The recognition and electrochemiluminescence response of benzo[6]urils to polycyclic aromatic hydrocarbons

Abstract

Fluorescence spectroscopy, ¹H NMR spectroscopy and quantum chemical calculations were used to investigate the interactions of benzo[6]urils with polycyclic aromatic hydrocarbons acting as the guest molecules. The fluorescence emission of the host was decreased upon the addition of an increasing amount of the guest molecules, providing an association constant in the range of 8.0 × 10²–7.5 × 10⁴ L mol⁻¹ obtained via non-linear curve fitting, and the formation of host–guest complexes in a 1 : 1 ratio was confirmed using Job's plot analysis. In addition, the ¹H NMR spectra also supported the formation of the interaction complexes with changes in the chemical shifts of the aromatic protons in the host molecules being observed in the presence of the guest molecules. The calculation results provided the structures of the encapsulation complexes with the driving force attributed to the formation of hydrogen bonds between the benzo[6]urils host and the guest molecules. The unique property of luminescence with electrochemical reaction was discovered in methyl-substituted benzo[6]uril, which has great potential as a new type of electrochemiluminescent material.