Interactions of meso-dicationic pyridinium-X-yl (X=2,4) porphyrins with DNA

This work has been divided into three chapters which represent the two major areas of the research completed: synthesis and the interaction of new ligands with different types of B-form DNA. The first chapter encompasses the synthetic aspect ranging from the preparation of the starting material through isolation of the desired di-cationic porphyrin with preferred counter-ion. The second chapter explores the nature of the di-cationic porphyrin ligands interacting with DNA. This includes the DNA interactions of meso -5,15-di(N-methylpyridinium-2-yl)porphyrin (H2D2), the last member of the sterically minimal H2DX series of porphyrins studied by this group. The interactions of higher yielding dimethyl dipyridiniumyl porphyrins, 5,15-dimethyl-10,20-di(N-methylpyridinium-2-yl)porphyrin [H 2(tMe2D2)], and its less rotationally restricted analogue 5,15-dimethyl-10,20-di(N-methylpyridinium-4-yl)porphyrin [H2(tMe 2D4)] with DNA were scrutinized. The final chapter elucidates metalloporphyrin/DNA interactions specifically of [meso-5,15-dimethyl-10,20-di(N-methylpyridinium-4-yl)porphyrinato]copper(II) [Cu(tMe2D4)] and [meso-5,15-dimethyl-10,20-di(N-methylpyridinium-4-yl)porphyrinato]zinc(II) [Zn(tMe2D4)]. The unique sensitivity of the four-coordinate copper(II) porphyrin\u27s emission to Lewis bases provided an additional spectroscopic handle in determining interactions with DNA. The five-coordinate zinc complex adds an additional steric cost to intercalation due to necessary loss of the fifth ligand. This additional cost exposed the strain of the 5,15 methyl groups. Also, cooperative binding titrations with the metalloporphyrins were conducted to establish that Zn(tMe2D4) binds in a positive cooperative manner