FERROELECTRIC METALLOMESOGENIC PALLADIUM(II) COMPLEXES DERIVED FROM BIDENTATE SCHIFF-BASES

The synthesis and characterization of four new chiral palladium(II) complexes (PdL2) derived from chiral Schiff bases of the ligands (L) are reported. The complexes are of the type {Pd-{4-(CnH2n+1O)C6H3(O)CH=NC6N4ZR*}2}, where n = 5, 10; Z = -CH=CHCOO-, -COO-, -O-; R* = -C*H(CH3)COOC4H9. The mesogenic properties of both ligands and complexes have been studied by DSC and optical microscopy. Although only two of the ligands exhibited mesogenic properties, all of the complexes were liquid crystals. Some of these materials display the potentially chiral ferroelectric smectic C phase in addition to a smectic A or cholesteric mesophase. The spontaneous polarization (P(s)) values were measured in the pure compounds. The values obtained are in the range of 40-98 nC/cm2. The relationship between molecular structure and ferroelectric properties is investigated.