Synthesis of coumarin based Tb3+ complex and its application in cell imaging

Mitochondria is an important site for ATP production from oxidative phosphorylation, and plays a crucial role in biochemical processes. It is a significant site for the production of ATP via oxidative phosphorylation, and plays crucial in regulation of apoptosis, redox homeostasis and calcium signalling. In the present work, Tb³⁺ complex was synthesized using coumarin based ligand L and 1, 10-phenanthroline as coligand. The coumarin is well known for its photophysical and medicinal importance in therapeutic research. Photophysical characterizations of the complex indicated that the ligand efficiently sensitizes the emissive level of Tb³⁺ ion. Thus, the long-excited state lifetime of 0.75 ms and high quantum yield of 57 % exhibited by the complex led to its employment in imaging of cellular organelles. Interestingly, the complex was found to be selectively localized to mitochondria, its positively charged chemical structure being permeable to the cell membrane and accumulating in mitochondria, which is well visualized under confocal microscopy. An attempt has been made to understand how the Tb³⁺ complex can be taken up by mitochondria and become a better target for drugs that exhibit therapeutic effect.