Mercury Ions Complexation with a Series of Heterocyclic Derivatives of 3-Hydroxychromone: Spectral Effects and Prospects for Ultrasensitive Hg²⁺Probing

Abstract

Complexation of three 3-hydroxychromone derivatives bearing a nitrogen-containing heterocyclic moiety in the position 2 of the chromone bicycle - benzimidazole, quinoline, and 2,5-diphenyloxazole, with mercury(II) ions is reported. Formation of chelate complexes with the metal cations coordinated with the cavity formed by 3-OH and 4-C═O groups was shown, as well as the possibility of side moiety heteroatom participation in binding of metal ions. High sensitivity to mercury of 2,5-diphenyloxazole-substituted 3-hydroxychromone was elucidated, allowing to detect Hg(2+) below the maximum permissible concentration for drinking water. This makes the above-mentioned compound a prospective basis for development of sensors for ultralow mercury concentration detection in water. Unusual fluorescence ignition of 2-(quinolin-2-yl)-3-hydroxychromone at low Hg(2+) concentrations, rarely observed for heavy metals ions complexation with organic fluorescent ligands, was discussed.

Fluorescent and colorimetric sensors for environmental mercury detection

“…These sensors provide more precise detection methods for Hg 2+ . 44 These sensors form complexes with Hg 2+ via 3-OH and 4-C=O groups and the side moiety heteroatoms. Their absorption and emission colors mainly depend on the substituents on the amino groups, which have limited energy variations.…”

“…44 Signal transduction has been proven to be the most important part of the sensing process, because of its potential for improving sensor performance. However, when the total mercury concentration in the solution reaches ~10 −5 M, a slight hypsochromic shift of this band is observed.…”

Fluorescence Enhancement/Quenching Based on Metal Orbital Control: Computational Studies of a 6-Thienyllumazine-Based Mercury Sensor

“…The binding behavior of Cd 2+ and Hg 2+ and receptors is often the key point in the investigation and discussion of the sensing mechanism. 19 The fluorescent intensity depends on how the metal binds to the ligand (fluorophore). The sensors can be regarded as either "turn-on" or "turn-off" sensors.…”

Selective Detection of Mercury Ion by a Fluorescent Sensor Based on Dipeptide Containing Cysteine

“…DNS-Cys-Glu showed high selectivity for Hg 2+ . It is well known that Hg 2+ can offer a strong and favorable electrostatic interaction with sulfur and nitrogen atoms which can act as soft binding sites for metal cations [30,31]. For DNS-Cys-Glu, the thiol group of Cys and the sulfonamide group adjacent to dansyl group can bind to Hg 2+ by electrostatic interactions.…”