Seon-Yeong Gwon

Synthesis and property of solvatochromic fluorophore based on D-π-A molecular system: 2-{[3-Cyano-4-(N-ethyl-N-(2-hydroxyethyl)amino)styryl]-5,5-dimethylfuran-2(5H)-ylidene}malononitrile dye

2-[[3-Cyano-4-(N-ethyl-N-(2-hydroxyethyl)amino)styryl]-5,5-dimethylfuran-2(5H)-ylidene]malononitrile styryl dye was prepared by the condensation of 4-[(2-hydroxy-ethyl)-methyl-amino]-benzaldehyde (donor moiety) with 2-cyanomethylene-3-cyano-4,5,5-trimethyl-2,5-dihydrofuran (acceptor moiety). The corresponding design, synthesis and solvatochromic characteristics of the intramolecular charge-transfer (ICT) dye chromophore were discussed and determined. Optical properties such as absorption and fluorescence emission spectra were monitored in several solvent media with different polarity. In this determination, the prepared dye chromophore showed positive solvatochromism effect and the resulting solvatochromic characteristics were studied with semiempirical calculations. The energy potentials of this dye chromophore such as HOMO and LUMO values were calculated by computational simulation approaches using Material Studio 4.3. Furthermore, the functions as a molecular switching sensor with pH stimulation of alkali-acid addition were determined in DMSO, which was operated by deprotonation/protonation effects based on intramolecular charge-transfer system.

The photo- and electrophysical properties of curcumin in aqueous solution

An investigation of the photo- and electrophysical properties of curcumin (1,7-bis[4-hydroxy-3-methoxyphenyl]-1,6-heptadiene-3,5-dione) revealed well-defined color changes upon the addition of Hg(2+) or OH(-). Curcumin exhibited high selectivity for Hg(2+) ions, as compared with Cu(2+), Fe(2+), Fe(3+), Zn(2+), Na(+) and Ni(2+) ions in DMSO/H(2)O (5:1, v/v) which was attributed to the formation of a 4:1 Hg(2+)-curcumin coordination complex. Spectral responses at lambda(max)=434nm revealed that curcumin can function as a NOR logic gate with OH(-) and Hg(2+) as input variables. The electrochromic properties of curcumin were studied using an ITO/curcumin-Bu(4)NClO(4)/ITO cell. The electrochromic cell colored red at 3V, but changed to yellow in open-circuit condition.

Anthraquinone-carbamodithiolate Assembly as Selective Chromogenic Chemosensor for Fe 3+

Abstract: A new assembly derived from 2,3-dibromo-5,6,7,8-tetrafluoroquinizarin and sodium diethyl-carbamodithiolate,was prepared as an efficient Fe 3+ colorimetric chemosensor with high selectivity over other cations Fe 3+ ,Na + ,Mg 2+ ,Pb 2+ ,Cd 2+ ,Ni 2+ ,Ca 2+ ,Cu 2+ ,Hg 2+ ,Zn 2+ : from the dark blue to brown color change that is visible by eyes. This assembly producedlarge bathochromic shift of 228 nm in the presence of Fe 3+ compared with the corresponding absorption maximum of theparent dye. Keywords: anthraquinone, Fe 3+ sensing, colorimetric, chemosensor, carbamodithiolate, intramolecular charge-transferdye Anthraquinone-carbamodithiolate Assembly as Selective ChromogenicChemosensor for Fe 3+ Jin-Seok Bae, Seon-Yeong Gwon 1 and Sung-Hoon Kim † Department of Textile System Engineering, Kyungpook National University, Daegu, Korea 1 Department of Advanced Organic Materials Science and Engineering, Kyungpook National University,Daegu, Korea (Received: February 21, 2013 / Revised: March 4, 2013 / Accepted: March 5, 2013)

Hemicyanine-based colorimetric chemosensors: Different recognition mechanisms for CN− sensing

Simple hemicyanine dyes were synthesized by a classical condensation reaction. The structures of these dyes were characterized by (1)H NMR spectroscopy, elemental analysis, and FAB-Mass spectrometry. The sensing behavior of the hemicyanines towards a selection of anions was investigated by UV-vis absorption spectroscopy. These structurally simple dyes displayed a rapid response and high selectivity for cyanide ion over other common anions in the DMSO/H(2)O solution. Different sensing mechanism of the dyes to cyanide ion were confirmed by (1)H NMR studies, together with theoretical calculations based on DFT and PPP-MO methods. These dyes show no colorimetric response for other anions investigated.

Squarylium-based chromogenic anion sensors

A squarylium (SQ) dye was synthesized by the reaction between squaric acid and 2,3,3-trimethylindolenine and its anion sensing properties were investigated using absorption and emission spectroscopy. This chemosensor exhibited high selectivity for CN(-) as compared with F(-), CH(3)CO(2)(-), Br(-), H(2)PO(4)(-), Cl(-), and NO(3)(-) in acetonitrile, which was attributed to the formation of a 1:1 squarylium:CN(-) coordination complex, the formation of which was supported by the calculated geometry of the complex.

Properties and characteristics of squarylium-based chemosensors for Hg2+

A chemosensor based on symmetrical squarylium (SQ) dye, 2,4-bis((3,3-dimethylindolin-2-ylidene)methyl)cyclobutane-1,3-bis(olate), was synthesised and its cation-sensing properties in acetonitrile were investigated by UV–vis spectroscopy. Upon the addition of Hg2+, the solution of SQ dye showed clear colour change. The absorption studies also indicate a higher affinity of Hg2+ towards the formation of 2:1 complexes, which is in good agreement with the experimental results. The selective detection of Hg2+ of the symmetrical-SQ unit gave rise to a significant absorption decrease at λmax 650 in acetonitrile solution.

Spectral properties of highly selective chemosensor for Hg2

A (E)-2-(2-(2-(1H-indol-3-yl)vinyl)-4H-chromen-4-ylidene)malononitrile (dye 1) was synthesized and its cation sensing properties in DMSO were investigated by UV-vis spectroscopy. Upon the addition of Hg2+, the solution of dye 1 showed color change and the absorption band shows a formation of a 1:1 dye 1-Hg2+ coordination complex. The dye 1 exhibited high selectivity for Hg2+ as compared with other cations. Interestingly, the dye 1-F- complex also could be recovered by adding Hg2+. We have investigated the ability of complex formation based on the association constant, Kass; the binding ability for the complex formation of dye 1-F- and Hg2+ is greater than that of the dye 1 with F-.

Benzothiazole and indole based dye sensor: Optical switching functions with pH stimuli

A new designed dye sensor based on indole as a donor unit and benzothiazole as an acceptor unit have provided very clear optical switching functions when monitored with a pH triggered molecular chemosensor effects in the presence of alkali/acid addition. The prepared dye sensor shows cleared fluorescence quenching effect with alkali addition. The level of energy potential and the electron distribution of this compound were calculated by computational simulation approaches.

Anion sensing and F(-)-induced reversible photoreaction of D-π-A type dye containing imidazole moiety as donor.

A new donor-π-acceptor (D-π-A) type dye was synthesized by the condensation reaction between 2-cyanomethylene-3-cyano-4,5,5-trimethyl-2,5-dihydrofuran and 4-imidazolecarboxaldehyde. The chemical structure of the dye was characterized by (1)H NMR, EA and MS. A novel chromogenic dye based on imidazole as donor unit and furan as acceptor unit displayed marked UV-visible absorption changes in the presence of fluoride ion. The levels of energy potential and the electron density distributions of this dye were also simulated and discussed using computational model calculation. The reversible photoreaction of the dye-F(-) complex was studied by time-dependent UV-visible absorption spectra.

Fluorescence quenching of carbazole by 2-chloro-3,5-dinitrobenzotrifluoride-ethylamines intermolecular charge-transfer complex

The interaction between carbazole and 2-chloro-3,5-dinitrobenzotrifluoride-ethylamines, (mono-, di-, and triethylamine) charge-transfer complex in DMSO was studied using fluorescence spectroscopy. The positive deviation from linearity has been observed in the Stern-Volmer plots. The experimental results showed that the fluorescence of carbazole was quenched by 2-chloro-3,5-dinitrobenzotrifluoride-ethylamines charge-transfer complex through a combined quenching procedure. The Stern-Volmer quenching constants, K(SV), have been determined and found to be greater quenching efficiency of ethylamine. Carbazole/2-chloro-3,5-dinitrobenzotrifluoride loaded PMMA film was exposed to ethylamine vapor, where the resulting absorption and emission changing properties were clearly monitored.