A highly selective acridine-based fluorescent probe for detection of Al³⁺ in alcoholic beverage samples

4,5-Bis(phtalimidomethyl)acridine (L) was studied as a chemosensor for metal ions in alcoholic matrices and showed to be selective for Al³⁺, through a linear fluorescence enhancement of 230% in the concentration range of 10-70 μmol L^-1. Benesi-Hildebrand and Job's formalisms indicated the formation of a 1:1 (Al³⁺:L) complex with a binding constant of 6.30 × 10³ L mol^-1. DFT/TDDFT calculations allowed access to the energies of frontier orbitals and could explain the fluorescence augmentation upon complex formation, due to the restraining of PET process. Limit of detection and limit of quantification (R² = 0.998, least squares method) are 1.130 and 3.768 μmol L^-1, respectively, and validation was verified based on the variation of several analytical conditions. Practical application in spiked Brazilian sugarcane spirit showed recovery of (84 ± 0.42)% with no effect of interfering ions.