Phosphines and phosphites have been investigated as ligands to tetraphenylporphinato iron(II) (FeTPP) by spectrophotometric titration in tetrahydrofuran. A least squares method for determination of the equilibrium constants K1 and K2 (K1 and K2 correspond to the sequential binding constants for the formation of FeTPPL and FeTPPL2, respectively) was developed. This method eliminates the errors associated with fundamental assumptions intrinsic to the more conventional Hill plot. The visible spectrum of the 5-coordinate complex, FeTPPL, was also determined for each ligand. The equilibrium constants obtained are: {L(logK1, logK 2)}, PMe3 (5.53, 4.60); PEt3 (5.61, 4.30); P(n- Bu)3 (6.13, 5.02); P(OEt)3 (3.87, 2.82); P(O-i-Pr)3 (3.28, 1.13). The equilibrium constants are dependent upon steric bulk, σ-basicity and π-acidity.

Radioiron labelled prophyrins were tested for tumor uptake using tissue culture and animal models. The following porphyrins were tested: hematohemin; protohemin; photo-protohemin; 2-formyl-4-vinyl, 2-vinyl-4 formyl, and 2,4-diformyl deuterohemin derivatives; meso-tetra (4 carbo-xyphenyl) hemin (TCP); tetra-Na-meso-tetra (4-sulfonato-phenyl) hemin (TPPS); and meso-tetra-(4-N-methylpyridyl) hemin tetraiodide (TMPI). ⁵²Fe was produced at TRIUMF by high energy proton spallation of a nickel target. The ⁵²Fe was separated from the other spallation products by solvent extraction with methyl isobutyl acetone and ion exchange chromatography when required. Tissue culture studies using P815 mouse tumor cells showed good uptake with protohemin, TCP, or TMPI. Mouse distribution and excretion studies indicated that the target organ for TMPI was the liver (and spleen) and its biological half-life was 270 days. Animal scans using rats with breast carcenomas with ⁵²Fe labelled protohemin, TCP and TMPI showed no tumor uptake at all. The radiation dose to a human was also calculated. / Pharmaceutical Sciences, Faculty of / Graduate

No description available.

With their unique photochemical properties, porphyrins have remained a central research topic for decades. Porphyrins can self-assemble into tubular structures at acidic pHs. However, the possibility of the disassembly of the aggregated porphyrin has not been investigated. Furthermore, quantitative understanding of the porphyrin optical activities is complicated by the complex interplay of the photon absorption, scattering, and fluorescence emission that can concurrently occur in porphyrin samples. Using meso- Tetrakis (4-sulfonato phenyl) porphyrin (TPPS) as the model molecule, discussed herein is combined UV-vis extinction, Stokes-shifted fluorescence, and polarized resonance synchronous spectroscopy (PRS2) study of porphyrin assembly and disassembly at acidic solutions. A series of optical constants, including photon absorption, scattering, and fluorescence emission cross-sections as well as its fluorescence and light scattering depolarizations has been quantified. Compared to UV-vis and SSF methods, the PRS2 is significantly more sensitivity in the detection of both concentration- and time-dependent porphyrin aggregation.

published_or_final_version / Chemistry / Doctoral / Doctor of Philosophy

published_or_final_version / Chemistry / Doctoral / Doctor of Philosophy

published_or_final_version / abstract / Chemistry / Doctoral / Doctor of Philosophy

published_or_final_version / Chemistry / Doctoral / Doctor of Philosophy

The axial ligands of the iron porphyrin in Cytochrome c, an electron transfer protein, are an imidazole group of a histidine residue and a methionine thioether. This ligand coordination sphere has been difficult to model and consequently the influence of these ligands on the properties of cytochrome c has been problematic. The electrochemical and spectroscopic study of a novel strapped porphyrin has been addressed toward this problem. Spectroscopic studies have demonstrated the ability of this porphyrin to hold a thioether ligand near the central metal atom. The influence of the thioether is not seen in the UV/visible spectrum of the iron complex of this porphyrin. The coordination of N-methyl imidazole to the iron complexes of several porphyrins has been studied by UV/visible spectroscopy. These studies indicate a reduced affinity of the strapped porphyrin for this ligand. Also, the oxidation products of several porphyrins were monitored by thin-layer spectroelectrochemistry. Cyclic voltammetry has been used to demonstrate the influence of the thioether on the Fe('+3)/Fe('+2) electron transfer reaction. It was found that the thioether stabilizes the lower oxidation state causing an anodic shift in the half-wave potential for the reaction. However, the stabilization seen with this model system is not sufficient to account for the large positive redox potential of Cytochrome c. The oxidations of a selected group of free base and metallo- porphyrins were also studied. It was found that the oxidation of strapped porphyrins was similar in many respects to those of non-strapped porphyrins. The notable acception to this generalization was the instability of the cation radical of the strapped porphyrins used in this work.

No description available.