Selective dual-mode detection of reactive oxygen species and metal ions by chemodosimetric chelation pathways: fluorescence 'turn-on' with OCl and Zn/Mn, employing theoretical, practical, and bioimaging applications.

An indole-coupled diaminomaleonitrile-based fluorescent chemosensor IMA has been designed and developed for the selective detection of ROS (OCl) and metal ions Zn and Mn 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 and Mn 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, H-NMR analysis, and Job's plot analysis have been used to validate the sensing mechanism of IMA with OCl, Zn, and Mn. 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 using green gram seeds in a physiological medium.