Photochromic molecules, which photoisomerize between two chemically and optically distinct states, are well suited for electron and energy transfer to covalently attached chromophores. This dissertation aims to manipulate electron and energy transfer by photochromic control in a number of organic molecular systems. Herein the synthesis, characterization and function of these organic molecular systems will be described. Electron and energy transfer were quantified by the use of steady state absorbance and fluorescence, as well as time-resolved fluorescence and transient absorbance. A dithienylethene-porphrin-fullerene triad was synthesized to investigate photochromic control of photo-induced electron transfer. Control of two distinct electron transfer pathways was achieved by photochromic switching. A molecular dyad was synthesized, in which fluorescence was modulated by energy transfer by photoinduced isomerization. Also described is a triplet-triplet annihilation upconversion system that covalently attaches fluorophores to improve quantum yield. Overall these studies demonstrate complex molecular switching systems, which may lead to advancement in organic electronic applications and organic based artificial photosynthesis systems.

Healthy mitochondria are essential for cell survival. Described herein is the synthesis of a family of novel aminoquinone antioxidants designed to alleviate oxidative stress and prevent the impairment of cellular function. In addition, a library of bleomycin disaccharide analogues has also been synthesized to better probe the tumor targeting properties of bleomycin. The first study involves the synthesis of a benzoquinone natural product and analogues that closely resemble the redox core of the natural product geldanamycin. The synthesized 5-amino-3-tridecyl-1,4-benzoquinone antioxidants were tested for their ability to protect Friedreich's ataxia (FRDA) lymphocytes from induced oxidative stress. Some of the analogues synthesized conferred cytoprotection in a dose-dependent manner in FRDA lymphocytes at micromolar concentrations. The biological assays suggest that the modification of the 2-hydroxyl and N-(3-carboxypropyl) groups in the natural product can improve its antioxidant activity and significantly enhance its ability to protect mitochondrial function under conditions of oxidative stress. The second project focused on the synthesis of a library of bleomycin disaccharide-dye conjugates and monitored their cellular uptake by fluorescence microscopy. The studies reveal that the position of the carbamoyl group plays an important role in modulating the cellular uptake of the disaccharide. It also led to the discovery of novel disaccharides with improved tumor selectivity.

Mitochondria produce most of the ATP needed for the cell as an energy source. It is well known that cellular respiration results in oxidative damage to the cell due to the production of reactive oxygen species (ROS). Mitochondrial dysfunction is believed to contribute to a number of degenerative diseases; because of this the mitochondrial respiratory chain is considered as potential drug target. A few series of idebenone analogues with quinone, pyridinol and pyrimidinol redox cores have been synthesized and evaluated as antioxidants able to protect cellular integrity and, more specifically, mitochondrial function. The compounds exhibited a range of activities. The activities observed were used for the design of analogues with enhanced properties as antioxidants. Compounds were identified which provide better protection against oxidative stress than idebenone, and it is thought that they do so catalytically.