An Ultrastable Luminescent Metal–Organic Framework for Selective Sensing of Nitroaromatic Compounds and Nitroimidazole-Based Drug Molecules

Abstract

A chemically stable and thermally stable luminescent Cd­(II)-based metal–organic framework (MOF), [Cd3(DBPT)2­(H2O)4]­·5H2O (1), featuring an open Lewis basic triazolyl active site in the host, was successfully assembled by using the multifunctional ligand of 3-(3,5-dicarboxylphenyl)-5-(4-carboxylphenyl)-1-H-1,2,4-triazole (H3DBPT) to bridge hexanuclear {Cd6} clusters. The host material exhibits ligand-based photoluminescence and solvent-dependent fluorescent intensities, which could selectively detect nitroaromatic compounds (NACs) of 2,4,6-trinitrophenol (TNP) and 4-nitroaniline (4-NA). The most striking property of 1 is the remarkable sensitivity and selectivity toward TNP and 4-NA even in the presence of other NACs of nitrobenzene (NB), which can be attributed to a photoinduced electron transfer mechanism and resonance energy transfer mechanism. Their photoluminescence quenching could be detected at very low concentrations of 1.14 and 0.70 ppm, respectively, and the maximum quenching efficiencies were found to be 98% and 95%, respectively, at 0.08 mM. Significantly, compound 1 also exhibits excellent sensing performance toward nitroimidazole-based drug molecules of ornidazole (ONZ), metronidazoles (MNZ), dimetridazole (DMZ), and 2-methyl-5-nitroimidazole (2-M-5-MZ), which represents one of the rare MOFs-based fluorescent sensors for simultaneous selective detecting drug molecules and NACs. Their photoluminescence quenching efficiencies increase drastically with the analyte amount even in the low concentration range (<0.15 mM) and reach nearly complete quenching (>95%). The remarkable chemical stability and the unusual sensing performance make this Cd-based MOF a promising multiresponsive sensory material for chemical sensing of NACs and nitroimidazole-based drugs.

A Water‐Stable Uranyl Organic Framework as a Highly Selective and Sensitive Bifunctional Luminescent Probe for Fe3+ and Tetracycline Hydrochloride

“…When antibiotic was added, the electrons excited into the conduction band no longer return to the ground state but were transfer to the LUMO orbit of antibiotics, resulting in fluorescence quenching of the compound (Figure ). And the lower the LUMO orbital level of antibiotics, the easier the electron transfer was, and the more pronounced the fluorescence quenching effect . Therefore, the reduction potential of antibiotics was determined by electrochemical cyclic voltammetry (Figure S12–S18) and used the formula LUMO=−(4.4+ E red onset + E Fc/Fc +) to obtain the LUMO orbital energy level .…”

“…And the lower the LUMO orbitall evel of antibiotics, the easier the electron transfer was, and the more pronounced the fluorescenceq uenching effect. [40][41][42] Therefore, the reduction potentialofa ntibiotics was determined by electrochemical cyclic voltammetry (Figure S12-S18)a nd used the formula LUMO = À(4.4 + E red onset + E Fc/Fc +)t oo btain the LUMO orbital energyl evel. [43,44] The test results exhibit that the order of antibiotic LUMO orbital level wasT CH < PC % AZ % ACT < SDZ < CF ( Figure 10 and Ta ble S3), and the LUMO orbital level of tetracycline hydrochloride was significantly lower than other antibiotics.…”

A Highly Stable (4, 8)‐Connected Tb‐MOF Exhibiting Efficiently Luminescent Sensing towards Nitroimidazole Antibiotics

“…To the best of our knowledge, only five complex‐derived probes for MDZ and DTZ have been reported by far (Table ). The emission signal of these complexes for sensing originates either from ligand‐centered charge transfer for transitional metal complexes or from ligand‐sensitized characteristic emission of Ln‐MOFs . In addition to the comparable K SV and LOD values, Tb‐MOF has the superior advantages of the smallest dose (0.1 mg · mL –1 vs. 0.5–1.5 mg · mL –1 ) and wider response range (0–132 μM vs. 0–80 μM) than those known sensors.…”

Preparation, characterization and luminescence-sensing properties of two ZnII MOFs with mixed 5-amino-2,4,6-tribromoisophthalic acid and bipyridyl-type ligands

“…MOFs show infinite high-dimensional structures with periodic repeat units obtained by coordination of inorganic metal ions and organic ligands (Feng et al, 2018), and are a new class of promising functional materials with applications in gas storage (Spanopoulos et al, 2016), catalysis (Deria et al, 2016), drug delivery (Wu et al, 2014), magnets (Qiao et al, 2017) and chemical sensing (Wang et al, 2015;Li et al, 2019;Dong et al, 2018) etc. It is still very difficult to predict the structure of a new MOF, although some progress has been made in the theoretical prediction of structures of coordination compounds (Yang et al, 2010).…”