Synthesis and spectral studies on some 3d metal complexes of a mesogenic ligand, N-(4′′′-n-butylphenyl)-4-(4′-hexyloxybenzoate)salicylaldimine

A mesogenic (nematic) Schiff's base, N-(4′′′-n-butylphenyl)-4-(4′-hexyloxy benzoate)salicylaldimine, Hbphbsal, (abbreviated as HL1), was synthesized and its structure studied by elemental analyses, mass, NMR and IR spectra. A series of mesogenic/non-mesogenic 3d metal complexes of the general formula, [M(L1)2]n where MII = Mn, Co, Ni, Cu and Zn has been prepared and structures were studied by various spectroscopic techniques. Spectral studies imply coordination of the ligand (HL1) as uni-negative bi/tri-dentate species to the metal ions, rendering overall geometry to distorted square planar (in case of CuII complex) and octahedral geometry. The ESR spectra confirmed the presence of mixed copper–nitrogen and oxygen bonds in the chelate based on the g׀׀ value. The CuII, CoII and NiII complexes were found to be mesogenic (nematic) and their transition, melting and clearing points deviated from the ligand upon complexation.

Research Highlights
► The work reveals the synthesis and spectral Studies of some 3d metal complexes.
► The mesogenic ligand yielded the metallomesogenic CoII, NiII and CuII complexes.
► We have included the non-mesogenic MnII, and ZnII complexes.
► The spectral studies for investigating the bonding nature of the ligand.
► Besides the physical characteristics and geometry of the complexes.