Our recent interest in the photophysics of Schiff base molecules was started by Dr. Tuhin Khan. He worked on time-resolved processes of salicylideneaniline type Schiff bases and their metal complexes. It is evident that various non-radiative processes like excited state intramolecular proton transfer (ESIPT), Conformational relaxations, and Hydrogen bonding interactions are mainly responsible for the weak emissivity of the Schiff base molecules. Some of these non-radiative channels are suppressed in the anionic congener and metal complexes of the Schiff bases. Currently, we are also focusing on some of the boron- Schiff base complexes. These boron complexes are found to be fluorescent rotors, feebly emissive in non-viscous solvents but fluorescence lifetime increased by an order in viscous solvents like glycerol. You may find the following publications interesting:

• Khan, T.; Vaidya, S.; Mhatre D.; Datta, A. The Prospect of Salophen in Fluorescence Lifetime Sensing of Al(III). J. Phys. Chem. B 2016, 120, 10319-10326

• Khan, T.; Datta, A. Impact of Molecular Arrangement and Torsional Motion on the Fluorescence of Salophen and Its Metal Complexes. J. Phys. Chem. C 2017, 121, 2410-2417

• Dasgupta, S.; Banerjee S.; Das, S.; Datta, A. From fluorogens to fluorophores by elucidation and suppression of ultrafast excited state processes of a Schiff base. Phys. Chem. Chem. Phys. 2021, 23, 19494-19502

We are also working on synthesizing terephthalate-based small organic molecules. This work is inspired by the studies of Dr. Soumyadipta Rakshit, an alumnus (postdoctoral student) of our lab. DBMPT, an aggregation-induced-emission-based fluorescent molecule (AIEgen), synthesized by Prof. Anil Kumar's group, was found to be an interesting system for intracellular imaging. Currently, we have developed a few DBMPT derivatives and carried out initial spectroscopic investigations. Not all the derivatives are AIEgens but have promising features to be used in specific organelle-targeted intracellular imaging. Here are the related publications:

• Rakshit, S.; Das, S.; Poonia, P.; Maini, R., Kumar, A.; Datta, A. White Light Generation from a Self Assembled Fluorogen-Surfactant Composite Light Harvesting Platform. J. Phys. Chem. B 2020, 124, 7484–7493

• Rakshit, S.; Das, S.; Govindaraj, V.; Maini, R., Kumar, A.; Datta, A. Morphological Evolution of Strongly Fluorescent Water Soluble AIEEgen-Triblock Copolymer Mixed Aggregates with Shape–Dependent Cell Permeability. J. Phys. Chem. B 2020, 124, 10282-10291