Porphyrin intercalation

Park, I. Y., Kuroda, K. and Kato, C. (1989). Preparation of a layered double hydroxide-porphyrin intercalation compound. Chem. Lett., 2057. 

Clays are colloidal layered hydrous aluminosilicates. There are relatively few examples of porphyrin intercalation into clays reported, mostly with either smectite clays or layered double hydroxides (LDH). Smectite clays consist of negatively charged layered aluminosilicate sheets. These sheets are separated by cations and water molecules. The... 

Porphyrins were first introduced into clays in 1977 by the physical absorption of porphyrin molecules into montmor-illonite in aqueous solutions." The most common examples are the binding of tetracationic M(TMPyP) porphyrins, M = Co(II), Mn(III), Fe(III), into montmor-illonite clays. Co(TMPyP) was the first porphyrin to be intercalated into montmorillonite by ion exchange in acid solution. The interlayer distance expanded from 27 to 37 A upon intercalation. UV-visible studies revealed the retention of cobalt ions in the porphyrin molecules. Mansuy and coworkers have extended this approach and prepared the Mn-porphyrin intercalated materials. These solids are efficient alkene epoxidation and alkane hydroxylation catalysts." Additionally, the catalyst exhibited a marked shape selectivity in favor of small linear alkanes when compared to more bulky substrates. It was also shown that... 

Gaillon, L., F. Bedioui, J. Devynck, P. Battioni, L. Barloy, and D. Mansuy (1991). Electrochemistry of manganese porphyrin intercalated into montmorillonite. J. Elec-troanal. Chem. 303(1-2), 283-287. 

Porphyrins intercalate with DNA and can cause unwinding, and increase in viscosity and melting point. This behaviour is influenced by substituent groups and the nature of the central metal atom [32]. 

This strategy is general and is also observed with other hosts such as layered materials (clays). Mn porphyrins intercalated in montmorillonite display a significant selectivity for small substrates in the competitive oxidation of a mixture of pentane and adamantane (Figure 9c). Such a selectivity is not observed when the catalyst is only adsorbed on the surface of silica, evidencing reactivity occurs in the interlayer space of the clay. ... 

Ma J, Wu J, Zheng J, Liu L, Zhang D, Xu X, Yang X, Tong Z (2012) Synthesis, characterization and electrochemical behavior of cationic iron porphyrin intercalated into layered niobate. Microporous Mesoporous Mater 151 325-329... 

Intensive research on the electrocatalytic properties of polymer-modified electrodes has been going on for many years Until recently, most known coatings were redox polymers. Combining redox polymers with conducting polymers should, in principle, further improve the electrocatalytic activity of such systems, as the conducting polymers are, in addition, electron carriers and reservoirs. One possibility of intercalating electroactive redox centres in the conducting polymer is to incorporate redoxactive anions — which act as dopants — into the polymer. Most research has been done on PPy, doped with inter alia Co 96) RyQ- 297) (--q. and Fe-phthalocyanines 298,299) Co-porphyrines Evidently, in these... 

Fujita and coworkers have also reported the encapsulation of multimeric porphyrin assemblies in the box-shaped cavities of ternary Pd6 coordination cages. Two types of cofacial porphine dimers A and B could be stabilized (133). In the smaller [Pd6(L14)2(L15)6]12+ cage 29, whose diameter is 10.4 A (Fig. 21), two porphyrin molecules can be stackedo directly on top of each other with an interplane distance of 3.4 A. In the larger cage 30, an additional molecule of L14 is intercalated between the two porphyrin bases. All complexes were found to be water-soluble in contrast to other 7i-stacked porphyrin dimers. The encapsulation... 

Sandwich complexes of porphyrazines are prepared by direct intercalation of lanthanides between two pz ligands, the route commonly utilized for the preparation of porphyrin sandwich complexes. Interestingly, the synthetic method used for the preparation of bis(phthalocyanines), starting from the dinitrile or the dilithium substituted monophthalocyanine, has never been successfully implemented for the synthesis of porphyrazines (77). 

It is essential to characterize the reactant species in solution. One of the problems, for example, in interpreting the rate law for oxidation by Ce(IV) or Co(III) arises from the difficulties in characterizing these species in aqueous solution, particularly the extent of formation of hydroxy or polymeric species. We used the catalyzed decomposition of HjOj by an Fe(III) macrocycle as an example of the initial rate approach (Sec. 1.2.1). With certain conditions, the iron complex dimerizes and this would have to be allowed for, since it transpires that the dimer is catalytically inactive. In a different approach, the problems of limited solubility, dimerization and aging of iron(III) and (Il)-hemin in aqueous solution can be avoided by intercalating the porphyrin in a micelle. Kinetic study is then eased. 

Excited state resonance Raman spectra of CuTMPyP bound to DNA or poly[d(A-T)] have been recorded [167,168], These are assigned to an exciplex formed between the porphyrin and the A-T sites of the polynucleotide. The excited state lifetime is estimated to be ca. 20 ps. Weak emission from CuTMPyP" bound to DNA has been reported and has been assigned to originate in a tripdoublet or tripquartet level [169]. It is believed that the emissive complexes are intercalated, whereas groove-bound CuTMPyP does not emit because of solvent quenching of the excited state. 

Certain manganese porphyrins adsorbed on silica or alumina, or intercalated in different mineral matrices such as montmorillonite, are also very efficient in alkane hydroxylation.150 151 Alcohol yields and alcohol ketone ratios are remarkably higher than those obtained with the corresponding soluble manganese porphyrins. Manganese tetra(4-Al-methylpyridiniumyl)porphyrin supported on montmorillonite, for instance, is efficient in the hydroxylation of compounds of low reactivity such as n-pentane and n-heptane.151... 

Ukrainczyk, L., Chibwe, M., Pinnavaia, T.J. Boyd, S. A. (1994). ESR study of cobalt(II) tetrakis(N-methyl-4-pyridiniumyl)porphyrin and cobalt(II) tetrasulfophthalocyanine intercalated in layered aluminosilicates and a layered double hydroxide. Journal of Physical Chemistry, 98, 2668-76. 

Nay zeolite, intercalation in, 12, 828-829 TV-confused porphyrin system, and silver(III) complexes,... 

Intercalation of tetra(4-carboxyphenyl)porphyrin (TPP-C) into the interlayer space of Zn-Al LDH, however, gave a different result [101]. The XRD pattern showed two peaks corresponding to interlayer spacings of 7.8 and 23.7 A. The 7.6-A spacing is attributed to the LDH in which the TPP-C molecules were arranged parallel to the plane of the host layers. Expansion of the layer to 23.7 A indicates that the plane of TPP-C was perpendicular to the plane of the Zn-Al LDH layers (Fig. 51) [101b],... 

Zinc me.w-tetrakis (p-carboxyphenyl)porphyrin (ZnTPPC), a neutral molecule, can be readily intercalated into the Li-Al LDH-myristate interlayers by replacing the myristate ions [101b], However, the uptake of the ZnTPPC into this material was minimal. The diffraction pattern showed that, as is the case with other porphyrins, ZnTPPC intercalates with its plane perpendicular to the metal hydroxide layer. The emission spectrum (excitation at 407 nm) of the intercalated guest is similar to that of nonaggregated ZnTPPC in solution (Fig. 53), suggesting that ZnTPPC is solubilized in the LDH in a dispersed form and not as an aggre-... 

Porphyrins are excellent sensitizers for the photochemical reduction of vio-logen in the presence of sacrificial electron donors. ZnTPPC intercalated into the interlayer spaces of LDH also acts as a sensitizer toward methyl viologen (MV2+) and PVS-EDTA promotes photoreduction of viologen. However, the rate of radical generation for the neutral viologen is higher than that for MV2+ (Fig. 54) [101d],... 

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