Unexpected Supramolecular Induced Redox Switching in Sandwich Gd Bisphthalocyaninate

The redox state of the phthalocyanine in sandwich lanthanide complexes is crucial for their applications. In this work, we demonstrate that the cation-induced supramolecular assembly of crown-substituted phthalocyanine lanthanide complexes Ln[(15C5)4Pc]2 can be used to control the redox state of the ligand simultaneously with the coordination sphere of the central metal. We achieve unprecedented redox switching of phthalocyanine ligands in a double-decker Gd(III) complex, resulting from the intramolecular inclusion of potassium cations between the decks with simultaneous twisting of the ligands (the skew angle between them decreases from 44.61° to 0.21°). Such a structural change leads to an increase in the deck to deck distance and drastically facilitates ligand reduction. It was demonstated that this process is anion dependent. Thus, only potassium salts of weak acids (KOPiv, KOAc) induce intramolecular inclusion of cations with redox switching in contrast to salts of strong acids (KBr, KOPic, KSCN and KPF6), where such a redox process does not occur. This breakthrough opens new avenues for controlling the electrochromic properties of phthalocyanines, along with other properties, such as electrical conductivity, optics, etc.