Studies on porphyrin based donor-acceptor systems and chemosensors

The research reported in this thesis deals with the synthesis, characterization and optical absorption and emission studies of noncovalently linked porphyrin based donor-acceptors systems and chemosensors. The first three chapters reports the synthesis and characterization of several "Quinhydrone" based porphyrin complexes. The first complex discussed show an enhanced fluorescence quenching upon formation of the "quinhydrone" complex. The reasons for the formation of and the mechanism by which the fluorescence of the porphyrin is quenched is discussed. The second complex described is a "quinhydrone-based" fluorescent chemosensor for hydroquinone detection. The selectivity and the mechanism by which fluorescence enhancement occurs, is described. The third type of complex discussed is a "quinhydrone" based multiporphyrinic array. The photoinduced energy transfer that is occurring in the supramolecular complex is discussed.Finally, formation of noncovalently linked porphyrin-C60 complexes is discussed in the chapter 5 and 6. The mode of binding between the zinc porphyrin and the 2(pyridyl)fulleropyrrolidine is discussed and characterized by 1H NMR, UV-visible, ESI-Mass and fluorescence spectroscopy. The binding constant and thermodynamic parameters for the various complexes are calculated using UV-Visible spectroscopy to probe the strength of the binding. Molecular modeling using semi empirical PM3 and ab initio calculations on these complexes were performed to gain insight into the structural aspects of these complexes.