Photoluminescence and nonlinear optical properties of triple stranded helicates based metallo-supramolecular architectures

Abstract

The present work is dedicated to the investigation of the linear and nonlinear optical properties of triple stranded metallohelicates in both solid state and in solution. The studied metallohelicates are obtained by a self-assembly process involving three ligands (strands) and “octahedral” like transition metal cations such as iron (II), cobalt (II), nickel (II) and zinc(II), The use of diverse metal cation is motivated by the study of their influence on the linear and the nonlinear optical properties. The morphology of the thin films of the resulting metallohelicates obtained by spin coating deposition were examined by means of Atomic Force Microscopy (AFM). The properties of these thin films were examined by means of Photoluminescence, Second and Third Harmonic Generation techniques and Z-scan method. The experimental studies allowed us to determine the optical constants. The nonlinear optical susceptibilities of the studied supramolecular metallohelicates were determined by using theoretical models. In this study we have used density functional theory (DFT) to calculate linear and nonlinear optical properties of the investigated molecule. The influence of the interligand π→π* transmetallic charge-transfer, energy gap and multipole moments at the linear and nonlinear optical properties were discussed.