Ji Hye Kang

Colorimetric detection of iron and fluorescence detection of zinc and cadmium by a chemosensor containing a bio-friendly octopamine

Chemosensor 1 was synthesized by the reaction of octopamine with 2,3-dihydroxybenzaldehyde. Sensor 1 determined iron with an obvious color change from pale yellow to brown in nearly-pure water. The detection limits (0.55 and 0.25 μM) for Fe2+ and Fe3+, respectively, were far lower than the EPA (Environmental Protection Agency) guideline concentration for drinking water (5.37 μM). In addition, 1 could be employed to quantify iron in environmental water samples. Moreover, sensor 1 exhibited different fluorescence emissions in response to zinc (green) and cadmium (blue). The binding structures and sensing mechanisms of 1 for iron, zinc and cadmium were proposed from various spectroscopic studies and theoretical calculations.

A multi-functional chemosensor for highly selective ratiometric fluorescent detection of silver(I) ion and dual turn-on fluorescent and colorimetric detection of sulfide

A multi-functional chemosensor 1 as silver and sulfide detector was synthesized by the combination of octopamine and 4-dimethylaminocinnamaldehyde. Sensor 1 exhibited a ratiometric fluorescence emission for Ag+ from blue to sky. The binding mode of 1 and Ag+ turned out to be a 1 : 1 ratio as determined using Job plot and electrospray ionization (ESI) mass spectral analyses. The sensing mechanism of 1 with silver ion was unravelled by 1H NMR titrations and theoretical calculations. Sensor 1 also discerned sulfide by enhancing fluorescence intensity and changing colour from yellow to colourless in aqueous solution. The sensing properties of 1 toward S2− were investigated by using ESI-mass analysis, Job plot and 1H NMR titrations. Moreover, 1 could be used as a detector for sulfide in a wide pH range.

A Multi-Responsive Naphthalimide-Based “Turn-on” Fluorescent Chemosensor for Sensitive Detection of Trivalent Cations Ga 3+ , Al 3+ and Cr 3+

A new multifunctional chemosensor 1, (E)-2-(((2-hydroxynaphthalen-1-yl)methylene)amino)-1H-benzo[de]isoquinoline-1,3(2H)-dione, based on naphtalimide and naphthaldehyde was developed, which showed the fluorescence responses to trivalent metal ions (Ga3+, Al3+ and Cr3+). Sensor 1 detected and differentiated selectively trivalent metal ions Ga3+, Al3+ and Cr3+ by fluorescence enhancement at different emissions. The association constant of Ga3+-2∙1 complex is the highest one among those of the organic chemosensors reported, to date. The sensing mechanisms for Ga3+, Al3+ and Cr3+ were explained by UV-vis titrations, Job plots, ESI-mass analyses and theoretical calculations.

Colorimetric detection of Fe3+/2+ and fluorescent detection of Al3+ in aqueous media: applications and DFT calculations

Abstract A new multifunctional colorimetric and fluorescent chemosensor 1 for Fe3+/2+ and Al3+ has been synthesized in the one-step procedure. The sensor 1 detected both Fe2+ and Fe3+ through the color change from yellow to brown and Al3+ via turn-on fluorescence. The binding stoichiometries of sensor 1 with Fe3+/2+ and Al3+ were proposed to be 1:1 with the analyses of ESI-mass and Job plot. Importantly, the detection limits of 1 for Fe3+/2+ (2.11 and 2.70 μM) and Al3+ (3.44 μM) were lower than the EPA guideline (5.37 μM) for Fe3+/2+ and WHO guideline (7.41 μM) for Al3+. Compound 1 was used to quantify ferric species (Fe3+) in real samples. Moreover, the sensing processes for Fe3+/2+ and Al3+ were proposed with the spectroscopic studies and theoretical calculations.