John Wesley Owens

PHOTOPHYSICAL PROPERTIES OF PORPHYRINS, PHTHALOCYANINES, AND BENZOCHLORINS

Abstract This work examines the photophysical properties of a series of porphyrin, phthalocyanine, and benzochlorin derivatives. The porphyrin group includes tetraphenylporphyrin, divinylporphyrin ether, dihematoporphyrin ether, the trivinylporphyrin ether, and the trihematoporphyrin ether. The phthalocyanine group includes phthalocyanine tetrasulfonate, chloroaluminum phthalocyanine tetrasulfonate, zinc phthalocyanine tetrasulfonate, and aluminum naphthalocyanine tetrasulfonate. The chlorins include octaethylbenzochlorin, zinc octaethylbenzochlorin, octaethylbenzochlorin sulfonic acid, and zinc octaethylbenzochlorin sulfonic acid. Ethyl etiopurpurin is also studied. The UV-Vis and fluorescence emission spectra, fluorescence quantum yields, fluorescence rate constants, radiative and singlet state lifetimes are compared for the series of compounds. Results indicate that while the octaethylbenzochlorin and phthalocyanine photosensitizers profile, this profile is very different from that observed for the porphyrin photosensitizers.

The novel low temperature synthesis of nanocrystalline MgAl2O4 spinel using “gel” precursors

Nanocrystalline MgAl 2 O 4 was synthesized by pyrolysis of the homogeneous spinel precursor, Mg(C 4 H 5 O 2 ) 2 (H 2 O):Al 2 (OH) 3 (C 3 H 3 O 2 ) 3 (H 2 O) 2 :NH 4 (C 3 H 3 O 2 )(H 2 O). The spinel precursor gel is composed of a mixture of magnesium and aluminum acrylate salts dissolved in an ammonium acrylate gel. The reaction of acrylic acid with magnesium hydroxide in water produced magnesium methacrylate, and a similar reaction of basic aluminum acetate produced the aluminum salt of acrylic acid. The reaction of acrylic acid with ammonium hydroxide produced the ammonium acrylate gel. Ammonium acrylate gel was found to absorb many times its own weight of water. Although similar properties have been identified in PMMA and in the polymer of sodium acrylate, only the ammonium acrylate gel exists as an unpolymerized monomer. The spinel precursor gel is a pre-ceramic material that yields an amorphous oxide phase at 425°C that begins to crystallize to the MgAl 2 O 4 spinel at 600°C and is fully crystalline at 1030°C with a uniform particle size of 7-100 nm. The spinel precursor gel and the nanocrystalline MgAl 2 O 4 spinel were characterized by XRD and TEM.

The behavior of ferric protoporphyrin-IX in alkaline DMF

Abstract The electronic and magnetic behavior of the azide adduct of ferric protoporphyrin-IX in neat and alkaline DMF has been examined. The electronic spectrum of this complex is different from that of other ferric porphyrins whether the porphyrin exists in a high or low spin state. The species has been characterized as Fe(3+)PPIX(DMF)(N 3 ). The electron spin resonance spectrum of this complex was examined in neat DMF from 298 to 4 K. These spectra are consistent with that expected for a system containing spin admixed S = 5/2 and S = 1/2 ground states, and, further suggests the possible existence of a spin equilibrium at low temperature. The behavior of hemin in a DMF/NaOH mixture was examined also. Results indicate that a ferric protoporphyrin dimer was formed, based on the appearance of a δ M s = 2 transition. While neither the chloride ion nor imidazole was able to split the porphyrin dimer, the azide ion does, and at the same time maintains the existence of a spin admixed configuration.

The influence of Hurricanes Katrina and Rita on the inflammatory cytokine response and protein expression in A549 cells exposed to PM2.5 collected in the Baton Rouge–Port Allen industrial corridor of Southeastern Louisiana in 2005

Abstract Hurricanes Katrina and Rita hit the coast of Louisiana in 2005 and killed more than 2000 people. The two storms resulted in a significant spike in particulate matter (PM2.5) levels across the state of Louisiana. This report focuses on PM2.5 samples collected in 2005 from two monitoring sites in the neighboring cities of Baton Rouge and Port Allen, Louisiana. Inductively coupled plasma (ICP) revealed the presence of PM2.5-adsorbed representative and Fenton-active transition metals. Gas chromatography/mass spectrometry (GC-MS) analyses revealed the presence of 23 PAH compounds. Endotoxins were also detected. Metals and endotoxins were extracted with water. PAH were extracted with dichloromethane. In order to assess cytotoxicity, aqueous PM2.5 extracts were introduced to A549 Human Epithelial Lung Carcinoma Cells. Results indicated decreased cell viability in a dose-dependent manner, with an LC50 of 235 µg/ml and 250 µg/ml, respectively, for the two sites featured here. Endotoxins alone were not cytotoxic. The concentration of reactive oxygen species (ROS) and released LDH activity increased following exposure of A549 cells to aqueous PM2.5 extracts. Fluorescence microscopy revealed apoptotic and necrotic cell death mechanisms. ELISA revealed increased secretion of primary pro-inflammatory cytokines, IL-6, IL-8, and TNF-α. Global PCR gene expression revealed up-regulation of proteins associated with the cytokine storm; e.g. interleukins, chemokines, and TNF-α. Global antibody microarray was consistent with an inflammatory response, with up-regulation of cytokines involved in the down-field activation of the caspase cascade and kinase pathways. The up-regulation of metal-redox sensitive transcription factors, NF-κβ and AP-1, is consistent with a cell death mechanism initiated by Fenton-active transition metal redox catalysis.

Synchrotron X-ray microtomography, X-ray absorption near edge structure, extended X-ray absorption fine structure, and voxel imaging of a cobalt-zeolite-Y complex

Abstract Cobalt–zeolite-Y (Co-Y), was investigated utilizing synchrotron X-ray microtomography, EXAFS, and XANES measurements. X-ray microtomography showed an inhomogeneous distribution of cobalt ions with cobalt-rich domains of 50 μm diameter. XANES measurements fixed the oxidation state of the cobalt ion to be +2.35. EXAFS measurements revealed the cobalt–oxygen bond distance to be 1.7 A. The cobalt–cobalt bond distance was fixed at 2.8 A. X-ray microtomography showed cobalt-rich regions made up 16.81% of the cobalt–zeolite complex. This information was used to characterize the transition metal–zeolite complex.

Adducts of nitric oxide with cobaltous tetraphenylporphyrin and phthalocyanines: potential nitric oxide sorbents

Abstract Cobaltous tetraphenylporphyrin (Co(II) TPP) and cobaltous phthalocyanine (Co(II) Pc) complexes were studied in a variety of solvents, including water. The imidazole and nitrosyl adducts were synthesized and characterized by UV-Vis spectrophotometry and electron spin resonance spectroscopy. The imidazole adducts were subsequently exposed to nitric oxide to study the competitive interactions between nitrosyl and imidazole ligands in these cobaltous compounds. This is important, since it has been suggested that aqueous solutions of cobaltous porphyrins and phthalocyanines can serve as denitrification agents when bound to an immobilized imidazole modified silica gel (IMSG) substrate. Our results indicate that while nitric oxide binds both Co(II) TPP and Co(II) Pc in organic solvents in the absence of a bound imidazole ligand, it will not bind when imidazole is axially bound to the cobalt ion. Neither Co(II) TPP nor Co(II) Pc are water soluble and both will dimerize in water. A water soluble NO sorbent which does not dimerize in water would be ideal for removing NO from flue gas streams. The Co(II) PcTs(IMSG) appears to meet these requirements. Preliminary results indicate that aqueous suspensions of Co(II) PcTs(IMSG) are capable of NO removal from a gas stream passed through these suspensions and may thus be suitable candidates for further development as NO sorbents for NO abatement.

Chromatographic analysis of photodynamically significant porphyrin dimers and trimers

Two porphyrin dimers, dihematoporphyrin dimer (DHD) and divinyl dimer (DVD), and two porphyrin trimers, dihematoporphyrin trimer (DHT) and divinyl trimer (DVT), have been analyzed utilizing isocratic ion-pair reversed-phase high-performance liquid chromatography. Results indicate that the vinyl porphyrins can be distinguished by three peaks appearing near 15, 38, and 42 min. The hematoporphyrin complexes are identified by the appearance of a peak located at 35 min. The DVT and DVD complexes present unique chromatographic markers at 28 and 15 min, respectively. Based on the location of these chromatographic markers, it was found that the Photofrin drug must contain the DVD and the DHT complexes, but does not contain the DVT complex. The purity of the DVT complex is compromised by the presence of DHD and DHT impurities.

Isolation and photodynamic effects of hematoporphyrin derivative components: a chromatographic analysis of the starting materials

Twenty different fractions of hematoporphyrin derivatives (HpD) and eight fractions of an HpD dimer mixture were isolated utilizing isocratic reversed-phase ion-pair high-performance liquid chromatography. These fractions were characterized by UV-visible and fluorescence spectrophotometry. Fluorescence quantum yields and photokill efficiency for each fraction in PTK2 epithelial cells were obtained. Results indicate that some part of the photoactivity exhibited by HpD may be due to impurities present in the HpD starting material, hematoporphyrin-IX dihydrochloride, depending on its source. It was also found that hematoporphyrin D, a commercial acetylated product formed during synthesis of HpD, contained a higher percentage of monomers than would be expected.

Synchrotron x-ray microtomography and solid state NMR of environmental wastes in cement

Synchrotron X-ray microtomography shows vesicular structures for toluene/cement mixtures prepared with 1.22 to 3.58 wt% toluene. Three-dimensional imaging of the cured samples shows spherical vesicles with diameters ranging from 20 to 250 microns; a search with electron microscopy for vesicles in the range of 1 - 20 microns proved negative. However, the total vesicle volume, as computed from the microtomography images, accounts for less than 10% of initial toluene. Evidence for toluene in the cement matrix comes from 29Si MAS NMR spectroscopy, which shows a reduction in chain silicates with added toluene. Also, 2H NMR of d8-toluene/cement samples shows high mobility for all toluene and thus no toluene/cement binding. A model that accounts for all observations follows: For loadings below about 3 wt%, most toluene is dispersed in the cement matrix, with a small fraction of the initial toluene phase separating from the cement paste and forming vesicular structures that are preserved in the cured cement. Furthermore, at loadings above 3 wt%, the abundance of vesicles formed during toluene/cement paste mixing leads to macroscopic phase separation.

A comparison of the magnetic and crystal field properties of protoporphyrin-IX, hemeoctapeptide and heme proteins

Abstract The electron spin resonance magnetic and crystal field characteristics of three different series of proteins are compared. The three series are represented by ferric protoporphyrin-IX, a relatively small protein derivative; ferric hemeoctapeptide, a synthetic protein containing a simple eight amino acid chain; and met-hemoglobin/myoglobin, both bulky proteins. The magnetic and crystal field effects for several nitrogenous adducts of these protein systems are calculated from ESR experiment at 4 K. A wide series of parameters is compared, including ESR g values and mixing coefficients, the degree of rhombic and tetragonal splitting, and the degree of covalency in the FeL bond. Results indicate that there is a direct correlation between crystal field effects and protein bulk.