We designed and synthesised coumarin-tris derivatives from a renewable resource and well characterized them using different spectral techniques. The self-assembly of coumarin-tris amphiphiles into hydrogels was examined relative to the molecular structure of the amphiphiles. The reversible morphological transition from nanofibers to vesicles and nanotubes has been observed, upon pH variation. Reversible processes and self-assembled structures such as gel, vesicle and nanotube formation have been investigated using optical microscopy and high resolution transmission electron microscopy (HRTEM). ¹H NMR and XRD studies clearly suggest that the π–π stacking interactions and hydrogen bonding were the driving force for the process of gelation. The flow behaviour of the hydrogel has been identified using rheological measurements. More importantly, the chemopreventive drug curcumin has been encapsulated into the gel and subsequent release has been achieved by a gel-to-sol transition induced by pH and Fe³⁺ metal ion stimuli. The reported hydrogel could play a substantial role in the development of new generation stimuli responsive drug delivery systems for in vivo formulations.

We designed and synthesized a simple fluorescent self-assembled molecular gel from a renewable resource and characterized it well using various techniques. The self-assembly mechanism was studied relative to the molecular structure. We also demonstrate that Fe₃O₄ nanoparticles were encapsulated in situ into the organogel by a simple process, which generated a magnetic gel with remarkable self-healing features. More importantly, stimuli responsive self-healing properties of the magnetic gel have been characterized by visual inspection, morphological and rheological analyses.

Three different coumarin coupled pyrene derivatives with varying hydrophobic units (alkyl chains) have been synthesised and well characterized using NMR and mass spectral analysis. The gelation behaviour and self-aggregation properties of these compounds were studied relative to the molecular structure and solvent affinity. Among these derivatives, the one which is not having any hydrophobic tail displays efficient gelation in higher alcohols such as decanol and dodecanol. However the other derivatives having saturated and unsaturated hydrophobic tails form weak gel in different solvents. The morphology of gel was investigated by optical microscopy and high resolution transmission electron microscopy (HRTEM). The investigation of absorption and emission spectra of these compounds revealed that the photo-physical properties were significantly influenced by the self-assembly process in different solvents. The concentration dependent emission and ¹H NMR studies clearly suggest that the π–π stacking interaction and hydrogen bonding between carbonyl groups of coumarin coupled pyrene with the –OH group of solvent were the driving forces for the process of gelation and self-aggregation. Rheological investigation clearly demonstrates the flow behaviour and reversible nature of organogel under temperature and strain ramp up and ramp down experimental conditions. By getting clue from the self-assembly mechanism in different solvents, we derived nano-flakes from coumarin coupled pyrene derivatives and further explored their potential applications in the field of cell imaging. The size of the self-aggregated particles in the DMSO–water mixture has been identified using HRTEM and a zetasizer. The nanomaterials obtained via the self-assembly process were used for fibroblast and PC3 prostate cancer cell imaging applications. Further investigation reveals that these compounds suppress the proliferation of PC3 cells.