Fluorescent metal ion chemosensors via cation exchange reactions of complexes, quantum dots, and metal–organic frameworks

Abstract

Due to their wide range of applications and biological significance, fluorescent sensors have been an active research area in the past few years. In the present review, recent research developments on fluorescent chemosensors that detect metal ions via cation exchange reactions (transmetalation, metal displacement, or metal exchange reactions) of complexes, quantum dots, and metal-organic frameworks are described. These complex-based chemosensors might have a much better selectivity than the corresponding free ligands/receptors because of the shielding function of the filled-in metal ions. Moreover, not only the chemical structure of the ligands/receptors but also the identity of the central metal ions have a tremendous impact on the sensing performances. Therefore, sensing via cation exchange reactions potentially provides a new, simple, and powerful way to design fluorescent chemosensors.

A Highly Selective and Efficient Copper(II) – “Turn‐On” Fluorescence Imaging Probe for l‐Cysteine

“…Furthermore, the fluorescence intensity is not enhanced by the treatment of 1 with biologically relevant cations at pH 7.34 (Figure b). This clearly indicates that no transmetalation of biologically relevant cations is possible for probe 1 . The turn‐on fluorescence behavior of 1 with l ‐cysteine is 182 times higher than that of 1 , and the quantum yield is 6 %.…”

A highly selective multi-responsive fluorescence sensor for Zn2+ based on a diarylethene with a 4,6-dimethylpyrimidine unit

“…50 In general, in order to detect metal ions, chemosensors bind with the target metal ions through non-covalent interactions to yield stable coordination complexes. 51 The Zn 2+ ion should have a stronger binding energy to the sensor 1 than EDTA. The stronger affinity of sensor 1 to Zn 2+ can not be reversed by EDTA.…”

2,4,5-Triaryl imidazole probes for the selective chromo-fluorogenic detection of Cu(II). Prospective use of the Cu(II) complexes for the optical recognition of biothiols

“…In the first case, interaction of transition metal cations with the binding sites induces rearrangements in the p-conjugated system of the signalling unit which are reflected in colour and/or emission changes [3]. In the second approach, interaction of the transition metal cation with the binding site induces the displacement of the signalling unit from the initial complex to the solution [4].…”