Eun Joo Song

A single colorimetric sensor for multiple target ions: the simultaneous detection of Fe2+ and Cu2+ in aqueous media

This study demonstrates the design, synthesis and sensing properties of a simple and efficient chemosensor 1 (1 = 2,6-bis((2-(((pyridine-2-yl)methylamino)methyl)phenol)ethylamido)pyridine) to rapidly detect Fe2+ and Cu2+ in aqueous solution (bis-tris buffer/DMF (8/2, v/v)), exploiting UV-vis spectral analysis, naked-eye and paper devices. The sensor 1 showed significant absorption spectra at 455 nm for Fe2+ and 660 nm for Cu2+, which are responsible for color changes due to the metal-to-ligand charge-transfer. The binding modes of 1 with Fe2+ or Cu2+ have been investigated by Job plot and ESI-mass analysis. In addition, the sensor 1 could be recyclable simply through treatment with a proper reagent such as EDTA. Moreover, the sensor has been used in the development of practically viable colorimetric kits.

A highly selective quinoline-based fluorescent sensor for Zn(II)

A quinoline-based simple receptor (bis(2-quinolinylmethyl)benzylamine = 1) as a Zn(2+) selective fluorescent chemosensor showed a large fluorescent enhancement with a blue shift in the presence of Zn(2+) which is attributed to a chelation enhanced fluorescence (CHEF) effect with inhibition of a photoinduced electron transfer (PET) process of 1. In particular, this receptor could clearly distinguish Zn(2+) from Cd(2+). The binding mode of 1 and Zn(2+) was found to be a 1:1 and confirmed by Job plot, (1)H NMR titration and ESI-mass spectrometry analysis.

Fluorescent chemosensor based on bispicolylamine for selective detection of magnesium ions

In this study, an assay to quantify the presence of magnesium ions with a chemosensor of bispicolylamine covalently attached to coumarin as a fluorephore was developed using a ratiometric fluorescence enhancement approach. Upon treatment with magnesium ions, the fluorescence wavelength of the chemosensor at 367 nm was shifted to 413 nm and the intensity was also enhanced. The formation of a 1:2 complex between the chemosensor and magnesium ions was confirmed based on the spectral changes of UV–vis, fluorescence and NMR as well as Jobs plot. An appreciable enhancement in the luminescence intensity for the emission band at 413 nm was evident when magnesium ions were added progressively. The maximum wavelength and intensity of the emission of the complex with Mg2+ were discriminated from those of other metal ions, such as Ca2+ and Zn2+.