the dramatic increase of the fluorescent intensity shown in Fig. 5
demonstrated the formation of 12.
As Kumari et al.67 proposed that the negative charge on the donor site
has a significant role on the red-shift, therefore, the two negative
charges of 12 would lead to the red-shift. ESI-mass spectrometry
analysis also supported the presence of naphtholate anion (m/z
177.7 [1-2Hþ], calcd m/z 178.1) (Fig. S5). Thus, these results illustrate
that the selective response of 1eCu2þ complex to CN could
be used as a novel cyanide sensor. Moreover, this is the first report
that 1 could sequentially recognize Cu2þ and CN using two different
sensing methods, color change, and fluorescence, to the best
of our knowledge.