S0 state geometries and 𝒑𝑲 𝒂 : HDMAPAN-(BF4)2 is composed of two ring systems, the N,N-3,5-tetramethylanilinium and the dibenzotropylium moieties, with a positive charge on each fragment. The crystal structure of HDMAPAN-(BF4)2 reveals that the two ring systems are orthogonal to each other (Fig. ). Furthermore, the dibenzotropylium moiety is nearly planar along the three fused rings, bending toward the H-atom bonded to the nitrogen. That is vastly different for the conjugate base DMAPAN-BF4, in which the crystal structure conformation is non-twisted (Fig. ), hereafter labelled as the folded conformation. In this case, the lower-rim seven-membered ring bent out of planarity, moving the rings of the flanking moieties away from the upper-rim ring system, which adopts a bent quinoidal structure with the positive charge formally placed at the nitrogen atom. Further functionals (ωB97X-D, B3LYP and M06-2X) in both gas phase and solvent phase were tested for the geometry optimizations and for the NMR chemical shifts, revealing the closest similarity between experimental and computational data for the CAM-B3LYP functional (Fig. , ESI). Using the CAM-B3LYP functional for the geometry optimization, we also tested a larger basis set (cc-pVTZ) and the Continuous Set of Gauge Transformations (CSGT) method for computing the NMR spectra (Fig. -S17, ESI), considering their reported better performance. The combination of GIAO at CAM-B3LYP-D3/6-311+G(d,p) level still provided the computed NMR spectra with highest agreement to the experimental one.