Fig. 3: Verification for the dixanthene derivative-CB[8] complexation mechanism.

a Illustration for three feasible binding modes between dixanthene derivatives and cucurbit[8]uril. b, c Structure of DXP and DXBTZ as optimized by density functional theory calculations. The maximum lateral dimensions of the entire molecule (DXP and DXBTZ) and their corresponding binding moieties were calculated, respectively. d, g Absorption spectra for the model guest compound dixanthene derivatives (10 μM) upon mixing with equivalent concentration of macrocyclic CB[6], CB[7], or CB[8]. e, h Left side: relative OA intensity of DXP and DXBTZ (10 μM) upon mixing with equivalent concentration of CB[6], CB[7], or CB[8] (n = 3 independent experiments). Right side: the typical OA images of dixanthene derivatives with equivalent concentration of CB[6], CB[7], or CB[8] in phantom (680 nm and 692 nm were selected as the excitation wavelength for e and h, respectively). f, i Absorption spectra for the control guest compound xanthene derivatives (10 μM) upon mixing with CB[8] (5 μM). Data are presented as mean values ± SD. Source data are provided as a Source Data file.