Double Hook Perylene Diimide as a New Receptor for PAHs: An Experimental and Theoretical Study

Abstract

In a one-step reaction, we prepared a dibenzylamine perylene diimide derivative (PDI). Its double hook structure allows for self-association with a constant of K_d ∼10⁸ M^-1 determined by fluorescence. We confirmed its ability to bind PAHs using UV/Vis, fluorescence, and ¹ H NMR titrations in CHCl₃ . The complex formation signature in UV/vis is a new band at 567 nm. The calculated binding constants (K_a ∼10⁴ M^-1 ) follow the trend pyrene>perylene>phenanthrene>naphthalene>anthracene. Theoretical modeling of these systems using DFT ωB97X-D/6-311G(d,p) proved helpful in rationalizing the complex formation and the observed association trend. The distinctive signal in UV/vis is due to a charge transfer in the complex from orbitals in the guest to the host. SAPT(DFT) confirmed that the driving forces in the complex formation are exchange and dispersion (π-π interactions). Still, the recognition ability depends on the electrostatic component of the interaction, a minor fraction.

Keywords: aromatic molecules; binding constants; noncovalent interaction analysis; perylene diimide; pi-interaction.