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

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 Kd ~108 M-1 determined by fluorescence. We confirmed its ability to bind PAHs using UV/Vis, fluorescence, and 1H NMR titrations in CHCl3. The complex formation signature in UV/vis is a new band at 567nm. The calculated binding constants (Ka~104 M-1) follow the trend pyrene > perylene > phenanthrene > naphthalene > anthracene. Theoretical modeling of these systems using DFTωB97X-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 minoritarian fraction.