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Coordination polymers porphyrins

The first examples of porphyrin coordination polymers that have been characterized according to our definition in Sect. 3.1 were reported in 1991 by Fleischer and Shachter [72]. Upon metalation of 5-pyridyl-10,15,20-triphenyl-porphyrin with a Zn " ion, a self-complementary building block was obtained which readily assembles to polymer 19 as confirmed by concentration dependent UV/vis spectroscopy and NMR studies. The structure of the polymer 19 in the solid state was established by X-ray analysis. Recent reinvestigations of this system suggest that in solution tetrameric squares prevail, and polymer formation may take place at higher concentration (> 1 M) as predicted by computer simulation [12]. [Pg.58]

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). [Pg.249]

Construction of organic nanotubes starting from porphyrin dendrimers with core/shell architecture is also feasible. Figure 8.29 also shows how covalent nanotubes can be produced by removal of the dendritic component of the molecule. A coordination polymer is first synthesised from a dendritic metallopor-phyrin with alkene end groups. This is subjected to intramolecular and intermo-lecular crosslinking by ring-closing metathesis at the periphery. [Pg.324]

Tetra(4-pyridyl) porphyrin (TPyP) metalloligands also were explored as potential MOF constituents. It is of more than passing interest that TPyPs are often capable of self-association via bonding of the pyridyl nitrogens to the coordina-tively unsaturated central metal of another porphyrin molecule. Several research groups have made an active study of such stmctures (111-117). However, because these coordination polymers tend to be formed from a single molecular component, rather than having the metalloporphyrin bound to a secondary metal center or SBU, they will be omitted from further discussion here. [Pg.359]

The porphyrins mth coordinative polymer bond are prepared under inert as follows ... [Pg.52]

These formation and dissociation equilibria can be used to manipulate the multi-porphyrin assemblies, as was demonstrated in the following experiments. A mixture of coordination polymer 52 and dimer 53 was dissociated by the addition of MeOH followed by simple evaporation. The GPC elution curves before (Fig. 24a) and after (Fig. 24b) the evaporation were completely different. The new peaks (1, 2, and 3) in Fig. 24b were separated and identified as oligomers terminated by monomeric porphyrins 54 (n = 0, 1, 2, and 3). This result demonstrates the possibility of controlling the length of the porphyrin array and terminating it with other imidazolyl zinc porphyrins... [Pg.79]

Because coordinatively bound complexes are quite easy to prepare, numerous papers on this subject have been published. Soluble complexes are prepared by dissolving stoichiometric amounts of polymer and metal complex in an organic solvent or water. To obtain solid materials, the solvent is removed or a film is cast. Cross-linked insoluble polymers are suspended in a solvent and a solution of a metal complex is added. The equilibrium of the coordinatively polymer-bound metal complex with the unbound one in solution is not favorable (Eq. 5-6), so an excess of strong low molecular weight donor base can destroy the polymer coordinative bond. Even the heme in myoglobin can be cleaved to give the apomyoglobin, as described in Section 2.3.1, and another porphyrin derivative subsequently coordinatively bound. [Pg.202]

Coordinatively polymer-boimd Co salenes and Co or Fe porphyrins have mainly been investigated for reversible binding of oxygen, which is of commercial interest for artificial blood and air separation by membrane processes (for a detailed discussion of these materials see Chapter 9) [5,124,147]. A chiral Mn(III) Schiff-base complex was bound to the insoluble cross-linked terpolymer of styrene, 4-vinylpyridine and divinylbenzene (formula 59) [148]. The materials have been used successfully as catalysts in the presence of iodosylbenzene as oxidant for the enantioselective epoxidation of styrenes, as can be seen from Table 5-3. [Pg.203]

A. The framework lattice occupies just 42% of the total crystal volume. Porphyrins gives access to coordination polymers, which are shaped by metal-ligand interactions and by a variation of substituents. [Pg.1000]

The second example relates to a functional nanopo-rous material based on the siipramolecular assembly of the CoTCPP tectons, which was fabricated by Suslick et al. with the aid of solvothermal techniques.Its structure is based on peripheral coordination of the porphyrin building blocks to each other, into a three-dimensional coordination polymer, with the aid of external cobalt ion auxiliaries (Fig. 7). The bending of... [Pg.1155]

Krupitsky, H. Stein. Z. Goldberg, I. Crytalline complexes, coordination polymers and aggregation modes of tetra(4-pyridyl)porphyrin. J. Inch Phenom. 1994. 18, 177-192. [Pg.1157]

A second motif encountered in tetrapyridylporphyiin systems is typified by inclusion compounds with wet methanol and water that produce three-dimensional coordination polymers. Ttv/ni-pyridyl substituents on a Zn(TPyP) were ob.served to axially ligate the metal centers of adjacent porphyrin moieties generating a polymeric chain in one dimension. Cross-linking in a second dimension occurs when the original porphyrin molecule is coordinated by two pyridyl moieties from two additional porphyrin molecules... [Pg.85]

While detection of cations via porphyrin-ba.sed materials has been explored less than anion sensing, the ability of a porphyrin to coordinate different metals and the unique spectral signatures that result form the basis for metal ion detection. Use of free-base porphyrins in polymer matrices has allowed for the detection of heavy metal ions by Ache et Immobilization of 5,10,15,20-tetrakis(4-N-methylpyridyOporphyrin on Nafion membranes pennitted detection of cadmium and mercury in solution with detection limits of 5 X 10 M and 2 x 10 M, respectively over a 20-minute measuring period. The method is subject to interferences from other metal ions, but the researchers were able to detect several ions simultaneously using pattern-recognition techniques such as principal component analysis. Sol-gel films doped with 5,l0,l5,20-tetra(p-sulfonatophenyDporphyrin have also been used by Ache and coworkers for the fluorimetric determination of mercury in solution, with a detection limit of approximately 7 X 10... [Pg.123]

Bedioui, R, M. Voisin, J. Devynck, and C. Bied-Charreton (1991). Electrochemistry of conducting polypyrrole films containing cobalt porphyrin. 2. New developments and inclusion of metallic aggregates in the coordination polymer. J. Electroanal. Chem. 297, 257-269. [Pg.426]

All of these examples show that the use of metal coordination at the periphery of the porphyrin chromophores can be extremely helpful in modular approaches targeting multiporphyrinic assemblies. As we will see later, the formation of coordination polymers has already found applications in the preparation of materials. [Pg.674]

While the majority of polynuclear lanthanide complexes and coordination polymers have been synthesized by the use of rigid ligands, such as multicarboxylic acids and carboxyphenyl porphyrin, relatively few studies involving more flexible ligands have been reported. However, the skeletal adapfabiUfy of flexible ligands enables them to form many different molecular systems and extended network... [Pg.286]

The Stability constant for the metal/ligand (monomer) complexation should be large to afford high molecular weight polymers in isotropic solution. Moreover, the complexation should be readily reversible (kinetically labile) to impart dynamic properties to the polymers. Two recent examples of soluble, reversible coordination polymers are the self-assembled porphyrins of Michelsen and Hunter [122] and the high molecular weight copper(II) coordination polymers of Leize, Lehn, and coworkers [123],... [Pg.187]


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See also in sourсe #XX -- [ Pg.301 , Pg.315 ]




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Metal coordination polymers porphyrins

Polymer coordination

Polymers coordinated

Porphyrin polymers

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