Design and synthesis of 1,10-phenanthroline based Zn(II) complexes bearing 1D push–pull NLO-phores for tunable quadratic nonlinear optical properties

Three Zn(II) complexes bearing 1,10-phenanthroline and one-dimensional (1D) push–pull NLO-phores with various acceptor strength as well as π-conjugation length have been synthesized in high yields for two-dimensional (2D) nonlinear optical response. The quadratic optical nonlinearity of the ligands and the complexes are measured by the HRS technique. The ligands show small second-order optical nonlinearity (β) comparable to the standard, para-nitroaniline (pNA). However, upon complexation with Zn(II), each complex exhibits large β values showing the importance of metal ion in enhancing the optical nonlinear effect.