• Bulletin of the Korean Chemical Society
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• v.23 no.9
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• pp.1309-1338
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• 2002

The fluorescence and photoisomerization quantum yields of trans-1-(9-anthryl)-2-(4-pyridyl)ethene (t-4-APyE), 1-(10-methyl-9-anthryl)-2-(4-pyridyl)ethene (t-4-MeAPyE), and 1-(10-chloro-9-anthryl)-2-(4- pyridyl)ethene (t-4-ClAPyE) were measured in cyclohexane, acetonitrile, and methanol at room temperature.Polar solvents result in the drastic reduction of fluorescence quantum yield and increase of photoisomerization quantum yield for all three compounds. These results are probably due to the stabilization of intramolecular charge transfer (ICT) excited state in polar solvent. The higher contribution of ICT in the presence of more electron-donating methyl substituent, manifested by largest positive fluorescence solvatochromism, indicates that the pyridine ring acts as an electron acceptor. Protonation or methylation makes pyridine ring stronger electron acceptor and causes long-wavelength ground state charge transfer absorption band and complete quenching of fluorescence. The fluorescence from t-4-APyE derivatives can be switched off responding external stimuli viz. medium polarity, protonation, or methylation.

• Textile Coloration and Finishing
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• v.23 no.3
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• pp.163-168
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• 2011

In this article, we synthesized an azo dye rotaxane containing bis(8-hydroxyquinoline) group and its polymeric metal complex with zinc. The azo dye rotaxane exhibits high pH sensitivity, solvatochromism and zinc (II) ion sensings in aqueous solution. These behaviors came from the tautomeric equilibrium between azo-hydrazone tautomers and the formation of extended conjugation. The structure of polymeric zinc complexed dye rotaxane was confirmed with NMR and FT-IR measurements. The existence of CD rings, provided by dye rotaxane formation, was found to be very beneficial in improving aqueous solubility of polymeric metal complex.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.44 no.7
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• pp.889-894
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• 1995

The structural changes of the merocyanine monolayer LB (Langmuir Blodgett) films were investigated. These changes were compared with the typical changes of the molecular structures of merocyanine solutions. The structural changes of quinoid/benzenoid were attained by exposure to atmosphere gases (HCl gas, N $H_{3}$ gas). The photoisomerization was not observed for the monolayer LB film due to their state of $M_{trans}$. But we could obtain the cis/trans photoisomerization characteristics reversibly, after the films were changed to M $H^{+}$$_{trans}$ structure by exposure to HCl gas. We also found that the cis/trans photoisomerization of the LB monolayer films show the memory characteristics.s.

• Bulletin of the Korean Chemical Society
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• v.26 no.1
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• pp.47-50
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• 2005

Solvatochromic fluorescence behavior of 8-aminoquinoline based benzothiazole derivative in varying solvent systems has been investigated. Benzothiazole appended 8-aminoquinoline 3 showed distinctive fluorescence color changes depending upon the solvent polarities and the fluorescence color changes occurred over relatively wide span in visible region from 486 nm to 598 nm which can be detected with naked eye. Compound 3 also exhibited significant spectral shifts in ${\lambda}_{em}$ as a function of water composition in binary aqueous solvent systems. The changes are due to the specific interaction of 3 by hydrogen bonding with water as well as general solvent effect. The observed solvatochromic fluorescence characteristics of 3 could be used as a new probe for the micro-environmental polarity changes as well as a sensitive sensor for the determination of water composition in binary aqueous solutions.

• Bulletin of the Korean Chemical Society
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• v.35 no.2
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• pp.610-616
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• 2014

The influence of solvent polarity on the absorption spectra of some synthesized azo dye with heterocyclic moieties and ${\beta}$-naphthol (1-3) have been investigated using a UV-Visible spectrophotometer. The spectral characteristics of the azo dyes (1-3) in different solvents at room temperature were analyzed. The solvatochromic empirical variables like ${\pi}^*$, ${\alpha}$, and ${\beta}$ have been used to discuss the solvatochromic behaviour of the dyes and to evaluate their contributions to the solute-solvent interactions. A multi-parameter regression model for quantitative assessment of the solute/solvent interaction and the absorption has been used to explain the solvent effect on azo dyes (1-3).

• Bulletin of the Korean Chemical Society
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• v.30 no.1
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• pp.197-200
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• 2009

A simple dye having phenol and indole moieties was synthesized and its chromogenic signaling behaviors for the determination of water content in organic solvents were investigated. The compound revealed a pronounced chromogenic behavior in response to the variation of water content in water miscible aprotic organic solvents of acetone, acetonitrile, THF, and dioxane. Significant red shifts and changes in absorption spectra allowed a ratiometric analysis of the signaling behavior. The chemosensing behaviors were particularly pronounced in water content in less than 10% that is suitable for the application of the compound as a probe for the determination of water content in binary aqueous organic solutions having lower water content.

• Proceedings of the Korean Society of Dyers and Finishers Conference
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• 2011.03a
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• pp.63-63
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• 2011

The donor-${\pi}$-acceptor (D-${\pi}$-A) chromophoric dye system has received great attention in variety fields such as electroluminescent materials, sensors and optoelectronic devices. There are many research activities focused on the development for abovementioned application materials with the high-performance properties. In the previous work, we are reported that novel D-${\pi}$-A dye, 2-[4-(9H-carbazol-9-yl)benzylidene]-2,3-dihydroinden-1-one, is successfully attained and exhibited a positive fluorescence solvatochromism. In this work, the molecular structure and packing geometry of 2-[4-(9H-carbazol-9-yl)benzylidene]-2,3-dihydroinden-1-one was discussed by their conformational structure. Their single yellow prism crystal having approximate dimensions of $0.30{\times}0.10{\times}0.10$ mm was carried out with a Rigaku RAXIS RAPID imaging plate area detector with graphite monochromated $CuK_{\alpha}$ radiation. Their crystal structure were solved by using the CrystalStructure crystallographic software package.

• Bulletin of the Korean Chemical Society
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• v.34 no.3
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• pp.863-867
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• 2013

A series of azo disperse dyes having dicyanovinyl groups was synthesized by the Knoevenagel condensation with malononitrile from carbonyl substituted phenylazo disperse dyes which were prepared by conventional diazo coupling reaction of aniline derivatives as diazo components. A variety of coupling components such as anilines, an indole and a pyridone were used. The azo disperse dyes were evaluated for their spectral properties and dyeing assessment on the polyester fabrics. The azo disperse dyes containing dicyanovinyl groups showed bathochromic shifts and darker colors due to increased electron withdrawing strength in their azo components and extended conjugation by dicyanovinyl groups than their parent carbonyl substituted azo dyes. The dyes containing 2-acetylamino-5-methoxy substituent in the coupling component exhibited higher wavelength of maximum absorbance (${\lambda}_{max}$) and significant negative solvatochromism than those of other dyes due to intramolecular hydrogen bonding.

• Journal of the Korean Chemical Society
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• v.34 no.6
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• pp.593-599
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• 1990

A series of new, square planar, and mixed-ligand complexes of Ni(Ⅱ), Pd(Ⅱ), and Pt(Ⅱ) have been prepared. From the observation of electronic spectrum for the variation of the ligand substituents, the very intense absorption band in the visible range is by the electronic transition of dithiolene to diimine ligand, HOMO to LUMO. In the various solvent systems the IT band shows the similar behavior to IT transition of mixed-valence dinuclear complexes followed with Hush theory, happens rto dominently by the inner sphere charge transfer transition. The negative solvatochromism represents that the excited-state electric dipole is reduced or reversed by the electronic transition.

• Bulletin of the Korean Chemical Society
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• v.25 no.9
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• pp.1361-1365
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• 2004

Solvatokinetic and solvatochromic behavior of bis(indolinobenzospiropyranyl) sulfide derivatives 1a-1c have been studied in various solvents. The marked negative solvatochromism is exhibited for 1a and 1b in the whole region of solvent polarity examined. Whereas, it is found only in the polar solvent region ($E_T$ > 37) for 1c. The sensitivity order to the solvent media (slope values) is 1a > 1b > 1c. The branched linear plot with a zero slope was shown for the most sterically-hindered compound 1c in the less polar-solvent region (($E_T$ < 37). The biphasic plot is indicative of dual mechanistic process, i.e., a transition state with increased zwitter-ionic character in more polar solvents and electrocyclic process with an isopolar transition state in less polar solvents.