annulen-5-ylium bis(tetrafluoroborate) HDMAPAN-(BF4)2 (Fig. ), which consists of an anilinium and a dibenzotropylium cationic moieties. The bench-stable protonated and doubly charged HDMAPAN-(BF4)2 has a bench-stable conjugate base (DMAPAN-BF4, Fig. ). Based on our computational results, we determined the 𝑝𝐾 𝑎 = 3.1 and 𝑝𝐾 𝑎 ℎ𝑣 = -12.3 for HDMAPAN-(BF4)2, and the ground state 𝑝𝐾 𝑎 was supported by experimental data. By further computational analyses of its photoacidity, we postulated that it operates by a novel mechanism that is beyond the traditional redistribution of charge densities in the proton donating group upon excitation.