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Polyvalent Catalysts Operating on Polyvalent Substrates: A Model for Surface‐Controlled Reactivity
Author(s) -
McKay Craig S.,
Finn M. G.
Publication year - 2016
Publication title -
angewandte chemie
Language(s) - English
Resource type - Journals
eISSN - 1521-3757
pISSN - 0044-8249
DOI - 10.1002/ange.201602797
Subject(s) - dendrimer , catalysis , chemistry , reactivity (psychology) , anthranilic acid , nucleophilic addition , nucleophile , combinatorial chemistry , kinetic energy , particle aggregation , aldehyde , surface modification , chemical engineering , photochemistry , polymer chemistry , organic chemistry , nanoparticle , medicine , physics , alternative medicine , pathology , quantum mechanics , engineering
Abstract Unusually fast rates of nucleophilic catalysis of hydrazone ligation were observed when polyvalent anthranilic acid catalysts operating on polyvalent aldehyde substrates were used with PAMAM dendrimers as the common platform. When presented in this way, the catalyst has a strong accelerating effect at concentrations 40–400 times lower than those required for similar monovalent catalysts and displays unique kinetic parameters. We attribute these properties to polyvalent engagement between the dendrimer surface groups, and a potential “rolling” effect leading to fast interparticle kinetic turnover. The phenomenon is sensitive to the density of functional groups on each dendrimer, and insensitive to factors that promote or inhibit nonspecific particle aggregation. These findings constitute a rare experimental example of an underappreciated phenomenon in biological and chemical systems that are organized on interacting surfaces.