A single molecule that acts as a fluorescence sensor for zinc and cadmium and a colorimetric sensor for cobalt

Abstract

A new metal ion sensor that contains quinoline and pyridylaminophenol has been synthesized. In acetonitrile and in the presence of Zn(2+), the sensor fluoresces. In contrast, in aqueous solutions the sensor fluoresces in the presence of Cd(2+). The fluorescence of the molecule is selective for Zn(2+) or Cd(2+) and shows no fluorescence with other metal ions. The crystal structure of the Cd(2+) complex shows coordination through the amide and phenol oxygens, as well as the amine nitrogen of the sensor. The sensor also acts as a colorimetric sensor for Co(2+) by changing color from colorless to yellow. The color change is selective for Co(2+) and is not observed with other metal ions. The unique combination of pyridine and phenol groups with quinoline results in the properties of this sensor.

Addressing of multiple-metal ions on a single platform

“…51). A versatile metal ion sensor 51, containing quinoline and pyridylaminophenol units has been reported by Song et al [80] Although addition of both Zn 2+ and Cd 2+ ions to aqueous solution of sensor (10 M) caused emission enhancement, but the degree of enhancement was greater for Cd 2+ (1 equiv.) than Zn 2+ (1 equiv.).…”

“…(a) Structure of probe 51 which shows dual-channel sensing behavior toward Cd 2+ , Zn 2+ and Co 2+ ions, (b) The proposed binding mode of the probe with Cd 2+ ion[80].…”

Chelate-type Schiff base acting as a colorimetric sensor for iron in aqueous solution

“…The binding constant (K) of 1 with Fe 3+ was calculated as 1.1 × 10 4 on the basis of Benesi-Hildebrand analysis [46,47] (Fig. S1).…”

Quinoline-functionalized norbornene for fluorescence recognition of metal ions

“…With tunable and suitable coordination structure, some sophisticated carboxamidoquinoline-base sensors for recognition of various metal ions, such as Zn 2+ , Cd 2+ and Cu 2+ , have been developed [30][31][32][33][34][35][36][37][38][39][40]. However, systems for recognition of Hg 2+ are still unknown, to the best of our knowledge.…”

“…Among them, the carboxamidoquinoline derivatives have attracted much attention for their tunable bonding mode. According to the types of the auxiliary binding sites and the center metal ions (Scheme 1), the carboxamidoquinoline ligands can bind with metal ions in an amide tautomeric form (type I) [30][31][32], an imidic acid tautomeric form (type II) [33,34], and a deprotonation amide tautomeric form (type III) [35][36][37][38].…”