Tuning the Dipolar Second-Order Nonlinear Optical Properties of Cyclometalated Platinum(II) Complexes with Tridentate N∧C∧N Binding Ligands

Appropriate functionalization of the cyclometalated ligand, L, and the choice of the ancillary ligand, X, allows the dipolar second-order nonlinear optical response of luminescent [PtLX] complexesin which L is an N<^>C<^>N-coordinated 1,3-di(2-pyridyl)benzene ligand and X is a monodentate halide or acetylide ligandto be controlled. The complementary use of electric-field-induced second-harmonic (EFISH) generation and harmonic light scattering (HLS) measurements demonstrates how the quadratic hyperpolarizability of this appealing family of multifunctional chromophores, characterized by a good transparency throughout much of the visible region, is dominated by an octupolar contribution.