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Switching Dual Catalysis without Molecular Switch: Using A Multicomponent Information System for Reversible Reconfiguration of Catalytic Machinery

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journal contribution
posted on 19.09.2019, 18:33 by Abir Goswami, Thomas Paululat, Michael Schmittel
Different from the current paradigms of chemistry, a switchable catalytic system is presented that does not rely on a molecular switch in different toggling states but on a smart seven-component mixture that manages the reversible ON/OFF regulation of two catalytic processes. Hereunto, the workflow of two multicomponent rotary catalytic machineries was interlinked by the simultaneous shuffling of two components (metal and ligand) requiring perfect signaling in a 13-component system (see Movie 1). This network underwent reversible switching over three cycles as demonstrated by 1H NMR, UV–vis, and fluorescence spectroscopies and electrospray ionization mass spectrometry. Addition and removal of zinc­(II) ions trigger three distinct events in parallel: the (i) mutually dependent self-assembly of three-component nanorotors and two-component reservoirs by resorting components, (ii) toggling between vastly different rotational exchange rates in the self-assembled rotors that directly affect catalysis, and (iii) toggling between two diverse catalytic reactions in a fully reproducible manner. Because of this information system, the concentrations of free aza-crown ether 7 and its complex with copper­(I), that is, [Cu­(7)]+, which represent the effective catalysts, are up- and downregulated in a manner to alternately switch ON/OFF a catalytic conjugate addition and a click reaction.