Minimal Self-Immolative Probe for Multimodal Fluoride Detection

Iodine-mediated photoinduced autoinductive tandem chromogenic system for visual colorimetric detection of triacetone triperoxide explosive

A long-standing challenge in colorimetric detection of triacetone triperoxide (TATP) explosive is low sensitivity. We herein developed an iodine-mediated photoinduced auto-inductive tandem chromogenic system to achieve exponential signal amplification. The strategy employs the KI-TATP reaction and photo-induced autocatalytical oxidation of o-phenylenediamine (OPD) that work in tandem. The resulting I₃^- from the KI-TATP reaction oxidizes OPD to yellow 2,3-diaminophenazine (DAP) that is further excited by blue light illumination to produce reactive oxygen species (ROS). The obtained ROS, in turn, promotes the oxidation of OPD to gain more DAP, causing the auto-inductive chromogenic reaction processes. This tandem chromogenic system is applied for visual colorimetric detection of TATP, allowing the selective and sensitive detection of TATP down to 42.8 μM. Moreover, analyses of TATP in real samples are performed, and the satisfactory recovery results are achieved. Furthermore, a field detection kit is also developed.

Recent advances in self-immolative linkers and their applications in polymeric reporting systems

Interest in self-immolative chemistry has grown over the past decade with more research groups harnessing the versatility to control the release of a compound from a larger chemical entity, given...

Aryl-Cl vs heteroatom-Si bond cleavage on the route to the photochemical generation of σ,π-heterodiradicals

The photochemistry of aryl chlorides having a X-SiMe₃ group (X = O, NR, S, SiMe₂) tethered to the aromatic ring has been investigated in detail, with the aim to generate valuable ϭ,π-heterodiradicals. Two competitive pathways arising from the excited triplet state of the aromatics have been observed, namely heterolysis of the aryl-chlorine bond and homolysis of the X-silicon bond. The former path is found in chlorinated phenols and anilines, whereas the latter is exclusive in the case of silylated thiophenols and aryl silanes. A combined experimental/computational approach was pursued to explain such a photochemical behavior.Graphical abstract.

Cascade Chromogenic System with Exponential Signal Amplification for Visual Colorimetric Detection of Acetone

The signal of the traditional chromogenic systems is directly proportional to analyte concentration, leading to an unsatisfactory sensitivity. Herein, we report a cascade chromogenic system to realize exponential amplification of colorimetric signal through coupling chemical oxidation with photoinduced radical chain reaction. The chemical oxidation of o-phenylenediamine (OPD) by Fe³⁺ generates Fe²⁺ and photoactive 2,3-diaminophenazine (DAP). Under blue-light irradiation, DAP initiates the formation of holes and H₂O₂ that reacts with Fe²⁺ to hydroxyl radicals (·OH) and Fe³⁺ via an intersystem crossing (ISC) process. Moreover, the holes oxidize water to yield ·OH as well. The resulting ·OH and regenerated Fe³⁺ in turn oxidize OPD to yield more DAP, leading to a self-propagating reaction cycle that continues to proceed until all the OPD molecules are consumed, along with a distinct color change from colorless to yellow. Through the generation of the complex between DAP and acetone that limits the ISC process, and therefore quenches the colorimetric signal, the highly sensitive and selective naked-eye detection of acetone is achieved from 50 μM to 3 mM, with a limit of detection of 35 μM. Additionally, the feasibility of this colorimetric assay to detect acetone in real water samples is also demonstrated.

A near-infrared fluorescent probe for selective detection of fluorion

In this work, we have designed and synthesized the fluorescent probe 1, which was capable to selectively detect fluoride anion (F−). More importantly, the probe 1 possessed near-infrared excitation and emission wavelengths (excitation at 650 nm and emission at 695), and the probe solution had changed dramatically from yellow to cyan with the addition of F–. In addition, the fluorescence intensity exhibited perfectly positive correlation with concentration of F− concentration from 0 to 40 μM (R2 = 0.9972), which offered the important condition for quantitative analysis. The probe 1 owned detection limit of 46 nM. Therefore, this near-infrared probe can be of great benefit for detecting F− in practical application.

A Colorimetric Chemosensor Based on a Nozoe Azulene That Detects Fluoride in Aqueous/Alcoholic Media

Colorimetry is an advantageous method for detecting fluoride in drinking water in a resource-limited context, e. g., in parts of the developing world where excess fluoride intake leads to harmful health effects. Here we report a selective colorimetric chemosensor for fluoride that employs an azulene as the reporter motif and a pinacolborane as the receptor motif. The chemosensor, NAz-6-Bpin, is prepared using the Nozoe azulene synthesis, which allows for its rapid and low-cost synthesis. The chemosensor gives a visually observable response to fluoride both in pure organic solvent and also in water/alcohol binary solvent mixtures.

A coumarin-based fluorescent probe for specific and rapid detection of fluoride ions

A simple and coumarin-based fluorescence probe has been designed and synthesized with silyl group as recognition group of fluoride ions (F−) in this study. The results showed that the fluorescence intensity of the probe displayed prominent enhancement with addition of F− at 445 nm with incubation of 1 min. There was an excellent linear relationship between fluorescence intensity and fluoride concentration from 0 to 30 μM (0~0.57 ppm), which offered the important condition for the quantitative analysis. In addition, the highly selective response to fluorion, the low detection limit with 28 nM (0.532 ppb), low toxicity and bioimaging afforded an advantage for practical application and detecting fluoride in biological systerms.

Amplified Chemiluminescence Signal for Sensing Fluoride Ions

Bringing together the concepts of self-immolative linkers and chemiluminogen dioxetane modules, a chemiluminescence-based sensor for fluoride with signal amplification is presented. Signal amplification is obtained by triggering two chemiluminescence events for each reacting fluoride ion that in turn releases two fluoride ions for each ion. As expected, the chemiluminescence signal starts to rise following an induction period. In addition to the analytical potential, this chemical system is also of interest as a demonstration of positive feedback loop character.