A simple and easily synthesized fluorescent and colorimetric chemosensor 1 , based on juloidine-imidazole moieties as a binding and signaling unit, has been synthesized in a one-step procedure. Receptor 1 showed immediate responses toward Zn 2+ and Al 3+ ions through selective fluorescence enhancement in buffer-acetonitrile and dimethylformamide (DMF) solution, respectively. Moreover, receptor 1 sensed the two states (Fe(II) and Fe(III)) of iron by “naked eye” with a different color. Upon the addition of Fe 2+ and Fe 3+ into each solution of 1 , the color of the solutions instantly changed from colorless to orange for Fe 2+ and to purple for Fe 3+ . Thus, this sensor provides a novel approach for selectively recognizing the biologically important three elements in the human body simultaneously, for Zn 2+ and Al 3+ by emission spectra and Fe 2+ and Fe 3+ by the naked eye.

A single schiff base molecule for recognizing multiple metal ions: A fluorescence sensor for Zn(II) and Al(III) and colorimetric sensor for Fe(II) and Fe(III)

A multifunctional fluorescent and colorimetric receptor 1 ((E)-N′-((8-hydroxy-1,2,3,5,6,7-hexahydropyrido[3,2,1-ij]quinolin-9-yl)methylene)benzohydrazide) for the detection of both Al3+ and CN− in aqueous solution has been developed. Receptor 1 exhibited an excellent selective fluorescence response toward Al3+. The sensitivity of the fluorescent based assay (0.193 μM) for Al3+ is far below the limit in the World Health Organization (WHO) guidelines for drinking water (7.41 μM). In addition, receptor 1 showed an excellent detection ability in a wide pH range of 4–10 and also in living cells. Moreover, receptor 1 showed a highly selective colorimetric response to CN− by changing its color from colorless to yellow immediately without any interference from other anions.

A new multifunctional Schiff base as a fluorescence sensor for Al3+ and a colorimetric sensor for CN− in aqueous media: an application to bioimaging

A colorimetric and fluorescent sensor for sequential detection of copper ion and cyanide

A new highly selective colorimetric chemosensor 1 (E)-9-(((5-mercapto-1,3,4-thiadiazol-2-yl)imino)methyl)-2,3,6,7-tetrahydro-1H,5H-pyrido[3,2,1-ij]quinolin-8-ol was designed and synthesized for the sequential detection of Cu2+ and CN−. This sensor 1 exhibited an obvious color change from yellow to orange in the presence of Cu2+ in a fully aqueous solution. The detection limit (0.9 μM) of 1 for Cu2+ is far lower than the WHO limit (31.5 μM) for drinking water. In addition, the resulting Cu2+-2·1 complex can be further used to detect toxic cyanide through a color change from orange to yellow, indicating the recovery of 1 from Cu2+-2·1. Importantly, chemosensor 1 could be used to detect and quantify Cu2+ in water samples, and a colorimetric test strip of 1 for the detection of Cu2+ could be useful for all practical purposes.

A colorimetric sensor for the sequential detection of Cu(2+) and CN(-) in fully aqueous media: practical performance of Cu(2+).

A new prototype of multifunctional chemosensor 1 has been synthesized for Fe2+/3+, Cu2+ and CN− in aqueous solution. This sensor could simultaneously detect biologically important metal ions (iron and copper) through colorimetric methods over most other competitive cations. The detection limit (2.9 μM) of 1 for Cu2+ is lower than WHO guideline (31.5 μM) in drinking water. Interestingly, the resulting 1-Cu2+ complex sensed cyanide in colorimetric and fluorometric ways, showing recovery from 1-Cu2+ to 1, over other common interference anions. These results demonstrate a novel type of versatile chemosensor for multiple target ions using two different sensing methods, simple colorimetric and sequential detections.

Ha Lim Kwon

Papers

A selective colorimetric and fluorescent chemosensor based-on naphthol for detection of Al3+ and Cu2+