Pyridine ligands polymers

Kureshy developed a polymer-based chiral Mn-salen complex (Figure 21). Copolymerization of styrene, divinylbenzene, and 4-vinylpyridine generated highly cross-linked (50%) porous beads loaded with pyridine ligands at 3.8 mmol g-1. Once the polymer was charged with the metal complex catalyst, enantioselective epoxidation of styrene derivatives was achieved with ee values in the range 16 46%. 79... 

Fig. 28. Schematic profile of polymer-Cu catalyst in steady state of oxidation of 2,6-dimethylphenol About 72 Cu ions are coordinated on a partially quaternized poly(4-vinyl-pyridine) ligand (DP = 200, Q% = 28). Fraction of Cu(II) = 0.24, fraction of substrate-coordinated Cu = 0.80...

Two approaches were taken to prepare polymer D [83]. The synthesis of the polymer involved combining methacrylate and styrene monomers with either a free pyridine ligand or a pyridine with Re(phen)(CO)3 attached. For the polymer with the free pyridine, Re(phen)(CO)3 was attached in a second step. Both routes led to polymers with similar properties. 

A material with nitrogen-coordinated Ru was obtained from a silica-linked 2-(phenylazo)pyridine ligand. Results for cyclobutanol oxidation with 02 and the sacrificial oxidant isobutyraldehyde indicate that one- and two-electron oxidations occur simultaneously. The stability of the catalyst is not always guaranteed, probably because acids may be formed in oxidations of alcohols (284). Leaching problems are also encountered with a polymer-bound Ru Schiff base complex, used in oxidation of benzyl alcohol (285). 

For each gold nanoparticle, it was coordinated to nine pyridine ligands from the P4VP block, and each particle was essentially labeled with an Os(bpy)2(pyridine) complex. Electrochemistry results suggested that the osmium complex enhanced the conductivity of the polymer/nano-particle composite film. 

Fig. 17 Self-assembly of a multicyclic homo-polymer via coordination of a cobalt porphyrin symmetrically functionalized with two pyridine ligands...

Fig. 16 Mechanochemical evolution of metallosupramolecular polymers generated by (a) combination of an Eu(III) salt and a telechelic poly(ethylene-co-butylene) with 2,6-bis(l- -methylbenzimidazolyl)pyridine ligands at the termini counterions are omitted for clarity, (b) Reversible dissociation upon ultrasonication (i) irreversible metal exchange with Fe(II) ions as a result of (ii) ultrasonication or (Hi) other mechanical forces, (c) Dipicolinic acid ligands bind strongly to Eu(III) and the supramolecular network cannot easily be disassembled under mechanical stress. Reproduced with permission from [88]. Copyright 2014 American Chemical Society...

Fig. 5 Pyridine ligands carrying a self-complementary hydrogen-bond moiety (carboxylic acid, in this example) provide a noncovalent directional tool for connecting infinite copper(I) chloride coordination polymers into an extended two-dimensional network.

C3-symmetric molecule, benzene-tricarboxamide, has been developed that forms a hydrogel via a similar mechanism [110]. Lee and coworkers synthesized coordination polymers by functionalization of pyridine ligands with dendritic tri(ethylene glycol) chains, which lead to helical chains after the addition of silver ions, forming a 3D network [111],... 

Shaver and coworkers [319] investigated the mechanism of bis(imino)pyridine ligand framework for transition metal systems-mediated polymerization of vinyl acetate. Initiation using azobisisobu-tyronitrile at 120°C results in excellent control over poly(vinyl acetate) molecular weights and polymer dispersities. The reaction yields vanadium-terminated polymer chains which can be readily converted to both proton-terminated poly(vinyl acetate) or poly(vinyl alcohol). Irreversible halogen transfer from the parent complex to a radical derived from azobisisobutyronitrile generates the active species. 

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