4 Conclusions
The different stable conformations of probe C23 were found through theoretical method which explained the no fluorescent character of the probe itself. The extreme points of electrostatic potential of C23 showed the potential reaction sites with the HSA and SO2. After the Michael addition reaction with SO2 (HSO3-1), some rotated C-C bonds in C23 were saturated in CS structure which reduced the number of the stable conformations and led to the blue fluorescence generation. The electron excitation analysis indicated the charge transfer process in the C23 and CS when the molecules were under optical excitation. These results provided the insights in preparing a wide range of fluorescent probes and great potential for widespread industrial applications.