Synthesis and characterization of the novel 4-(1-(pyridin-4-yl) ethoxyl) substituted bis(phthalocyaninato) rare earth complexes and investigation of their two-photon absorption-based third-order non-linear optical properties

Novel 4-(1-(pyridin-4-yl) ethoxyl) substituted double-decker rare earth phthalocyanine complexes were synthesized starting from (R)-4-(1-(pyridin-4-yl) ethoxy) phthalonitrile with proper rare earth metal acetates in octanol catalyzed by 1,8-diazabicyclo[5.4.0]undec‑7-ene at 300 °C. The new starting phthalonitrile compound was obtained from (R)-1-(pyridin-4-yl) ethan-1-ol and 4-nitrophthalonitrile in acetonitrile at reflux temperature in the presence of potassium carbonate as a catalyst. The characterization of the synthesized and isolated compounds was performed by elemental analysis, infrared, ultraviolet-visible, proton and correlation spectroscopy nuclear magnetic resonance, and matrix-assisted laser desorption/ionization time-of-flight mass spectroscopic methods. Nonlinear optical responses of all complexes are investigated using the Z-scan method. The nonlinear absorption coefficient, two-photon absorption cross-section, and the imaginary part of the nonlinear susceptibility of complexes are calculated for each discrete concentration. All these nonlinear parameters of our rare-earth coordinated double-decker phthalocyanines present a decrement due to the aggregation under high optic powers, which result in sequential two-photon absorption for smaller ionic radii.