Fluorescence properties of 4-amino salicylic acid in polymers

In this manuscript we report spectral and photophysical parameters of 4-amino salicylic acid in protic polar and less polar aprotic polymer matrices. Dual emission is observed in both the polymers. The band appearing at longer wavelengths (B band) is attributed to excited state intramolecular proton transfer (ESIPT) whereas the band around 330 nm (U band) is due to those conformers, which fail to undergo ESIPT. We attribute the difference in spectral behaviour in these polymers to the simultaneous presence of different neutral/ionic species, free volume and polarity effects.