Homo dinuclear lanthanide(III) complexes of a mesogenic Schiff-base, N,N′-di-(4-decyloxysalicylidene)-1′,6′-diaminohexane: Synthesis and characterization

摘要

A mesogenic Schiff-base, N,N′-di-(4-decyloxysalicylidene)-1′, 6′-diaminohexane, H_2ddsdh (abbreviated as H_2L ~2) that exhibits smectic-B (SmB) mesophase, was synthesized and its structure studied by elemental analysis, mass spectrometry, NMR && IR spectral techniques. The Schiff-base, H_2L~2, upon condensation with hydrated lanthanide(III) nitrates, yields LnIII complexes of the general composition [Ln_2(L~2H _2)_3(NO_3)_4](NO_3)_ 2, where Ln = La, Pr, Nd, Sm, Eu, Gd, Tb, Dy and Ho. IR and NMR spectral data imply a bi-dentate bonding of the Schiff-base in its zwitterionic form (as L2H2) to the LnIII ions through two phenolate oxygens. The POM and DSC studies reveal that none of the Ln III complexes exhibits mesomorphism. Fluorescence studies show that the TbIII complex displays characteristic metal-centered fluorescence (solution state).