Transition metal catalyzed selective nitrene insertion into C-H bonds, which allows direct incorporation of nitrogen functionality into hydrocarbons, represents an appealing methodology for C-N bond formation, a type of bond formation of great importance in organic synthesis due to the prevalence of amino groups in biologically active natural products and pharmaceuticals. Organic azides are atom-economic and an environment-benign nitrene source. This dissertation reports the use of organic azides as a nitrene source to develop a series of protocols for C-H bond functionalization by metal-catalyzed nitrene insertion, including the diimination of indoles, the phosphoramidation of aldehydes and the amination of hydrocarbons catalyzed by ruthenium porphyrins. Carbonylruthenium(II) porphyrin complex Ru(TTP)(CO) (TTP = meso-tetrakis(p-tolyl)porphyrinato dianion) is an effective catalyst for nitrene transfer to sp2 C-H bonds of indoles using aryl azides (ArN3) as a nitrene source. This “Ru(TTP)(CO) + ArN3” protocol selectively results in the diimination of indoles without the corresponding monoimination products being detected. In the presence of a catalyst Ru(TTP)(CO), the reactions of N-methylindole with ArN3 (Ar = 4-nitrophenyl; 3,5-bis(trifluoromethyl)phenyl), and reactions of a variety of N-substituted indoles with 4-nitrophenylazide, afford 2,3-diiminoindoles in good to excellent yields (up to 90%). This unique type of 2,3-diimination products was characterized by NMR spectroscopy, mass spectrometry and single crystal X-ray crystallography. The catalytic diimination product from N-methylindole and ArN3 (Ar = 3,5-bis(trifluoromethyl)phenyl) can also be obtained through stoichiometric reaction of N-methylindole with the corresponding bis(arylimido)ruthenium(VI) porphyrin, suggesting the possible involvement of RuVI(TTP)(NAr)2 intermediates in the Ru(TTP)(CO)-catalyzed diimination reactions. Dichlororuthenium(IV) porphyrin complex Ru(TTP)Cl2 efficiently catalyzes the phosphoramidation of aldehydes with phosphoryl azides (RO)2P(O)N3 via a nitrene insertion into sp2 C-H bonds of aldehydes. This represents the first study on the catalytic activity of a ruthenium(IV) porphyrin towards nitrene insertion into C-H bonds. The “Ru(TTP)Cl2 + (RO)2P(O)N3” protocol exhibits high chemoselectivity and functional group tolerability. Good to excellent product yields (up to 99%) have been obtained for the Ru(TTP)Cl2-catalyzed phosphoramidation of a wide variety of aldehydes with commercially available (PhO)2P(O)N3 (DPPA) and phosphoramidation of p-tolualdehyde with various (RO)2P(O)N3 (R = Me, Et, CCl3CH2, 4-nitrophenyl). The reaction can be scaled up by adding phosphoryl azide dropwise. The use of commercially available DPPA in this protocol offers a convenient and practical method for the synthesis of N-acylphosphoramidates. “Ru(TDCPP)Cl2 + (CCl3CH2O)2P(O)N3” (TDCPP = meso-tetrakis(2,6-dichlorophenyl)porphyrinato dianion) serves as an effective protocol for intermolecular nitrene insertion into sp3 C-H bonds of hydrocarbons. Using this protocol, a variety of hydrocarbons including cycloalkanes (such as cyclohexane) and ethylbenzenes undergo sp3 C-H amination in moderate to high yields (up to 86%). Compared with ruthenium(II) porphyrins such as Ru(TDCPP)(CO) and dirhodium carboxylates such as Rh2(OAc)4, Ru(TDCPP)Cl2 displays a markedly higher catalytic activity towards the nitrene sp3 C-H insertion with (CCl3CH2O)2P(O)N3. In addition, intramolecular nitrene insertion into sp3 C-H bond can also take place in good yields with Ru(TDCPP)Cl2 as the catalyst. / published_or_final_version / Chemistry / Doctoral / Doctor of Philosophy

published_or_final_version / Chemistry / Doctoral / Doctor of Philosophy

Porphyrins are naturally occurring molecules. Porphysomes are simple multimodal nanoparticles that derive their multifunctionality from porphyrin-based building-blocks. While previous studies have probed their interactions with light, their capacity to stably chelate metal ions has gone largely uninvestigated. Herein are presented and discussed two investigations into metalloporphysomes. First is a method for non-invasively labeling porphysomes with radioactive copper-64. Utilizing exceptionally simple chemistry, this method produces a highly stable radiotracer capable of both PET and fluorescence imaging. Second is a profile of a MRI-detectable, photothermal agent whose photonic properties are serendipitously improved by the incorporation of MRI-active metal ions. By taking advantage of simple chemical substitutions, these studies illustrate methods of accessing new functionalities while maintaining a deeply simple construct, an often overlooked aspect in the development of multimodal nanoparticles.

Porphyrins are naturally occurring molecules. Porphysomes are simple multimodal nanoparticles that derive their multifunctionality from porphyrin-based building-blocks. While previous studies have probed their interactions with light, their capacity to stably chelate metal ions has gone largely uninvestigated. Herein are presented and discussed two investigations into metalloporphysomes. First is a method for non-invasively labeling porphysomes with radioactive copper-64. Utilizing exceptionally simple chemistry, this method produces a highly stable radiotracer capable of both PET and fluorescence imaging. Second is a profile of a MRI-detectable, photothermal agent whose photonic properties are serendipitously improved by the incorporation of MRI-active metal ions. By taking advantage of simple chemical substitutions, these studies illustrate methods of accessing new functionalities while maintaining a deeply simple construct, an often overlooked aspect in the development of multimodal nanoparticles.

Field effect transistors (FETs) are a key component of modern electronic devices. They require a semiconducting material that is traditionally made from doped silicon. Recently however it has been shown that porphyrin systems can be used in the same capacity. This thesis therefore describes the investigation of new methods of porphyrin functionalization to synthesise 1,4,5,8-tetraazaanthracene-bridged porphyrin arrays, and their application to the synthesis of extended arrays for use in FETs. The 1,4,5,8- tetraazaanthracene bridge is synthesised through the condensation of a porphyrin alpha-dione with 1,2,4,5-tetraaminobenzene. Accordingly, the synthesis of an extended array requires a porphyrin tetra-one monomer unit. Two methods for the synthesis of porphyrin tetra-ones have been investigated. The first approach attempts to adapt Knudsen's hydroxylation of an aryl halide by sodium benzaldoximate to a porphyrin system. Initial regiospecific halogenation of a porphyrin has been successfully achieved. However when hydroxylation was attempted, partial dehalogenation of the substrate was observed; and when applied to the synthesis of the porphyrin tetra-one the methodology failed. The second approach involves the allylic oxidation of a chlorin (a reduced porphyrin) on silica. The transformation's mechanism has been thoroughly investigated and it has been successfully applied to the synthesis of a porphyrin tetra-one. This methodology has then been applied to the synthesis of extended porphyrin arrays. A sample incorporating 12 porphyrin units has been successfully constructed. It has been characterised by NMR, MALDI, GPC and UV-VIS spectroscopy. By comparison with previous results it has been concluded that the aromatic system- which spans 181 Ǻngstroms from end to end- can be described as a series of weakly interacting chromophores, in agreement with theoretical predictions made by Hush. In addition a medium-scale synthesis of an array incorporating four porphyrins has been achieved so that it may now be tested as the semiconducting material in a FET.

This thesis reports the spectroscopic and computational studies of two classes of compounds, which have applications in new optoelectronic materials technology. Substituted ligands of dipyrido-[3,2a:2�,3�c]phenazine (dppz), and their Cu(I), Re(I) and Ru(II) complexes have utility in organic electroluminescent devices. A series of Zn(II) tetraphenylporphyrins with conjugated functional groups at the β-position have been used with success in liquid heterojunction dye-sensitized solar cells. The vibrational spectra and optoelectronic properties of the two classes were investigated using Raman, resonance Raman and transient resonance Raman spectroscopy, in conjunction with density functional theory methods. Density functional theory frequency calculations were used to aid vibrational mode assignments for the dppz compounds, and show close agreement with the experimental non-resonance Raman spectra. The enhancement of modes which are localized on differing sections of the ligand was identified. The nature of the absorbing chromophores for the dppz ligands and complexes was established using resonance Raman spectroscopy in concert with vibrational assignments from calculations. Transient resonance Raman spectra of the ligands provided spectral signatures for the triplet ligand-centred state; these features were observed in the TR� spectra of the metal complexes, along with other features attributable to MLCT states. Electroluminescent devices were fabricated using the dppz ligands and complexes as emissive dopants, and their properties investigated. The optoelectronic behaviour of the devices was found to be influenced by the mechanism of exciton formation on the dopant. The device properties were also dependent on the dopant concentration, the concentrations of other components and the driving voltage. The electronic structure of the porphyrin compounds was investigated using time-dependent density functional theory methods. Comparison of calculated optical transitions with experimental data shows that the calculations predict trends in the optical absorption spectra with change of functional group and with increase in conjugation chain length. The calculations suggest that the electron-withdrawing substituent decreases the configuration interaction effect by breaking the degeneracy of the two lowest unoccupied MOs, and other configuration interaction effects come into play involving other frontier MOs. Interrupting the conjugation of the functional group is shown to mitigate the breakdown of the configuration interaction. The perturbation of the normal electronic structure of the porphyrin by the substituent was also investigated using resonance Raman spectroscopy. Vibrational analysis identified bands due to the substituent, implying coupling between the porphyrin and substituent chromophores. Changes in frequency of porphyrin core modes due to the differing substituents and different metal centres were reproduced by density functional theory calculations. This project has allowed the spectroscopic investigation of the active optical states in a number of polypyridyl and porphyrin compounds, and determined the efficacy of DFT and TDDFT calculations to predict the properties of these compounds.

Thesis (Ph. D.)--University of Washington, 1997. / Vita. Includes bibliographical references (p. [201]-216).

Thesis (M.S.)--West Virginia University, 2004. / Title from document title page. Document formatted into pages; contains xi, 94 p. : ill. (some col.). Includes abstract. Includes bibliographical references and index.

Thesis (Ph. D.)--Montana State University--Bozeman, 2003. / Typescript. Chairperson, Graduate Committee: Aleksander Rebane. Includes bibliographical references (p. 178-199).

Thesis (Ph. D.)--University of Hong Kong, 1999. / Includes bibliographical references.