Ionic manipulation of charge-transfer and photodynamics of [60]fullerene confined in pyrrolo-tetrathiafulvalene cage

Abstract

A cage molecule incorporating three electron donating monopyrrolotetrathiafulvalene units was synthesised to host electron accepting [60]fullerenes. Formation of a strong 1:1 donor-acceptor (D-A) complex C60⊂1 was confirmed by solid state X-ray analysis as well as 1H NMR and absorption spectroscopic analyses of the arising charge-transfer (CT) band (λ = 735 nm, ϵ ≈ 840 M-1 cm-1). Inserting Li+ inside the [60]fullerene increased the binding 28-fold (Ka = 3.7 × 106 M-1) and a large bathochromic shift of the CT band to the near infrared (NIR) region (λ = 1104 nm, ϵ ≈ 4800 M-1 cm-1) was observed.