Complexes of some 4f metal ions of the mesogenic Schiff-base, N,N′-di-(4-decyloxysalicylidene)-1′,3′-diaminobenzene: synthesis and spectral studies

A mesogenic Schiff-base, N, N'-di-(4-decyloxysalicylidene)-1',3'-diaminobenzene, H(2)ddsdbz (abbreviated as H2L), that exhibits a nematic mesophase was synthesized and its structure was studied by elemental analysis, mass spectrometry, NMR, and IR spectral techniques. The Schiff-base, H2L, upon condensation with hydrated lanthanide(III) nitrates yields Ln(III) complexes, [Ln(2)(LH2)(3)(NO3)(4)](NO3)(2), where Ln=La, Pr, Nd, Sm, Eu, Gd, Tb, Dy, and Ho. Analyses of the IR and NMR spectral data imply bidentate Schiff-base through two phenolate oxygen atoms in its zwitterionic form to Ln(III), rendering the overall geometry of the complexes as a seven-coordinate polyhedron-possibly distorted mono-capped octahedron. Polarizing optical microscope and differential scanning calorimetry studies reveal that despite H2L being mesogenic, none of the Ln(III) complexes synthesized under this study exhibits mesomorphism.