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dc.contributor.authorJones, Sumner Weston Jr.en_US

The goal of this research was to develop stereochemically defined multimetallic systems for use as light absorbers and electron donor / light absorber dyads in photoinitiated electron transfer and electron collection. The basis for the stereochemical control was provided by the symmetric bridging ligands 2,3,5,6-tetra(pyridyl)pyrazine (tpp) and 2,2'-bipyrimidine (bpm). The symmetric bidentate ligand 4N-perylene was designed and the majority of the synthesis was completed.

The bimetallic complexes [(tpy)M(tpp)Ru(LLL)]n+, where M = Ru or Os and LLL = Cl3, (CH3CN)3, tpp, or (dpq)Cl, and the model monometallic complexes [(tpy)M(tpp)]2+, where M = Ru or Os, and [(tpy)Ru(CH3CN)3]2+ were synthesized and characterized using electrochemistry, UV-vis spectroscopy, and UV-vis spectroelectrochemistry. The bimetallic complexes were investigated as potential light-absorber / electron-donor complexes to be used in larger supramolecular devices for photoinitiated electron collection and electron transfer. The electrochemistry showed that the relative energy of the metal orbitals is suitable for the metal in the (tpy)M(tpp) coordination environment to act as an electron donor. These bimetallic complexes possess extremely complicated UV-vis spectroscopy due to the number of possible transitions. The assignment of the UV-vis spectroscopy and the electrochemistry of these complexes was greatly facilitated by the UV-vis spectroelectrochemistry. The metal-to-metal charge transfer spectra of the mixed-valence species of the bimetallic complexes were obtained using NIR spectroelectrochemistry and indicate a significant degree of metal-metal communication through the bridging tpp. The bimetallic complexes [(tpy)Ru(tpp)Ru(tpy)]4+, [(tpy)Ru(tpp)Ru(tpp)]4+, [(tpy)Os(tpp)Ru(tpp)]4+, and [(tpy)Ru(tpp)Ru(CH3CN)3]4+ were found to have emission lifetimes on the order of 100 ns.

The complexes [(bpy)2Ru(bpm)]2+, [(bpy)2Ru(bpm)Ru(bpy)2]4+, [(bpm)2IrCl2]+, and {[(bpy)2Ru(bpm)]2IrCl2}5+ were synthesized and characterized using electrochemistry, UV-vis spectroscopy, and UV-vis spectroelectrochemistry. The complex {[(bpy)2Ru(bpm)]2IrCl2}5+ is a LA-EC-LA device for photoinitiated electron collection. The UV-vis spectroelectrochemistry of these complexes facilitated the assignment of the UV-vis spectroscopy as well as the electrochemistry. The UV-vis spectrum of the electrochemically generated two electron reduced form of {[(bpy)2Ru(bpm)]2IrCl2}5+ was obtained. This spectrum is critical in the understanding of future studies of the photochemically generated two electron reduced species.

The symmetric, planar, bidentate bridging ligand 4N-perylene was designed. This ligand would eliminate some of the isomers associated with multimetallic complexes bridged by unsymmetric bidentate bridging ligands. The large pi system of 4N-perylene would likely result in a low energy pi* orbital compared to dpp, dpq, or bpm. The ligand 4N-perylene would hold bridged metals at a greater distance than 2,2'-bipyrimidine and should facilitate the formation of multimetallic complexes. The synthesis of 1,8-dichloro-2,7-naphthyridine has been completed. 1,8-dichloro-2,7-naphthyridine is a possible reactant in the homo-coupling reaction of a substituted 2,7-naphthyridine to form 4N-perylene.

The stereochemically defined molecular systems developed in this work show great promise for use in larger supramolecular complexes designed for photoinitiated electron transfer and electron collection.

dc.publisherVirginia Techen_US
dc.rightsI hereby grant to Virginia Tech or its agents the right to archive and to make available my thesis or dissertation in whole or in part in the University Libraries in all forms of media, now or hereafter known. I retain all proprietary rights, such as patent rights. I also retain the right to use in future works (such as articles or books) all or part of this thesis or dissertation.en_US
dc.subjectphotoinitated electron collectionen_US
dc.subjectsolar energy conversionen_US
dc.titleThe Synthesis and Photophysical Properties of New Polymetallic Complexes Designed for Use in Photoinitiated Electron Collectionen_US
dc.description.degreePh. D.en_US D.en_US Polytechnic Institute and State Universityen_US
dc.contributor.committeechairBrewer, Karen J.en_US
dc.contributor.committeememberAnderson, Mark R.en_US
dc.contributor.committeememberTissue, Brian M.en_US
dc.contributor.committeememberMerola, Joseph S.en_US
dc.contributor.committeememberHanson, Brian E.en_US

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