Kyung Beom Kim

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 and sensitive fluorescent turn-on Al3+ chemosensor in aqueous media and living cells: experimental and theoretical studies

A highly selective and sensitive fluorescent chemosensor (1) based on a 2-aminobenzoic acid Schiff base has been synthesized in one step. The binding properties of 1 with metal ions were investigated by fluorescence, UV-vis, 1H NMR and electrospray ionization mass spectra. This sensor exhibited enhanced fluorescence in the presence of Al3+ in aqueous solution and also in living cells. The sensing mechanism of 1 toward Al3+ was explained by DFT/TDDFT calculations. The binding constant was determined to be 3.1 × 108 M−1 which is one of the highest binding affinities among such simple Schiff bases for Al3+ in buffer solution. The calibration curve for the analytical performance of Al3+ was found to be linear over a concentration range with a very low detection limit of 290 nM (3σ).

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.

5-Carbamoyl-2-methyl-1-(2-methyl-benz-yl)pyridinium bromide.

In the title molecular salt, C15H17N2O+·Br−, the benzene and pyridinium rings form a dihedral angle of 83.0 (1)°. In the crystal, N—H⋯Br and N—H⋯O hydrogen bonds link the components into chains along [010]. These chains are linked by weak C—H⋯O and C—H⋯Br hydrogen bonds, forming a three-dimensional network.

3-Carbamoyl-1-(2-nitrobenzyl)pyridin-ium bromide.

In the title compound, C13H12N3O3 +·Br−, the benzene and pyridinium rings form a dihedral angle of 82.0 (1)°. In the crystal, N—H⋯Br and N—H⋯O hydrogen bonds link the components into chains along [001]. In addition, weak C—H⋯O and C—H⋯Br hydrogen bonds are observed.