Electrochemical and Spectroelectrochemical Studies of Dipyrrolylquinoxaline, Porphyrins and Pyrazinoporphyrazines

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2012-05

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Abstract

In this Dissertation, the redox and UV-visible spectroscopic properties of a series of dipyrrolylquinoxalines, porphyrins and pyrazinoporphyraines are characterized in nonaqueous solvents. Electron-transfer reduction mechanisms and acid-base properties of dipyrrolylquinoxaline and its nitro-substituted derivatives are studied in PhCN and MeCN have been examined by means of cyclic voltammetry, UV-visible, NMR and ESR spectroscopy. Disproportionation reactions are coupled with the electron transfer reduction processes of the dipyrrolylquinoxalines to give the pi-anion radical. Tris- and tetrakis-quinoxalinoporphyrins and metal complexes, i.e. (PQ3)M and (PQ4)M, where M = H2II, CuII, PdII, NiII, ZnII, or AuIIIPF6 were also investigated by cyclic voltammetry and thin-layer spectroelectrochemistry in CH2Cl2, PhCN and pyridine. Stable antiaromatic 16 pi,17 pi-electron porphyrinoid CuII and ZnII complexes of tetraphenyltetrabenzoporphyrin (TPTBP) were also characterized in CH2Cl2 or PhCN. Finally, the electrochemical and spectroelectrochemical behavior of a new series of tetra-2,3-pyrazinoporphyrazines were investigated in DMSO, DMF and pyridine. These compounds are represented as [Th8TPyzPzM] where Th8TPyzPz = the tetrakis-2,3-[5,6-di-(2-thienyl)-pyrazino]porphyrazino anion and M = MgII(H2O), CoII, CuII, ZnII or H2I. The related pentametallic species having the formula [(PtCl2)4Py8TPyzPzM], M = PdII, PtII, CdII, CuII, ZnII, MgII, were also investigated in DMSO, DMF and pyridine and described in this Dissertation.

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Electrochemistry, Spectroelectrochemistry, Dipyrrolylquinoxaline, Porphyrins, Porphyrazines

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