Novel axially substituted lanthanum phthalocyanines: Synthesis, photophysical and nonlinear optical properties

Materials with excellent nonlinear optical (NLO) properties are usually applied in optoelectronics and optical limiting devices. Photoinduced intramolecular electron transfer (PET) and energy transfer (ET) play an important role in enhanced NLO properties. Through axially connected anthraquinone to phthalocyanine, two types of novel lanthanum phthalocyanine (LaPc-Aqn and HLaPc-Aqn) were designed to effectively improve PET/ET process, and thus leading to excellent NLO properties. Hyperbranched phthalocyanines possess enhanced NLO properties owing to their special three-dimensional structures that have more donor–acceptor (D–A) systems in their cell structure than lanthanum phthalocyanines. The uniform polyphenylsulfone composite film(HLaPc-Aqn-PPSU) was prepared by a simple solution casting method according to the “like dissolves like” theory. The values of large third-order nonlinear susceptibility (Im[χ (3) ]) and low limit threshold (I lim ) were 1.51 × 10 −9  esu and 0.015 J/cm 2 , respectively, demonstrating that the film had great optical limiting performance. Such research can contribute to the development of novel phthalocyanine materials for nonlinear optics and optical limiting devices.