Abstract
The main content of this thesis to explore the various supramolecular surface chemistry and the excited state properties of the incarcerated guest molecules within the nanocapsules. This research presented consolidated account of photophysical and photochemical reactions carried in water soluble and water-insoluble cavitands. With the aid of NMR and emission spectroscopic techniques, the host-guest complex characterization is executed. Chapter 1 introduces the main concept and developments of supramolecular chemistry. Also, the invention of carcerends and hemicarcerends and their significances over than organic chemistry. Introduction of water soluble cavitands, macrocycles and their host-guest properties in solution and functionalization of macrocycles on the surfaces, studies of communication between the included guest to the surface. In addition, the FRET was explained between the incarcerated energy donor guest to energy acceptor present on the walls of the capsule. Chapter 2 comprised the synthesis of two new water-soluble cavitands RTA and ROA and characterization of these two by 1D NMR, 2D-COSY NMR, and ESI-MS. The molecular recognition properties of these two new cavitands with various organic guest molecules were studied in solution and were analyzed by 1D NMR, DOSY NMR and emission spectroscopic techniques. Then, the formed capsular assemblies in solution were transferred to silica surface and confirmed that the capsules are intact on solid silica surface. These results were supported by photophysics and photochemistry of the incarcerated guest molecules. In Chapter 3, water-insoluble hosts (RCTA and RCMTA) formed supramolecular capsular assemblies with various hydrophobic guest molecules on silica surface. The formations of capsules were confirmed by photophysics and photochemistry of included guest molecules. Also, the RCTA cavitand was covalently functionalized on silica surface and studied the potential to form the capsular assembly. In this chapter, it is proved that the water is acting as major driving force to form capsules rather than organic solvents on silica surface. In order to avoid the aggregation and segregation process of various organic molecules in solution, we used supramolecular strategy to overcome this problem. In Chapter 4, we encapsulated the guests molecules within the cationic cavitands and adsorbed on anionic inorganic α-ZrP layer. The UV-Vis absorption and emission spectra supported that the capsules are intact in the galleries of inorganic layers. The XRD pattern reveals that there are two possible orientations of the capsules in the galleries. Chapter 5 comprised the synthesize of the CB[7] functionalized gold nanoparticles (AuNPs) and studied the host-guest complex formation with various guest molecules. The interaction between the host CB[7] and surface of the gold nanoparticles were studied by TEM, DLS, FT-IR and TGA experiments. Also, the communication between the excited state guest within bound CB[7] to the gold surface were investigated. Chapter 6 comprised the two projects and it was separated by part I and part II. The part I explains the multistep energy transferred of coumarin derivatives, encapsulated within the cationic capsule and adsorbed on anionic clay nanosheets. Also, the energy and electron transferred occurred on clay surfaces. Here, energy transferred occurred between two molecules and electron transferred to the third molecule assembled on clay surfaces. The fluorescence spectroscopy supported the energy and electron transfer reaction. In part II, the supramolecular host octa acid was used to encapsulate the water insoluble guest to favor the Excited State Intramolecular Proton Transfer (ESIPT) in aqueous media.