Silicon complexes porphyrins

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. 

Supramolecular systems assembled by peripheral and axial coordination were also thoroughly described. For example, heteroarrays held by axial coordination, particularly of zinc, nickel, ruthenium, tin, silicon, etc. porphyrins and phthalo-cyanines to peripheral pyridyl and 4,4-bipyridyl groups were described. Another interesting class of compounds are porphyrin dimers prepared by coordinative assembly of cw- icso-(4-pyridyl)porphyrins with PdCla forming two [PtCl2(pyP)2] complexes, and more complex tesselated structures by substitution of the platinum complex chloro ligands by 2,3-diamine(azaporphyrins), as depicted in Fig. 12. 

Porphyrin, octaethyl-, silicon dihydroxide complex cyclic voltammetry, 4, 399 <73JA5140)... 

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. 

The range of organo-silicon, germanium, tin, and lead porphyrin complexes reported to date are given in Table Some mono- and dialkyltin... 

The stability of the germanium and silicon porphyrin alkylperoxide complexes contrasts with the lability of the corresponding iron porphyrin alkylperoxide complexes. For example, Fe(Por)(OOEt) was formed from the reaction of Fe(Por)Et with O2 and has been characterized only by spectroscopy as it decomposes to Fe(Por)OH and CH3CHO above —80°C. The key to the difference in stability is likely to be the availability of higher oxidation states in the iron porphyrins as... 

Abstract Pressure-sensitive paint (PSP) is applied to the areodynamics measurement. PSP is optical sensor based on the luminescence of dye probe molecules quenching by oxygen gas. Many PSPs are composed of probe dye molecules, such as polycyclic aromatic hydrocarbons (pyrene, pyrene derivative etc.), transition metal complexes (ruthenium(II), osumium(II), iridium(III) etc.), and metalloporphyrins (platinum (II), palladium(II), etc.) immobilized in oxygen permeable polymer (silicone, polystyrene, fluorinated polymer, cellulose derivative, etc.) film. Dye probe molecules adsorbed layer based PSPs such as pyrene derivative and porphyrins directly adsorbed onto anodic oxidised aluminium plat substrate also developed. In this section the properties of various oxygen permeable polymer for matrix and various dye probes for PSP are described. 

The first silylene complexes of osmium porphyrin, (TTP)Os=SiR2-THF, were prepared by treating K2[Os(TTP)] with Cl2SiR2 or the reaction of [Os(TTP)]2 with hexamethylsilacyclopropane (116). The molecular structure of (TTP)Os=SiEt2-2THF is stabilized by coordination of THF to the silicon, as shown by X-ray crystallography (Fig. 5). The measured Os—Si distance of 2.325(8) A is the shortest ever reported (116). 

Metal-catalyzed silylene extrusion from hexamethylsilirane 20 was also used to generate transition metal silylenoids [equation (7.2)] 47 In the presence of a metallo-porphyrin, [Os(TTP)]2 (where TTP = the dianion of meso-tetra-p-tolylporphyrin), hexamethylsilirane 20 extruded dimethylsilylene to produce the THF-stabilized osmium silylenoid complex 21. Despite the coordinated THF molecule, crystallographic analysis of the silylosmium complex 21 revealed the sp2 nature of the silicon atom (Os-C-Si bond angles 121° and 117°). Osmium silylenoid 21 was also synthesized from the reaction of [Os(TPP)]2- and dimethyldichlorosilane.47... 

Certain porphyrin complexes have been shown to be remarkably stable to redox cycling. The Zn and Eu complexes shown in Figure 5, can be attached to device-grade silicon surfaces and exhibit two or four reversible redox waves, respectively. Remarkably, these systems are stable over as... 

Some new lanthanide porphyrin complexes of general formula Ln(iii)TAP(/i-diketonate), where TAP = tetraarylporphine, have been prepared (468,469) and their shift reagent capabilities assessed. The complexes of the early lanthanides (Pr, Nd, Sm, Eu) induce very small shifts whereas the complexes of Tb, Dy, and Ho produce quite large low frequency shifts in y-picoline. Analogous shift reagents based on silicon, germanium, low-spin iron, (517, 518) and cobalt (519) have been reported. 

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