Compound 1, containing an octamethylferrocene donor linked to a nitrothiophene acceptor via an ethenyl linker, shows a static first hyperpolarisability β0 of 95(±10) × 10−30 esu, which is reduced to 10(±2) × 10−30 esu on oxidation of the octamethylferrocene unit; this provides for a simple redox-based switching of the NLO characteristics of the compound.
