• Journal of Integrative Natural Science
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• v.3 no.1
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• pp.28-32
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• 2010

Thiophene-derivatized pentiptycenes were synthesized and characterized by NMR and UV-Vis spectroscopy. Aggregation behavior of thiophene-derivatized pentiptycenes was monitored by the measurement of fluorescence. Fluorescence intensities for the thiophene-derivatized pentiptycenes and thiophene-derivatized pentiptycenes aggregates were compared. There is no shift in the maximum of the emission wavelength. In the range of water fraction between 20% and 40%, the emission intensity of thiophene-derivatized pentiptycene aggregates remains almost identical. Fluorescence efficiency incresaed by about 5 times higher when the thiophene-derivatized pentiptycenes forms the aggregates in solution.

• Journal of Photoscience
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• v.2 no.1
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• pp.13-18
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• 1995

The steady-state emission spectra of dicoumarol (DC) in ethanol and EPA have been examined at various temperatures (77-298 K). At room temperature, a fluorescence spectrum of DC in ethanol shows a emission maximum at 350 nm. In EPA a Stokes-shifted emission band appears around 470 nm in addition to the 350 nm emission, and its intensity is enhanced as temperature decreases. This emission is attributed to a zwitterionic tautomer of DC formed by a single excited-state intramolecular proton transfer (ESIPT) along the internal hydrogen-bonding. The fluorescence lifetimes have been measured at 350 and 450 nm as a function of temperature. The fluorescence decay at 350 nm is single exponential at any temperature, whereas the one at 450 nm becomes biexponential at temperatures below 250 K. These results are discussed in terms of a conformational change followed by the ESIPT. The activation energy barrier for the conformational change has been determined to be 3.7 $\pm$ 0.2 kJ/mole.

• Textile Coloration and Finishing
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• v.29 no.4
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• pp.223-230
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• 2017

Three super hydrophobic fluorescence dyes were selected to dye high molecular weight polyethylene fiber and their molar absorptivity, emission spectrum, and quantum yield were measured. From the results of color strength on the fiber, all the three dyes exhibited linear increase according to the dye concentration and Fluoro3 dye showed the highest color strength among them. Emission strength of the fluorescence dyes on the fiber was investigated according to the dye concentrations. The emission was increased with the increase of the dye concentration at relatively low dye concentration and then after showing the maximum emission strength the emission was decreased at higher dye concentrations. The highest emission was obtained in Fluoro2 dye. Color fastness to washing and rubbing was generally good enough, however, especially to light, only Fluoro3 dye exhibited rating 3 acceptable practically and Fluoro1 and 2 was ratings 1 which is unacceptable level.

• Bulletin of the Korean Chemical Society
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• v.34 no.10
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• pp.2937-2941
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• 2013

Fluorescence imaging is considered as one of the most powerful techniques for monitoring biomolecule activities in living systems. Near-infrared (NIR) light is advantageous for minimum photodamage, deep tissue penetration, and minimum background autofluorescence interference. Herein, we have developed a new NIR fluorescent dye, namely, RB-1, based on the Rhodamine B scaffold. RB-1 exhibits excellent photophysical properties including large absorption extinction coefficients, high fluorescence quantum yields, and high photostability. In particular, RB-1 displays both absorption and emission in the NIR region of the "biological window" (650-900 nm) for imaging in biological samples. RB-1 shows absorption maximum at 614 nm (500-725 nm) and emission maximum at 712 nm (650-825 nm) in ethanol, which is superior to those of traditional rhodamine B in the selected spectral region. Furthermore, applications of RB-1 for fluorescence imaging in living cells and small animals were investigated using confocal fluorescence microscopy and in vivo imaging system with a high signal-to-noise ratio (SNR = 10.1).

• Journal of Industrial and Engineering Chemistry
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• v.67
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• pp.236-243
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• 2018

A series of $Er^{3+}/Yb^{3+}$ co-doped fluorophosphate glasses with varying $YbF_3$ concentration were prepared by a high temperature melt quenching technique. Absorption and emission cross-sections were determined by using the McCumber theory. The larger emission cross-section ($9.86{\times}10^{-21}cm^2$) and longer fluorescence lifetime (12.37 ms) were obtained for the $^4I_{13/2}{\rightarrow}^4I_{15/2}$ transition of ABS3Er4Yb glass. The sensitivity and temperature of the maximum sensitivity were evaluated by the fluorescence intensity ratio method from the measured upconversion spectra. The results were discussed and compared to the other reported glasses.

• BMB Reports
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• v.30 no.4
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• pp.240-245
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• 1997

Interactions between ganglioside $G_{M3}$ and glucose transporter, GLUT1 were studied by measuring the effect of $G_{M3}$ on steady-state and time-resolved fluorescence of purified GLUT1 in synthetic lipids and on the 3-O-methylglucose uptake by human erythrocytes. The intrinsic tryptophan fluorescence showed a GLUT 1 emission maximum of 335 nm, and increased in the presence of $G_{M3}$ by 12% without shifting the emission maximum, The fluorescence lifetimes of intrinsic tryptophan on GLUT1 consisted of a long component of 7.8 ns and a short component of 2,3 ns and $G_{M3}$ increased both lifetime components. Lifetime components were quenched by acrylamide and KI. Acrylarnide-mduced quenching of long-lifetime components was partly recovered by $G_{M3}$ However. KI-induccd quenching of short- and long-lifetime components was not rescued by $G_{M3}$. The anisotropy of 1.6-diphenyl-1.3.5-hexatriene (DPH)-probed dimyristoylphosphatidylcholine (DMPC) model membrane was also increased with $G_{M3}$ incorporation, The transport rate of 3-O-methylglucose increased by 20% with $G_{M3}$ incorporation on the erythrocytes, Therefore, $G_{M3}$ altered the environment of lipid membrane and induced the conformational change of GLUT1.

• Bulletin of the Korean Chemical Society
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• v.23 no.9
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• pp.1315-1327
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• 2002

The model compounds, 8-methoxypsoralen-CH2O(CH2)n-adenine (MOPCH2OCnAd, n=2, 3, 5, 6, 8, and 10) in which 5 position of 8-methoxypsoralen (8-MOP) is linked by various lengths of polymethylene bridge to N9 of adenine. UV absorption spectra are identical with the sum of MOPCH2OC3 and adenine absorption spectra. Solvent effects on the UV absorption and fluorescence emission spectra indicate that the lowest excited singlet state is the $(\pi${\rightarrow}$\pi*)$ state. The spectral characteristics of the fluorescence of MOPCH2OCnAd are strongly dependent upon the nature of the solvents. The fluorescence emission spectra in aprotic solvents are broad and structureless due to the excimer formation through the folded conformation accelerated by hydrophobic ${\pi}-{\pi}$ stacking interaction. Increasing polarity of the protic solvents leads to higher population of unfolded conformation stabilized through favorable solvation and H-bonding, and consequently to an increase in the fluorescence intensity, fluorescence lifetime, and a shift of fluorescence maximum to longer wavelengths. The decay characteristics of the fluorescence in polar protic solvents shows two exponential decays with the lifetimes of 0.6-0.8 and 1.6-1.9 ns in 5% ethanol/water, while MOPCH2OC3 shows 0.5 and 1.7 ns fluorescence lifetimes. The long-lived component of fluorescence can be attributed to the relaxed species (i.e., the species for which the solvent reorientation (or relaxation) has occurred), while the short-lived components can be associated with the unrelaxed, or only partially relaxed, species.

• Journal of Korean Society of Environmental Engineers
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• v.28 no.2
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• pp.223-228
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• 2006

High-performance liquid chromatography(HPLC) and fluorescence derivatization were applied for a trace-level N-nitrosodimethylamine(NDMA) analysis of water samples. Fluorescence intensity was optimized with the excitation wavelength of 340 nm and the emission wavelength of 530 nm. pH adjustment after denitrosation was necessary to get a maximum intensity at pH between 9 and 12. Maximum intensity was found with a dansyl chloride concentration of 330 to 500 mg/L. Percentile error in the water sample analyses through solid phase extraction was 12-162% and 6-23% for the lower concentration level(10-200 ng/L NDMA) and the higher level(100-1000 ng/L NDMA), respectively, showing more discrepancy in lower level. However, the average ratios of estimated NDMA to the standard NDMA were close to 1 for both concentration ranges, presenting this HPLC method could detect from tens to hundreds nanograms NDMA per liter. Accurate determination of NDMA, which was injected to a wastewater effluent, revealed the selectivity of fluorescence derivatization for the target compound(NDMA) in the presence of complex interfering compounds. The HPLC with fluorescence derivatization may be applicable for determining NDMA of water and wastewater samples fur various research purposes.

• Bulletin of the Korean Chemical Society
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• v.9 no.3
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• pp.171-175
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• 1988

The spectral properties of piroxicam in different solvents are similar to those of its skeletal precursor, HMBDC. The maximum absorption and emission wavelengths strongly depend on the hydrogen bonding ability of the solvent, and it is shown that intramolecular hydrogen bonding between the -OH and the ortho carbonyl group of the parent benzothiazine ring plays an important role in the solvent-dependence of their spectroscopic properties. The fluorescence spectra in aprotic nonpolar solvent exhibit abnormally large Stokes-shifted (${\sim}9,000cm^{-1}$) emission bands in contrast to the spectra in water. In ethanol, dual emission bands with two different fractional components of lifetimes have been observed. These results suggest that the abnormally red-shifted emission is attributed to the proton transferred form of an intramolecularly hydrogen-bonded closed conformer.

• BMB Reports
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• v.32 no.6
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• pp.521-528
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• 1999

The folding of recombinant hepatitis B virus X-protein (rHBx) solubilized from Escherichia coli inclusion bodies was investigated. By sequential dialysis of urea, rHBx was folded into its native structure, which was demonstrated by the efficacy of its transcriptional activation of the adenovirus major late promoter (MLP), fluorescence spectroscopy, and circular dichroism (CD) analysis. The decrease in CD values at 220 nm and a corresponding blue shift of the intrinsic fluorescence emission confirmed the ability of rHBx to refold in lower concentrations of urea, yielding the active protein. Equilibrium and kinetic studies of the refolding of rHBx were carried out by tryptophan fluorescence measurements. From the biphasic nature of the fluorescence curves, the existence of stable intermediate states in the renaturation process was inferred. Reverse phase-high performance liquid chromatography (RP-HPLC) analysis further demonstrated the existence of these intermediates and their apparent compactness.