An efficient theoretical study on host-guest interactions of a fluoride chemosensor with F−, Cl− and Br−

The interactions between chemosensor, 4-benzoylamido-N-butyl-1,8-naphthalimide (1), and different halides (F−, Cl− and Br−) were theoretically investigated. The unique selectivity for fluoride was definitely demonstrated, which can be ascribed to its ability of deprotonating the amido of host sensor. Both absorption and fluorescence spectra of neutral and deprotonated sensor were successfully simulated using TD-DFT method. The nature of characteristic electronic transition was analyzed by charge difference density (CDD) and frontier molecular orbital (FMO). It was found that intermolecular proton transfer (IPT) is responsible to the colorimetric and fluorescent signaling of chemosensor 1 for fluoride ion. The efficient quantum calculation methods can be used for both qualitative and quantitative studies on the host-guest interactions for such kind of chemosensor compounds.