Fluorescence characteristics of 5-amino salicylic acid: An iodide recognition study

In this paper we report the effect of iodide on the fluorescence of 5-amino salicylic acid (5-ASA). In the absence of iodide, prominent blue green (BG) emission band at ∼465 nm (broad) is observed in aprotic solvents whereas violet (V) emission at ∼408 nm, blue green (BG) at ∼480 nm and green (G) at ∼500 nm are observed in case of protic solvents. On the addition of iodide ion (I−), the intensity of BG fluorescence is enhanced in case of aprotic solvents. On the other hand the G band is enhanced in protic solvents and decrease in the intensity of the V band is observed. The effect of hydrogen bonding as well as the interplay of neutral and ionic species is invoked to explain the observed results. The study projects the application of this system in iodide recognition in protic/aprotic environments.

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► Effect of iodide on the fluorescence of 5-amino salicylic acid is studied.
► The effect of hydrogen bonding as well as the interplay of neutral/ionic species is invoked to explain the observations.
► The study projects the application of this system in iodide recognition in physiological environments.