Synthesis and evaluation of a novel rhodamine B-based 'off-on' fluorescent chemosensor for the selective determination of Fe3+ ions

A new rhodamine B derivative, namely, N-1-(benzo[d]thiazol-2-yl)-N-4-(2'-(3',6'-bis (diethylamino)-3-oxospiro[isoindoline-1,9'-xanthen]-2-yl)ethyl)malea-mide (RDBSF), was designed, synthesized, and structurally characterized to develop a new chemosensor. UV-vis absorption and fluorescence spectroscopic studies show that RDBSF exhibits high sensitivity and selectivity toward Fe3+ in the presence of many other metal cations in a Tris-HCI solution (1 mM, pH = 7.4) containing 30% MeCN by forming a 1:1 complex with Fe3+. The binding association constant (K-a) of RDBSF for Fe3+ was estimated as 1.52 x 10(4) M-1 in the solution. The detection limit of Fe3+ by RDBSF was further determined as 11.6 nM. Intracellular imaging applications demonstrated that RDBSF can be used as a fluorescent probe for the detection of Fe3+ in HepG-2 cells. (C) 2016 Elsevier B.V. All rights reserved.