Synthesis and nonlinear optical properties of a range of 1-ferrocenyl(2-(4-alkyl)pyridiniumyl)ethylene iodides

The preparation of a range of compounds of general formula FcCHCHC5H4N+X, where X=CnH2n+1 (n=1–5, 10 or 18) and O−, was achieved via condensation of the relevant picolinium iodide with ferrocene carboxaldehyde. The spectroscopic properties of these materials were shown to be very similar, however the SHG, measured by the Kurtz powder technique, showed that increasing the alkyl chain above three carbons resulted in a dramatic loss of SHG efficiency. The O− compound also yielded very little SHG.