title: Self-assembled nanospheres with multiple endohedral binding sites pre-organize catalysts and substrates for highly efficient reactions.
abstract: Tuning reagent and catalyst concentrations is crucial in the development of efficient catalytic transformations. In enzyme-catalysed reactions the substrate is bound-often by multiple non-covalent interactions-in a well-defined pocket close to the active site of the enzyme; this pre-organization facilitates highly efficient transformations. Here we report an artificial system that co-encapsulates multiple catalysts and substrates within the confined space defined by an M12L24 nanosphere that contains 24 endohedral guanidinium-binding sites. Cooperative binding means that sulfonate guests are bound much more strongly than carboxylates. This difference has been used to fix gold-based catalysts firmly, with the remaining binding sites left to pre-organize substrates. This strategy was applied to a Au(I)-catalysed cyclization of acetylenic acid to enol lactone in which the pre-organization resulted in much higher reaction rates. We also found that the encapsulated sulfonate-containing Au(I) catalysts did not convert neutral (acid) substrates, and so could have potential in the development of substrate-selective catalysis and base-triggered on/off switching of catalysis.
authors.affiliation: Homogeneous, Supramolecular and Bio-Inspired Catalysis, Van 't Hoff Institute for Molecular Sciences, University of Amsterdam, Science Park 904, Amsterdam 1098XH, The Netherlands.
authors.forename: Qi-Qiang
authors.initials: QQ
authors.lastname: Wang
authors.affiliation: Homogeneous, Supramolecular and Bio-Inspired Catalysis, Van 't Hoff Institute for Molecular Sciences, University of Amsterdam, Science Park 904, Amsterdam 1098XH, The Netherlands.
authors.forename: Sergio
authors.initials: S
authors.lastname: Gonell
authors.affiliation: Homogeneous, Supramolecular and Bio-Inspired Catalysis, Van 't Hoff Institute for Molecular Sciences, University of Amsterdam, Science Park 904, Amsterdam 1098XH, The Netherlands.
authors.forename: Stefan H A M
authors.initials: SH
authors.lastname: Leenders
authors.affiliation: Lehrstuhl für Bioanorganische Chemie, Department Chemie und Pharmazie, Friedrich-Alexander-Universitaet Erlangen, Egerlandstrasse 3, Erlangen 91058, Germany.
authors.forename: Maximilian
authors.initials: M
authors.lastname: Dürr
authors.affiliation: Lehrstuhl für Bioanorganische Chemie, Department Chemie und Pharmazie, Friedrich-Alexander-Universitaet Erlangen, Egerlandstrasse 3, Erlangen 91058, Germany.
authors.forename: Ivana
authors.initials: I
authors.lastname: Ivanović-Burmazović
authors.affiliation: Homogeneous, Supramolecular and Bio-Inspired Catalysis, Van 't Hoff Institute for Molecular Sciences, University of Amsterdam, Science Park 904, Amsterdam 1098XH, The Netherlands.
authors.forename: Joost N H
authors.initials: JN
authors.lastname: Reek
mesh_terms: D001665:Binding Sites; D001671:Biochemistry / Q000379:methods*; D002384:Catalysis; D019791:Guanidine / Q000378:metabolism; D054118:Nanospheres / Q000737:chemistry / Q000378:metabolism / Q000648:ultrastructure; D036103:Nanotechnology / Q000379:methods*
chemical_list: D019791:Guanidine