María Jesús Baena

Influence of the host–guest interactions on the ferroelectric properties of mononuclear orthopalladated metallomesogen mixtures

A new series of four mononuclear orthopalladated complexes which contain a Schiff base and an aliphatic β-diketone as ligands is described. The miscibility of the modified complexes in a standard organic host material is improved in comparison with complexes studied previously. The increased solubility of the complexes leads to ferroelectric organometallic–organic mixtures with lower viscosities and switching times than purely organometallic mixtures, while the spontaneous polarization (Ps) values are maintained or increased.

ortho-Palladated metallomesogens: the effects of structural modifications on their liquid crystalline behaviour

The influence of structural changes such as the length, nature or number of terminal chains and the nature of the intermetallic bridge, on the liquid crystalline properties of palladium complexes [Pd(µ-X)Lj]2 (X–= CH3COO–, Cl–, Br–) derived from imines is reported. Acetato bridges are unfavourable for liquid crystal behaviour, but both halogen bridges clearly promote mesophase formation; SA and SC where X is Cl, and SA and N where X is Br. As far as the terminal tails are concerned, three main conclusions can be drawn: (i) the longer the terminal chains, the lower the melting points and the more ordered the mesophases, (ii) alkoxy tails increase the melting points but stabilize more ordered phases in comparison with alkyl tails, and (iii) the presence of a terminal substituent in the freely rotating anilinic ring has a more favourable effect on mesophase formation than when it is in the fixed (ortho-palladated) aldehydic ring. X-Ray experiments in the mesophase have revealed that molecular interdigitation is only present for the complexes containing two tails.