The nonlinear refraction and nonlinear absorption in 4-(4,6-diaminopyrimidin-2-ylthio) substituted double-decker Lu(III) phthalocyanine

A 4-(4,6-diaminopyrimidin-2-ylthio) substituted double-decker Lu(III) phthalocyanines (4) have been prepared and characterized by elemental analysis, IR, UV–vis and 1H NMR spectroscopies. The nonlinear refractive index, nonlinear absorption and the optical limiting (OL) performance of the compound 4 in a 0.5 mm spectroscopic cell in DMF solution were investigated by using 4 ns pulse laser at 532 nm. Z-scan experiments have been conducted between 0.24 and 2.39 GW/cm2 peak intensities for 10 Hz repetition rate and also between 2.39 and 23.89 GW/cm2 peak intensities for 1 Hz repetition rate. The thermal effect contributes to the nonlinear response of the material higher than 0.72 GW/cm2 peak intensity at 10 Hz. We measured the effective nonlinear refractive index of the material as 1.2×10−11 esu at 3.5×10−4 M concentration with the peak intensity less than 0.72 GW/cm2 and we found that nonlinear absorption was very small. On the other hand, when concentration is increased to 2.4×10−3 M material's nonlinear absorption becomes dominant mechanism for the nonlinear response and the compound 4 indicates OL behavior at 2.4×10−3 M concentration.