Synthesis and nonlinear optical properties of novel conjugated small molecules based on coumarin donor

Novel electronic donor with polycyclic structure based on coumarin was designed and prepared. Pyrrolidine acting as an isolated group was introduced to the donor by the Buchwald-Hartwig amination reaction. Such a novel electronic donor demonstrated great electron-donating capability and an excellent isolation effect. Both chromophores exhibited a D-π-A-π-A molecular structure. Such a structure has great advantages in energy matching, dipole interaction, and electron transfer, compared to the single D-π-A structure. The chemical structures of novel chromophores based on this donor were characterized by ¹H nuclear magnetic resonance spectroscopy, ¹³C nuclear magnetic resonance spectroscopy, and mass spectrometry. The largest electro-optic coefficients are approximately 31.2 and 42.6 pm/V for chromophores NLO-C and NLO-P, respectively, at 1310 nm; otherwise, both chromophores NLO-C and NLO-P exhibit high thermal decomposition temperatures, i.e., 276 and 237 °C, respectively.