving antifouling coatings, which are required in the fields of biosensors, marine equipment, and medical devices.

The increasing sophistication of handwriting forgery techniques highlights the need for reliable document authentication methods. This study reports an online nonaqueous capillary electrophoresis–mass spectrometry method for the simultaneous screening of several synthetic organic dyes, namely methylene blue, malachite green, crystal violet, methyl violet, Victoria blue basic oxide, and rhodamine B. All dyes were analyzed within 18 min under an electric field of 389 V/cm using a nonaqueous running buffer system (pH 4.5; 50 mM ammonium acetate and 850 mM acetic acid in 100% ethanol) and the single-ion monitoring scan mode for signal enhancement. Ink organic dyes in documents handwritten using commercial red and blue ballpoint pens were extracted with ethanol from pieces of paper created by punching and successfully identified using the developed method to validate its applicability to real forensic samples and demonstrate its suitability for the rapid and effective forensic ink analysis coupled with document authentication.

Lipid droplets (LDs) are dynamic organelles involved in lipid storage and metabolism, interacting with other organelles to maintain cellular homeostasis. Changes in LD number, size, or polarity are linked to metabolic disorders such as fatty liver disease, diabetes, and drug-induced liver injury. Fluorescence imaging is a sensitive, non-invasive method for monitoring LD dynamics in living systems. However, many existing LD-targeting dyes lack the specificity and functionality required to track real-time changes in the lipid microenvironment. Recent advances in environment-sensitive fluorophores, particularly those using excited-state intramolecular proton transfer, offer promising tools for visualizing LD behavior and detecting early hepatic steatosis. In this study, probe 1 demonstrated high lipid selectivity, excellent biocompatibility, and pronounced polarity sensitivity, enabling real-time visualization of LD dynamics and early-stage hepatic steatosis detection in living cells. Its photophysical behavior and selectivity were analyzed using density functional theory (DFT), time-dependent DFT, and confocal laser scanning microscopy.

Noncentrosymmetric (NCS) solid-state materials play a vital role in modern photonic and optoelectronic technologies attributable to their ability to exhibit second-order nonlinear optical (NLO) phenomena such as second-harmonic generation (SHG), the bulk photovoltaic effect (BPVE), and directionally selective photoluminescence. The design of such materials requires a nuanced understanding of how structural asymmetry at the atomic and molecular levels translates into macroscopic physical properties. This tutorial review introduces a selection of representative NCS compounds—CsScP₂S₇, [Zn(pvb)₂]·(DMF) (pvb = trans-2-(4-pyridyl)-4-vinylbenzoate), (4AMPY)(MA)Ge₂I₇ (4AMPY = 4-(aminomethyl)pyridinium; MA = methylammonium), and (MIPA)₂PbI₄ (MIPA = N-methyliodopropylammonium)—each synthesized via distinct routes, including solid-state reaction, hydrothermal synthesis, and solution-phase crystallization. Through structural analyses, we illustrate how features such as asymmetric coordination geometries, layered or chain-type connectivity, and the incorporation of polar organic cations govern key functional behaviors. By systematically correlating synthetic strategies, crystallographic features, and physical responses such as SHG efficiency, optical anisotropy, and photoreactivity, we highlight the critical role of structural design in achieving desirable NLO and optoelectronic performance. This review serves as an accessible guide for students and early-career researchers, offering both theoretical foundations and practical insights into the rational design of NCS materials through solid-state chemistry.

This review explores the electrochemical behavior of various redox electrolytes in water-in-salt electrolytes (WISEs), a class of highly concentrated salt electrolytes—mainly composed of LiTFSI—that significantly expand the electrochemical window in aqueous systems. In addition to the hydrogen evolution reaction and the oxygen evolution reaction, the review covers the electrochemical behavior in electrodeposition of metals, halides, ferri/ferrocyanide, and several organic redox electrolytes (TEMPO, Quinone, and Pyrazine) in WISEs. The influence of highly concentrated salt electrolytes on solvation structures and their impact on the stability, reversibility, and degradation mechanisms of these redox-active species are discussed, emphasizing the impact of solvation structure transitions on the electrochemical nature of various redox electrolytes.

The cover image depicts a protease-associated enzyme-linked immunosorbent assay using biotinylated α-chymotrypsin (α-CTB) to detect matrix metalloproteinase-9. A fluorogenic peptide substrate emits fluorescence upon enzymatic cleavage, enabling sensitive quantification. The image illustrates the α-CTB-based fluorescence assay, highlighting its enhanced sensitivity. Details are in the article by Saodat Nurulloeva, Yeon-Ju Lee, Hana Cho, and Dong-Sik Shin. Details are in the article by Saodat Nurulloeva, Yeon-Ju Lee, Hana Cho, Dong-Sik Shin.

Advances in time-resolved spectroscopy have greatly enhanced our ability to observe ultrafast processes in chemical and physical systems. Femtosecond spectroscopies enable the initiation and real-time observation of coherent nuclear motions. The coherent vibrational spectrum (CVS), obtained from the propagation of nuclear wave packets (NWPs), serves as a powerful tool for probing the nature of chemical processes, including potential energy surfaces and structural dynamics. Time-resolved fluorescence (TF) is a classical technique for studying excited-state dynamics. By recording spontaneous emission, TF offers the unique advantage of selectively detecting emitting species. Continued improvements in time resolution have expanded the capabilities of TF beyond simple population kinetics to include direct observation of ultrafast coherent phenomena and structural changes. Modern TF apparatus based on fluorescence upconversion can now achieve time resolutions of 30 fs, allowing detection of NWP motions. Moreover, because TF-derived CVS reflects only excited-state processes, its integration with quantum chemical calculations enables more accurate and detailed interpretations of excited-state molecular dynamics. In this review, we present the development of high time-resolution TF, including techniques and apparatus for achieving time resolutions as short as 30 fs, suitable for capturing NWP dynamics. We also provide a brief theoretical overview of TF, along with approaches for calculating NWPs using quantum chemical and molecular dynamics simulations. Two application examples are discussed. First, in the photoexcitation of coumarin 153 to the Franck–Condon region of the S₁ state, the feasibility of recording NWP motions by TF is demonstrated. The experimental and calculated CVS from vibrational displacements show good agreement. Second, TF is used to investigate the excited-state intramolecular proton transfer (ESIPT) dynamics in 10-hydroxybenzo[h]quinoline (HBQ). Because HBQ undergoes ultrafast ESIPT in <20 fs, TF captures the CVS of the product, whose amplitudes and phases reflect the potential energy surfaces associated with the chemical reaction. Combined with quantum chemical calculations and molecular dynamics simulations, TF provides a detailed picture of the ESIPT process. Further development of TF toward even higher time resolution of ~20 fs, extending into the fingerprint region, holds great promise for capturing comprehensive vibrational spectra and time-resolved structural changes during chemical reactions.

This study presents an approach for discriminating omega-3 fatty acid forms using proton nuclear magnetic resonance (¹H-NMR) spectroscopy combined with machine learning and deep learning techniques. A total of 90 samples, comprising triglyceride, re-esterified triglyceride, and ethyl ester forms, were analyzed. Principal component analysis–linear discriminant analysis, support vector machine (SVM), artificial neural network (ANN), and one-dimensional convolutional neural network (1D CNN) models were applied using binned spectral data. In contrast, a two-dimensional convolutional neural network (2D CNN) was constructed using spectral images. To prevent overfitting and optimize model hyperparameters, early stopping, cross-validation, and Bayesian optimization were used across the different machine learning and deep learning models. The 1D and 2D CNN models both achieved 100% accuracy on the training and test sets, while the SVM and ANN models yielded slightly lower but still excellent performance, with a test accuracy of 94.4%. Model interpretability was enhanced through SHapley Additive exPlanations and Gradient-weighted Class Activation Mapping, which identified critical spectral regions associated with classification decisions. These results demonstrate that the integration of artificial intelligence techniques with ¹H-NMR spectroscopy enables accurate, interpretable discrimination of omega-3 fatty acid forms, offering a promising strategy for supplement authentication and quality control.

Understanding the fundamental motions of molecules, particularly vibrational motions, is essential for elucidating chemical reaction mechanisms. Time-resolved X-ray scattering (TRXS) has emerged as a powerful technique for investigating molecular vibrations, as it simultaneously provides both temporal and spatial information on vibrational modes. However, visualizing these vibrations via TRXS remains challenging due to technical limitations in achieving a high signal-to-noise ratio (SNR) and temporal resolution, making it difficult to resolve subtle oscillatory signals arising from molecular vibrations. Here, we present an integrative analysis framework developed to efficiently extract oscillatory signals from TRXS data and verify their association with molecular vibrations. The framework comprises two key steps: the extraction of oscillatory signals using singular spectrum analysis (SSA) and posterior structural analysis to assess the physical relevance of the extracted signals. By applying this scheme to simulated TRXS datasets, we demonstrate that it identifies oscillatory signals embedded in the data more effectively than conventional Fourier transform analysis, even under low SNR conditions. Furthermore, the structural analysis step effectively discriminates physically irrelevant components, such as harmonic and combination frequencies, and high-frequency artifacts from signals corresponding to the fundamental frequencies of molecular vibrations. The proposed data analysis framework is expected to advance studies of molecular vibrations and wavepacket dynamics using TRXS, ultimately providing deeper insights into the ultrafast reaction dynamics.

The stability and catalytic properties of coordination polymers (CPs) in electrochemical reactions can be improved by incorporating supporting materials. In this study, the enhancement of the electrocatalytic performance of two isostructural CP electrocatalysts, Ni and Co trans-cinnamate (t-ca), was investigated using three carbon-based supports: reduced graphene oxide (rGO), multi-walled carbon nanotubes (MWCNT), and carboxylic acid-functionalized MWCNT (MWCNT-COOH). The objective was to improve the catalytic performance in the oxygen evolution reaction (OER). Investigation of the OER characteristics of each catalyst/support combination, Ni t-ca/MWCNT-COOH and Co t-ca/rGO combinations, exhibited overpotential reductions of approximately 20 and 35 mV, respectively, compared to the unsupported catalyst. The enhanced electrocatalytic properties can be attributed to chemical interactions such as π–π interactions and hydrogen bonding between the supports and the π-conjugated hydrocarbon and carboxylate groups present in the t-ca ligand.