A new Schiff-base as fluorescent chemosensor for selective detection of Cr3+: An experimental and theoretical study. Issue 18 (3rd May 2018)

• Record Type: Journal Article
• Authors: Chalmardi, Gholam Babaei; Tajbakhsh, Mahmood; Hasani, Nahid; Bekhradnia, Ahmadreza
• Is Part Of: Tetrahedron. Volume 74:Issue 18(2018)
• Page Start: 2251
• Page End: 2260
• Publication Date: 2018-05-03
• Subjects: Fluorescence -- Chemosensors -- Schiff-base -- PET -- DFT -- Chromium ion; Chemistry, Organic -- Periodicals; 547.005
• DOI: 10.1016/j.tet.2018.03.046
• Languages: English
• ISSNs: 0040-4020

Abstract

Abstract: A novel Schiff base fluorescent sensor N, N′-bis(salicylidene)-2, 6-bis(4-aminophenyl)-4-phenylpyridine (P3 ) was synthesized through condensation of 2, 6-bis(4-aminophenyl)-4-phenylpyridine and 2-hydroxybenzaldehyde. The obtained results from fluorescence analysis revealed that by excess of Cr 3+ toP3, a remarkable increase was observed in the fluorescent intensity of the Schiff base at 663 nm with the ratio of CH3 CN/H2 O (95/5%), even though the other cations would likely have no impact on the fluorescence intensity. The cause of this trend might be ascribed to the formation of a 1:1 stoichiometricP3 -Cr 3+ complex, confirmed by Job's plot, which is resulted in preventing the photo-induced electron transfer (PET) process. From fluorescence titration, the association constant Ka was gained 2.28 × 10 5 M −1 and the limit of detection (LOD) was determined to be 1.3 × 10 −7 M. Furthermore, the optimized structure together with the electronic spectra of the proposed complex was determined by DFT and TDDFT calculations. Graphical abstract: Highlights: The Schiff base (P3 ) shows high selectivity towards Cr 3+ ion compared with other competing metal ions. DFT calculations together with the experimental results obtained from Job's plot method showed a 1:1 binding ratio of Cr 3+ with ligandP3. The sensing mechanism are explained by photoinduced electron transfer (PET) and chelation - enhanced fluorescence (CHEF). It has high affinity (Ka = 2.28 × 10 5 M −1 ) and selectivity for Cr 3+ . The detection limit of the sensor towards Cr 3+ is 1.3 × 10 −7 M.