Iron is one of the most important elements in metabolic processes, being indispensable for all living systems and therefore it is extensively distributed in environmental and biological materials. However, both its deficiency and excess from the normal permissible limit can induce serious disorders. Therefore, several analytical techniques have been adopted for the detection of iron. Among the various techniques used for its detection, the method based on fluorescent sensors has received considerable interest in recent years because of its ability to provide online monitoring of very low concentrations without any pre-treatment of the sample together with the advantages of spatial and temporal resolution. In this article, efforts have been made to review the various molecular and supramolecular fluorescent sensors that have been developed for the selective detection of iron(III).

Iron(III) selective molecular and supramolecular fluorescent probes

Iron is one of the most important elements in the metabolic process for all living system. However, both its deficiency and excess from normal permissible limits can induce serious disorders. We synthesized a europium-based metal-organic framework (Eu-MOF), EuL(3) (L = 4'-(4-carboxyphenyl)-2,2': 6',2″-terpyridine), under hydrothermal conditions, and used it as a solid luminescence sensor for Fe(3+) ions. The robust EuL(3) shows fast response (∼ 1 min) and high sensitivity (Stern-Volmer constant K(SV) = 4.1 × 10(3) L/mol) for Fe(3+) ions in aqueous solution or biological systems due to the existence of chelating terpyridine and open channels. The simple and portable test paper based on the EuL(3) fluorescent sensor system provides a convenient and reliable detection of Fe(3+) in every day applications. This pioneering work contributes to extend the potential application of Ln-MOFs to the biological and environmental areas.

Fast response and high sensitivity europium metal organic framework fluorescent probe with chelating terpyridine sites for Fe3

A tubular europium–organic framework exhibiting selective sensing of Fe3+ and Al3+ over mixed metal ions

A new metal–organic framework [Zn5(hfipbb)4(trz)2(H2O)2] (NNU-1) [H2hfipbb = 4,4′-(hexafluoroisopropylidene)bis(benzoic acid), Htrz = 1H-1,2,3-triazole] was assembled by hydrothermal synthesis. Single-crystal X-ray diffraction analysis reveals that NNU-1 displays a twofold interpenetrating three-dimensional (3D) framework with a {424·64}-bcu topology. Interestingly, the 3D framework contains a two-dimensional (2D) layered structure that consists of alternating left- and right-handed double helical chains. On the basis of the hydrophobic −CF3 groups from H2hfipbb ligand, NNU-1 possesses excellent stability in water. It is worth noting that NNU-1 not only shows a highly selective fluorescence quenching effect to Fe3+ ion in aqueous solution but also resists the interference of other metals including Fe2+ ion. Accordingly, NNU-1 probably functions as a potential promising fluorescence sensor for detecting Fe3+ ion with high sensitivity and selectivity.

A Water-Stable Metal–Organic Framework for Highly Sensitive and Selective Sensing of Fe3+ Ion

A luminescent lanthanide metal–organic framework [Tb(L)(H2O)5]n solvents (Tb-MOF, H2L− = 3,5-dicarboxyphenol anion ligand) with a 2D network structure was synthesized. The size of the Tb-MOF single crystal can reach up to 6 mm; such large-scale single crystals of MOFs are rarely reported in the literature. Tb-MOF exhibits a strong green luminescence induced by the efficient antenna effect of the ligands. Importantly, it shows an excellent recognition ability on detecting the Pb2+ ion, which is a noxious inorganic pollutant and causes permanent damage to human health and living environments. The perfect linear correlation between the luminescence intensity of Tb-MOF and the concentration of the Pb2+ ions provides this crystal as a reliable and easy-to-use luminescent sensor, which can be applied in pollutant monitoring. As far as we know, it is the first example of a high-efficiency luminescent MOF sensor with millimeter level for detecting Pb2+ ions at a very low concentration with a detection limit down to 10−7 M.

A luminescent lanthanide MOF for selectively and ultra-high sensitively detecting Pb2+ ions in aqueous solution

Sequential injection spectrophotometric determination of iron as Fe(II) in multi-vitamin preparations using 1,10-phenanthroline as complexing agent.

Sequential injection spectrophotometric determination of trace amounts of iodide by its catalytic effect on the 4,4'-methylenebis(N,N-dimethylaniline)-chloramine-T reaction.

Zeriet O Tesfaldet

Papers

Sequential injection spectrophotometric determination of iron as Fe(II) in multi-vitamin preparations using 1,10-phenanthroline as complexing agent.

Sequential injection spectrophotometric determination of trace amounts of iodide by its catalytic effect on the 4,4'-methylenebis(N,N-dimethylaniline)-chloramine-T reaction.

Spectrophotometric determination of magnesium in pharmaceutical preparations by cost-effective sequential injection analysis