Porphyrin networks

The additional reaction intermediates in the Ni-tetra(3-methylphenyl)-porphyrin network coupled with slower rates of metal deposition result in deeper penetration of the internal maxima and higher concentration of metals in the pellets center compared to Ni-etioporphyrin. Likewise, the selective enhancement in the metal deposition rates of Ni-T3MPP on the sulfided catalyst is apparent by the steeper profiles in Fig. 28 relative to the results in Fig. 27 on the oxide form of CoMo/A1203. ... 

A mixed organic-inorganic 3D porphyrin network was obtained by cocrystallization of palladium mc n-tetrapyridylporphyrinate and cadmium nitrate. All four pyridyl units are bound to octahedral cadmium centres which are each coordinated by two nitrate, water and pyridyl ligands (Figure 7.27). One half of the py-Cd-py connections is linear, the other half bent (103°), having two cis pyridine ligands. As is common in mc o-tetraarylporphyrins,... 

Phthalocyanine and porphyrin networks (Sect. 2.2.3) 450-1,000 Up to 0.29 Both thermal and chemical stability high Networks can bind metals [50, 51]... 

Phthalocynanine-containing polymers are well-known [49] but till relatively recently, phthalocynanine-containing network polymers were generally rendered non-porous by strong non-covalent n-n stacking between sub-units. The introduction of contorted spiro centres allowed the preparation of phthalocynanine networks with BET surface areas in the range 500-1,000 m g (Fig. 6) [41,50]. These materials also demonstrated marked gas sorption hysteresis [50]. In the same study, dioxane-linked porphyrin network PIMs were produced with high BET surface areas (900-1,100 m g" ) [51]. An important aspect of these network polymers is their potential use in catalysis [52] (Sect. 4.1). 

The good chemical and physical stability of many MOPs, coupled with synthetic diversity and potential for pore size control, bodes well for applications in heterogeneous catalysis. For example, microporous phthalocyanine and porphyrin network polymers are used as heterogeneous catalysts for the oxidation of cyclohexene, the decomposition of hydrogen peroxide, and the oxidation of hydro-quinone [52]. Enhanced catalytic activity was observed with respect to low molar mass analogues. There is considerable scope for future development here -for example, the design of electrocatalytic materials using CMPs [11, 12, 19]. 

There are an increasing number of reports of useful, specific chemical and physical properties in MOPs. Recent examples include high gas separation efficiencies in PIM membranes [41, 78], catalytically-active phthalocyanine and porphyrin network polymers [52], and HCPs with elevated isosteric heats of sorption for CH [39], Many more possibilities for exploration exist - the following list suggests just a few such opportunities ... 

Attempting to mimic the topology of the PtS. structure, Robson and coworkers explored metal-to-ligand coordina-tive bonding as a means to build more robust porphyrinic materials. They reported a structure in which Pd(TPyP) molecules are interconnected by Cd(II) centers. "" Each porphyrin is coordinated by two frani-pyridyl donor porphyrin molecules and by two cis donor porphyrin molecules (Figure 99). The overall neutral framework IPd(TPyP) Cd(NOj)2 8.6FI2O] features infinite interwoven layers of the porphyrin network. 

Figure 99. Schematic illustration of three-dimensional porphyrin network in Pd(TPyP) Cd(NO3)2 8.6H20 in which porphyrins are represented as squares and cadmium ions as circles. Solvent molecules are omitted for clarity. Reprinted with permission from Abrahams, B. F. Hoskins, B. F. Robsin, R. /. Amer. Chem. Soc. 1991, / / 3, 3606. 1991 American Chemical Society.

Figure 8.17 Schematic of the chemical structures of (a) reduced GO [r-GO], [b] G-dye, (c) TCPR (d) (Fe-P) MOF, (e) (G-dye-FeP) MOF, and [f) magnified view of layers inside the framework of (G-dye-FeP) MOF showing how graphene sheets intercalated between porphyrin networks. The synthetic process to form chemicals (I) G-dye S3mthesized from r-GO sheets via diazotization with 4-[4-aminostyryl) pyridine, (II) (Fe-P) MOF synthesized via reaction between TCPPs and Fe ions, (III) (G-dye-FeP) MOF formed via reaction between (Fe-P) MOF and G-dye. Reprinted with permission from reference [113], Copyright 2012 American Chemical Society.

Spiro-linked CMPs functionalized with metal phthalocyanine units show enhanced catalytic activity towards different reactions." The Co-phthalocyanine-incorporated CMP acts as a catalyst with improved activity for cyclohexene oxidation, hydroquinone oxidation and H2O2 decomposition, whereas the spiro-linked Fe-porphyrin network shows increased catalytic activity for hydroquinone oxidation. The spiro linkages in these networks open up a lot of free space around the catalytic sites to enhance the accessibility of substrates to reach more catalytic sites. More functionalization in this vray of conjugated networks by various metals improves the scope of these networks in heterogeneous catalysis. Oxidation of sulfides, reductive aminations and photocatalyzed aza-Heniy reactions are reactions effectively catalyzed by different metal-incorporated CMPs" (Figure 10.6). 

FIGURE 14.10 (a) Construction of porphyrin network on MWCNTs, (b) idealized scheme of the nanotubes coated with the porphyrin polymer, (c) SEM and TEM images of Co-potphyrin-coated MWCNTs. (Adapted from Ref. [202] with permission of American Chemical Society. Copyright 2014.)... 

Hijazi I, Bourgeteau T, C nut R, Morozan A, Filoramo A, Leroy J, Derycke V, Jousselme B, Campidelli S. Carbon nanotube-templated synthesis of covalent porphyrin network for oxygen reduction reaction. J Am Chem Soc 2014 136 6348-54. 

Figure 6 Self-assembly of highly stable 3D porphyrinic networks with large ID opening channels by M-TCPP linking up Zrg clusters...

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