In recent years, fluorescence sensor systems for Ca2+ and F−
detection have attracted great attentions owing to their operational
simplicity and real-time detection, etc. Most of the reported sensors are based on organic dyes with special ion recognition unites
containing rich amino, hydroxyl and carboxyl groups that can bind
strongly to Ca2+ or F− [15–23]. For instance, Dong et al. studied
an organic salt as a fluorescent probe with ratiometric emission at
490 and 594 nm based on intramolecular charge transfer for Ca2+
determination. And the probe displayed high selectivity for Ca2+
and a large Stokes shift of 189 nm [16]. Wang and co-workers synthesized benzoselenadiazole based diarylamine as a near-infrared
optical sensor for F−, and the designed sensor showed a turn-on
ratiometric fluorescence signalling with F− by inhibiting the excited
state intramolecular proton transfer processes [21]. However, these
reported dyes based probes for Ca2+ and F− are faced with the poor
water solubility which severely restricts their application in water
environment systems. Moreover, synthesis of many organic dyes is
complex and expensive.