Porphyrin complexes synthesis

Although direct reaction of lanthanide mono-porphyrins with free phthalo-cyanine or its lithium derivatives is generally more efficient than the template synthesis, and gives rise to mixed-ligand complexes, the template strategy can also be applied for synthesis of phthalocyanine-porphyrin complexes, as in the case of unsymmetric bisphthalocyanine complexes (Scheme 8.2, B(b)) [106, 136, 145, 146]. Thus, metallation of free porphyrins with lanthanide salts in TCB or n-octanol leads to single-decker complexes, which then react with phthalonitriles under the action of DBU in alcoholic media to give the desired compounds. 

The electrosynthesis of metalloporphyrins which contain a metal-carbon a-bond is reviewed in this paper. The electron transfer mechanisms of a-bonded rhodium, cobalt, germanium, and silicon porphyrin complexes were also determined on the basis of voltammetric measurements and controlled-potential electrooxidation/reduction. The four described electrochemical systems demonstrate the versatility and selectivity of electrochemical methods for the synthesis and characterization of metal-carbon o-bonded metalloporphyrins. The reactions between rhodium and cobalt metalloporphyrins and the commonly used CH2CI2 is also discussed. 

Most of the studies on organo-gallium, indium, and thallium porphyrin complexes have focused on synthesis and properties of the complexes, and rather little attention has been devoted to reaction chemistry. Two areas which have received some attention are the insertion of small molecules (SO2 or CO2) into the metal—carbon bonds and photochemical metal—carbon bond cleavage. The... 

A similar reservation applies to the need to remove ligand precursors or byproducts from the support. This is a particular issue in relation to intrazeolite com-plexation reactions in which the corresponding homogeneous synthesis is less than quantitative. Another difficulty relates to estabUshing the efficacy of ligand synthesis within a zeoUte. Thus, for example, although several reports of the syntheses of metal porphyrin complexes within zeolites have appeared, the ligands are, in fact, domed porphodimethenes (diameter -14 A), or protoporphyrins [138,... 

The formation of circular or linear forms seems to depend on balances between kinetic and thermodynamic control iron(II)-poly-2,2 -diimine systems with their substitutionally inert metal centers provide useful systems for disentangling thermodynamic and kinetic contributions. The mechanism of formation of circular helicates is believed to entail a kinetically favored triple helicate intermediate. Self-assembly of chiral dinuclear binaphthol-linked iron(III) porphyrin complexes into extended polynuclear species takes place through the intermediacy of fi-oxo dimers. Predetermined //-oxo-di-iron-dimers may be used in this type of synthesis. 

An anionic ligand effect in iron porphyrin complex-catalyzed competitive epoxidations of cis- and frawi-stilbenes by BU4NHSO5 has been studied in detail . Oxidation of the thiophosphite to the thiophosphate in solid phase oligonucleotide synthesis using BU4NHSO5 was also reported. ... 

The above three studies on the synthesis of oxygen carriers are of great significance because they have demonstrated steric and environmental effects on reversible oxygenation. Recently the porphyrin ring was perfectly bonded to a polymer by a covalent bond in order to inhibit the dimerization of the porphyrin complex. 

Evidence is growing that chromium is an essential trace element (Section 35.4.8.3). If mammalian diets are supplemented with simple 51Cr-labelled salts it is found that less than 1% of the dose is absorbed because at intestinal pHs (>6) insoluble Cr111 hydrolysis products are produced. Complexes which remain intact in the add conditions of the stomach as well as in more alkaline conditions are required. As Cr porphyrin complexes are stable in these respects, methods for synthesis of the complexes and incorporation of 51Cr have been surveyed.1248... 

The synthesis of porphyrins in many cases depends upon reactions, especially cyclizations, of ligands coordinated to suitable metals. In this section, only this aspect will be considered. The enormous array of organic reactions carried out on porphyrin complexes is not appropriate for... 

It has been suggested [95] that the synthesis of structured porphyrins with controllable steric ambience is a strategic direction in the reproduction of enzyme protein cavities, which control the selectivity and stability of biochemical reactions such as cytochrome P-450. Such an approach to the synthesis of biomimics has considerable potential, especially in their application on mineral matrices silicon dioxide, alumina and zeolites. Data exist on the synthesis of a biomimic [96] with a complex porphyrin complex (5-pentafluorophenyl-10,15,20-tri(2,6-dichlorophenyl)porphyrin (FeMPFDCPP)) covalently linked to aminopropyl silicon dioxide, which is applied in oxidation of ds-cyclooctene, cyclohexene, cyclohexane and adamantane with participation of iodosylbenzene dissolved in dichloromethane. 

The synthesis of a stable Felll-porphyrin complex-alcenethiolate complex, in which the sulphur atom is sterically protected from reactive molecules such as 02 and NO by bulky groups, has been reported (Suzuki et al., 2000). The electronic absorption and infrared spectra indicate that NO coordinates reversibly to the Fein atom of the complex. 

The lithium compounds, which, as noted earlier have square planar Li, are very soluble in polar solvents, are useful reagents for the synthesis of transition metal porphyrin complexes. There are also ionic species of the type [Li solv ]+[Li porph]". 

L. A. Yatsimyk, Ph.D. dissertation, Synthesis, Structures, Redox and Magnetic Resonance Spectroscopy of Saddle-Distorted Porphyrin Complexes of Iron, University of Arizona, 2003. 

Figure 4.34 (a) Perspective view and (b) side view of compound [Yb(III)(TMPP)(H20)3]Cl [51]. (Reproduced from W. Wong et al, Synthesis and crystal structures of cationic lanthanide (fi) mono-porphyrinate complexes, Journal of the Chemical Society, Dalton Transactions, 615, 1999 (doi 10.1039/a809696a), by permission of The Royal Society of Chemistry.)... 

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