Photophysical properties of lamotrigine (LMT) were investigated at different pH values. Lamotrigine exhibited a broad absorption band at 308 nm that was shifted to 268 nm at pH due to protonation (HLMT+). Emission spectra of LMT at different pH values showed a single band at 483 nm except for at pH , where a second band at 502 nm was observed due to the deprotonation from the singlet excited state. LMT pH profile was used to calculate pK a of LMT in excited and ground states (pK a* = and pK a = ). Absorption spectra of LMT at different pH values for LMT in the presence of β-CD showed an isosbestic point at 290 nm. A significant enhancement in the emission intensity of LMT upon increasing β-CD (0–7 mmol L−1 ) was reported. |
