Sign Response Mechanism of TCA Self-assembled Fluorescence Probe for Cu2+ Detection: FRET Evidence by DFT

A new type of self-assembled molecule ON-OFF fluorescence probe for toxic transition metal ions, made up of thiacalix[4]arene, micelle and fluorescence group, has been studied by DFT/TDDFT method combined with experiment spectra. Since the mechanism of the optical quenching signal response of such self-assembled micelle probe has always been a controversial issue of uncertainty, the spatial construction and geometric structures of the functional units of probe in the Cu2+ ion detecting process were calculated and the mechanism was investigated by the molecular transition orbital pairs method to explore the origination of ON-OFF fluorescence sign response. The results presented that the signal response mechanism of the micelle probe is ascribed to Forster resonance energy transfer (FRET) which provides new sights different from most of the conclusions by the related research work reported.