Catalytic Three‐Component Machinery: Control of Catalytic Activity by Machine Speed

• Published in: Angewandte Chemie International Edition 2018-01, Vol.57 (1), p.354-358
• Main Authors: Paul, Indrajit, Goswami, Abir, Mittal, Nikita, Schmittel, Michael
• Format: Article
• Language: English
• Subjects: Binding sites; Catalysis; Catalytic activity; Decks; Machinery and equipment; multicomponent assembly; Porphyrins; Pyridines; self-sorting; Sliders; speed; Steric hindrance; supramolecular machinery; Zinc
• ISSN: 1433-7851; 1521-3773
• DOI: 10.1002/anie.201709644

Three supramolecular slider‐on‐deck systems DS1–DS3 were obtained as two‐component aggregates from the sliders S1–S3 and deck D with its three zinc porphyrin (ZnPor) binding sites. The binding of the two‐footed slider to the deck varies with the donor qualities of and the steric hindrance at the pyridine/pyrimidine (pyr) feet, and was effected by two Npyr→ZnPor interactions. Accordingly, the sliders move over the three zinc porphyrins in the deck at different speeds, namely with 32.2, 220, and 440 kHz at room temperature. The addition of N‐methylpyrrolidine as an organocatalyst to DS1–DS3 generates catalytic three‐component machineries. By using a conjugate addition as a probe reaction, we observed a correlation between the operating speed of the slider‐on‐deck systems and the yields of the catalytic reaction. As the thermodynamic binding of the slider decreases, both the frequency of the sliding motion and the yield of the catalytic reaction increase. It's the engine speed! The coupling of an output (here catalysis) to the speed of a mechanical motion is a characteristic feature of machinery. With increasing sliding speed of the three‐component machinery, the catalysis of an organic transformation is enhanced. The effect may be explained by a dynamic neighboring‐group participation.