Synthesis, characterization and third-order nonlinear optical properties of bromo[tri-α-(2,4-dimethyl-3-pentyloxy)subphthalocyanine]boron complex

A new subphthalocyanine complex, bromo[tri-α-(2,4-dimethyl-3- pentyloxy)subphthalocyanine]boron, has been synthesized and characterized by elemental analysis, MALDI-TOF-MS, FT-IR and UV-vis spectroscopy. Its third-order nonlinear optical (NLO) properties in ethanol solution have been studied by Z-scan technique using 8 ns laser pulses at 532 nm. The results reveal that the new complex exhibits strong NLO absorption effect (α₂ = 3.7 × 10^-10 m W^-1) and self-focusing refractive performance (n₂ = 2.1 × 10^-17 m² W ^-1). The effective third-order NLO susceptibility (χ⁽³⁾) and the molecular second-order hyperpolarizability (γ) value were calculated to be 1.12 × 10^-11 and ∼6.8 × 10^-28 esu, respectively. All of the values are comparable to those of the reported good NLO materials. In addition, the effects of cone-shaped molecular structure and axially heavy-atom (Br) substitution on third-order NLO properties are discussed.