Synthesis, characterization and photophysical measurements of photoactive chromophore-fullerene derivatives for biomedical and photovoltaic applications

Improvement of current technology and investigation of better methods is the major driving force behind the research and development efforts pursued by many research groups. In this dissertation, our main research focus is to extend the scope and applicability of fullerene based nano-materials. This thesis demonstrates the synthesis and applicability of photoresponsive fullerene derivatives. Fullerenes and their derivatives comprise an important class of molecules that are highly studied for their vast applications including nonlinear optics, photoconductors, photovoltaic and biomedical areas. A brief introduction of fullerene and fluorene (chromophoric unit attached to fullerene) derivatives is discussed with emphasis on their functionalization chemistries and applications. Also an account of the work done prior to our research and factors inspiring our structural design are described in detail.;In the first study, fluorene derivative was prepared as a precursor with effective electron donating capabilities via multi-step synthetic reactions. Sequential purifications and characterizations led to a diphenylaminofluorene derivative, which was attached to the 3-dimensional [60]fullerene cage structure using Bingel-cyclopropanation reaction. Various monoadducts as well as multi-dimensional derivatives were prepared and discussed in detail. This donor-acceptor linked fullerene-diphenylaminofluorene derivative was further modified to incorporate hydrophilic functional groups into the system. Poly(ethylene glycol) was the polymer of choice to incorporate water solubility and its attachment to hydrophobic donor linked acceptor molecule was tried using various chemical as well as enzymatic methods. Different chain lengths of poly (ethylene glycol) were attached and synthesis with detailed purifications and characterizations on each step are discussed using various nuclear magnetic resonances (nmr), optical and microscopy techniques like 1H/13C-NMR, FT-IR, UV-visible spectroscopy, etc.;A novel fullerene-diphenylaminofluorene precursor with very high two-photon absorption was also modified to improve its absorption in visible region and further analyze its photovoltaic applications. Modifications involved attachment of aliphatic chains at C-9 position of fluorene to enhance the compatibility of our derivative with other components in solar-cell design. Fullerene-diphenylaminofluorene derivative shows absorption at 400 nm. Our next goal was to move this absorption to the visible region of spectrum for enhanced photovoltaic device application. (Abstract shortened by UMI.)...