Fig. 2. (A) Synthetic routes of the AIE fluorophore HLZ-BTED based on BBTD and TPE. (B) NIR-II fluorescence images (808 nm excitation, 1000 LP, 10 ms) of HLZ-BTED in pure tetrahydrofuran (THF) and a THF/water mixture with 95% water volume fraction (f_w). The concentration is 2 × 10^–5 M. (C) Fluorescence (FL) emission spectra of HLZ-BTED in THF/water mixtures with different f_w (0% to 95%). Excitation wavelength at 785 nm. (D) FL intensity ratio (calculated from Fig. 2C) (I/I₀) of the HLZ-BTED fluorophore in different f_ws. I₀ is the FL intensity of HLZ-BTED in pure THF.