Theoretical investigation of chemosensor for fluoride anion based on amidophthalimide derivatives

Abstract

The interactions among chemosensor substrate, 4-benzoylamido-N-methylphthalimide (BMP1), and different halide anions (F−, Cl−, and Br−) have been theoretically investigated at the B3LYP/6-31+G(d) level with the basis set superposition error correction. It turned out that the intermolecular proton transfer causes the colorimetric and fluorescent signaling of BMP1 for F−. The deprotonated complex BMP1−···H+···F− is formed for the deprotonation process of chemosensor, and the P orbitals of F− play the key role in the prediction of the optical properties of BMP1−···H+···F−. The inclusion of diffuse functions to the basis set has a significant effect in the structural optimization for investigated complexes. The properties of six designed BMP1 derivatives [containing –CN and/or –N(CH3)2 substituent(s)] have been calculated. Our results suggest that the mono-substituted (on the methylphthalimide moiety) and bi-substituted [–N(CH3)2 and –CN groups on benzoylamido and methylphthalimide moieties, respectively] derivatives are expected to be the promising candidates for ratiometric fluorescent fluoride chemosensors as well as chromogenic chemosensor, whereas for mono-substituted (on the benzoylamido moiety) and bi-substituted [–CN and –N(CH3)2 on benzoylamido and methylphthalimide moieties, respectively] derivatives can serve as chromogenic fluoride chemosensor only. Furthermore, the derivatives with mono-CN substituents are promising luminescent materials for organic light emitting diodes as well. The interactions between chemosensor substrate (BMP1) and different halide anions (F−, Cl−, and Br−) have been theoretically investigated. Six derivatives of BMP1 have been designed by introducing electron-donating [–N(CH3)2] or -withdrawing (–CN) group with the aim to design novel chemosensors.