Indolo[3,2-b]carbazole derivative as a fluorescent probe for fluoride ion and carbon dioxide detections

Abstract

Fluorescent probes can detect fluoride ion and carbon dioxide to ensure their concentrations at reasonable levels to protect human health. Although numerous fluorescent probes have been developed in the last decades, these probes still face some performance challenges: complicated molecular structures, unremarkable changes and long responsive times. Moreover, the detections of fluoride ion and carbon dioxide are usually separated and fluorescent probes which can detect fluoride ion and carbon dioxide simultaneously are rare. To improve this situation, in this work, an indolo[3,2-b]carbazole derivative, DP-ICZ, was designed. This compound had simple structure and facile preparation procedure. It displayed high selectivity toward fluoride ion over other ions. Obvious changes of color, fluorescence band and intensity happened in a few seconds after the addition of fluoride ion. Meanwhile, after activated by fluoride ion, DP-ICZ was also suitable for carbon dioxide detection. Its detection limits for fluoride ion and carbon dioxide were 23.3μM and 1.07μM respectively. Through PL spectra and NMR analysis, its detection mechanisms were proved to be deprotonation by fluoride ion and recovery by carbon dioxide respectively. Our study presents an effective basic group based on which researchers can develop new fluorescent probes with simple structures, high sensitivities, short responsive times and the abilities to detect fluoride ion and carbon dioxide simultaneously.