Fig. 3: Characterization of the formation of TpPBr dimer for its robust RTP.
a Prompt luminescence spectra and b UV-vis absorption of TpPBr in 1,4-dioxane solutions with incremental concentrations (Prompt: 298 K, in air, λex = 310 nm; UV-vis: 298 K, in air). The blue arrow indicates the decrease in emission intensity around 430 nm, while the red arrow for the increase around 460 nm in 3a. The green arrow in 3b indicates the appearance of the absorption peak at about 440 nm. c, Normalized delayed luminescence spectra of TpPBr in 1,4-dioxane (0.01 mM) measured at 77 K and TpPBr crystalline powder measured at 298 K in air (upper); Delayed luminescence spectra of TpPBr in 1,4-dioxane solutions after deoxygenation with incremental concentrations measured at 273 K (lower, λex = 365 nm, delayed 8 ms). The packing structure of TpPBr dimer in its crystal structure, viewed along a axis (d) and another non-axial angle (e). f Distribution regions and (g) scatter plots of intramolecular/intermolecular interactions in TpPBr dimers revealed by the interaction region indicator (IRI), a natural space function. The sign(λ2)p function is coloured on IRI isosurfaces to illustrate the nature of interaction regions. A decrease in sign(λ2)p is indicated by the colour bar changing from red to green and then to blue, which implies a notable repulsion, a noticeable interaction, and a significant attractive effect, respectively. vDW for van der Waals. h Delayed luminescence spectra of TpPBr in 1,4-dioxane solutions with incremental concentrations measured at 77 K (λex = 365 nm, delayed 8 ms). i,j Normalized time-resolved emission spectroscopy (TRES) of TpPBr powder in air at 298 K in nanosecond scale (λex = 405 nm).
