Dual Fluorophore Containing Efficient Photoinduced Electron Transfer Based Molecular Probe for Selective Detection of Cr and PO Ions through Fluorescence " Turn-On-Off" Response in Partial Aqueous and Biological Medium: Live Cell Imaging and Logic Application.

The present work describes a new photoinduced electron transfer (PET) based molecular probe in which naphthalimide (NPI) and anthracene (AN) chromophores are linked through a molecular bridge of piperazine and triazole units by the Click reaction. A typical meaningful structural variation has made the present probe highly selective for Cr ion (limit of detection (LOD), 5.567 × 10 M) that displayed enhanced, " turn-On" emission (due to the PET- Off photophysical mechanism) and naked-eye sensitive bright green color fluorescence in the environment of interfering and competitive ions, in Tris-HCl buffer. The minimum energy structure obtained through theoretical calculations (density functional theory (DFT) and time-dependent (TD)-DFT) revealed a "tub" shape structure for probe 10. Upon complexation, the conformation of piperazine fragment changes from chair to boat in which the triazole and piperazine units create a cavity to tether Cr. Moreover, the probe showed excellent biocompatibility and cell permeability to sense Cr sensitively in live cells and, thus, holds great promise for application in biological and environmental sciences. Additionally, the sensitive " Off-On-Off" sensing behavior of probe 10 providing two chemical inputs (Cr and PO) helps to construct an INHIBIT logic gate. Also the probe has been utilized as printing material to decode secret information through the Cr ion containing "marker ink" under UV light.