LIGHT-TRIGGERED EVENTS IN CONFINED SPACE OF SUPRAMOLECULAR CAGES

This thesis presents innovative research on light-triggered events in confined spaces using supramolecular cages based on tris(2-pyridylmethyl)amine (TPMA) complexes. The work extends the applications of these architectures to photoresponsive and chiroptical properties, exploring novel ways to control and enhance molecular interactions within confined environments. The study begins by investigating the disassembly of supramolecular cages, revealing a significant correlation between encapsulated guest size and cage hydrolysis rates. Building on this insight, a photoswitchable azobenzene-3,3'-dicarboxylic acid guest was successfully implemented to achieve light-controlled modulation of cage disassembly kinetics. This approach demonstrates a powerful method for using light to precisely control supramolecular cage transformations. Further investigation focused on the profound effects of supramolecular confinement on the photochemical properties of azobenzene derivatives within TPMA-based molecular cages. By systematically examining the behaviour of encapsulated azobenzene in cages of varying sizes, the research revealed that confinement significantly influences the photostationary state, isomerization kinetics, and thermal stability of the azobenzene guest. Notably, smaller cages strongly favour the cis isomer and can completely inhibit thermal relaxation, while larger cages progressively accommodate the trans isomer. Exploiting these unique properties, the research demonstrated light-triggered guest exchange between azobenzene and suberic acid, as well as dynamic cage-to-cage transformations induced by azobenzene photoisomerization. These achievements showcase the potential for creating adaptive supramolecular systems with applications in controlled release and responsive materials. The final chapter introduces a novel approach to enhance circularly polarized luminescence (CPL) using a chiral supramolecular cage system. A fluorene-modified TPMA-based chiral cage that acts as a donor in a Förster Resonance Energy Transfer (FRET) system was developed. When combined with an encapsulated achiral diphenyl-diketopyrrolopyrrole (DPP) dye, the system achieved highly efficient energy transfer, with FRET efficiency reaching up to 90%. This strategy resulted in enhanced CPL properties, demonstrating the potential for developing more efficient and stable CPL systems. Overall, this thesis represents a significant advancement in the field of supramolecular chemistry and chiral photonics. By harnessing the unique properties of confined spaces within TPMA-based molecular cages, the research opens new avenues for creating sophisticated, light-responsive molecular systems with potential applications ranging from controlled drug delivery to advanced optoelectronic devices.