Metalloporphyrins zinc porphyrinates

Sanders (14) has exploited the strong and selective coordination of phosphine donor groups to Ru(II) to construct hetero-dimetallic porphyrin dimers (17, Fig. 5). An alkyne-phosphine moiety introduced on the periphery of a free base or metalloporphyrin (M = Zn or Ni) spontaneously coordinates to a Ru(II)(CO) porphyrin when the two porphyrins are mixed in a 1 1 ratio. Coordination is characterized by a downfield shift of the 31P resonance (A<531P = 19 ppm). There is no evidence of self-coordination of the zinc porphyrin at 10 6 m in toluene, there is no shift in the Soret band in the UV-Vis absorption spectrum. The Ni-Ru dimer was observed by MALDI-TOF mass spectrometry. Heating the Ru(II)CO porphyrin with 2 equivalents of the phosphine porphyrins led to quantitative formation of trimeric assemblies. 

A polymeric structure can be generated by intermolecular coordination of a metalloporphyrin equipped with a suitable ligand. Fleischer (18,90) solved the crystal structure of a zinc porphyrin with one 4-pyridyl group attached at the meso position. In the solid state, a coordination polymer is formed (75, Fig. 30). The authors reported that the open polymer persists in solution, but the association constant of 3 x 104 M 1 is rather high, and it seems more likely, in the light of later work on closed macrocycles (see above), that this system forms a cyclic tetramer at 10-3 M concentrations in solution (71,73). 

Functionalization can be used to alter the redox properties of the zinc metalloporphyrin the zinc heptanitroporphyrin shows facile reduction to the air-stable 7r-anion radical.768 Modification of the zinc porphyrin at the, 8 position with chlorine or bromine to induce saddling of the... 

Recently, the high inhibitory efficiency of metalloporphyrins has been shown in lipid peroxidation of rat brain homogenates [346]. It was found that manganese and cobalt porphyrins were very effective inhibitors of lipid peroxidation while iron and especially zinc porphyrins had very weak inhibitory activity, if any. For example, /50 values were equal to 21, 29, 212, 946 pmol 1 1 for CoTBAP, MnTBAP, FeTBAP, and ZnTBAP, respectively, where TBAP is 5,10,15,20-tetrakis [4-carboxyphenyl]porphyrin similar values were obtained for other porphyrin derivatives. 

Metallooctaethylporphyrins Zinc tetra(benzo-15-crown-5)porphyrin See also Metallotetraphenylporphrins dimerization effects, 141,147 Zinc tetrabenzoporphyrin—See Metalloporphyrins Zinc tetraphenylporphyrin See also Metalloporphyrins See also... 

Porphyrin and its derivatives are well-known model compounds for photosynthetic processes that involve charge separation [87], A zinc porphyrin, a copper porphyrin, and a zinc phthalocyanine (Pc) are chosen and incorporated into PPV backbones. Four polymers are synthesized via the Heck polycondensation [88], The incorporation of these metal complex moieties in polymers XI to XIII is manifested by the appearance of Q bands from metalloporphyrin and zinc Pc... 

The mechanism of cooperativity has also been probed by the substitution of other metalloporphyrins into the globin for example, zinc porphyrins have been used for their excited triplet-state properties,"" manganese porphyrins for their EPR activity, and ruthenium porphyrins as a member of the iron triad." ... 

Metalloporphyrins constitute an important family of complexes which frequently emit from porphyrin IL states [13, 126, 184]. The characterization of emitting IL states outlined above also applies to metalloporphyrins and related complexes. For example, since zinc exerts only a moderate heavy atom effect, zinc porphyrins show an IL fluorescence at r. t. and a relatively long-lived phosphorescence at 77 K [185,186],e.g.,... 

Finally, a DEER study on models for molecular wires made from butadiyne-linked zinc porphyrin oligomers, end-labeled with nitroxide radicals, was performed by Lovett, Anderson, and coworkers [107]. Unlike in [104—106], one can control the conformations of these metalloporphyrin-based strucmres by self-assembly with multidentate amine ligands, which bend the rigid oligomeric structure. The experimentally found end-to-end distances in these complexes match the predictions from molecular dynamics calculations. This study thus presents a proof-of-principle that DEER spectroscopy is also well suited for understanding more complex supramolecular stmctures. 

Metal complexes of dimers linked with flexible spacers give rise to polymeric complexes at a higher concentration of diamine. Two metalloporphyrins with C2 symmetry linked with a rigid chiral amine spacer (Troger s base) show diastereomeric recognition for optically active, basic amino acids.- - Chiral diamine derivatives such as basic amino-acid esters are tightly bound with moderate enantioselec-tivity to the zinc porphyrin tweezers in the inner-homochiral cavity of the host (Figure 7). It is noted that... 

As we have just seen, electrostatic interactions can reinforce the formation of axial base complexes in metalloporphyrins, but other thermodynamically favored processes, such as chelation around a bidentate base like pyrazine, can be used. This approach has led Kuroda to the preparation of self-assembled dendrimer-type structures 86-89 represented in Figure 13.50 ". In these structures, the zinc porphyrin dimer formed by multihydrogen bonding of tetracar-boxylate derivatives of TPP is considered as a chelate. 

The electrochemistry of zinc, cadmium, and mercury porphyrins is uncomphcated and only macrocycle-centered electrode reactions are observed in nonaqueous solvents [7, 21]. Metalloporphyrins with this type of metal ion have been studied in some detail, but the best characterization of the electrochemical reaction products has been obtained with zinc porphyrins... 

Anderson and coworkers [81] have extended this approach of metal-ligand mediated self-assembly of dyes to construct double-stranded, conjugated ladders 30 through cofacial bridging of metalloporphyrins. The zinc porphyrin polymer 29, which is soluble in chloroform even in aggregated form, is transformed into the ladder complex by the addition of the ditopic hgand 4,4 -... 

Dime AKD, Devillers CH, Cattey H, Habermeyer B, Lucas D (2012) Control over the oxidative reactivity of metalloporphyrins. Efficient electrosynthesis of meso, meso-linked zinc porphyrin dimer. Dalton Trans 41 929-936... 

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