The study and application of exciplex quenching in platinum(II) polypyridine and copper porphyrin systems
Abstract
Metal complexes containing open coordination spheres present a unique class of compounds exceptionally sensitive to the local environment. In particular, metal complexes that are photoluminescent may be subject to quenching in coordinating solvents. This has been demonstrated in pseudo-square planar platinum(II) terpyridine complexes as well as metalloporphyrins. Chapter one of this thesis will introduce the photochemistry of platinum(II) terpyridine complexes and porphyrin systems, as well as the concept of exciplex quenching. Chapter two describes the introduction of a phenazine moiety into a tridentate ligand which provides potential for Lewis acid quenching at a distal site within a molecule already susceptible to Lewis base quenching. The synthesis, photophysics, and photochemistry of a series of such compounds with platinum is described. The intraligand character of the monocationic platinum(II) terpyridyl system does not afford a unique quenching mechanism. A carbometalating system proves to have an emissive state with intraligand charge transfer character that imparts susceptibility to both Lewis acid and base quenching on the system. This molecular framework and the dual-sensing ability is to date unprecedented. Chapter three deals with a series of porphyrin chromophores. It has previously been shown that the steric requirements of meso-substituted porphyrins is important in how these molecules bind to B form DNA. Current interest in how porphyrin molecules bind to genetically important molecules has focused on the quaternary structures adopted by guanine rich sequences. Porphyrins have been shown to associate with small oligo mimics of these guanine rich sequences and in some cases stabilize the formation of guanine tetrads. By taking advantage of the Lewis base sensitivity of a series of copper porphyrins with different steric requirements, steric effects in binding can be assessed. As a result a unique binding mode is defined and described. These studies collectively are of significance with respect to applications in chemo- and biological sensing, therapeutics, and inorganic photochemistry.
Degree
Ph.D.
Advisors
McMillin, Purdue University.
Subject Area
Inorganic chemistry
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