Introduction
Methods
Fig.1 Synthesis of HABI-TPE conjugate.Reaction conditions. i, bis(pinacolato)diboron, Pd(dppf)Cl2, KOAc, in DMF at 90°C for 8 h; ii, PTC, K2CO3, Pd(PPh3)4, toluene/H2O at 90°C for 1 day; iii, benzyl, ammonium acetate, acetic acid at 90°C for 12 h; iv, K3Fe(CN)6, KOH, benzene/H2O at room temperature for 8 h |
Results and discussion
Fig.2 Absorption properties of HABI-TPE. (a) Absorption spectra of HABI-TPE in benzene, THF and solid state PMMA film before and after UV irradiation; (b) absorbance spectrum change of HABI-TPE in solution (2.5 × 10-4 M<FootNote>M= 1 mol/L </FootNote>) at different 302 nm light irradiation time; (c) absorption spectrum change of HABI-TPE in solution (2.5 × 10-4 M) in darkness after 302 nm irradiation at different time (from top to bottom: 0 min, 5 min, 10 min, 15 min, 20 min, 30 min, 45 min, 60 min, 75 min, 90 min, 2 h, 3 h, 6 h; (d) absorbance change of HABI-TPE with 302 nm irradiation and heat fade of HABI-TPE in darkness. Inset: pictures of HABI-TPE before and after 302 nm irradiation |
Fig.3 Fluorescence properties of HABI-TPE. (a) Fluorescence spectra of HABI-TPE in THF and solid state PMMA film under excitation with 490 nm before and after UV irradiation; (b) excitation wavelength-dependent emission spectra of HABI-TPE in condensed state films; (c) change of emission wavelength versus excitation wavelength; (d) identification of excitation wavelength for photoswitching by fluorescence spectra. The change of fluorescent intensity at 550 nm of HABI-TPE in condensed state with excitation time upon excitation of different wavelength was determined |
Fig.4 Fluorescence switching of HABI-TPE. (a) Fluorescence spectra change of HABI-TPE in solid state at excitation of 450 nm with scanning time; (b) fluorescence spectra changes of HABI-TPE in solid state at excitation of 490 nm with scanning time; (c) fluorescence spectra changes of HABI-TPE in solid state upon 302 nm irradiation for 5, 10, 20, 30, 60, 120 s, excitation wavelength: 490 nm; (d) fluorescence spectra changes of HABI-TPE in solid state at excitation of 490 nm with fading time for 5, 10, 15, 30, 60, and 90 min in darkness after 302 nm irradiation for 120 s |
Fig.6 Super-resolution imaging of spin-coated HABI-TPE-loaded PMMA film. (a) Conventional fluorescent image displaying the distribution of HABI-TPE fluorophores in solid film; (b) super-resolution fluorescent image for (a); (c) and (f) expanded view of the marked regions in (a); (d) and (g) expanded super-resolution fluorescent images of the marked regions in (b), corresponding to (c) and (f); (e) and (h) expanded super-resolution fluorescent images of two pairs of vicinal HABI-TPE emitters in (d) and (g), respectively; (i) and (j) fluorescence cross-sectional profiles of two pairs of vicinal HABI-TPE emitters along the dashed lines in (e) and (h), indicating the spatial resolution of 110 and 90 nm, respectively |