A Divalent Pentastable Redox-Switchable Donor-Acceptor Rotaxane
H.V. Schröder, H. Hupatz, A.J. Achazi, S. Sobottka, B. Sarkar, B. Paulus, C.A. Schalley – 2017
Donor-acceptor materials with small HOMO-LUMO gaps are important in molecular electronics, but often difficult to synthesise. A simple and efficient way to position tetrathiafulvalene (TTF) as the donor and naphthalene diamide (NDI) as the acceptor in close proximity to each other in a divalent crown/ammonium pseudorotaxane is presented. The divalent design provides high chelate cooperativity and much stronger binding compared to a monovalent analogue. The pseudorotaxane is then doubly interlocked by stoppering it in a catalyst-free 1,3-dipolar cycloaddition. UV/Vis and cyclic voltammetry experiments with the resulting rotaxane reveal the optoelectronic properties of the intramolecular charge-transfer with a small HOMO-LUMO energy gap. Redox-switching experiments show the rotaxane to be pentastable. DFT calculations provide insight into the electronic structures of the five redox-states.