Bis‐Pyridyl Diimines as Selective and Ratiometric Chemosensor for Ni(II) and Cd(II) Metal Ions

Abstract

A pyridyl based Schiff base compound, (1E,1′E)‐N,N′‐(butane‐1,4‐diyl)bis(1‐(pyridin‐2‐yl)methanimine) (2pdab) was observed to serve as a highly selective and sensitive ratiometric chemosensor for Ni2+ and Cd2+ ions. Mole ratio method and Yoe Jone's method showed a 1:1 binding mode of metal ions (Ni2+ and Cd2+) with 2pdab, while a binding constant of 26.88 ×106 L/mol and 4.29×106 L/mol, for Ni2+ and Cd2+, respectively, was determined. The limit of detection of 2pdab in sensing Ni2+ and Cd2+ was observed to be 3.08 μM and 1.4688 μM, respectively. The selectivity of 2pdab to detect Cd2+ and Ni2+ among various other competitive ions was also studied. The sensor, 2pdab, was applied in real time application for detection of nickel ion in river water sample.

Recent progress in cadmium fluorescent and colorimetric probes

“…23 ). 73 In methanol solution, under excitation wavelength at 290 nm, adding Cd 2+ and Ni 2+ quenched the fluorescence of sensor 64. The sensor 64 has maximum absorption at 234 nm and 272 nm, adding Cd 2+ /Ni 2+ led to the maximum absorption peaks red-shift from 272 nm to 280/281 nm, and the interference of other metal ions and anions was neglected.…”

A pyridine based Schiff base as a selective and sensitive fluorescent probe for cadmium ions with “turn-on” fluorescence responses

“…The binding stoichiometry between 2pdab and Cd 2+ was 1 : 1 as confirmed by the mole ratio method, FE-SEM analysis and 1 H NMR titration experiment of the cadmium complex. 27 Yang et al synthesized a new Schiff-base fluorescent probe, 7 0 -methoxychromone-3 0 -methylidene-1,2,4-triazole-3imine (L), based on the CQN isomerization mechanism for selective recognition of Cd 2+ , which showed a strong fluorescence enhancement (l ex = 409 nm, l em = 462 nm) in the ethanol system. 28 The sensor synthesized by Cai and co-workers can distinguish Zn II and Cd II sensing with different fluorescence emission wavelengths and the detection limit is down to micromole range concentration in ethanol solution.…”

Naphthyridine derived colorimetric and fluorescent turn off sensors for Ni2+ in aqueous media

“…Colorimetric chemosensors show a distinct visible color change on selectively binding with a specific analyte without the use of expensive equipment, while the fluorescent sensors show fast responses towards analytes through fluorescence quenching or enhancement. These sensors have some drawbacks like poor solubility of probe, lack of selectivity, low sensitivity, and serious interference by other metals 20 .…”