A new turn-on cell permeable chemodosimetric probe has been developed and its application in the selective detection of trivalent cations (Fe(3+)/Cr(3+)/Al(3+)) at a sub-nanomolar level has been demonstrated. The selectivity of over a broad spectrum of mono- and divalent metal ions was established using fluorescence spectroscopy. Moreover, the changes in the absorption spectra of in the presence of trivalent cations enabled the most bio-relevant metal ion Fe(3+) over Cr(3+)/Al(3+) to be distinguished. The probe was found to be successful in the fluorescence imaging of native cellular iron pools. The fluorescence imaging of the native iron pools of banana pith further supported the high sensitivity of towards Fe(3+) present in living systems. To the best of our knowledge, this is the first example of a turn-on chemodosimetric probe to image native cellular Fe(3+) pools.

Structure-interaction/fluorescence relationship studies led to the development of a small chemical library of Zn(2+)-specific cysteamine-based molecular probes. The probe L5 with higher excitation/emission wavelengths, which absorbs in the visible region and emits in the green, was chosen as a model imaging material for biological studies. After successful imaging of intracellular zinc in four different kinds of cells including living organisms, plant, and animal cells, in vivo imaging potential of L5 was evaluated using plant systems. In vivo imaging of translocation of zinc through the stem of a small herb with a transparent stem, Peperomia pellucida, confirmed the stability of L5 inside biological systems and the suitability of L5 for real-time analysis. Similarly, fluorescence imaging of zinc in gram sprouts revealed the efficacy of the probe in the detection and localization of zinc in cereal crops. This imaging technique will help in knowing the efficiency of various techniques used for zinc enrichment of cereal crops. Computational analyses were carried out to better understand the structure, the formation of probe-Zn(2+) complexes, and the emission properties of these complexes.