The sensing potential of 1 toward HSO3
− was investigated carefully
in PBS buffer (pH = 7.4, 10 mM). Fig. 2 shows the fluorescence
response of probe 1 (10 M) with different amounts of HSO3
−.
The free probe 1 exhibited very weak fluorescence emission at
560 nm which was induced by the – conjugation of probe 1.
Upon addition of HSO3
−,the emission at 465 nm increased remarkably,
which could be attributed to the new formed 2-methylene
benzo[e]indoline moiety. The fluorescence intensities became constant
when the amount of HSO3
− reached 5 equiv., led to a ca.
90-fold fluorescence enhancement. Meanwhile, an obvious fluorescence
color change from dark to cyan was also observed (inset
0