Tuning radical structures and nonlinear optical properties of benzoanthanthrenyl/phenalenyl heterodimers under external electric field

The organic radical dimers with unique electronic structure and properties have vast potential applications in multifunctional materials. Herein, a novel radical heterodimer was designed by integrating the benzoanthanthrenyl radical (BR) and the phenalenyl radical (PR). We innovatively employ external electric fields (F_±z) for radical heterodimer (BR-PR) by using the density functional theory (DFT), thereby effectively regulating radical structure and electronic properties. Excitingly, the geometric structure of BR-PR undergoes significant changes under the F_±z. Furthermore, the analyses of natural population analysis (NPA) and electrostatic potential (ESP) maps reveal that the F_±z effectively modulates the interlayer charge transfer in BR-PR. Intriguingly, the critical electric field is found at the F_−z = − 20 × 10^–4 au, and the first hyperpolarizabilities (β_tot) depend on the critical electric field. Compared to the F_−z, the F_z induces a large β_tot value of 2.60 × 10⁴ au (F_z = 60 × 10⁻⁴ au). This important discovery not only opens up new ways for the application of radical heterodimer in the field of nonlinear optics, but also provides valuable insights into the molecular behavior under external electric field regulation.

Graphical Abstract

A novel heterodimer is designed by integrating the benzoanthanthrenyl and the phenalenyl radicals. Under the influence of the F_±z, the radical structure and second-order NLO property of heterodimer are regulated effectively.

A novel heterodimer is designed by integrating the benzoanthanthrenyl and the phenalenyl radicals. Under the influence of the F_±z, the radical structure and second-order NLO property of heterodimer are regulated effectively.