Aggregation-induced emission effect of hydrazinyldiphenyl sulfone central fluorophores

We synthesized 4, 4′-Di ((E)-2-(4-4-aniline) hydrazinyldiphenyl sulfones (DHS1-4) of D-π-A-π-D and characterized them using NMR, IR, and element analysis. The investigation of photophysical properties in THF and aggregation-induced emission (AIE) effects in THF/H2O mixture solvent of these fluorophores were carried out respectively. DHS-4 displayed the strongest AIE effect in THF/H2O mixture solvent, and the value of I/I0 reached to 136. The nano-size aggregate states in THF/H2O mixture solvent of these compounds were determined by Scanning Electronic Microscopy (SEM) technology and fluorescent microscope imaging. AIE mechanism was explained by molecular dynamics (MD) simulation methods. The special packing manners of V-shape molecules can avoid effectively face-to-face π-π stacking. The inter-molecular hydrogen bonding interactions affected the packing in the aggregate state and assisted their RIR (restricted intramolecular rotation) processes. Furthermore, living cell imaging of DHS-3 showed the bright blue fluorescence in A549 living cell. It indicates that DHS-3 can penetrate the cell membrane and aggregate in A549 living cell, which expands a new area to cell fluorescence staining.