Publications by authors named "Younghwan Jeong"

With the emerging of the problems of environmental pollution and energy crisis, the development of high-efficiency energy storage technology and green renewable energy is imminent. Supercapacitors have drawn great attention in wearable electronics because of their good performance and portability. Electrodes are the key to fabricate high-performance supercapacitors with good electrochemical properties and flexibility.

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Federated learning (FL) is a promising collaborative learning approach in edge computing, reducing communication costs and addressing the data privacy concerns of traditional cloud-based training. Owing to this, diverse studies have been conducted to distribute FL into industry. However, there still remain the practical issues of FL to be solved (e.

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Fisch. ex Turcz (ASFT), belonging to the family of Betulaceae, grows naturally in Asia, Europe, and America. The aims of this study are determining the efficacy of various biomarkers related to hair loss, evaluated by extracting the branch with 60% alcohol, and purely separating diarylheptanoid oregonin, an indicator and active substance, from 60% alcohol extract of the tree.

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We report the formation of supramolecular coordination polymers formed from multiporphyrin dendrimers (PZnPM; M = FB or Cu), composed of the focal freebase porphyrin (PFB) or cupper porphyrin (PCu) with eight zinc porphyrin (PZn) wings, and multipyridyl porphyrins (PyPM; M = FB or Cu), PFB or PCu with eight pyridyl groups, through multiple axial coordination interactions of pyridyl groups to PZns. UV-vis absorption spectra were recorded upon titration of PyPFB to PZnPFB. Differential spectra, obtained by subtracting the absorption of PZnPFB without guest addition as well as the absorption of PyPFB, exhibited clear isosbestic points with saturation binding at 1 equiv addition of PyPFB to PZnPFB.

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An imidazole-bearing zinc porphyrin (PZn) has been designed for the selective detection of Au(3+), and the porphyrin and gold complex (PZn·Au(3+)) can additionally be used to identify gold-binding functional groups such as cysteine residues and other mercaptans.

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Article Synopsis
  • An artificial light-harvesting dendrimer, 8P(Zn)P(FB), contains a focal freebase porphyrin and eight zinc(II) porphyrin wings, demonstrating significant changes in its photophysical properties when specific guest molecules are bound.
  • UV/Vis titration studies revealed a strong 1:2 complex formation with meso-tetrakis(4-pyridyl)-porphyrin (TPyP), indicating high association constants for the binding process.
  • Upon complex formation, the energy transfer efficiency from the zinc wings to the freebase core decreases markedly, shifting the process towards ultrafast electron transfer rather than energy transfer.
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A bisindole-bridged-porphyrin tweezer (1), a pair of zinc porphyrins (PZn's) connected to bisindole bridge (BB) via the Cu(I)-mediated alkyne-azide click chemistry, exhibited unique switching in forward and backward photoinduced energy transfer by specific guest bindings. The addition of Cu(2+) caused a change in electronic absorption and fluorescence quenching of 1. MALDI-TOF-MS and FT-IR analyses indicated the formation of stable coordination complex between 1 and Cu(2+) (1-Cu(II)).

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A zinc porphyrin-based receptor containing four triazole groups at the ortho-position of each phenyl group (1) was utilized as a useful probe for the determination of contaminants in acetonitrile (MeCN). Through the simple observation of the absorption spectrum of 1 in MeCN, the cyanide contamination concentration could be directly determined.

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Red means CN: A new type of diketopyrrolopyrrole-based chromophore has been synthesized as a colorimetric and fluorescent probe for the detection of cyanide using only two reaction steps. Through the addition of cyanide to the chromophore, the fluorescence emission and color were greatly changed in a highly sensitive and selective manner.

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A new type of fluorescent probe (1) with two triazole groups that are conjugated with a carbazole moiety was synthesized by a Cu(I)-catalyzed alkyne-azide click reaction for the selective and sensitive detection of cyanide via fluorescence enhancement by ligand exchange and metal ion removal.

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Internally grafted bent rod molecules consisting of a bent-shaped nona-p-phenylene and different lengths of oligoether chains at the bay position were synthesized and characterized. All of the bent-shaped molecules showed ordered bulk-state structures as characterized by differential scanning calorimetry, X-ray scatterings, and transmission electron microscopy. The bent rod based on a short oligo(propylene oxide) chain self-assembles into a 2-D channel-like columnar structure, whereas the molecules with an intermediate length of flexible chains self-assemble into discrete channels that self-organize into honeycomb layers.

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