A Recent Update on Rhodamine Dye Based Sensor Molecules: A Review

Herein we have discussed such important modified rhodamine compounds which have been used as chemosensors for the last 7-8 years. This review covered some chemosensors for the detection of metal ions like Al(III), Cu(II), Hg(II), Co(II), Fe(III), Au(III), Cr(III), and some anion like CN^-. The selectivity, sensitivity, photophysical properties (i.e., UV-Vis spectral studies, fluorescence studies giving special emphasis to absorption wavelength in UV-Vis spectra and excitation and emission wavelength in fluorescence spectra), binding affinity, the limit of detection, and the application of those chemosensors are described clearly. Here we have also discussed some functionalized rhodamine-based chemosensors that emit in the near-infrared region (NIR) and can target lysosomes and detect lysosomal pH. Their versatile applicability in the medicinal ground is also delineated. We have focused on the photophysical properties of spirolactam rhodamine photoswitches and applications in single-molecule localization microscopy and volumetric 3D light photoactivable dye displays. The real-time detection of radical intermediates has also been exemplified.