A naphthimide-based ratiometric fluorescent probe for selective and visual detection of phosgene in solution and the gas phase

A Ratiometric Benzimidazole-Based Fluorescent Probe for The Recognition of Phosgene in Solution and Gaseous Phases

Considering the high toxicity and widespread application of phosgene, there is an urgent need to develop a simple and sensitive method for detecting phosgene. In this work, we designed and synthesized a novel ratiometric fluorescent probe 1 containing fluorophores of benzimidazole and benzothiazole. Probe 1 showed excellent sensitivity (< 30 s) and selectivity (LOD = 3.82 nM) for phosgene and significant ratiometric fluorescence changes. In addition, 1-loaded polystyrene membrane test strips were used to conveniently and efficiently detect phosgene gas (0.5 ppm) via the naked eye and the RGB APP of the smartphone, indicating that this probe has great potential for phosgene detection in the gaseous phase.

Ratiometric Fluorescent Probe for the Detection of Nanomolar Phosgene in Solution and Gaseous Phase: Advancing Crime Detection Applications

Phosgene, an exceptionally hazardous gas, poses a grave concern for the health and safety of the general public. The present study describes a fluorescent ratiometric probe for phosgene employing 2-(naphthalen-2-yl) benzo[d]oxazol-5-amine (NOA) with an amino group as the recognition site. NOA detects phosgene through the intramolecular charge transfer mechanism. The electron-rich amine group of NOA attacks the electrophilic carbonyl group of phosgene, resulting in a quick response within 20 s. NOA demonstrates a low detection limit of 60 nM while maintaining high selectivity and sensitivity toward phosgene. The final product was isolated and verified by nuclear magnetic resonance spectroscopy. The probe can detect phosgene not just quickly in a solution environment but also in its solid state. The probe's applications in fingerprint imaging and bioimaging are also demonstrated.

A new highly sensitive fluorescent probe for visualization of phosgene in liquid and gas phases

Phosgene is an important and widely used highly toxic chemical that poses a serious potential threat to public health and property if leaked or abused. Therefore, developing an efficient and convenient detection method for phosgene is of great significance. In this work, we synthesized a novel fluorescent probe, BCyP, based on benzohemicyanine for highly selective and sensitive detection of phosgene in both liquid and gas phases. The probe uses amino alcohol as a specific recognition group for phosgene and does not fluoresce due to the strong intramolecular charge transfer effect (ICT). However, in the presence of phosgene, the amino alcohol part in the probe can form oxazolidinone in situ with phosgene, reducing the ICT effect in the probe molecule and lighting fluorescence, thus realizing the selective phosgene detection. The probe exhibits good specificity towards phosgene, with significant fluorescence enhancement (approximately 400-fold), a remarkable Stokes shift (139 nm), a fast response speed (less than 17 s), and a low detection limit (0.12 ppm). Additionally, we prepared a phosgene detection paper strip loaded with the probe on filter paper and combined it with color recognition software on a smartphone to achieve visual detection of phosgene in the gas phase.

A novel benzo hemicyanine-based fluorescent probe for susceptible visualizing detection of phosgene

Leakage and misuse of phosgene, a common and highly hazardous industrial chemical, have always constituted a safety risk. Therefore, it is crucial to develop sensitive detection methods for gaseous phosgene. This work describes the design and development of a new fluorescent dye based on benzohemicyanine, as well as the synthesis of fluorescent probes for the sensitive detection of gaseous phosgene. Due to the excellent intramolecular charge transfer (ICT) effect from the strong electron-donating impact of the o-aminophenol group on benzo hemicyanine, the probe does not emit fluorescence. When the probe reacts with phosgene, the ICT effect is inhibited, and the result exhibits observable green fluorescence, thereby visualizing the response to phosgene. The probe offers exceptional sensitivity, a rapid response, and a low phosgene detection limit. In addition, we developed probe-loaded, portable test strips for the quick and sensitive detection of phosgene in the gas phase. Finally, the constructed probe-loaded test strips were utilized effectively to monitor the simulated phosgene leakage.

Synthesis, structure and mechanofluorochromic properties of phenothiazine-S-oxide and phenothiazine-S,S-dioxide derivatives

In this work, two novel luminescent molecules containing distorted phenothiazine-S-oxide and phenothiazine-S,S dioxide skeletons were synthesized by oxidation reactions using different oxidants (m-chloroperoxybenzoic acid, acetic acid /hydrogen peroxide). The target compounds were all confirmed by ¹H NMR, ¹³C NMR and EI-MS. Combined with the results of UV-vis absorption spectra and fluorescence emission spectra, we found that the different oxidation states of S-atom, from sulfide (+2) to sulfoxide (+4) and sulfone (+6), led to the blue, yellow-green and yellowish fluorescence of these compounds in the solid states. Subsequent studies showed that the molecule containing the phenothiazine-S-oxide skeleton exhibited obvious solvatochromism, and the increase of solvent polarity induced a red-shift in the emission wavelength. Moreover, this molecule also exhibited a rare self-recovery mechanochromatic behavior. In addition, these properties were further confirmed by theoretical calculations and X-ray single-crystal diffraction analysis.

An effective fluorescent probe for detection of phosgene based on naphthalimide dyes in liquid and gaseous phases

A fluorescent probe was developed for the detection of phosgene based on 1,8-naphthalimide, of which o-diaminobenzene was used as the recognition moiety. The probe does not fluoresce due to nonradiative decay. The probe reacts rapidly with phosgene via an intramolecular cyclization reaction, which induces large fluorescence due to increased rigidity in the resulting molecule and a low detection limit (0.23 nM). This probe has excellent selectivity for phosgene against competing interference analytes and, in the form of probe-loaded test paper, is an extremely sensitive method for phosgene sensing in the gas phase below 1 ppm concentrations.

Bifunctional Fluorescent Probes for the Detection of Mustard Gas and Phosgene

Mustard gas [sulfur mustard (SM)] and phosgene are the most frequently used chemical warfare agents (CWAs), which pose a serious threat to human health and national security, and their rapid and accurate detection is essential to respond to terrorist attacks and industrial accidents. Herein, we developed a fluorescent probe with o-hydroxythioketone as two sensing sites, AQso, which can detect and distinguish mustard gas and phosgene. The dual-sensing-site probe AQso reacts with mustard gas to form a cyclic product with high sensitivity [limit of detection (LOD) = 70 nM] and is highly selective to SM over phosgene, SM analogues, active alkylhalides, acylhalides, and nerve agent mimics, in ethanol solutions. When encountering phosgene, AQso rapidly converts to cyclic carbonate, which is sensitive (LOD = 14 nM) and highly selective. Their sensing mechanisms of AQso to mustard gas and phosgene were well demonstrated by separation and characterization of the sensing products. Furthermore, a facile test strip with the probe was prepared to distinguish 2-chloroethyl ethyl sulfide (CEES) and phosgene in the gas phase by different fluorescence colors and response rates. Not using the complicated instrument, the qualitative and quantitative detection of CEES or phosgene can be achieved only by measuring the red-green-blue (RGB) channel intensity of the test strip after being exposed to CEES or phosgene gas by the smartphone with an RGB color application.

Synthesis and Solvent Dependent Fluorescence of Some Piperidine-Substituted Naphthalimide Derivatives and Consequences for Water Sensing

Novel fluorescent strigolactone derivatives that contain the piperidine-substituted 1,8-naphthalimide ring system connected through an ether link to a bioactive 3-methyl-furan-2-one unit were synthesized and their spectroscopic properties investigated. The solvatochromic behavior of these piperidine-naphthalimides was monitored in solvents of different polarity using the electronic absorption and fluorescence spectra. These compounds exhibited a strong positive solvatochromism taking into account the change of solvent polarity, and the response mechanism was analyzed by fluorescence lifetime measurements. According to Catalan and [f(n), f(ε), β, α] solvent scales, the dipolarity and polarizability are relevant to describe the solute-solvent interactions. The emission chemosensing activity was discussed in order to determine the water content in organic environments. The emission intensity of these compounds decreased rapidly in dioxane, increasing water level up to 10%. Measuring of quantum yield indicated that the highest values of quantum efficiency were obtained in nonpolar solvents, while in polar solvents these derivatives revealed the lowest quantum yield. The fluorescence decay can be described by a monoexponential model for low water levels, and for higher water contents a biexponential model was valid.