A Divalent Pentastable Redox-Switchable Donor-Acceptor Rotaxane
H. V. Schröder, H. Hupatz, A. J. Achazi, S. Sobottka, B. Sarkar, B. Paulus and C. A. Schalley – 2017
Donor–acceptor materials with small HOMO–LUMO gaps are important in molecular electronics, but are 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 with a monovalent analogue. The pseudorotaxane was then doubly interlocked by stoppering it in a catalyst-free 1,3-dipolar cycloaddition. UV/Vis and cyclic voltammetry experiments with the resulting rotaxane revealed the optoelectronic properties of an intramolecular charge transfer with a small HOMO–LUMO energy gap. Redox-switching experiments showed the rotaxane to be pentastable. DFT calculations provided insights into the electronic structures of the five redox states.