Photoluminescent Hemidisc‐Shaped Liquid Crystalline Nickel(II) Schiff‐Base Complexes

Abstract

Abstract A series of new photoluminescent hemidisc‐shaped Ni II Schiff‐base complexes has been synthesized. The ligands and their complexes were characterized by FTIR and 1 H and 13 C NMR spectroscopy, FAB‐MS and elemental analysis. The mesomorphic behaviour of the ligands and their complexes was probed by polarizing optical microscopy and differential scanning calorimetry. The molecular organization in the mesophase was determined by X‐ray diffraction techniques. The ligands are nonmesogenic but their complexes exhibited thermally stable rectangular columnar (Col r ) mesophases at about 227 °C. The complexes are blue‐light emitters in solution (ca. 434 nm, Φ = 19 %) and in the solid state (ca. 469 nm, Φ = 7 %) at λ ex = 350 nm. A DFT study was carried out using DMol3 at the BLYP/DNP level to obtain a stable, optimized structure, which revealed a distorted square‐planar geometry for the nickel complexes.