Ferroelectric and luminescence properties of zinc(ii) and platinum(ii) soft complexes

Zinc(ii) and platinum(ii) complexes [M(X-4-C₁₈-salmmen)] (M = Zn (1) and Pt (2), X = R, S (optical isomer) and rac (racemate), salmmen = N,N′-monomethylenebis-salicylideneimine) were synthesized and investigated. The series of compounds represented by 1 (R, S and rac forms) display liquid crystalline state behaviour at 413 K, and exhibit both ferroelectric and fluorescence properties, while the compounds represented by 2 (R and S, and rac forms) do not display liquid crystal behaviour but do exhibit ferroelectric and fluorescence properties. The ferroelectric behaviour was confirmed by second harmonic generation (SHG) experiments. It is considered that the motion and fluctuation of the long alkyl chains in these complexes results in the observed ferroelectric properties.