Novel axial fullerenol-substituted hyperbranched phthalocyanines:Synthesis, photophysical and nonlinear optical properties

In this study, we designed and synthesized a novel hyperbranched structure of phthalocyanine compound, which was axially linked with fullerenol to form a D-A (donor and acceptor) type compound HLaPc-C 60 (OH) n . In this configuration, phthalocyanine acts as the electron donor, while fullerenol as the acceptor. The formation of hyperbranched structures and the introduction of fullerenol expanded the π-conjugation system and weakened the aggregation phenomenon. The unique three-dimensional hyperbranched structure with abundance of D-A enhances the photoinduced intramolecular electron transfer (PET) and energy transfer (ET) processes. This improvement contributes to the compound's excellent nonlinear optical properties. In addition, we prepared a PPSU-based composite film (HLaPc-C 60 (OH) n /PPSU) in which the interaction between the similar sulfonyl structures and HLaPc enhances its dispersion. The values of large third-order nonlinear susceptibility (Im[χ (3) ]) of 2.20 × 10 −8  esu and a low limit threshold (Ilim) of 0.91 J/cm 2 demonstrate that the composite film material has considerable potential applications as optical limiters.