Preparation, characterization, two-photon absorption and optical limiting properties of a novel metal complex containing carbazole

The title complex, NiL2 · C6H6, has been successfully synthesized in good yield from reaction of a novel Schiff base ligand and nickel acetate in ethanol. The ligand (hereafter abbreviated as HL), derived from S-methyldithiocarbazate and N-ethyl-3-formylcarbazole, loses a proton from its tautomeric thiol form and coordinates to Ni(II) via the mercapto sulphur and β-nitrogen atoms upon complex formation. The structural, optical and physicochemical properties of the complex were characterized by X-ray diffraction, infrared spectroscopy, electronic spectra, thermal analyse and photoluminescence measurement. Single crystal X-ray diffraction analysis established that the geometry of Ni(II) is in a distorted square planar cis-configuration with two carbazole moieties on the same side and the two carbazole rings are almost parallel, forming a conjugated and electronic delocalization system. Two-photon absorption (TPA) coefficient β and cross-section of the complex were obtained by using the open aperture Z-scan technique. The optical limiting (OL) response was also measured.