Photochemical and photophysical properties and potential applications of pyrenesulfonyl derivatives and novel azo dye cations

This dissertation is focused on two aspects of a photochemical mechanism of particular interest in recent years involving light-induced electron transfer that occurs between two chemical constituents that are separated by a short molecular linker. The first involves a pyrenesulfonamide or pyrenesulfonate chromophore, that acts as either an electron donor or an electron acceptor moiety. It is linked to a variety of redox-active groups; attachment of these groups leads to the quenching of fluorescence assigned to the pyrene. The mechanism was investigated further in terms of the fate of the products that result from intramolecular electron transfer, namely the radical ion intermediates that are predicted to undergo bond breaking thus fragmentation of the donor-acceptor linkage.; A goal that was reached in this investigation is the demonstration that a pyrene labeled molecule can fragment under irradiation with ultra-violet light providing a bioactive ligand in high chemical yield. The investigation encompassed fluorescence quantum yield and lifetime measurements for the pyrenesulfonyl derivatives from which kinetic and mechanistic data could be obtained, and associated photoproduct studies. The data are consistent with the electron transfer-fragmentation pathway and suggested a utility for a pyrenesulfonyl labeling protocol for controlled release, at an irradiated site, a variety of candidate drugs.; Azo dyes constitute one of the largest of the classes of commercial dye stuffs. They are known to undergo either reduction or oxidation reactions in natural aquatic environments. Products of these reactions are often hazardous, including several known cancer-causing agents. Following the intramolecular electron transfer theme, a series of modified azo, dyes was produced which display the donor-link-acceptor motif. Electron acceptors included pyridinium or acridinium moieties; amide groups completed linkages to various azo benzene derivative dye structures. The photochemical properties of new dyes were investigated, in particular a comparison of their tendencies to undergo cis-trans isomerization of the azo group and photodegradation. The finding was that isomerization is inhibited as the result of modification by the electron acceptor groups and overall light fastness for the dyes is improved vs. the commercial azo dyes.