Abstract
An indole-coupled diaminomaleonitrile-based fluorescent chemosensor IMA has been designed and developed for the selective detection of ROS (OCl(-)) and metal ions Zn(2+) and Mn(2+) via chemodosimetric and chelation pathways respectively. The selective sensing of OCl(-) is induced by a method of oxidatively cleaving of the imine bond of IMA, forming free indole aldehyde, which results in a 21-fold enhancement of fluorescence at 521 nm, with a detection limit of 2.8 µM. On the other hand, the selective binding of IMA with Zn(2+) and Mn(2+) results in chelation-induced enhanced fluorescence (CHEF) and increased intermolecular charge transfer (ICT), leading to a 4-fold and 3-fold fluorescence enhancement at 432 nm and 435 nm, with the detection limits of 12.71 µM and 17.34 µM, respectively. UV-vis spectroscopy, fluorescence, DFT study, mass spectra, (1)H-NMR analysis, and Job's plot analysis have been used to validate the sensing mechanism of IMA with OCl(-), Zn(2+), and Mn(2+). For practical applications, the binding of IMA with OCl(-) has been utilized in the detection of commercial samples like bleaching powder and water analysis. Bio-imaging studies were conducted with IMA in the presence of OCl(-) and Zn(2+) using green gram seeds in a physiological medium.