• Bulletin of the Korean Chemical Society
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• v.1 no.4
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• pp.123-126
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• 1980

Benzene solution of trans-1,2-bispyrazylethylene and electron deficient olefin, tetracyanoethylene, as a ${\pi}$-acceptor gave 1,2-bispyrazyl-3,3,4,4-tetracyanocyclobutane, a 2${\pi}$ + 2${\pi}$ cycloaddition product, on irradiation with 350 nm UV light. Fluorescence studies revealed the reaction to proceed through a singlet exciplex. The fluorescence of trans-1,2-bispyrazylethylene was quenched very efficiently by tetracyanoethylene with the quenching constant of 1.6 ${\times}$ 10$^{10}$M$^{-1}$s$^{-1}$ while electron rich olefin, tetramethylethylene, did not quench the fluorescence of bispyrazylethylene.

• Bulletin of the Korean Chemical Society
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• v.19 no.10
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• pp.1042-1047
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• 1998

The fluorescence excitation (FE) spectrum of the S1-S0 (1B2-1A1) transition of dimethyldiazirine cooled in supersonic jet expansions has been obtained. Dispersed fluorescence (DF) spectra have also been taken for some prominent features of the FE spectrum. Vibrational analyses of the FE and DF spectra with the help of an ab initio molecular orbital calculation lead to some new vibrational assignments and refined fundamental frequencies.

• Bulletin of the Korean Chemical Society
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• v.12 no.4
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• pp.441-444
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• 1991

The intramolecular proton transfers of 2-hydroxy-4,5-naphthotropone in room temperature solutions are studied using static and time-resolved absorption and emission spectroscopy. Dual normal and tautomer fluorescence is observed in ethanol solution, while only the tautomer fluorescence is observed in cyclohexane solution. The fluorescence lifetimes and quantum yields in ethanol and cyclohexane solutions indicate that in hydrocarbon solvents, rapid intersystem crossing competes with proton transfer in the first excited singlet state. Transient absorption spectra and kinetics indicate that proton transfer also undergoes in the first triplet state with a transfer time of ∼ 3 ns. No transient absorption from the tautomer ground state indicates a rapid back proton transfer in the ground state.

• Microbiology and Biotechnology Letters
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• v.49 no.3
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• pp.316-319
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• 2021

Restriction endonucleases play an important role in molecular cloning, clinical diagnosis, and pharmacological drug studies. In this study, DNA-templated copper nanoclusters (DNA-CuNCs) were used to detect AluI endonuclease activity due to their high fluorescence emission and rapid synthesis of DNA-CuNCs under ambient conditions. Results showed that AluI activity was detected in a highly sensitive manner at low concentrations of AluI endonuclease by the fluorescence intensity of DNA-CuNCs. Additionally, its inhibition was monitored in the presence of daidzein under optimal conditions.

• Bulletin of the Korean Chemical Society
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• v.6 no.3
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• pp.164-168
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• 1985

The fluorescence emission of polystyrene-acrylic acid copolymers containing $Eu^{3+}$ in tetrahydrofuran solution was investigated by spectrofluorimetry. The excimer emission increased linearly with the polymer concentration up to approximately $5{\times}10^{-3}$M. Benzene and toluene collisionally quenched the excimer fluorescence and thier rate constants of quenching were determined. Quenching efficiencies decreased in the order: naphthalene > toluene > benzene. Analyses of Rayleigh scattering and europium emission showed no measurable structural changes observed under the experimental conditions.

• Archives of Pharmacal Research
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• v.7 no.1
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• pp.11-15
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• 1984

Binding of sic cephalosporins (cefotaxime, cefuroxime, cafazoline, cephalothin, cephaloridine, cephacetrile) to human serum albumin was studied. Fluorescence probe technique and difference spectrophotometry were employed to evaluate the nature and degree of association of cephalosporin-albumin complex. 1-anilinonaphthalene-8-surfonate was used as the fluorescence probe, and 2-(4'-hydroxybenzeneazo)benzoic acid as the UV spectrophotometric probe. Competitive bindings between cephalosporins and probe were observed. For the binding of cephalosporins to human serum albumin, three binding sites were identified by fluorescence probe technique but four binding constants of cephalosporins to human serum albumin measured by fluorescence probe technique are higher than those meausred by UV spectrophotometry.

• Bulletin of the Korean Chemical Society
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• v.26 no.11
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• pp.1706-1710
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• 2005

The excited-state intramolecular proton transfer (ESIPT) fluorescence in the 2-(2'-hydroxyphenyl)benzoxazole (HBO) derivatives with different electron donor and acceptor substituents was studied by spectroscopic and theoretical methods. Changes in the electronic transition, energy levels, and orbital diagrams of HBO analogues were investigated by the semi-empirical molecular orbital calculation and were correlated with the experimental spectral position of ESIPT keto emission. It was found that the presence of substituents, regardless of their nature, resulted in the red-shifted absorption relative to HBO. However, the spectral change of the ESIPT fluorescence was differently affected by the nature of substituent: hypsochromic shift with electron donor and bathochromic shift with electron acceptor.

• Bulletin of the Korean Chemical Society
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• v.32 no.5
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• pp.1599-1603
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• 2011

Novel chemosensors based on 2-(2'-hydroxyphenyl)quinoline were prepared and evaluated for sensing metal cations. The photophysical properties of chemosensors 1-3 were examined and their ion-selectivity was evaluated by measuring their fluorescent emission responses to alkali, alkaline earth, and transition metal ions. Chemosensors 1, 2 and 3 show ratiometric and enhanced fluorescence changes with transitional metals that are efficient fluorescence quenchers, especially 3 has a high binding constant with $Hg^{+2}$ in $CH_3CN$.

• Bulletin of the Korean Chemical Society
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• v.33 no.3
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• pp.958-962
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• 2012

In single-molecule fluorescence experiment, the oxygen scavenging system is indispensable for avoiding photo-bleaching of fluorescent dyes. Here we report that the gloxy-based oxygen scavenging system commonly used in single molecule fluorescence experiments can disturb the solution pH considerably. To track in situ pH change, we utilized the pH-sensitive conformational transition of i-motif and examined the transition with ensemble and single-molecule FRET measurements. Based on our results, we also suggested several practical remedies for the stability of the solution pH.

• BMB Reports
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• v.53 no.5
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• pp.241-247
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• 2020

As an intracellular degradation system, autophagy is an essential and defensive cellular program required for cell survival and cellular metabolic homeostasis in response to various stresses, such as nutrient deprivation and the accumulation of damaged organelles. In general, autophagy flux consists of four steps: (1) initiation (formation of phagophore), (2) maturation and completion of autophagosome, (3) fusion of autophagosomes with lysosomes (formation of autolysosome), and (4) degradation of intravesicular components within autolysosomes. The number of genes and reagents that modulate autophagy is increasing. Investigation of their effect on autophagy flux is critical to understanding the roles of autophagy in many physiological and pathological processes. In this review, we summarize and discuss ways to analyze autophagy flux quantitatively and qualitatively with the use of imaging tools. The suggested imaging method can help estimate whether each modulator is an inhibitor or a promoter of autophagy and elucidate the mode of action of specific genes and reagents on autophagy processes.