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A Double‐Cavity‐Containing Porphyrin Host as a Highly Stable Epoxidation Catalyst
Author(s) -
Thomassen Paul J.,
Varghese Shaji,
Bijsterveld Edward J. A.,
Thordarson Pall,
Elemans Johannes A. A. W.,
Rowan Alan E.,
Nolte Roeland J. M.
Publication year - 2015
Publication title -
european journal of organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.825
H-Index - 155
eISSN - 1099-0690
pISSN - 1434-193X
DOI - 10.1002/ejoc.201500492
Subject(s) - chemistry , catalysis , porphyrin , selectivity , manganese , pyridine , photochemistry , active site , alkene , ligand (biochemistry) , substrate (aquarium) , combinatorial chemistry , inorganic chemistry , organic chemistry , biochemistry , oceanography , receptor , geology
We describe a manganese porphyrin catalyst containing two adjacent cavities, which can be used for the epoxidation of alkenes by sodium hypochlorite. A pyridine ligand bound in one of the cavities regulates the rate and selectivity of the epoxidation reaction that takes place in the adjoining cavity. Pyridine binding studies suggest that site‐to‐site communication exists between the two cavities. The alkene substrates are completely converted into epoxides by the manganese double‐cavity catalyst, but the observed epoxidation rates are low. These low rates are proposed to be a result of the energetically less favourable binding of the substrate into the cavity containing the active site due to an allosteric pinching effect. In the manganese double‐cavity arrangement the catalytically active manganese complex is efficiently protected against decomposition, leading to a catalytic system with enhanced stability. The presented work may open a new route to the construction of highly stable catalysts of which the activity and selectivity may eventually be controlled by allosteric interactions.