Dual colorimetric and fluorescent chemosensor of Fe3+ and Cu2+ based on 2,5-bis[(4-carboxylic-piperidylamino)thiophenyl]-croconine

A croconium dye, 2,5-bis[(4-carboxylic-piperidylamino)thiophenyl]-croconine (BCTC) based dual signaling probe was found to exhibit colorimetric and fluorescent properties on selective binding towards Fe3+ and Cu2+ in ethanol/water (4:1, v/v) solution, respectively. The binding constants were determined to be 2.12 x 10(4) M-1 and 8.58 x 10(4) M-1 for Fe3+ and Cu2+, respectively. Most importantly, the 1:1 stoichiometry of the host-guest complexation was confirmed by Job's method. This result was further confirmed by H-1 NMR analysis. Meanwhile, the selectivity experiments revealed that the colorimetric and fluorescent sensor were specific for Fe3+ and Cu2+ even with interference by high concentrations of other metal ions. Moreover, the sensing abilities of the receptor toward Fe3+ and Cu2+ were also investigated by electrochemical technique. The present results indicated that the BCTC chemosensor could be adopted as a selective, sensitive and reversible colorimetric and fluorescent sensor for Fe3+ and Cu2+. (C) 2015 Elsevier Ltd. All rights reserved.