Design and synthesis of chromophore-quencher molecular assemblies

Three new series of molecular assemblies have been designed and synthesized for the study of photoinduced electron and energy transfer. Chapter I introduces theoretical aspects of photoinduced electron transfer involving ruthenium(II) polypyridyl complexes and explains the relationship of these fundamental processes within the framework of attempts to create chemical systems capable of artificial photosynthesis. Chapter 2 describes the synthesis of the amino acid, trans-4-hydroxy-L-proline, and explains its use as a starting material for further substitution with redox active substituents. Once substituted, this amino acid is useful in constructing molecular assemblies based on oligoproline peptides and has the potential for use in a wide range of other peptide-based molecular assemblies. The design, synthesis, and characterization of four new oligoproline molecular assemblies is presented in Chapter 3. These peptides each have a ruthenium(II) polypyridyl complex that functions as a chromophore/electron transfer acceptor and a phenothiazine electron transfer donor. These peptides are of the general form Pro₆-Pra(PTZ)-Pro_x-Pra(Rud ₂m)-Pro₆, where x = 2–5. Electron transfer in these peptides shows a unique distance dependence. Chapter 4 describes the synthesis of five new chromophore-quencher type molecular assemblies based on energy transfer quenching of a ruthenium(II) polypyridyl complex by covalently bound anthracene. These complexes are of the general form Ru(bpy′) ₂(bpy-An)2+ where bpy′ varies in its electronic structure. Synthesis, characterization, and preliminary photophysical data is presented. Chapter 5 describes the synthesis of five chromophore-quencher complexes based on electron transfer quenching of a ruthenium(II) polypyridyl complex by covalently bound methyl viologen. These complexes are also of the general form Ru(bpy′)₂(bpy-MV)4+ where bpy′ varies in its electronic structure. The synthesis and characterization of these complexes is presented.