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Me-N4 chelates

Me-N4 macrocyclic complexes (with N4-macrocycles being, for instance, tetraazaannulene [TAA], tetramethoxypheny 1-porphyrin [TMPP], phthalocyanine [Pc]), and Me = Co or Fe were the first to be used as precursors of the catalytic sites. In particular, unsupported C0-N4 chelates (CoTAA, CoTMPP, and CoPc) or C0-N4 chelates adsorbed on a carbon support were used in the 1970s as ORR electrocatalysts [11]. However, both unsupported and carbon-supported C0-N4 chelate electrocatalysts underwent a rapid decline in the activity. An important discovery in these early years was that catalyst stability as well as activity toward ORR could be improved by subjecting C0-N4 chelate/carbon samples to thermal treatment in an inert gas like N2 or Ar [12]. [Pg.275]

The question then was the following what happens to the Me-N4 catalytic site of the chelate after the heat treatment This topic was strongly debated in the early days and is still not completely understood today. Essentially, three models of the catalytic site for ORR were presented, one each by van Veen, Yeager, and Wiesener, and their respective collaborators. [Pg.275]

The rapid aminolysis of cobalt(llI)-chelated glycine esters in aprotic solvents (Scheme 10 N4 = (en)2 or trien, R = Me, Et, R = H, CHR"C02Et) could be of value in peptide synthesis. The cobalt atom acts as both an N-protecting and an activating group. The synthesis of the chelated amino acid esters has presented some difficulties.207 A recent paper208 describes the use of methyl trifluoromethanesulfonate for the alkylation of chelated amino acids using dry trimethyl phosphate... [Pg.436]


See other pages where Me-N4 chelates is mentioned: [Pg.88]    [Pg.89]    [Pg.90]    [Pg.91]    [Pg.106]    [Pg.107]    [Pg.276]    [Pg.276]    [Pg.476]    [Pg.476]    [Pg.88]    [Pg.89]    [Pg.90]    [Pg.91]    [Pg.106]    [Pg.107]    [Pg.276]    [Pg.276]    [Pg.476]    [Pg.476]    [Pg.94]    [Pg.102]    [Pg.104]    [Pg.449]    [Pg.29]    [Pg.181]   
See also in sourсe #XX -- [ Pg.88 ]




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N4-chelates

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