Title

Synthesis, characterization, DNA binding, photocleavage and the cell studies of a novel supramolecular [5,10,15-Tris(4-Pyridyl)-20-Pentafluorophenyl] porphyrin containing copper(II), ruthenium(II) and platinum(II)

Author

Zhiming Xu

Date of Award

2012

Degree Name

M.S. in Chemistry

Department

Department of Chemistry

Advisor/Chair

Advisor: Shawn Swavey

Abstract

Coordination of two [Ru(bipy)2Cl]+ moieties (where bipy = 2,2'-bipyridine) to the pyridyl nitrogens in the 5,10-positions of meso-5,10,15-(4-pyridyl)-20-(pentafluorophenyl)porphyrin gives the diruthenium porphyrin complex II. Insertion of copper(II) into the porphyrin center allows for the third pyridyl nitrogen to be coordinated to Pt(dmso)Cl2. Electronic transitions associated with the ruthenium porphyrin include an intense Soret band and four less intense Q-bands in the visible region of the spectrum. An intense [pi]-[pi]* transition in the UV region associated with the bipyridyl groups and a metal to ligand charge transfer (MLCT) band appearing as a shoulder to the Soret band are also observed. A slight blue shift of the Soret band and collapse of the Q-bands into one band is observed upon insertion of Cu(II) into the porphyrin center. No change in the electronic spectrum is observed upon coordination of the Pt(dmso)Cl2 moiety. Electrochemical properties associated with the complexes include a redox couple in the cathodic region attributed to the porphyrin and a redox couple in the anodic region due to the RuIII/II couple. DNA titrations of the complex III and IV indicate that both complexes interact strongly with DNA potentially through a partial intercalation mechanism. Gel electrophoresis studies indicate that complex IV has a greater effect on DNA migration through the gel than the well-known DNA binding agent cis-platin. Irradiation of aqueous solutions of complex III and supercoiled DNA at a 5:1 base pair to complex ratio (in the absence of oxygen) with visible light above 400 nm shows a nicking of the DNA. Repeat experiments in the presence of oxygen show that the complex III photocleaves the DNA, giving the linear form, as evidenced by gel electrophoresis. The cell studies show that the diruthenium porphyrin, complex II, is very toxic to the melanoma cells but appears to be overly toxic to normal cells when irradiated to be a feasible photosensitizer for PDT. However, only a little or no effect on the normal fibroblast or melanoma cells was observed after an irradiation time of 60 minutes for complexes III or IV.

Keywords

Porphyrins Research, Supramolecular organometallic chemistry Research

Rights Statement

Copyright 2012, author

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