Computational and experimental assessment on the nonlinear optical properties of platinum(II) arylacetylides with donor-acceptor structures

Abstract

The nonlinear optical properties of eight platinum acetylides with donor-acceptor structures were investigated via computational and experimental methods, and the relationship between the structures and the properties was discussed deeply based on the computational and experimental results. The contributions of all the atoms to the electronic density of HOMO and LUMO of the platinum acetylide complexes were calculated using the time-dependent density functional theory (TD-DFT) with exchange correlation function B3LYP, and the first-order hyperpolarizabilities of them were also calculated in the same conditions. Z-scan results indicated that the electronic asymmetric property is an important factor affected the nonlinear optical properties, and the nonlinear absorption properties of a molecule can be enhanced by enlarging the conjugate length of the molecule. The nonlinear optical property of the molecules with two electron donor groups at both sides of their skeletons are better than that of the molecules with two electron withdrawing groups. Enlarging the conjugated area in the center of the molecule was disadvantageous to the nonlinear absorption property of the molecule, and the large contribution of the heavy-atom to the electronic density of HOMO of a molecule doesn’t mean the better nonlinear absorption property. The large values of σe/σg and the short fluorescence lifetimes of the complexes infer that the nonlinear absorption behavior of the titles complexes should be originated reverse saturable absorption.