A coumarin-based fluorescent probe for ratiometric detection of hydrazine and its application in living cells

A V-shaped bis-coumarin based fluorescence probe for F- detection in tea infusions and potable water and bioimaging applications in living systems

Fluorine (F) is a pivotal element in the formation of human dental and skeletal tissues, and the consumption of water and tea constitutes a significant source of fluoride intake. However, prolonged ingestion of water and tea with excessive fluoride content can lead to fluorosis, which poses a serious health hazard. In this manuscript, a novel turn-on fluorescent probe DCF synthesized by bis-coumarin and tert-butyldiphenylsilane (TBDPS) was introduced for detecting F- in potable water and tea infusions. By leveraging the unique chemical affinity between fluoride and silicon, F- triggers the silicon-oxygen bond cleavage in DCF, culminating in a conspicuous emission of yellow fluorescence. Validated through a succession of optical tests, this probe exhibits remarkable advantages in terms of superior selectivity, a low detection limit, a large Stokes shift, and robust interference resistance when detecting inorganic fluoride. Moreover, it can serve as portable test strips for on-site real-time identification and quantitative analysis of F-. Furthermore, the application of DCF for in-situ monitoring and imaging of F- in zebrafish and soybean root tissues proved its significant value for F- detection in both animal and plant systems. This probe potentially functions as an efficient instrument for delving into the toxic mechanisms of fluoride in physiological processes.

Advances in Optical Probes for the Detection of Hydrazine in Environmental and Biological Systems

Hydrazine, as a crucial raw material in the fine chemical industry, plays an indispensable role in fuel, catalyst, pesticide and drug synthesis. Due to its good water solubility and high toxicity, hydrazine can cause irreparable damage to water and soil in the environment, and it can also be released by taking certain drugs, which brings potential risks to human health. Therefore, it is vital to develop a method that can specifically detect hydrazine in the environment and in vivo. As an effective analysis and detection tool, fluorescence probe has attracted extensive attention in recent years. In this review, we summarized and classified hydrazine fluorescence probes based on various reaction mechanisms, and discussed their structures and applications in the past ten years. At least, we briefly outline the challenges and prospects in this field.

A novel fluorescent molecule based on 1,2,3-triazole for determination of palladium (II) and hydrazine hydrate in aqueous system

In recent years, hydrazine hydrate has been widely used in various fields as fuel and chemical raw materials, etc. However, hydrazine hydrate is also a potential threat to living body and natural environment. The effective method is urgently needed to detect hydrazine hydrate in our living environment. Secondly, as a precious metal, palladium has attracted more and more attention because of its excellent properties in industrial manufacturing and chemical catalysis. However, its potential danger is also slowly approaching, so it is necessary to find an excellent way to detect palladium, too. Herein, a fluorescent molecule, 4,4',4'',4'''-(1,4-phenylenebis(2H-1,2,3-triazole-2,4,5-triyl)) tetrabenzoic acid (NAT), was synthesized. Firstly, NAT has very high selectivity and sensitivity for determination of Pd²⁺, because Pd²⁺ can coordinate well with carboxyl oxygen of NAT. The detection performance of Pd²⁺ is that the linear range is from 0.06 to 4.50 μM and the detection limit is 16.4 nM. Furthermore, the chelate (NAT-Pd²⁺) can continue to be used for quantitative determination of hydrazine hydrate with a linear range of 0.05-6.00 μM and the detection limit is 19.1 nM. The interaction time of NAT-Pd²⁺ and hydrazine hydrate is about 10 min. Of course, it also has good selectivity and strong anti-interference ability for many common metal ions, anions and amine like compounds. At last, the ability of NAT to quantitatively detect Pd²⁺ and hydrazine hydrate in actual samples has also been verified and the results are very satisfactory.

Coumarin-cyanine hybrid: A ratiometric fluorescent probe for accurate detection of peroxynitrite in mitochondria

There is an urgent need to develop highly sensitive and selective fluorescence probes for ONOO^- in mitochondria. Herein, we reported a ratiometric fluorescent probe COUS with coumarin-cyanine hybrid as fluorophore and C = C bonds as reaction sites of ONOO^-. The probe COUS was sensitive and selective to ONOO^-, and had a large fluorescence emission shift (239 nm) as well as a low detection limit (41.88 nM). Moreover, COUS showed the mitochondrial targeting ability, and the targeting moiety could dissociate from the probe when reacting with ONOO^-, which enabled COUS to accurately detect ONOO^- in mitochondria.

Naphthalene-based fluorescent probe for on-site detection of hydrazine in the environment

The widespread occurrence of hydrazine residues in the environment, including in water, soil, and organisms, is a potential health threat to humans. Therefore, the development of an efficient method for the detection of hydrazine in environmental samples is highly desirable although it poses a significant challenge. In this study, we designed and synthesized a series of naphthalene-based fluorescent dyes through structural engineering and developed a novel probe for hydrazine detection. The probe could provide a distinct fluorescence response toward hydrazine in aqueous solution with high sensitivity and selectivity. Moreover, paper-based test strips can be easily fabricated using this probe, enabling the portable on-site detection of hydrazine with the aid of a smartphone. Furthermore, we demonstrated that this probe is capable of recognizing hydrazine in various environmental samples, including water, soil, plants, and zebrafish embryos. This research provides a promising tool for the detection of hydrazine in the environment.

A hemicyanine-based near-infrared fluorescent probe for vapor-phase hydrazine detection and bioimaging in a complete aqueous media

A novel near-infrared fluorescent probe CyOE based on hemicyanine dye containing acetyl as a recognition site is reported. The probe CyOE shows high selectivity and sensitivity (LOD = 82 nM, 2.58 ppb), as well as good water solubility and quantitative detectability of hydrazine in the concentration range of 0-75 μM (R² = 0.993). Moreover, CyOE has a significant increase in fluorescence at 735 nm with the addition of N₂H₄, which provides a rapid, colorimetric and gas-phase detection method for N₂H₄ in both aqueous solution and real water samples. In addition, CyOE is successfully utilized to visualize hydrazine in cells with low cytotoxicity and high cell permeability.

An ICT-Based Coumarin Fluorescent Probe for the Detection of Hydrazine and Its Application in Environmental Water Samples and Organisms

As an inorganic small molecule pollutant, the toxicity and potential carcinogenicity of hydrazine (N₂H₄) are of increasing concern. In this work, A water-soluble fluorescent probe (OCYB) based on the intramolecular charge transfer (ICT) mechanism for the detection of hydrazine was designed and synthesized. Taking the advantage of 4-bromobutyryl as the recognition group, the high selectivity of OCYB to N₂H₄ was confirmed by steady-state fluorescence spectroscopy. The limit of detection (LOD) was calculated to be 78 nM in the DMSO-HEPES (pH 7.4) system. The detection mechanism was verified by NMR, HRMS and density functional theory (DFT) calculations. In addition, OCYB exhibits strong anti-interference ability and an “Off-On” fluorescence enhancement effect. Importantly, OCYB can be used to effectively monitor the fluorescence distribution of N₂H₄ in environmental water samples and organisms.

Ratiometric fluorescence chemodosimeter for hydrazine in aqueous solution and gas phase based on Quinoline-Malononitrile

The widespread use of Hydrazine (N₂H₄) in many areas of the chemical industry, brings potential risks to human health and environmental pollution. To detect N₂H₄ effectively, a simple ratio fluorescence probe (QMM), designed and synthesized through Vilsmeier reaction and Knoevenagel reaction, was prepared for the specific response of N₂H₄ based on the irreversible chemical reaction. The ratiometric fluorescence chemodosimeter displayed a response for hydrazine with high selectivity, sensitivity and anti-interference ability. The measured detection limit is 38.30 nm (0.122 ppb), which is far lower than the maximum allowable level of the U.S. Environmental Protection Agency (10 ppb). Moreover, test paper and TLC plates loading QMM had been made, which could be utilized to detect hydrazine both in aqueous solution samples and in gas phase samples. Thus QMM could serve as an easily manufactured, low-cost, efficient and portable solid-state optical probe to detect hydrazine in field measurements.

Development of a ratiometric fluorescent probe with large Stokes shift and emission wavelength shift for real-time tracking of hydrazine and its multiple applications in environmental analysis and biological imaging

As a tremendously noxious and extensively utilized chemical reagent, hydrazine (N₂H₄) has become a serious threat to ecosystem and human health. Thus, it is desirable to exploit an efficient method for real-time tracking of hydrazine. Here, a novel ratiometric fluorescent probe PBQ-AB for hydrazine was rationally constructed from isolongifolanone. This probe displayed an extremely large Stokes shift of 230 nm and could selectively recognize hydrazine in the presence of other competitive species within an extremely short time ( 40 s). PBQ-AB also displayed some fascinating merits in the detection of hydrazine, including low detection limit (48 nM), wide pH range (5-12), excellent photostability (>240 min), and well-resolved emission wavelength shift (148 nm). Moreover, this probe was utilized to fabricate a ready-to-use electrospinning nanofibrous membrane for convenient detection of hydrazine vapor by virtue of smartphone. Furthermore, PBQ-AB was capable of determining hydrazine contaminant in environmental soil and water samples. Additionally, its favorable performance for detecting hydrazine was successfully demonstrated in live HeLa cells as well as in live Arabidopsis thaliana tissues, manifesting its promising application for labeling hydrazine in living systems. Therefore, we believed that this probe has great potential in environmental analysis and health supervision.

Irreversible coumarin based fluorescent probe for selective detection of Cu2+ in living cells

Copper ion (Cu²⁺) is an essential part of the living organisms. Cu²⁺ ions play a vital role in many biotic processes. An abnormal amount of Cu²⁺ ions may result in serious diseases. Herein, a novel "fluorescent ON" probe NC-Cu to trace minute levels of Cu²⁺ ions in presence of various biological active species has been developed. Lysosomal cells targeting group (Morpholine) was added to the probe. The spectral properties of probe NC-Cu were recorded in HEPES buffer (0.01 M, pH = 7.4, comprising 50% CH₃CN, λ_ex = 430 nm, slit: 5 nm). The synthesized probe NC-Cu work based on copper promoted catalytic hydrolysis of hydrazone and shows remarkable fluorescence enhancement. The reaction of the probe with Cu²⁺ ions was completed within 20 min. An excellent linear relationship (R² = 0.9952) was found and the limit of detection (LOD, according to the 3σ/slope) for Cu²⁺ ions was calculated to be 5.8 µM. Furthermore, NC-Cu was effectively functional in the living cells (KYSE30 cells) to trace Cu²⁺ ions.

Synthesis and optical properties of Schiff base derivatives based on 2-(2-hydroxyphenyl)benzothiazole (HBT) and application in the detection of N2H4

Four 2-(2-hydroxyphenyl)benzothiazole-based Schiff base derivatives incorporating different substituents were synthesized. Their optical properties were characterized by UV-visible and fluorescence spectra. The electron-withdrawing and electron-donating actions of substituents can change the orbital energy level distributions of molecules resulting in the difference of their luminescence properties. And the fluorescence microscopic images showed that these derivatives had different aggregation behaviors to form aggregates of different shapes. Furthermore, compound HBT-4 has been proved to have excellent recognition performance for N₂H₄ in real aqueous solution. Finally, HBT-4 could be prepared into a simple test paper as an efficient tool for the rapid detection of N₂H₄.

Hydrazine exposure: A near-infrared ICT-based fluorescent probe and its application in bioimaging and sewage analysis

Hydrazine (N₂H₄) is an environment pollutant with high acute toxicity and potential carcinogenicity, and detection of N₂H₄ has attracted increasing attention. In the present study, a low toxicity near-infrared fluorescent probe (DCDB) based on the intramolecular charge transfer (ICT) principle was developed. The probe DCDB exhibits excellent selectivity and high sensitivity (LOD = 1.27 ppb) for N₂H₄, fast reaction rate (5 min), extremely large Stokes shift (160 nm). The color transformation of the DCDB-N₂H₄ system from purple to pink can be observed with the naked eye. The success of N₂H₄ test strips to detect trace N₂H₄ in actual sewage strongly illustrates the practical application potential of DCDB. Importantly, DCDB can be utilized to monitor the distribution of exogenous N₂H₄ in vivo and in vitro.

The preparation of a special fluorescent probe with an aggregation-induced emission effect for detecting hydrazine in water

A novel phenyl-carbazole fluorescent molecule, PCBI, with an AIE effect is used as an excellent special probe for the detection of N2H4 in a DMF–H2O system.

A Coumarin-Based Fluorescent Probe for Ratiometric Detection of Cu2+ and Its Application in Bioimaging

The fluorescent probe L, based on naphthalimide-modified coumarin, was designed, synthesized, and characterized, which could recognize Cu2+ from other cations selectively and sensitively in HEPES buffer (10 mM, Ph = 7. 4)/CH3CN (1:4, V/V). When the probe L interacted with Cu2+, the color and the fluorescent intensity changed obviously and it provided the naked-eye detection for Cu2+. The recognition mode between them was achieved by Job's plot, IR, MS, SEM, and 1HNMR. In addition, test strips made from L could still interact with Cu2+ in tap water effectively. The limit of detection (LOD) of L was 3.5 × 10-6 M. Additionally, the density functional theory (DFT) calculation method was used to analyze the action mechanism of L toward Cu2+. Importantly, the fluorescent probe L could demonstrate favorable selectivity toward Cu2+ in Caenorhabditis elegans. Thus, L was considered to have some potential for application in bioimaging.

Overview on developed synthesis procedures of coumarin heterocycles

Considering highly valuable biological and pharmaceutical properties of coumarins, the synthesis of these heterocycles has been considered for many organic and pharmaceutical chemists. This review includes the recent research in synthesis methods of coumarin systems, investigating their biological properties and describing the literature reports for the period of 2016 to the middle of 2020. In this review, we have classified the contents based on co-groups of coumarin ring. These reported methods are carried out in the classical and non-classical conditions particularly under green condition such as using green solvent, catalyst and other procedures.

Ultra-fast and visual detection of hydrazine hydrate based on a simple coumarin derivative

A cleverish fluorescence probe based on coumarin was developed, exhibiting remarkable color change, strong fluorescence enhancement and fast response when it interacts with hydrazine in water solution. The limit of detection (LOD) is 5.59 × 10^-6 M for ultraviolet analysis and 8.18 × 10^-8 M for fluorescence analysis, respectively. Taking advantage of good sensitivity and short response time, the probe was applied to test hydrazine in water and to observe hydrazine in living cells.

Rhodol-based fluorescent probes for the detection of fluoride ion and its application in water, tea and live animal imaging

Herein, we presented two novel turn-on colorimetric and fluorescent probes based on a F^- triggered SiO bond cleavage reaction, which displayed several desired properties for the quantitative detection for F^-, such as high specificity, rapid response time (within 3 min) and naked-eye visualization. The fluorescence intensity at 574 nm (absorbance at 544 nm) of the solution was found to increase linearly with the concentration of F^- (0.00-30.0 μM) with the detection limit was estimated to be 0.47 μM/0.48 μM. Based on these excellent optical properties, the probes were employed to monitor F^- in real water samples and tea samples with satisfactory. Furthermore, it was successfully applied for fluorescent imaging of F^- in living nude mice, suggesting that it could be used as a powerful tool to predict and explore the biological functions of F^- in physiological and pathological processes.

A New Fluorescent Turn-on Dual Interaction Position Probe for Determination of Hydrazine

Hydrazine is an important catalyst and chemical raw material. But it is highly toxic and potentially carcinogenic. We designed a new hydrazine probe based on a synergistic effect by introducing acetate and phthalimide into 2-phenyl-benzimidazole (PBI). Comparative experiments proved that "the dual position interaction" had a "synergistic effect" on fluorescence enhancement. The fluorescence enhancement caused by the probe (15.0 fold) is much larger than the sum of the fluorescence enhancement of the two monomer compounds (2.6 and 1.4 folds, respectively). A theoretical calculation showed an inhibition of the PET process and a recovery of the ICT process led to a fluorescence enhancement. The probe was specific to hydrazine and showed a linear response to it in the concentrations range of 0.2 - 200 μM with a LOD of 0.062 μM (1.99 ppb). Moreover, the probe could detect hydrazine in tap water; the recovery of hydrazine from the tap water was between 98.86 - 103.28%.

Recent Progress in the Development of Fluorescent Probes for Thiophenol

Thiophenol (PhSH) belongs to a class of highly reactive and toxic aromatic thiols with widespread applications in the chemical industry for preparing pesticides, polymers, and pharmaceuticals. In this review, we comprehensively summarize recent progress in the development of fluorescent probes for detecting and imaging PhSH. These probes are classified according to recognition moieties and are detailed on the basis of their structures and sensing performances. In addition, prospects for future research are also discussed.