Aggregation porphyrin complex

Other aspects of solvation have included the use of surfactants (SDS, CTAB, Triton X-100), sometimes in pyridine-containing solution, to solubilize and de-aggregate hemes, i.e., to dissolve them in water (see porphyrin complexes, Section 5.4.3.7.2). An example is provided by the solubilization of an iron-copper diporphyrin to permit a study of its reactions with dioxygen and with carbon monoxide in an aqueous environment. Iron complexes have provided the lipophilic and hydrophilic components in the bifunctional phase transfer catalysts [Fe(diimine)2Cl2]Cl and [EtsBzNJpeCU], respectively. 

Several metal insertion mechanisms have been proposed, but none of them is conclusive.18 The rate of metallation varies from square root to second order in metal salt from one system to another, and apparently there exists more than one pathway. Where the rate law is second order in metal salt, a so called sitting-atop metal ion-porphyrin complex intermediate or metal ion-deformed porphyrin intermediate, which then incorporates another metal ion into the porphyrin centre, has been postulated (Figure 3).19 For the reactions with the square root dependence on the metal salt concentration, the aggregation of metal salts is suggested.18 Of course, there are many examples which follow simple kinetics, i.e. d[M(Por)]/df = k[M salt][H2Porj. 

The mechanism of binding of 16b with o-glucose was assessed by H NMR spectroscopy in DMSO-avoid problems with aggregation at NMR-relevant concentrations). It was found that the metal-ffee porphyrin complex, 16b, binds o-glucose in a 1 1... 

All solutions were prepared immediately before the experiments, using triply distilled water from a quartz apparatus. For achieving the reduced form cytochrome(II)c see reference (5). All reactions including porphyrin complexes were measured under pseudo-first-order conditions so that the exact concentrations of the porphyrin compounds were not necessary to calculate the rate constants. This avoids uncertainties caused by aggregation of the porphyrin complexes. 

Phthalocyanine complexes of copper and zinc have also been incorporated into copolymers of polyethers and polystyrene. Polymer 38 is an example of a polystyrene prepared by free-radical polymerization of a zinc porphyrin complex and styrene. This high molecular weight metallopolymer formed aggregates in solution. 

S. Takagi, T. Shimada, T. Yui, H. Inoue, High density adsorption of porphyrins onto clay layer without aggregation characterization of smectite-cationic porphyrin complex, Chem. Lett. 30, 128-129 (2001). 

In metal complexes of FTF5 and DPA, both single two-electron and double one-electron redox couples were observed. [(FTF5)Zn2] is diamagnetic, whereas the EPR spectmm of [(DPA)Zn2] was interpreted as that of a triplet that was complicated by aggregation. Why the ground electronic state of [(DPA)Zn2] is a triplet remains to be established a triplet porphyrin diradical was thought to be unique in porphyrin chemistry [LeMest et al., 1992]. 

Anderson has produced a range of improved zinc porphyrin-DABCO ladder complexes where an aromatic substituent in the meso position reduces aggregation (57). The 1H NMR spectra show a characteristic... 

It has been recently demonstrated that the simplest of the cobalt porphyrins (Co porphine) adsorbed on a pyrolytic graphite electrode is also an efficient electrocatalyst for reduction of 02 into 1120.376 The catalytic activity was attributed to the spontaneous aggregation of the complex on the electrode surface to produce a structure in which the cobalt-cobalt separation is small enough to bridge and activate 02 molecules. The stability of the catalyst is quite poor and largely improved by using porphyrin rings with mew-substitu-tion.377-380 Flowever, as the size of the mew-substituents increases the four-electron reduction efficiency decreases. 

Like the palladium(II) complexes, the platinum(II) porphyrins show appreciable phosphorescence even in aqueous media at room temperature in one study,169 singlet oxygen quantum yields ranged from 0.1 to 0.9 and were strongly influenced by dimerization/aggregation. Platinum(II) 5,10,15,20-tetrakis(/>-carboxyphenyl)porphyrin and platinum(II)coproporphyrin-I ((36) for Pd read Pt) have been studied as phosphorescent labels of antibodies for use in time-resolved microscopy.189... 

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