Thesis (Ph.D.)--Case Western Reserve University, 2009 / Abstract Department of Chemistry Title from PDF (viewed on 13 April 2009) Available online via the OhioLINK ETD Center

Thesis (Ph. D. in Chemistry)--University of California, Berkeley, June 1960. / Includes bibliographical references : p. 119-120.

The syntheses, spectral and electrochemical characterization of new family electropolymerizable pyrrole, thiophene and mercaptopyrimidin substituted metallophthalocyanine (MPc) complexes are described. Tetraamino substituted chromium and manganese phthalocyanine complexes were also synthesized and characterized. The spectral and electrochemical results are comparable to literature reports. The complexes formed stable films when deposited on electrode surfaces. The MPc films were formed by electropolymerization, drop-dry method and self-assembling. Nickel hydroxide-like electrodes were formed by electrotransformation of nickel-tetra-4- (pyrrol-1-yl)phenoxy phthalocyanine polymer films to the corresponding PcNi-O-NiPc modified electrodes in alkaline solution. The thiophene, mercaptopyrimidine functionalized MPcs and amino group containing complexes formed good self-assembled monolayers (SAMs) on gold electrode. The electrode modification processes were reproducible. The conductivities of the electrode were dependent on the surface concentrations of the complexes as a function of electropolymerization scan numbers. The electrodes showed good catalytic responses toward L-cysteine, nitrite, nitric oxide (NO), glycine, phenol and its derivative and oxygen. The results also suggest that the presence of thio groups on the ring substituents lowers the oxidation potential of Lcysteine more compared to literature values. The stability of the amperometric responses toward the various analytes is used to diagnose the applicability of the materials for electroanalytical purposes. The limits of detection for L-cysteine, nitrite, NO and glycine were in the range of ~10⁻⁷ to 10⁻⁵ mol dm⁻³.

No description available.

No description available.

At the end of this thesis, the 1H and 13C{ 1H} NMR spectra for all the new compounds and the crystallographic data are given as an Appendix. / Chapter 1 presents an overview of phthalocyanines and subphthalocyanines, including their general synthesis, properties, photosensitizing applications, and supramolecular chemistry. / Chapter 2 describes the synthesis and spectroscopic characterization of a series of subphthalocyanines axially substituted with an oligoethylene glycol chain [SPcB(OCH2CH2)nOH] (n = 3, 4) or a p-phenoxy oligoethylene glycol methyl ether chain [SPcBOC 6H4(OCH2CH2)nOCH3] (n = 2, 3). Their in vitro photodynamic activities toward HT29 human colorectal adenocarcinoma and HepG2 human hepatocarcinoma cells have also been investigated. In general, these compounds are essentially non-aggregated, resulting in a strong fluorescence emission and high efficiency to generate singlet oxygen. Being formulated with Cremophor EL, these subphthalocyanines function as efficient photosensitizers and exhibit a high photocytotoxicity. The phenoxy analogues show a relatively high photostability and are particularly potent toward these cell lines. / Chapter 3 reports the synthesis, spectroscopic characterization, and in vitro photodynamic activities of a new series of water-soluble subphthalocyanines. The photodynamic activities of these compounds against HepG2 and HT29 cells have also been evaluated. They exhibit high singlet oxygen quantum yields, but different degree of photostability, which greatly affects their photocytotoxicity. The relatively high photostability of the carboxy subphthalocyanine and its salts renders them highly photocytotoxic. / Chapter 4 describes the axial coordination of two subphthalocyanines having an axial pyridyl group with several tetrapyrrole derivatives, including zinc(II) and ruthenium(II) porphyrins and phthalocyanines. By using various spectroscopic methods and X-ray diffraction analyses, the formation of 1:1 hetero-dyads has been confirmed. The binding constants between the pyridyl subphthalocyanines and these metallotetrapyrrole derivatives have also been determined by a fluorescence titration method. / Chapter 5 presents the synthesis and spectroscopic characterization of a covalently linked subphthalocyanine-cyclodextrin conjugate. The host-guest interactions between this compound and a tetra-sulfonated porphyrin in aqueous medium have been investigated by various spectroscopic methods. This supramolecular system exhibits an efficient photo-induced energy transfer process from the excited subphthalocyanine core to the porphyrin moiety. This host-guest approach provides a new strategy to construct mixed subphthalocyanine and porphyrin systems, which have not been explored so far. / Chapter 6 reports the use of a series of zinc(II) and silicon(IV) phthalocyanines as photocatalysts for the photooxidation of olefins and 1-naphthol. These compounds are efficient photosensitizers producing singlet oxygen to form the oxidized products in high yields. The only exceptions are two dendritic silicon(IV) phthalocyanines which have a relatively low efficiency to generate singlet oxygen. Three photosensitizers have also been examined for their recyclability in the photooxidation of alpha-terpinene and furan-2-carboxylic acid. All of them can be recycled at least four times without a significant loss of catalytic activity. / This thesis reports our investigation of two versatile classes of functional dyes, namely phthalocyanines and subphthalocyanines, focusing on their photosensitizing applications and supramolecular chemistry. / Xu, Hu. / Adviser: Dennis K. P. Ng. / Source: Dissertation Abstracts International, Volume: 70-06, Section: B, page: 3506. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2008. / Includes bibliographical references. / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstracts in English and Chinese. / School code: 1307.

The results of solution electrochemical and photoelectrochemical studies on a series of well-defined silicon phthalocyanine (SiPc) stacked-ring oligomers are presented. These molecules consist of one (monomer), two (dimer), and three (trimer) SiPc rings which are axially stacked through a O-Si-O backbone with t-butyldimethylsilyl "end cap" groups. The interplanar spacing in the dimer and trimer SiPc is about 3.4 Å which facilitates the through-space molecular orbital overlap that gives them unique spectroscopic and electrochemical properties intermediate between those observed for other systems in which the electroactive centers are non-interacting or have exclusively through-bond interaction. There is a blue-shift in both the Q- and Soret absorbance maxima which is accompanied by an increased oscillator strength as more SiPc subunits are added per molecule. In dichloromethane solution, the cyclic voltammograms of these molecules exhibit multiple, one-electron, chemically reversible oxidations and reductions. The number of oxidations and reductions observed for each molecule increases with the addition of more SiPc rings and the energy difference between successive electron transfers decreases. In addition, there is a large cathodic shift of 0.52 V in the first oxidation potential between the monomer and trimer SiPc indicating a net stabilization of the dimer and trimer towards oxidation with respect to the monomer SiPc. These electrochemical results are shown to correlate well with Ultraviolet Photoelectron Spectroscopic (UPS) and UV-visible absorption spectroscopic data and energy level diagrams for the monomer, dimer, and trimer SiPc as well as higher-order polymeric SiPc are developed. Extensive photoelectrochemical studies on SiPc-modified electrodes are also reported. The effects of the chemical nature, E⁰, and concentration of the solution redox couple, as well as the influence of changing the electrode substrate and incident light intensity and wavelength on the photoresponse characteristics of these electrodes are presented and discussed. A solid-state band model for the dyesensitization process is discussed that treats the SiPc layer as a photoconductor that is capable of causing Fermi level pinning to occur at the SiPc/SnO₂ interface, resulting in an open-circuit photovoltage of about 200 mV which is independent of the solution E⁰. A molecular model is also developed that considers the specific molecular interactions which occur between the SiPc and the substrate, between adjacent SiPc molecules in the dye layer, and between the SiPc molecules and the solution redox species. Photoexcitation of the SiPc layer results in the formation of excitons in which the excited-state is delocalized over an aggregate containing several SiPc molecules.

published_or_final_version / abstract / Physics / Master / Master of Philosophy

No description available.

The frontier orbitals of organic semiconductors at interfaces as they relate to organic electronic device applications, both relative energy and possible relative orientations, are the focus of this work. Heterojunctions between perylenetetracarboxylicdianhydride (PTCDA) or N,N'-di-n-butylperylene bis(dicarboximide) (C4-PTCDI) and metal centered phthalocyanines, including chloroaluminum, chloroindium, zinc, and copper phthalocyanine, have been characterized with ultraviolet photoelectron spectroscopy (UPS).Organic semiconductors heterojunctions clearly demonstrate that they cannot be treated as insulators, that vacuum level shifts occur at many organic semiconductor heterojunctions, and that Fermi level alignment is achieved but the individual nature of the organic Fermi levels must considered. UPS shows that the n-type semiconductors PTCDA and C4-PTCDI have organic Fermi levels pinned at the lower edge of the LUMO. Phthalocyanines have organic Fermi levels approximately midway between the HOMO and LUMO. The same Fermi levels are applicable for organic semiconductors at interfaces with gold as with other organic semiconductors. Further, heterojunctions of the organic semiconductors on gold show that although the alignment farther from the interface is determined by Fermi level alignment, at the immediate interface the interface dipole is determined by different factors as described by the additive model of interface dipole formation which includes factors for metal surface dipole, charge transfer, and molecular dipole moments. This model and the role of the molecular dipolar have been well characterized with alkanethiol and fluorinated alkanethiol self-assembled monolayers on gold, leading to the conclusions that the effective work function of the gold surface could be modified over a range of ca. 1.5eV with the SAM dipole and that the gold-sulfur bond is largely covalent.Fluorescence spectroscopy of phthalocyanine heterojunctions with PTCDA and C4-PTCDI was able to determine favored interfacial exciton dissociation pathways, and that charge transfer dissociation to form mobile charges is favored at PTCDA heterojunctions but energy transfer to create phthalocyanine excitons dominates at C4-PTCDI heterojunctions. The wavelength and progression of fluorescence emission from monomer phthalocyanines and aggregated phthalocyanine structures was also able to characterize thin film growth and the resultant polymorphs created by vacuum deposition of phthalocyanines on KCl (100) surfaces and on PTCDA and C4-PTCDI thin films.