Synthesis of ytterbium bisphthalocyanines: Photophysicochemical properties and nonlinear absorption behavior

• The nonlinear absorption parameters of tetrapyridin-2-yloxy or tetrapyridin-4-yloxy phthalocyaninato ytterbium are reported.
• Both complexes exhibit low fluorescence and singlet oxygen quantum yields and high triplet quantum yields.
• Very low limiting intensity values were obtained.

Herein we report on the syntheses, photophysico-chemical properties and nonlinear absorption parameters of bis-{1(4), 8(11), 15(18), 22(25)-(tetrapyridin-2-yloxy phthalocyaninato)} ytterbium (III) (3) and bis-{1(4), 8(11), 15(18), 22(25)-(tetrapyridin-4-yloxy phthalocyaninato)} ytterbium (III) (4). The fluorescence and singlet oxygen quantum yields obtained for complexes 3 and 4 are low. The triplet quantum yield obtained for complex 3 is high at ΦT = 0.89 whereas for complex 4ΦT = 0.48. The third order optical susceptibility values are of the order: 10−11 esu (for complex 3), and 10−13 esu (for complex 4) while the hyperpolarizability values are of the order: 10−28 esu (for complex 3) and 10−31 esu (for complex 4). Complexes 3 and 4 show two-photon absorption coefficients of the order of 10−46 cm4 s/photon and 10−48 cm4 s/photon, and threshold intensities as low as 0.3 J cm−2 and 0.0045 J cm−2, respectively.

Nonlinear absorption parameters are larger for bis-{1(4), 8(11), 15(18), 22(25)-(tetrapyridin-2-yloxy phthalocyaninato)} ytterbium (III) compared to bis-{1(4), 8(11), 15(18), 22(25)-(tetrapyridin-4-yloxy phthalocyaninato)} ytterbium (III), showing the effects of low symmetry in the latter.Figure optionsDownload high-quality image (60 K)Download as PowerPoint slide