Design and synthesis of a novel chromium(III) selective fluorescent chemosensor bearing a thiodiacetamide moiety and two rhodamine B fluorophores

A new rhodamine spirolactam derivative bearing a thiodiacetamide moiety and two rhodamine B fluorophores (RBTDA) was designed, synthesized and structurally characterized to develop a chemosensor. The interactions of RBTDA with different metal ions have been studied over UV-vis absorption spectra and fluorescent spectra. The results indicated that RBTDA exhibited a highly sensitive and selective turn-on fluorescent response for Cr3+ in the presence of many other metal cations in a methanol-HEPES buffer (3:1, v/v, 0.5 mM, pH 7.25) solution. The binding analysis based on mass spectroscopic data and a job plot suggested that the RBTDA formed a 1:1 complex with Cr3+. The binding association constant (K-a) for Cr3+ based on a 1:1 stoichiometry was estimated to be 5.01 x 10(4) M-1 in the solution. The detection limit of Cr3+ by RBTDA was further determined to be 0.378 mu M. (C) 2015 Elsevier B.V. All rights reserved.