Synthesis and characterization of transition metal complexes for nonlinear optical activity

Abstract

Transition metal complexes have become an integral part of nonlinear optics. The design of technologically useful metal complexes poses a continuous challenge for inorganic chemists. Keeping this in view, the present thesis addresses three major areas. First, to design and develop transition metal complexes using ligands with extensive π- conjugation. Second, to synthesize and characterize all the complexes by established techniques like Elemental analysis, FT-IR spectroscopy, UV-Vis spectroscopy, Single crystal XRD and NMR spectroscopy. Lastly, to evaluate the nonlinear optical activity of the complexes using techniques like Z-scan technique and Optical Kerr Gate method and thereby establishing a relationship between the complex structure and optical nonlinearity. All the complexes exhibited third-order optical nonlinearity. The Fe(II), Ni(II) and Zn(II) complexes of 1,2-diaminobenzene and 2-hydroxynaphthaldehyde and Co(II), Ni(II) and Zn(II) complexes of 3,4-diaminobenzophenone and 2- hydroxynaphthaldehyde displayed a two-photon absorption. On the other hand, Ni(II), Cu(II) and Zn(II) complexes of Schiff base ligands of dimethylamino benzaldehyde and thiosemicarbazide and Cu(I) complex with 1,10-phenanthroline and triphenylphosphine exhibited three-photon absorption mechanism. The ionic liquid tagged Schiff base metal complex also revealed effective two photon absorption with good third-order optical response. The nonlinear optical study on the complexes revealed encouraging results which can act as a base for any further improvement and their usage as optical limiters.