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Circular dichroism (CD) spectra and density functional theory (DFT) calculations are reported for a series of conformationally distable chiroporphyrins with 8-methylene bridles MBCP-8, which could display either an alpha-alpha-alpha-alpha or an alpha-beta-alpha-beta orientation of their meso substituents. The CD signals are found to result from a combination of both the inherent chirality of the prophyrin and of extrinsic contributions due to the chiral bridles.

The view that the large red shifts seen in the UV-visible adsorption bands of peripherally crowded nonplanar porphyrins are the result of nonplanar deformations of the macrocycle is challenged by the suggestion that the red shifts arise from substituent-induced changes in the macrocycle bond length and bond angles. Results of studies suggest that UV-visible band shifts of tetrapyrroles in proteins are potentially useful indicators of changes in nonplanarity provided other structural and electronic factors can be eliminated.

Research describes structural and magnetic properties of six chiroporphyrins. Results show bond-stretch isomerism exists in the form of hydrogen bonding from an aqua ligand of iron(III) extending to ethanol or water molecule, which may be involved in the regulation of hemoprotein structure and function.

Research has been conducted on the lanthanide(III) bis(porphyrin) sandwich complexes. The use of UV-vis, IR and NMR spectroscopies in synthesizing and characterizing these sandwiches is discussed.

Research was conducted to examine various spectroscopic studies of WOs and MoRu porphyrin dimers using variable-temperature 1H NMR, resonance Raman, magnetic susceptibility and X-ray crystallography. The objective was to determine a proper molecular orbital diagram for the dimers. Results demonstrate an unusual molecular orbital diagram which has never been observed before in metal-metal bonded metalloporphyrin dimers.

The x-ray structures and synthesis of nickel(II) and zinc(II) meso-tetracyclohexylporphyrin H2(TCHP) were described. It was noted that substitution by cyclohexyl groups on the meso positions of a metalloporphyrin has notable stereochemical and electronic effects. The meso-cyclohexyl groups had lower rotation barriers than meso-phenyl groups, despite their greater steric bulk and they imparted easier oxidation and harder reduction to the porphyrin as compared to tetraphenylporphyrin derivatives.

The chloroiron(III) complex of alpha-beta-alpha-beta-tetramethylchiroporphyrin, FeCl(TMCP), was synthesized and structurally characterized. The structure has a unique five-coordinate high-spin iron(III) center in a strongly ruffled and domed porphyrin, with short equatorial distances and the iron 0.64 angstrom out of the porphyrin mean plane toward the chlorine atom. The pyrrole proton resonances are shifted downfield to 80-100 ppm at 293 K, more than in the corresponding tetraaryl derivatives.

The bis-ligation of iron(III) tetracyclohexylporphyrin by cyanide and R-imidazole produced low-spin complexes. These were characterized by contribution of two electronic configurations, (d(sub xy))(super 2)(d(sub xz)d(sub yz))(super 4)(d(sub xy)), to the ground states as controlled by the axial ligand used. The pattern of pyrrole beta-H and axial imidazole 1H NMR resonance were used as sensitive probes providing details of the iron(III) electronic structure.

A study was conducted on the chlorocobalt(III) complex of alphaBetaalphaBeta-tetramethylchiroporphyrin, CoCl(TMCP), as a potential enantioselective host or chiral NMR shift reagent for optically active amines. The findings indicate that CoCl(TMCP) may be act as a chiral NMR shift reagent for conformational studies of chiral amines and as an analytical reagent for determining their enantiomer composition.

Research was conducted on low-spin complexes of iron(III) chiroporphyrin, obtained from (1R)-cis-caronaldehyde acid methyl ester and pyrrole as the atropisomer, with R-imidazoles and cyanide using 1D and 2D 1H nuclear magnetic resonance spectroscopy. Results reveal that low-spin iron(III) chiroporphyrin complexes exhibit significantly different properties in relation to analogous low-spin iron(III) tetrarylporphyrins.

The anionic derivative of bis(azido)(tetraphenylporphinato)ferrate(III) was prepared and characterized using various techniques including crystal structure determination, temperature-dependent infrared spectroscopy and Mossbauer spectroscopy. In an effort to stabilize the six-coordinate anionic porphyrin and solubilize sodium azide crown ether 18C6 was used. A link between a high spin state and high temperature was also established.

Chemical research has established the solid state magnetic susceptibility properties of group eight metal-to-metal doubly bonded porphyrin and tetraazaporphyrin dimers [Ru(Octaethylporphyrin)]2, Ru(octaethyltetraazaporphyrin)]2 and [Os(OEP)]. Nuclear magnetic resonance analysis indicates that each of the group eight dimers exhibits similar behaviour in zero-field splitting of the triplet ground electronic state.

Protonation of an oxo-bridged manganese complex or hydrolysis of monomeric manganese complex or monomeric manganese(III) octaethylporphyrinates results in the formation of (mu-hydroxo)bis(octaethylporphinato)manganese (III) perchlorate. X-ray diffraction data shows that each Mn(III) ion is axially coordinated with an Mn-O(H)-Mn bridge angle of 152.73(11) degree. The two porphyrin ring are nearly eclipsed. The Mn(III)...Mn(III) bond interaction in Mn(OEP)2(OH)CLO4 is fairly antiferromagnetic and is controlled by zero field-splitting effect.

The synthesis and characterization of the hydroxo-bridged complex, (mu-hydroxo)bis( tetraphenylprophinato manganese III ) perchlorate, are described. The complex has been prepared by the controlled hydrolysis of monomeric diaquo(tetraphenylporphinato)manganese(III) perchlorate. X-ray structure analysis showed two five-coordinate manganese(III) ions bridged by a single hydroxo ligand.

The perchlorate and tetrafluoroborate salts of the (Fe TPP EtOH 2)1+ cation were characterized. Both (Fe TPP EtOH 2)ClO4 and (Fe TPP EtOH 2)BF4 crystallize in the same monoclinic space group with rhombic crystals at room temperature. The similarity also extends to the length of the axial Fe-O bonds. The temperature-dependent effective magnetic moments of the salts differ, however. Differences in the hydrogen bonding between the ethanol ligands and the anion are presumed to result from the presence or absence of ferromagnetic ordering.

The effects of ruffling on the axial ligation properties of a series of nickel(II) tetra(alkyl)porphyrins are investigated with UV-visible absorption spectroscopy, resonance Raman spectroscopy, X-ray crystallography, classical molecular mechanics calculations and normal-coordinate structural decomposition analysis. The study suggests that molecular mechanics calculations might aid in designing nano-devices with appropriate conformations and switching characteristics.

The hydrogen-bonding capabilities of CoCl(TMCP) allow the conformation of coordinated amino esters to be uniquely defined within the chiral cavity on the time scale of NMR analysis and the porphyrin ring current amplifies the chemical shift differences between the diastereomeric adducts. These structural features make CoCl(TMCP) a very powerful derivatizing agent for the chiral analysis of amino acid derivatives.

An investigation of the chloromanganese complexes as catalysts in the asymmetric epoxidation of 1,2-dihydronaphthalene by iodosylbenzene was conducted. High levels of stereoinduction were derived in the epoxidation of 1,2-dihydronaphthalene catalyzed by sterically crowded manganese chiroporphyrin catalysts. Assymetric induction was correlated to the degree of nonplanar distortion of the porphyrin free base in solution.

The first structural and magnetic investigations of a polar, unsupported Mo-Ru bond were conducted. When combined with magnetic susceptibility data, the crystal structure of ((OEP)MoRu(TPP))PF6, 1+PF6- (OEP = octaethylporphyrin, TPP = tetraphenylporphyrin) offers a wide range of data regarding the molecular orbital diagram for inter-triad heterometallic multiple bonds.

Experiments were performed to investigate the kinetic and structural factors regulating chiral recognition of beta-amino alcohols by the cobalt(III) complex. X-ray analyses revealed strongly ruffled porphyrin rings. The findings demonstrated a multicomponent bonding between host and guest manifesting crystallographically obvious noncovalent bonds. Moreover, the dissociation rate of the Co-N coordination bond was observed to be slower than hydrogen bonds.

An open zinc porphyrin host molecule which takes on a closed form upon binding on binding a pyridine base, is reported. The reversible, conformational flip, is based on rotating porphyrin substituents around the bonds to the meso positions. The system is described as a pyridine-sensitive Venus flytrap porphyrin.