Spectroscopic Exploration of Various aspects of Guest-Host Interactions using Small Molecules and Some Pyrene Derivatives as Guests

Ghosh, Ashutosh (2020) Spectroscopic Exploration of Various aspects of Guest-Host Interactions using Small Molecules and Some Pyrene Derivatives as Guests. PhD thesis, Indian Institute of Science Education and Research Kolkata.

Text (PhD thesis of Ashutosh Ghosh (15RS065)) 15RS065.pdf - Submitted Version Restricted to Repository staff only Download (11MB)

Abstract

The thesis focuses on the host-guest chemistry and the related modulations in the probe microenvironment. In this route, some pyrene-tagged small molecules have been synthesized and characterized. Biocompatible host, such as, β-cyclodextrin, β-cyclodextrin nanoparicles, micelle and vesicles in aqueous solution were used to serve the purpose of the investigation. The pyrene derivatives provide a number of important advantages over the currently available dyes due to their excimer formation, combined with long-lived excited states, high fluorescence quantum yield, exceptional distinction of the fluorescence bands for monomer and excimer, and the sensitivity of the excitation spectra to the changes in the microenvironment. Because of to this attractive combination of properties, pyrene and its derivatives have subjects of vivid research in terms of their photophysical properties. The tendency of pyrene and its derivatives to form excimers has been widely employed for designing supramolecules and probing the structural properties of macromolecular systems. These complexes are highly efficient in sensing, bioimaging, light emitting electrochemical cells, catalysis for water splitting, dye sensitized solar cells and organic transformations. The dissertation includes five chapters on the works performed. The works have been summarized here in sequence of their appearance in the thesis. Chapter IV accommodates a brief discussion on the modulation of the proton transfer dynamics of a small molecule, 2,2'-Bipyridine-3,3'-diol (BP(OH)₂), using β-cyclodextrin (β-CD) and β-CD nanoparticles (NPs) as macrocyclic hosts. Chapter V has shown the application of an ultrasensitive pyrene-benzothiazole molecule that helps in controlled formation of hydrated micelles by the intervention of CDs. Chapter VI presents a comparative study on the degree of electron acceptance by edge-oxidized graphene oxide (EOGO) and carboxilic acid functionalized single walled carbon nanotubes (SWCNTs) by using fluorescence spectroscopy. Chapter VII explains a method of surfactant and CD induced vesicle to micelle to vesicle transformation in aqueous medium. Chapter VIII proposes a process of micelle mediated rapid thiazolidine ring formation putting pyrene tag to L-cysteine. The work has developed a simple and convenient method to catalyze thiazolidine ring formation. The works have opened broad conceptual avenues of methods and processes with prospects of applications in biological microenvironments.

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