A Multi‐responsive Regenerable Europium–Organic Framework Luminescent Sensor for Fe³⁺, Cr^VI Anions, and Picric Acid

Abstract

A novel luminescent microporous lanthanide metal-organic framework (Ln-MOF) based on a urea-containing ligand has been successfully assembled. Structural analysis revealed that the framework features two types of 1D channels, with urea N-H bonds projecting into the pores. Luminescence studies have revealed that the Ln-MOF exhibits high sensitivity, good selectivity, and a fast luminescence quenching response towards Fe , Cr anions, and picric acid. In particular, in the detection of Cr O and picric acid, the Ln-MOF can be simply and quickly regenerated, thus exhibiting excellent recyclability. To the best of our knowledge, this is the first example of a multi-responsive luminescent Ln-MOF sensor for Fe , Cr anions, and picric acid based on a urea derivative. This Ln-MOF may potentially be used as a multi-responsive regenerable luminescent sensor for the quantitative detection of toxic and harmful substances.

A Water‐Stable Luminescent ZnII Metal‐Organic Framework as Chemosensor for High‐Efficiency Detection of CrVI‐Anions (Cr2O72− and CrO42−) in Aqueous Solution

“…The patterns in Figure S11 confirmed that the sample of NUM‐5 maintained the crystallinity after titration and cyclic experiments. Hence, the fluorescence intensity reduction was not due to the decomposition of crystalline structures . Then, we examined the filtrate of NUM‐5 with Cr VI (Cr 2 O 7 2− /CrO 4 2− ) in titration experiments by ICP analysis and solid‐state fluorescence spectra measurement.…”

“…Therefore, they are a good candidates for detecting Cr VI (Cr 2 O 7 2− /CrO 4 2− ) in aqueous solution . In this regard, some LMOF probes for Cr VI (Cr 2 O 7 2− /CrO 4 2− ) have been reported recently; however, the lack of water stability and recyclability impedes their applications in practice . Thus, the development of a new LMOF for sensing Cr VI (Cr 2 O 7 2− /CrO 4 2− ) in aqueous solution with high sensitivity, selectivity and excellent recyclability is extremely beneficial.…”

Cobalt(II) and silver(I) coordination polymers containing flexible bis (benzimidazol‐1‐yl)hexane ligands: synthesis, crystal structures, sensing and photocatalytic properties

“…To further understand the results, the luminescence quenching efficiency can be calculated by using the Stern‐Volmer equation: I 0 /I = K sv [BZH] + 1, The Stern‐Volmer plots display an almost linear relationship for benzaldehyde, with the K sv values of 1.6073 × 10 4 (R 2 = 0.9964) and 8.1164 × 10 2 (R 2 = 0.9953) for 1 and 2 , respectively. Further detailed analysis denotes that the detection limits for benzaldehyde are 2.10 μM and 9.68 μM for 1 and 2 , respectively, according to 3 σ / k ( σ : standard error; k : slope), illustrating 1 and 2 had a sensitive quenching effect towards BZH (Figure c).…”

Crystallographic investigation into the self-assembly, guest binding, and flexibility of urea functionalised metal-organic frameworks

“…For example, grafting hydrogen bond donor functionality, such as amides (11)(12)(13)(14)(15)(16)(17)(18)(19)(20), ureas (21)(22)(23)(24)(25)(26)(27)(28)(29)(30)(31)(32), thioureas (33), and squaramides (34)(35)(36), (Figure 1(a)) onto the organic scaffold of the MOF can enhance properties including carbon dioxide capture (13,15,17,18), anion binding (20,21), sensing (28), and organocatalytic activity (6). Urea-functionalised MOFs in particular have been found to catalyse FriedelCrafts reactions between pyrroles and nitroalkenes (22,24,27,29,31), Henry reactions between aldehydes and nitromethane (23), and the methanolysis of epoxides (25).…”