Metalloporphyrins and

Eullerene-based donor-acceptor complexes and ion-radical salts with tetrathia-fulvalenes, metalloporphyrins, and cyclic amines as donors 99UK23. 

Metalloporphyrins and their analogs as photo- andradiosensitizers 99CRV2379. 

Recent developments in the studies of titanium and vanadium porphyrins with special emphasis on oxygen adducts, low valent metalloporphyrins and related systems of sulphur and selenium. R. Gui-lard and C. Lecomte, Coord. Chem. Rev., 1985, 65, 87 (76). 

NON-COVALENT INTERACTIONS BETWEEN METALLOPORPHYRINS AND ORGANIC MOLECULES... 

The qualitative stabihty constants of metalloporphyrins are summarized in Table 1. The metals classified in class I produce the most stable metalloporphyrins and the demetalation reaction does not proceed smoothly even under concentrated sulfuric acid condition. The incorporated metals classified in classes 11 and III are removed using mild acids such as hydrochloric acid. Calcium classified in class V is removed by (the pH of) water. The mixed cyclization reactions afford the heterometalated CPO, and the acid treatment of the CPO obtained produces the CPO containing 2HPor moiety. Further treatment of the metal salt classified in a class lower than that of the unremoved metal(s), which is classified in a class higher in Table 1, produces another heterometalated CPO. Representative examples are summarized in Fig. 5 [25]. The initial cyclization reaction is carried out by using Ru (CO)Por 6, the metal of which is classified in class 1, and ZnPor 5, clas-... 

Of considerable interest was the demonstration that metalloporphyrins and the like can be used as nonmetallic catalysts in electrochemical reactions, nourishing hopes that in the future, expensive platinum catalysts could be replaced. Starting in 1968, dimensionally stable electrodes with a catalyst prepared from the mixed oxides of titanium and ruthenium found widespread use in the chlorine industry. 

Although impressive progress has been made in unraveling the mechanism of ORR catalysis by cofacial porphyrins, much remains to be learned before we can understand how this mechanism relates to those in heme enzymes and simple metalloporphyrins and use our mechanistic knowledge to rationally design improved metalloporphyrin catalysts for the ORR. 

At the outset it is to be observed that these metal complexes, although they need to be circumspectly handled, are user-friendly substances, and are usually readily obtained. The preparation of metalloporphyrins and metallophthalocyanines is accomplished in three ways, as described below. 

The typical metalloporphyrins and metallophthalocyanines have in general very high thermodynamic stabilities. However, because it is difficult to establish conditions under which the... 

D. Catalytic Oxidation with Metalloporphyrins and Metal Salen... 

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. 

Copper porphyrin is one of the best-characterized of the metalloporphyrins, and its electron spin resonance (ESR) spectrum has been known for a quarter of a century.(17) More recently, electron nuclear double resonance (ENDOR) investigations have provided the complete hyperfine tensors for the metal, the nitrogens and the pyrrole protons.(18) We have used this detailed knowledge earlier(, ) to assess the quality of scattered-wave calculations. 

Other excited-state effects besides coordination changes are observed in the transient Raman spectra (10,11). Further analysis of the excited states and dynamics of Ni-porphyrin complexes and Ni-reconstituted heme proteins should benefit from Raman spectroscopy s inherently rich structural information content. Transient Raman methods are now being applied to other metalloporphyrins and metalloporphyrin-based systems. 

Much of the work on the photoreduction of carbon dioxide centres on the use of transition metal catalysts to produce formic acid and carbon monoxide. A large number of these catalysts are metalloporphyrins and phthalocyanines. These include cobalt porphyrins and iron porphyrins, in which the metal in the porphyrin is first of all photochemically reduced from M(ii) to M(o), the latter reacting rapidly with CO to produce formic acid and CO. ° Because the M(o) is oxidised in the process to M(ii) the process is catalytic with high percentage conversion rates. However, there is a problem with light energy conversion and the major issue of porphyrin stability. 

It has been observed that PI14PHSO5 alone does not transfer its oxygen to manganese porphyrin. It is necessary to add either imidazole or pyridine derivatives, i.e. species which act as axial ligands in metalloporphyrins and are known to accelerate also the catalytic oxidation of organic substances . The kinetics and mechanism of manganese porphyrins oxidation by PI14PHSO5 were well studied . ... 

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