Porphyrins metallation

Dendrimers with a Porphyrin Metal Complex as a Core.212... 

Porphyrin-metal complexes are natural mimetic substances that have attracted much attention during the past decade. The epoxidation of olefins by porphyrin complexes proceeds well, but with only modest enantioselectivity. As this area of research is growing, description of a few selected publications may be useful.96... 

Porphyrin-Metal and Similar Complexes, Properties of (Braterman, Davies, Williams). Power Electrodes and their Application (Tomassi). Pressure, Effect on Electronic Structure (Drickamer ... 

Figure 3.4 Mechanism of porphyrin metallation. (a) Out-of-plane saddle structure in which two pyrrole rings with unprotonated nitrogens (blue spheres) point upwards, while the other two, protonated (blue and white spheres) point downwards, (b) Steps in the mechanism for incorporation of the metal ion (red) into the porphyrin (pyrrole rings in green), described in the text. (From Al-Karadaghi et al., 2006. Copyright 2006, with permission from Elsevier.)...

Fig. 9 A schematic diagram of the diffusion-controlled porphyrin metalation in a small nanomatrix (left) and a larger nanomatrix (right). Reproduced with permission from Ref. [39]...

Chiral porphyrin metal complex catalysts have also received much attention. In this situation, the flat, symmetrical porphyrin structure must be modified dramatically in order to incorporate dissymmetry. This has been achieved through strapping techniques. " Some examples are shown in Figure 11.7. 

The only indirect selection that led to a catalytic DNA is a deoxyribozyme that catalyzes the same class of porphyrin metallation as the aforementioned ribozyme. The ssDNA oligonucleotide showed a k at of 13 h" for the insertion of into mesoporphyrin IX [93, 96-99]. This corresponds to a rate enhancement of 1400 compared to the uncatalyzed reaction which is as good as a catalytic antibody for the same reaction. 

HO-1 is controlled at the level of transcription by oxidative stress and several inducers such as porphyrins, metals, and progesterone (8). The absence of HO-1 is associated with severe growth retardation, anemia, and enhanced endothelial cell injury 156, 157). In addition, HO-1 has been implicated in protection against transplant rejection 158, 159). HO-2 is constitutively expressed, and its presence in brain and the noted similar effects of CO and NO has led to the proposal that CO-generated by HO-2 is involved in signaling processes 8, 160-162). 

C. Direct Porphyrin Metalation Under Ultra-High Vacuum... 

Until now, only a few theoretical studies of porphyrin metalation by divalent metal ions in solution have been reported (72,94,95). In the first theoretical work (94,96) on this topic, insertion of Fe2+ and Mg2+ into the porphyrin ring was studied by DFT methods. The authors followed the reaction from the outer-sphere complex formation via stepwise displacement of the solvent molecules until... 

Porphyrin-Metal and Similar Complexes, Properties of (Braterman,... 

Multidentate Macrocyclic Ligands Table 1 Summary of Porphyrin Metallation Conditions17... 

Figure 3 Sitting-atop and deformed intermediates in porphyrins metallation...

Alkaline earth metalloporphyrins, M(Por), are obtained by porphyrin metallation with meta perchlorates in pyridine or metal hydroxides in methanol.175 They dissociate under mild conditions even in acetic acid. 

If an MU1 acetylaoetonate is used for the porphyrin metallation, Min(Por)(acac) is formed, in which the acetylacetonato coordinates to the metal as a bidentate ligand (Scheme 7).1703 The paramagnetic NMR shift of the phenyl proton in Euni(TPP)(acac) suggests a large displacement of the europium atom from the centre of the porphyrin ( 2.0 A) with long Eu—Np r bonds ( 2.83 A). Sandwich complexes Ce(TPP)2 and PrH(TTP)2 have been reported.34... 

Generally, the same procedure for porphyrin metallation seems to be applicable for azaporphyrins, but the examples are not abundant (Scheme 54).I83,186-188... 

Photoinduced Hydrogen Evolution with Porphyrin Metal... 

Table 18.1 Typical photoinduced hydrogen evolution systems using porphyrin metal complexes...

Photoinduced Hydrogen Evolution with Water-soluble Viologen-linked Cationic Porphyrin Metal Complexes and Hydrogenase... 

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