The studies performed allowed the verification that thefilms of 3aare applicable for the detection of CN− within a pH range of 7.4−8.8. Since BM is fluorescent, 31 the same system was exposed to UV light after immersion in the solutions (Figure 1B), and it is possible to observe that the blue
fluorescent color of thefilm corresponding to 3ais changed only if the dye is deprotonated to3b, which has a pale red color.