Simple fluorescence "turn-off" assay for Congo red using commercial 2-aminophthalic acid

In this work, the fluorescence properties of 2-aminophthalic acid (NH2-BDC) were studied. NH2-BDC possessed excellent optical properties including bright blue emission with maximum emission at 425 nm, a high quantum yield of 38.49% and excellent photostability. And the fluorescence of NH2-BDC could be selectively quenched by Congo red, which was ascribed to the inner filter effect. Accordingly, NH2-BDC was further employed for fluorescence "turn-off" assay of Congo red with a linear range of 0.05-50 μM and a limit of detection of 1.72 μM. And the sensor was used for the detection of Congo red in real water samples with acceptable results.

An on-off-on fluorescent probe for the detection of glyphosate based on a Cu2+-assisted squaraine dye sensor

The herbicide glyphosate, N-(phosphonomethyl)glycine, has been widely used in the past 40 years, and has had many adverse effects on human health. Here, we constructed a convenient "on-off-on" fluorescent platform for detection of glyphosate via Cu2+ modulated squaraine dye fluorescence quenching. The squaraine dye F-0 exhibited strong fluorescence, which could be quenched by the addition of Cu2+. However, the addition of glyphosate restored the fluorescence intensity of F-0 due to the formation of a Cu2+-glyphosate complex. F-0 was utilized as a fluorescent probe for the quantitative detection of glyphosate, with the lowest detection limit of 13.16 nmol L-1. Furthermore, this method demonstrated high selectivity and anti-interference capabilities. The successful monitoring of glyphosate in real samples was achieved using this detection strategy.

A two-step strategy for simultaneous dual-mode detection of methyl-paraoxon and Ni (Ⅱ)

Exogenous pollution of Chinese medicinal materials by pesticide residues and heavy metal ions has attracted great attention. Relying on the rapid development of nanotechnology and multidisciplinary fields, fluorescent techniques have been widely applied in contaminant detection and pollution monitoring due to their advantages of simple preparation, low cost, high throughput and others. Most importantly, synchronous detection of multi-targets has always been pursued as one of the major goals in the design of fluorescent probes. Herein, we firstly develop a simultaneous sensing method for methyl-paraoxon (MP) and Nickel ion (Ni, Ⅱ) by using carbon based fluorescent nanocomposite with ratiometric signal readout and nanozyme. Notably, the designed system showed excellent effectiveness even when the two pollutants co-exist. Under the optimum conditions, this method provides low limits of detection of 1.25 µM for methyl-paraoxon and 0.01 µM for Ni (Ⅱ). To further verify the reliability, recovery studies of these two analytes were performed on ginseng radix et rhizoma, nelumbinis semen, and water samples. In addition, smartphone-based visual analysis has been introduced to expand its applicability in point of care detection. This work not only expands the application of the dual-mode approach to pollutant detection, but also provides insights into the analysis of multiple pollutants in a single assay.

Recent Progress in Metal-Organic Framework Based Fluorescent Sensors for Hazardous Materials Detection

Population growth and industrial development have exacerbated environmental pollution of both land and aquatic environments with toxic and harmful materials. Luminescence-based chemical sensors crafted for specific hazardous substances operate on host-guest interactions, leading to the detection of target molecules down to the nanomolar range. Particularly, the luminescence-based sensors constructed on the basis of metal-organic frameworks (MOFs) are of increasing interest, as they can not only compensate for the shortcomings of traditional detection techniques, but also can provide more sensitive detection for analytes. Recent years have seen MOFs-based fluorescent sensors show outstanding advantages in the field of hazardous substance identification and detection. Here, we critically discuss the application of MOFs for the detection of a broad scope of hazardous substances, including hazardous gases, heavy metal ions, radioactive ions, antibiotics, pesticides, nitro-explosives, and some harmful solvents as well as luminous and sensing mechanisms of MOF-based fluorescent sensors. The outlook and several crucial issues of this area are also discussed, with the expectation that it may help arouse widespread attention on exploring fluorescent MOFs (LMOFs) in potential sensing applications.

Recent progress on porous MOFs for process-efficient hydrocarbon separation, luminescent sensing, and information encryption

Metal-organic frameworks (MOFs), as an emerging class of porous materials, excel in designability, regulatability, and modifiability in terms of their composition, topology, pore size, and surface chemistry, thus affording a huge potential for addressing environment and energy-related challenges. In particular, MOFs can be applied as porous adsorbents for the purification of industrially important hydrocarbons through certain process-efficient separation schemes based on selectivity-reversed adsorption and multicomponent separation. Moreover, the vast combination possibilities and controllable and engineerable luminescent units of MOFs make them a versatile platform to develop functionally tailored materials for luminescent sensing and optical data encryption. In this feature article, we summarize the recent progress in the use of porous MOFs for the separation and purification of acetylene (C₂H₂) and ethylene (C₂H₄) based on selectivity-reversed adsorption and multicomponent separation strategies. Moreover, we highlight the advances over the past three years in the field of MOF-based luminescent materials for thermometry, turn-on sensing, and information encryption.

A Two-Fold Interpenetrated Dual-Emitting Luminescent Metal-Organic Framework as a Ratiometric Sensor for Chromium(III)

A novel two-fold interpenetrated metal-organic framework, namely Co-EDDA, was synthesized by hydrothermal reaction of 5,5'-[ethane-1,2-diylbis(oxy)]diisophthalic acid (H₄EDDA), Co(NO₃)₂·6H₂O, and 1,4-di(1H-imidazol-1-yl)benzene in water in an alkaline environment and structurally characterized. Co-EDDA could display clear dual-emission signals at 350 and 430 nm, representing the charge transfer emission between metal ions and the ligand and the ligand-based emission, respectively, which represents the ratiometric luminescence response to chromium(III) with high selectivity and sensitivity (limit of detection of 0.54 μM). Comprehensive studies indicate that the detection can be attributed to the interaction between the Cr³⁺ ions and the O atoms on the ether bond in Co-EDDA.

Metal–organic architectures designed from a triphenyl-pentacarboxylate linker: hydrothermal assembly, structural multiplicity, and catalytic Knoevenagel condensation

Eight new metal(ii) coordination compounds driven by a triphenyl-pentacarboxylate linker were hydrothermally assembled and fully characterized. Their structural features and catalytic behavior were investigated.

Various carboxylates induced eight Zn(ii)/Cd(ii) coordination polymers with fluorescence sensing activities for Fe(iii), Cr(vi) and oxytetracycline

Eight new Zn(ii)/Cd(ii) coordination polymers constructed from a naphthalene-amide-pyridyl ligand and various carboxylates were synthesized and characterized, which show multifunctional fluorescence responses for cations, anions and antibiotics.