The first crystal and molecular structure of an indium porphyrin, α,β,δ,γ-tetraphenylporphinatoindium(III) chloride (InTPP:Cl) has been determined by X-ray diffraction. The indium is five-coordinate in a square-pyramidal complex with chloride as the axial ligand. The average In-N bond is 2.156(6) Å, with an In-Cl distance of 2.369(2) Å. The porphinato core is somewhat expanded with an average radius of 2.067(3) Å, and the macrocycle is non-planar with a net doming (0.1Å) toward the indium. The indium atom is located 0.61 Å above the mean plane of the four pyrrole nitrogen atoms. Based on the high degree of analogy between the principal structural features of InTPP:Cl, Fe(III) porphyrins, and Fe(II) deoxyhemoglobin (e.g., displacement of metal atom above the mean porphyrin plane, distance from the metal to pyrrole nitrogen, porphyrin core expansion, doming of porphyrin skeletal core atoms), the present study suggests that reconstitution of an indium porphyrin into apohemoglobin and apomyoglobin should produce the quaternary "tense" conformation. This provides an unique opportunity to study the porphyrin-apoprotein interactions in the "T" state of hemoglobin and myoglobin. The present reconstitution of indium-Ill meso-protoporphyrin IX (¹¹¹InMPP IX) into myoglobin represents the first location of a motional probe at the central metal of the active site of the protein. The rotational correlation time (T[sub c]) of the reconstituted myoglobin has been determined by the Perturbed Angular Correlations (P.A.C.) technique. Since. ¹¹¹InMPP IX is structurally similar to ferro-protoporphyrin IX (heme), there should be very little internal rotation of the ¹¹¹InMPP IX at the active site of the reconstituted myoglobin. Furthermore, the indium-labelled myoglobin is very likely to retain its native conformation, in contrast to other labelling techniques in which there is always uncertainty as how much the label distorts the structure of the protein being studied. Finally, since no additional flexibility is introduced at the labelled site of the protein, the present determination of T[sub c](P.A.C.) for myoglobin is more direct than fluorescence depolarization or ESR determinations. / Science, Faculty of / Chemistry, Department of / Graduate

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The photophysics of highly electronically excited states of a set of d0 and d10 metallated tetrapyrroles, which have different peripheral substituents and central metal atoms, macrocycle substitution patterns and macrocycle conformations, have been investigated both theoretically and experimentally. Theoretically, the energies of ground state molecular orbitals and the energies and rank in energy of the excited states have been calculated using density functional theory and time-dependent density functional theory methods. Experimentally, the steady-state absorption and fluorescence spectra have been measured. Temporal fluorescence profiles have been measured using a time correlated single photon counting system for the S1 state and a fluorescence upconversion system for the S2 state.<p> The decay mechanisms of highly electronically excited states are governed by the nonradiative S2 S1 internal conversion. The possible existence of any excited state (such as S2' or dark state) lying close to the S2 state and its participation in the nonradiative decay processes of the S2 state has been discussed. The ultrafast nonradiative decay rates of the S2 S1 internal conversion were interpreted on the basis of the energy gap law of radiationless transition theory. For magnesium tetraphenylporphyrin (MgTPP), the radiationless rates (knr)of its S2 state follows the prediction of the energy gap law for the weak coupling statistical limit case. However, the S2 S1 electronic coupling energies of the other metalloporphyrins investigated fall within the inermediate to strong coupling range. The difference of knr relative to the weak coupling limit can be rationalized by the different magnitudes of electronic coupling energies. The magnitude of electronic coupling energies is the major factor in determining the radiationless depopulation rate constants of the S2 states in metallated tetrapyrroles which have S2 S1 electronic coupling energies exceeding the weak coupling limit. In some cases, such as ZnOEP, the magnitude of Frack-Condon factor has only minor effect.<p> The photophysics of Soret-excited metallated corroles have also been investigated in this study. Primary work has shown that two metallated corroles examined have similar S2 S1 interstate electronic coupling energies to that of CdTPP and thus the radiationless decay rates of Soret-excited S2 state are also determined by the magnitude of electronic coupling energies.

The photophysics of highly electronically excited states of a set of d0 and d10 metallated tetrapyrroles, which have different peripheral substituents and central metal atoms, macrocycle substitution patterns and macrocycle conformations, have been investigated both theoretically and experimentally. Theoretically, the energies of ground state molecular orbitals and the energies and rank in energy of the excited states have been calculated using density functional theory and time-dependent density functional theory methods. Experimentally, the steady-state absorption and fluorescence spectra have been measured. Temporal fluorescence profiles have been measured using a time correlated single photon counting system for the S1 state and a fluorescence upconversion system for the S2 state.<p> The decay mechanisms of highly electronically excited states are governed by the nonradiative S2 S1 internal conversion. The possible existence of any excited state (such as S2' or dark state) lying close to the S2 state and its participation in the nonradiative decay processes of the S2 state has been discussed. The ultrafast nonradiative decay rates of the S2 S1 internal conversion were interpreted on the basis of the energy gap law of radiationless transition theory. For magnesium tetraphenylporphyrin (MgTPP), the radiationless rates (knr)of its S2 state follows the prediction of the energy gap law for the weak coupling statistical limit case. However, the S2 S1 electronic coupling energies of the other metalloporphyrins investigated fall within the inermediate to strong coupling range. The difference of knr relative to the weak coupling limit can be rationalized by the different magnitudes of electronic coupling energies. The magnitude of electronic coupling energies is the major factor in determining the radiationless depopulation rate constants of the S2 states in metallated tetrapyrroles which have S2 S1 electronic coupling energies exceeding the weak coupling limit. In some cases, such as ZnOEP, the magnitude of Frack-Condon factor has only minor effect.<p> The photophysics of Soret-excited metallated corroles have also been investigated in this study. Primary work has shown that two metallated corroles examined have similar S2 S1 interstate electronic coupling energies to that of CdTPP and thus the radiationless decay rates of Soret-excited S2 state are also determined by the magnitude of electronic coupling energies.

In order to investigate the unusual oxidation properties of a meso-substituted porphyrin, tetrakis(3,5-di-tert-butylhydroxyphenyl)-porphyrin (H[2]T[t]BHPP), X-ray crystallography and computer modelling have been used. The crystal structure of a number of complexes of TtBHPP (Pd(II), Zn(II), Ni(II), Fe(III)Cl and Ha[4][2+]), its oxidation product, H[2]PDM, and (H[2]O)ZnTPP have been determined. The Pd(II) and Zn(II) complexes have unusual structures, with approximately 28 cyclohexane solvent molecules per unit cell very loosely bound within the lattice. The Ni(II) complex has the most extensively ruffled core reported for a metalloporphyrin, with a short Ni-N bond distance 1.913(3)A. The crystal structures of H[2]PDM.6H[2]O and [H[4]T[t]BHPP][2+][Zn(CF[3]COO)[4]][2-]. 6H[2]O show interesting clathrate-like structures with extensive intermolecular hydrogen-bonding. The oxidised porphyrin, H[2]PDM, has a tetraquinone structure in the solid state which contrasts with the proposed diquinone/diphenol structure found in solution. Molecular Mechanics and Molecular Orbital calculations were used to investigate both geometric and electronic structures of the porphyrins and their oxidised counterparts. Due to the size and complexity of these calculations and the lack of experimental data these methods were not as useful as anticipated. The difference in behaviour of various metallo complexes of T[t]BHPP to oxidation is attributed to electronic effects rather than the geometric structures of the metalloporphyrins.

Manganês(III)porfirinas têm sido relatadas como eficientes catalisadores em reações de oxigenação de hidrocarbonetos por vários doadores de oxigênio. Numa primeira etapa, foram realizadas a síntese e caracterização das porfirinas base-livre, posterior introdução de grupo sulfonato na H2(MPTFPP), a fim de que esta pudesse ser utilizada em reações em meio heterogêneo, e inserção de metal nas porfirinas base-livre, obtendo-se os catalisadores cis-[Mn(BFPBPP)]Cl, trans-[Mn(BFPBPP)]Cl, [Mn(MSO3TFPP)]Cl e [Mn(TSO3PP)]Cl. Realizou-se a funcionalização da sílica gel contendo grupos trimetilamônio, que permitia sua ligação com metaloporfirinas contendo cargas negativas periféricas, com grupos imidazol, que permitem ligação com a metaloporfirina via ligação coordenativa, favorecendo o aumento da atividade catalítica destes sistemas. Os catalisadores [Mn(BFPBPP)]Cl, trans-[Mn(BFPBPP)]Cl, [Mn(MSO3TFPP)]Cl foram utilizados na epoxidação do (Z)-cicloocteno e na oxidação do cicloexano por PhIO em meio homogêneo. A Mn(III)porfirina aniônica apresentou rendimentos comparáveis a sistemas clássicos, acompanhados de uma melhor seletividade. Tais resultados, acompanhados da vantagem de que este sistema poderia ser utilizado em meio heterogêneo, levaram à sua escolha para prosseguimento dos estudos. [Mn(MSO3TFPP)]Cl e [Mn(TSO3PP)]Cl foram então utilizadas em meio homogêneo e imobilizadas nos suportes IPG, SiN+, SiN+(IPG) como catalisadores na reação de epoxidação do (Z)-cicloocteno. No caso do PhIO, para ambas o suporte exerceu um efeito positivo, alcançando-se 100% de ciclooctenóxido com os sistemas [Mn(MSO3PTFPP)]-IPG, [Mn(MSO3PTFPP)]-SiN(IPG) e [Mn(TSO3PP)]-SiN(IPG). A presença de substituintes pentafluorofenis na [Mn(MSO3TFPP)]Cl tornaram-na mais ativa na catálise de epoxidação do (Z)-cicloocteno por H2O2, o que levou a considerar o efeito dos substituintes eletronegativos no sentido de tornar o centro metal-oxo mais eletrofílico, aumentando sua reatividade. Além disso, um aumento na atividade catalítica dos catalisadores utilizados em sistema heterogêneo, aliado à presença de imidazol adicionado, evidenciam o efeito positivo do suporte e papel duplo do co-catalisador, atuando como catalisador ácido-base e ligante trans ao Mn(III). Tais resultados comparam-se aos obtidos para sistemas clássicos, mas com a vantagem dos catalisadores obtidos neste trabalho poderem ser recuperados ao final da reação, podendo ser reutilizados. / Manganese(III)porphyrins have been described as efficient catalysts in hidrocarbon oxygenation reactions by a variety of oxygen donors. In a first step, the free-base porphyrins synthesis and characterization were performed, with posterior introduction of a sulfonato group in H2(MPTFPP), in order to use its heterogeneous catalyst, and metal insertion, rendering cis-[Mn(BFPBPP)]Cl, trans-[Mn(BFPBPP)]Cl, [Mn(MSO3TFPP)]Cl and [Mn(TSO3PP)]Cl. The silica gel containing trimethylammonium groups was functionalized with imidazole groups. The first allowed the linkage of anionic metalloporphyrins containing peripherical negative charges and the latter allows its linkage to metalloporphyrins via coordinative binding. Homogeneous [Mn(BFPBPP)]Cl, trans-[Mn(BFPBPP)]Cl, [Mn(MSO3TFPP)]Cl were used in the (Z)-cyclooctene epoxydation and cicloexane oxidation by PhIO. The anionic Mn(III)porphyrin had presented yields comparable to classic systems with a better selectivity. Such results allied to the possibility of use in heterogeneous system led to its choice to posterior studies. Homogeneous and heterogeneous [Mn(MSO3TFPP)]Cl e [Mn(TSO3PP)]Cl immobilized on IPG, SiN+, SiN+(IPG) supports were then used as catalysts in the epoxydation reaction of (Z)-cyclooctene. When PhIO was used, the support had a positive effect for both catalysts, reaching 100% epoxycyclooctane in [Mn(MSO3PTFPP)]-IPG, [Mn(MSO3PTFPP)]-SiN(IPG) e [Mn(TSO3PP)]-SiN(IPG). Because of bearing pentafluorophenyl groups, [Mn(MSO3TFPP)]Cl was more active in epoxydation reaction of (Z)-cyclooctene catalysis by H2O2, which led considering the effect of electronegative groups leading to a metal-oxo species more eletrophylic, increasing its reactivity. A rise in the catalytic activity of heterogeneous catalysts allied to imidazole addition show the positive effect of the support and the two-fold hole of the co-catalyst, acting as acid-base catalyst and trans ligand to Mn(III). Such results are comparable to that obtained for classical system with the advantage that the catalysts obtained in this work allow its recuperation and reuse.

High-valent metal-oxo complexes are vital as active oxidants in enzymatic and synthetic catalytic oxidations. Inspired by the ubiquitous cytochrome P450 enzyme, researchers have explored the power of metalloporphyrins to mimic one of Nature’s premier catalytic entities. In this work, four manganese(III)porphyrin systems, including three electronwithdrawing ligands and one electron-donating ligand, were investigated with regard to their ability to form high-valent manganese(IV)-oxo porphyrin systems. The porphyrin ligands studied were 5,10,15,20-tetra(2,6-difluorophenyl)porphyrin [H2(2,6-F2TPP)], 5,10,15,20-tetra(4-trifluoromethylphenyl)porphyrin [H2(4-CF3TPP)], 5,10,15,20-tetra(4- fluorophenyl)porphyrin [H2(4-FTPP)], and 5,10,15,20-tetra(2,6- dimethoxyphenyl)porphyrin [H2(TDMPP)]. All were synthesized purified and characterized spectroscopically. Using the mild oxidant iodobenzene diacetate, manganese(IV)-oxo porphyrins [MnIV(Por)O] were successfully generated in all systems as confirmed through spectroscopic methods. Meanwhile, a new photochemical approach was explored for its efficacy in producing the MnIV-oxo complexes by visible light irradiation of manganese(III) precursors containing the photolabile chlorate as the axial ligand. More importantly, the MnIV-oxo complexes obtained by chemical generation were tested for their abilities as oxygen atom transfer agents (OATs) with aryl alkenes, alkenes and thioanisoles in CH3CN. The apparent second-order rate constants for sulfoxidation ranged between (2.29 ± 0.08) and (12.9 ± 2.0) M-1s-1 x 10-2 which were, on average, a magnitude larger than the rates for epoxidation of the aryl alkenes. Most notably in reactions with substrate, the order of reactivity of [MnIV(Por)O] was [(4-F)TPP] > [(4- CF3)TPP] > [(2,6-F2)TPP], which is inverted from the expected result based on the electron-demands of the porphyrin ligands. The apparent rate constants for reaction with cyclohexene was found to be 1 to 2 orders of magnitude larger than those with sulfide substrates. The kinetic results are consistent with a reaction model involving disproportionation of MnIV(Por)O to give MnIII(Por) and MnV(Por)O species, the latter of the two being the active oxidant. Alternatively, the results from the sulfoxidations are consistent in part with a direct oxygen atom transfer by [MnIV(Por)O]