Nonlinear optical properties of push-pull systems containing [2.2]paracyclophane: Theoretical study via elongation method

We report a systematic theoretical study of nonlinear optical (NLO) properties of [2.2]paracyclophane-based push-pull polymers substituted in the terminal positions. The effect of substituents as well as extension of through-bond/through-space conjugation in molecular linker were estimated using elongation finite-field method. The results show that inclusion of paracyclophane (pCp) into the linker framework reduces the NLO response and generates a barrier for intramolecular charge transfer. However, the molecules containing extended π-conjugated chain in combination with pCp show sufficient nonlinearity and, in particular, first hyperpolarizability which is sensitive to substituents push-pull strength similarly with classical NLO organic polymers.