Photoinduced electron transfer and redox-type photochromism of a TiO₂-anchored molecular diad

A linear, rigid molecular diad constituted of an electron donor (triarylamine, D) linked to a chromophore [Ru–bis(terpyridine), S] is synthesized; upon anchoring onto a nanocrystalline TiO2 electrodes this produces a charge-separated state D+–S |(e–) TiO2 under illumination decaying with k= 7 × 107 s–1(70%), 3 × 105 s–1(20%) and 4 × 103 s–1(10%) and yielding a photochromic effect at positive polarization.