Fluorescent sensors based on small organic molecules have been most widely developed as sensors for monitoring in vitro and in vivo biological targets because of their simplicity and high sensitivity.^1,2  Fluorescence spectroscopy works as a prominent technique to identify interactions between the analyte and the probe by observing changes occurring in the spectroscopic characteristics of the probe. These changes can be either based on reversible supramolecular (non-covalent) interactions, such as hydrogen bonding, π–π donor–acceptor, electrostatic, hydrophobic, hydrophilic, co-ordination based, or irreversible covalent interactions. The fluorescence technique is effective due to its high sensitivity, excellent temporal–spatial resolution, and fairly simple implementation.³  Among the various imaging methods such as nuclear, ultrasound, and magnetic resonance imaging, fluorescence bioimaging gives a spatial approach for visualizing morphological details in tissue.^4–6  Thus, fluorescence spectroscopy is an essential technique to investigate biologically important analytes by using synthetic fluorescent probes.^7,8  Organochalcogen-based fluorescent sensors have received more attention due to their fast response and reversibility.^9–11  In organochalcogen-based probes, Se and Te act as active reaction sites for the sensitive and selective detection of reactive oxygen species (ROS), nitrogen species (RNS), biothiols, and metal ions.¹²  These reactions include oxidation of selenium and tellurium to the corresponding chalcogenoxides, deselenation, binding of metal ions according to their chalcogenophilicity, substitution of Se by S, and so on.^12–14  In general, the absorption and emission maxima shift towards a longer wavelength on going from Se to Te due to a heavy atom effect.¹³  Additionally, organotellurium compounds display a lower emission intensity (low quantum yield) compared to organoselenium compounds.¹⁴