Complexes of 3d metal ions of the Schiff-base, 4-hydroxy-N′-(4′-octadecyloxybenzylidene)benzohydrazide: Synthesis, spectral studies, crystal structure and magnetic interactions

A novel hydrazide-based mesogenic (nematic) Schiff-base, 4-hydroxy-N′-(4′-octadecyloxybenzylidene)benzohydrazide, (Hhodbbh) (abbreviated as HL3), was prepared and its structure studied by elemental analyses, mass, NMR and IR spectra and single crystal XRD (triclinic space group P  1¯ with Z = 2) techniques. The Schiff-base behaves as a non-deprotonated bi-dentate species in its metal complexes of the general formula, [M(HL3)2](OAc)2 [M = Mn, Co, Ni, Cu and Zn]. The IR and NMR spectral data imply bonding of HL3 species through amidic oxygen and azomethine nitrogen atoms. The MnII and CoII complexes show gradual decrease in the χMT product with lowering of temperature and negative Weiss constants characteristic of anti-ferromagnetic interaction. The MnII complex shows magnetic hysteresis loops at 2.0 K.

Graphical abstractA nematic hydrazide-based Schiff-base, 4-Hydroxy-N′-(4′-octadecyloxybenzylidene)benzohydrazide, (HL3), yields non-mesogenic complexes, [M(HL3)2](OAc)2, (M = Mn, Co, Cu and Zn) and a mesogenic NiII complex. The MnII and CoII complexes show anti-ferromagnetic interaction and a weak ferromagnetic coupling at lower temperatures; further, the former complex shows magnetic hysteresis loops.Figure optionsDownload full-size imageDownload as PowerPoint slide