• Journal of the Korean Chemical Society
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• v.37 no.5
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• pp.523-526
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• 1993

Absorption spectra of photochromic spironaphthoxazine dye in various solvents were examined and exhibited a positive solvatochromism. The positive solvatochromism of this dye strongly suggests that the structure of open chain forms is keto type structure, 4a. The effect of structural change on the electronic spectra, on replacement of the C=C bond by C=N bond, is discussed.

• Journal of Photoscience
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• v.10 no.1
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• pp.105-119
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• 2003

Fullerenes, $C_{60}$ and $C_{70}$, display interesting physicochemical properties in solutions, especially due to their unique chemical structures and their good electron accepting abilities. Solubility of fullerenes in different organic solvents and their unusual solvatochromic behavior, the ability of the fullerenes to form aggregates in solutions, and their electron transfer and charge transfer interactions with variety of electron donors, are the subjects of extensive research activities for more than one decade. Many research groups including ours have contributed substantially in the understanding of the solvatochromism, aggregation behavior, and the photoinduced electron transfer and charge transfer chemistry of fullerenes, in condensed phase. Present article is aimed to summarize the important results reported on the above aspects of fullerenes, subsequent to the earlier report from our group (D.K. Palit and J.P. Mittal, Full. Sci. & Tech. 3, 1995, 643-659).)., 643-659)..

• Journal of Photoscience
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• v.12 no.2
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• pp.57-61
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• 2005

The ground and excited state dipole moments of Coumarin 450 (C 450) laser dye were measured at room temperature in several solvents of varying dipole moments. The ground state dipole moment (${\mu}_g$) is estimated by using the modified Onsagar model and the excited state dipole moments (${\mu}_e$) were estimated by the method of solvatochromism as well as by utilizing the microscopic solvent polarity parameter ($E^N_T$). Further, the deviation of some of the points from the linearity of the $E^N_T$ versus Stokes shift indicates the existence of specific type of solute-solvent interaction. The excited state dipole moment of C 450 were found to be higher than those of the ground state and is interpreted in terms of the resonance structure of the molecule. A reasonable agreement has been observed between the values obtained by the method of solvatochromism and modified Onsagar model. It is observed that, corresponding to cyclohexane solution, the fluorescence maxima shift towards the red region with increasing the polarity of the solvents, hence the transition involved are of ${\pi}-{\pi}^*$ type.

• Bulletin of the Korean Chemical Society
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• v.32 no.2
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• pp.664-672
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• 2011

A series of hydrophilic chromophores was synthesized through introduction of dendritic sulfonate anions using click chemistry. A dendron structure bearing several sulfonate groups enhances hydrophilicity of attached chromophores. A click triazole formation connects chromophores with hydrophilic groups. A neutral trichloroethyl sulfonate has versatile features such as easy introduction, chemical endurance for isolation or storage, and convenient transformation to a hydrophilic anion. Zinc and OH mediated cleavage of trichloroethyl group from the neutral sulfonate undergoes to generate a water-soluble sulfonate anion. The solubility was examined with different counter cations and in different pH media and thus increased with the number of attached sulfonate ion. Two hydrophilic chromophores of stilbene-derived and azobenzene-derived dipolar structures exhibit clear negative and positive solvatochromism in protic solvents, respectively.

• Proceedings of the Korean Society of Dyers and Finishers Conference
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• 2007.11a
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• pp.39-40
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• 2007

• Journal of the Korean Chemical Society
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• v.40 no.12
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• pp.741-747
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• 1996

The syntheses and absorption spectra of squarylium and croconium dyes were studied. IR data and negative solvatochromism revealed that squarylium dyes have symmetrical 1,3-bonded squarylium rings. A new class of unsymmetrical squarylium dyes and their precursor have also been synthesized. The λmax of croconium dyes undergoes a bathochromic shift of about 100 nm compared with corresponding squarylium dyes. This shift can he calculated by the Pariser-Parr-Pople molecular orbital method.

• Bulletin of the Korean Chemical Society
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• v.30 no.7
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• pp.1452-1458
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• 2009

The change in the electronic absorption and emission energy of 7-aminocoumarin derivatives in binary solvent mixtures has been studied. The electronic transition energy along with the Stokes' shift is correlated with the orientation polarizability of the solvent as well as the empirical solvent polarity parameters $E_T$ (30). It is observed that the emission peak shift traces the change of $E_T$ (30) value very closely in binary solvent mixtures. The emission transition more strongly depends on the solvent polarity than the absorption, which indicates the dipole moment gets larger on excitation. From the dependence of the Stokes’ shift of 7-aminocoumarins with the solvent polarity parameters and the ground state dipole moment obtained by the semi-empirical calculations, the excited state dipole moment was estimated. The fluorescence lifetime change of 7-aminocoumarins in binary solvent mixtures was measured and the results are explained in terms of molecular conformation and solvent polarity. The study indicates the empirical solvent polarity $E_T$ (30) is a good measure of microscopic solvent polarity and it probes in general the non-specific solvent interactions.

• Journal of Sensor Science and Technology
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• v.19 no.6
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• pp.428-434
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• 2010

In this study, a novel gas sensor based on evanescent field coupling between single mode side polished fiber and solvatochromic dye dispersed polymer waveguide was demonstrated. We fabricated a side polished optical fiber device as a volatile organic compounds gas detector. Solvatochromic dye was coated on the top of the side polished optical fiber to take advantage of evanescent field coupling. The solvatochromism can be defined as the phenomenon whereby a compound changes color, either by a change in the absorption or emission spectra of molecule, when reacted in different VOCs. The device reacted to polarity gases like a hexane, butane, xylene etc. The resonance wavelength was shifted by the xylene concentration which range was 0.1 ppm ~ 100 ppm. Also, the response with the concentration was lineer and the detection limit was 0.1 ppb.

• Bulletin of the Korean Chemical Society
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• v.31 no.4
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• pp.1073-1076
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• 2010

• Proceedings of the Korean Society of Dyers and Finishers Conference
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• 2010.03a
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• pp.132-132
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• 2010