A highly sensitive and selective novel fluorescent chemosensor for detection of Cr3+ based on a Schiff base

摘要

N, N'-bis(salicylidene)-2-(6-(2-aminophenyl)-4-phenylpyridin-2-yl) (3) was synthesized by condensation reaction of 2,6-bis(2-aminophenyl)-4-phenylpyridine and 2-hydroxybenzaldehyde in EtOH and characterized by its melting point, H-1, C-13 NMR and molecular mass. The addition of Cr3+ ion makes the significant increase of its fluorescent intensity at 537 nm in CH3CN/H2O (95/5%), however, other metal ions have almost no influence on the fluorescence. The reason for this phenomenon might be attributed to the formation of a 1: 1 stoichiometric 3-Cr3+ complex which inhibits photo-induced electron transfer (PET) process. The 1: 1 binding stoichiometry between 3 and Cr3+ was established using Job's plot, and the complex structure was proposed by DFT calculation. The association constant (K-a) was determined to be 8.77 x 10(4) M (1) and the limit of detection (LOD) was calculated to be 2.2 x 10 (7) M. (C) 2017 Elsevier B.V. All rights reserved.