frst adding anions like cyanide then copper. In addition, to
further explore the utility of sensor 6-CN as an ion-selective
chemosensor for Cu2+, competitive experiments were carried
out in the presence of 20 equiv. of Cu2+ and 20 equiv. of various
other metal ions, the fuorescent emission spectrum of sensor
6-CN with Cu2+ was not infuenced by the subsequent addition
of other competing metal ions (ESI, Fig. S13†).