Redox-Switchable Poly-Lewis Acids Allow the Controlled Release of Guests

Presently, there is a notable interest in poly-Lewis acids (PLAs), their host-guest chemistry and their application in catalytic processes. The present study combines PLAs with redox-active dibenzo[a,e]cyclooctatetraene (dbCOT) units. dbCOT-based PLAs can be planarised by a two-electron reduction. The molecular structures of the reduced PLAs, studied by sc-XRD experiments and DFT calculations, show the formation of extended $\pi$ -systems. This $\pi$ -system extends to the Lewis acid functions and reduces their acidity. This allows a controlled release of complexed guest molecules. Oxidation regenerates the original Lewis acidity. Such reduction/oxidation cycles were also applied to an Al─P coordination polymer. sc-XRD shows the connectivity of the coordination polymer to remain unchanged, so that the polymer is stable in the neutral and reduced state. The possibility of switching such dbCOT-based PLAs and their adducts as well as the formed coordination polymers between two states with different structures and electronic compositions is of interest for the development of functional materials in the fields of electronics, optics and magnetism as well as for the development of switchable catalysts.