“…The solvatochromic properties as well as ESPT kinetics , have been studied experimentally in a variety of solvents including water, methanol, ethanol, and DMSO. Recently, the dynamics and ESPT intermediates of a strongly hydrogen-bonded complex of compound A with a trialkylphosphine oxide in nitrile solution were elucidated. , Furthermore, for the strongest superphotoacid B of that class, namely tris(1,1,1,3,3,3-hexafluoropropan-2-yl)-8-hydroxypyrene-1,3,6-trisulfonate (p K a * ≈ −4 in water), the possibility of ESPT in acetone–water mixtures and in neat acetone were demonstrated . Despite the wealth of experimental knowledge regarding this photoacid, only limited information on the molecular origin of the exceptionally high photoacidity is yet available in the literature.…”