A Facile Preparation of a New Water-Soluble Acridine Derivative and Application as a Turn-off Fluorescence Chemosensor for Selective Detection of Hg2.

A new acridine-based chemosensor was prepared, characterized and investigated for quantitative detection of Hg2+ ions in aqueous solutions. DFT and TD-DFT calculations showed that formation of a coordination bond between Hg2+ and the thiolate-sensor accounts for the fluorescence quenching, forming [HgLSCl2]2- as the most stable species. Limit of detection and limit of quantification were as low as 4.40 and 14.7 µmol L-1, respectively (R2 = 0.9892, least squares method), and a linear concentration range of 14.7-100 µmol L-1. Benesi-Hildebrand and Job formalisms are in accordance with the formation of a stable complex with a 1:1 (metal ion/sensor) ratio, and a determined binding constant of 5.14 × 103 L mol-1. Robustness was verified based on the variation of several analytical conditions. In addition, the method presented maximum relative standard deviation of 4.6%, and recovery results was (90.3 ± 4,6)% from distilled water, with no effect of interfering ions. Analytical figures of merit showed that the sensor can be an attractive low cost alternative for detection of Hg2+.

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.