A Metalloregulated Four-State Nanoswitch Controls Two-Step Sequential Catalysis in an Eleven-Component System

• Published in: Angewandte Chemie International Edition 2016-08, Vol.55 (35), p.10512-10517
• Main Authors: Gaikwad, Sudhakar, Goswami, Abir, De, Soumen, Schmittel, Michael
• Format: Article
• Language: English
• Subjects: allosteric control; Binding; Catalysis; Chemical reactions; coordination chemistry; molecular switches; nanomechanical motion; sequential catalysis; Shutdowns; Switching; Zinc
• ISSN: 1433-7851; 1521-3773
• DOI: 10.1002/anie.201604658

The nanomechanical switch 1 with its three orthogonal binding motifs—the zinc(II) porphyrin, azaterpyridine, and shielded phenanthroline binding station—is quantitatively and reversibly toggled back and forth between four different switching states by means of addition and removal of appropriate metal‐ion inputs. Two of the four switching stages are able to initiate catalytic transformations (ON1, ON2), while the two others shut down any reaction (OFF1, OFF2). Thus, in a cyclic four‐state switching process the sequential transformation A+B+C→AB+C→ABC can be controlled, which proceeds stepwise along the switching states OFF1→ON1 (click reaction: A+B→AB)→OFF2→ON2 (Michael addition: AB+C→ABC)→OFF1. Two consecutive cycles of the sequential catalysis were realized without loss in activity in a reaction system with eleven different components. Connect four: The first nanoswitch with four states can control a sequential transformation A+B+C→AB+C→ABC with 11 components over two complete cycles. The cycle proceeds stepwise along the switching states OFF1→ON1 (click reaction: A+B→AB)→OFF2→ON2 (Michael addition: AB+C→ABC)→OFF1 (see scheme). The system′s preformance is superior to that of systems with only two switching states.