Excited-state acidity aromatic hydroxy compound

Aromatic hydroxy compounds are known to show remarkable enhancement in their acidity in the excited singlet state and often serve as prototypes in this area of research. They are some of the earliest ESPT molecules studied by Forster [2-4], Their ESPT behavior has been extensively studied over the past three decades [1,7-12,17-19], The ultrafast nature of ESPT rate constants was realized as early as 1979 [30], Picosecond time-resolved measurements by Webb et al. 

There are three sections in the review. This section is a brief introduction to the subject. Because aromatic hydroxy compounds are taken as prototype excited-state acids, they have been discussed in a separate subsection. Section II has subsections for each medium and each subsection is further branched according to the classes of ESPT molecules studied in the medium. Section III gives conclusions. 

The phenomenal increase in excited-singlet-state acidity of aromatic hydroxy compounds makes them good excited-state proton emitters, with deprotonation... 

It is well known that the acidity of many hydroxy-aromatic compounds is strongly affected by electronic excitation and that these molecules become significantly more acidic in the excited states than in the ground state. For example, phenol and 1-naphthol... 

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