A study of the dimethyl 3-benzoyl-5(2′-pyridyl)-indolisine-1,2-dicarboxylate exciplexes with alcohols

The formation of fluorescent intermolecular exciplexes between dimethyl 3-benzoyl-5(2′-pyridyl)-indolisine-1,2-dicarboxylate (DBI) and 15 alcohols as well as with acetic acid, has been proved. The probability of formation of these exciplexes is less than unity, except for the acetic acid, ranging between 0.14 and 0.92, depending on the nature of the alcohol. This is exactly the reason for a strong alteration in the fluorescence band of the DBI in different alcohols, consisting in both large shifts of the maximum, from 18,920 cm−1 in cyclohexanol to 16,260 cm−1 in benzyl alcohol, and changes in its shape and half-width.