Related Experiment Video
Updated: Mar 3, 2026

An Aptamer-based Sensor for Unchelated GadoliniumIII
Published on: January 9, 2017
A Unique Sensitive and Highly Selective Fluorescent Naphthodiaza-Crown Macrocyclic Ligand Chemosensor for Hg2+ in
Bahram Ghanbari1, Morteza Zarepour-Jevinani2
1Department of Chemistry, Sharif University of Technology, PO Box 11155-3516, Tehran, Iran. ghanbari@sharif.edu.
Abstract:
The noticeable enhancement in fluorescence emission of O2N2-donor naphthodiaza-crown macrocyclic ligand (L) in the presence of Hg2+ was observed in which the fluorescence quantum yield of free ligand L as well as L/Hg2+ complex were found to be as 0.29 and 0.49, respectively. The observed ultra-low limit of detection (LOD) for Hg2+ by L was determined as low as 1.0 × 10-11 M in water. A 1:1 stoichiometry was also established for L/Hg2+ together with a binding constant K BH = 66,543 by employing fluorescence spectrophotometry. The competition experiments on L/Hg2+ demonstrated highly selective detection of Hg2+ in the presence of the library cations. A two path mechanism for detection of metal ion in terms of coordination of metal ion to L and/or the formation of counter ion was proposed by using of 1H NMR and fluorescence spectroscopy. Graphical Abstract pH dependence mechanism of interaction between Hg2+ and macrocyclic ligand L.
Related Concept Videos
Complexometric Titration: Ligands
EDTA: Chemistry and Properties
Metal-Ligand Bonds
In these complexes, transition metals form coordinate covalent bonds, a kind of Lewis acid-base interaction in which both of the electrons in the bond are contributed by a donor (Lewis base) to an electron acceptor (Lewis acid). The Lewis acid in...
Ladder Diagrams: Complexation Equilibria
The formation constant, K1, for the formation of Cd(NH3)2+ complex from cadmium and ammonia is 3.55 × 102. Log K1 (i.e. pNH3) is 2.55, and...
Extraction: Advanced Methods
Crystal Field Theory - Octahedral Complexes
To explain the observed behavior of transition metal complexes (such as colors), a model involving electrostatic interactions between the electrons from the ligands and the electrons in the unhybridized d orbitals of the central metal atom has been developed. This electrostatic model is crystal field theory (CFT). It helps to understand, interpret, and predict the colors, magnetic behavior, and some structures of coordination compounds of transition metals.
CFT focuses on...

