First, increasing the distance between the two ring systems, i.e., the anilinium and dibenzotropylium units, should affect the Δ𝑝𝐾 𝑎 as the electrostatic Coulomb repulsion will decrease with the square of the distance. Therefore, we inserted saturated bicyclo[1. 1.1]pentane groups between the two units to act as rigid insulating spacers (Fig. ). The structures were optimized at the same computational level as the tw-HDMAPAN, and then their 𝑝𝐾 𝑎 and 𝑝𝐾 𝑎 ℎ𝑣 values were determined by using the Born-Haber cycle. We found that the absolute Δ𝑝𝐾 𝑎 of these three different structures were very much affected by the presence of the spacers (Fig. ). By inserting one spacer (HDMAPAN-bcp), a large drop of the Δ𝑝𝐾 𝑎 is observed (from 13.8 to 3.0), and the insertion of two spacers still affects the Δ𝑝𝐾 𝑎 , reducing it to 1.0 (HDMAPAN-(bcp)2). These results show that, even though the proton attached to the nitrogen becomes more acidic in the excited S1 state, it occurs to a lower extent the longer is the distance between the dibenzotropylium and anilinium units. Yet, it is important to note that the dibenzotropylium unit loses some of its planarity in the derivatives with spacers, slightly puckering in the central ring. Interestingly, as the spacers are added the changes in the charge rearrangement in the dibenzotropylium unit starts to resemble more that of an isolated 5Hdibenzo[a,d]tropylium cation (Fig. , ESI), revealing clear mutual influences of the anilinium and dibenzotropylium units (see Fig. , S29-S30, ESI). Furthermore, replacing the dibenzotropylium unit in HDMAPAN by an isoelectronic, yet neutral dibenzoborepin unit also decreases the Δ𝑝𝐾 𝑎 , but only to 6.8 (Fig. ). This also supports that the positive charge in the dibenzotropylium unit affects the photoacidity in HDMAPAN since the dibenzoborepin analogue is not doubly charged when protonated, and as a consequence, there is no change in the electrostatic repulsion upon excitation. Noteworthy, the S0 → S1 transition in the dibenzoborepin analogue is also localized in the dibenzoborepin unit (Fig. , ESI). In a final computational experiment, we investigated the effect of a positive point charge approaching an independent anilinium ring. We considered a positive fractional charge of +0.5 a.u. placed at different distances from an optimized N,N-3,5-tetramethylanilinium, for which we computed the energies of the system (Fig. ). A clear effect of the approaching charge is observed as the relative energy of the N,N-3,5-tetramethylanilinium substantially increases when the distance to the point charge is reduced, reaching +28.7 kcal mol -1 at the distance of 1.50 Å (note that the C-C bond length between the tropylium and anilinium units in the crystal structure is 1.508 Å) with respect to infinite separation. Such a large destabilization of the system should give the proton a much more acidic character. Comparing this result to the same experiment using the neutral N,N-3,5-tetramethylaniline reveals the opposite trend: As the point charge approaches the molecule, the relative energy of the system is reduced and, therefore, stability increases (Fig. ). The charge of +0.5 a.u. is likely far too large compared to the charge shift in HDMAPAN upon excitation, yet even the much smaller positive fractional charge of +0.05 a.u. causes destabilization in the N,N-3,5-tetramethylanilinium (+3.4 kcal mol -1 at the distance of 1.50 Å). From these results, we can conclude that the charge redistribution within the dibenzotropylium unit upon excitation from S0 to S1 electrostatically impacts on the acidity, turning HDMAPAN-(BF4)2 into a (super)strong photoacid.