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The "New Journal of Chemistry" published by the Royal Society of Chemistry features a variety of research articles on topics such as synthetic developments in thioethers, gas nanogenerators, luminescent probes, and wastewater treatment absorbents. The journal covers a wide range of chemistry-related subjects, including batteries, catalysis, organic polymers, and nanocomposites. Researchers interested in cutting-edge advancements in chemistry will find valuable insights and innovative approaches in this issue of the journal. [Extracted from the article]

The New Journal of Chemistry, published by the Royal Society of Chemistry, features a variety of research articles on topics such as solar energy, catalysis, nanotechnology, and bioimaging. The latest issue includes papers on topics like the synthesis of amides, metal-organic frameworks for imaging, and the development of nonisocyanate polyurethane nanocomposites. Researchers interested in cutting-edge advancements in chemistry will find valuable insights in this journal. [Extracted from the article]

Rheumatoid arthritis (RA) is a common inflammatory disease that greatly restricts normal joint movement. The excessive production of Cys (Cysteine) is one of the biomarkers of rheumatoid arthritis. However, research on relevant fluorescent probes mainly focused on the NIR-I region, with few developments of fluorescent probes in the NIR-II region. Therefore, in this study, we designed and synthesized a NIR-II fluorescent (NIR-II FL) probe, GY-G, for specific detection of endogenous Cys in RA with excellent NIR-II FL imaging performance. This probe exhibited a NIR-II FL emission exceeding 920 nm and a large Stokes shift of 110 nm. Additionally, GY-G responded to Cys with high sensitivity and selectivity in an RA model. Notably, we successfully achieved NIR-II FL imaging of endogenous Cys in an RA model by using GY-G. Significantly, GY-G is expected to be a potential candidate for early diagnosis of RA. A NIR-II fluorescent probe for detecting endogenous Cys in arthritis models was developed for the first time. Overall, this probe has great potential in exploring the pathophysiological processes of Cys-associated arthritis with a range of biomedical tools that can be used for NIR-II fluorescence imaging. [ABSTRACT FROM AUTHOR]

Biogenic amines (BAs), produced in fish and seafood due to microbial contamination, pose significant health risks. This study introduces a novel ratiometric fluorescent probe, synthesized by integrating rhodamine 6G(R6G) and gold nanoparticles (AuNCs), for the sensitive and specific detection of BAs. The probe operates on the principle of BAs hydrolysis, catalyzed by diamine oxidase, to produce hydrogen peroxide (H2O2), which selectively quenches the fluorescence of AuNCs at 620 nm, while the fluorescence of R6Gat 533 nm remains unaffected. The ratio of I620/I553 demonstrated excellent linearity with a wide dynamic range (1–1000 μM) and a low detection limit of 0.1 μM. Validation using grass carp samples showed high recovery rates (97.57% to 104.29%), confirming the probe's efficacy and potential for practical application in food safety monitoring. [ABSTRACT FROM AUTHOR]

The article discusses a new approach for the synthesis and purification of spiro[fluorene-9,5'-[1,3]-dioxan]-2'-one, focusing on the use of crystallization-driven self-assembly (CDSA) of coil-crystalline block copolymers. The research highlights the synthesis of polyferrocenyldimethylsilane (PFS) and the challenges associated with its monomer synthesis. Additionally, the article presents a new method for synthesizing fluorene trimethylene carbonate (F-TMC) as a promising alternative to PFS, with a simplified two-step synthesis process using N,N'-carbonyldiimidazole (CDI). The study aims to facilitate the large-scale industrial production of F-TMC for potential applications in polymer synthesis and crystallization-driven self-assembly. [Extracted from the article]

Mercury, a highly toxic heavy metal, poses significant environmental and health risks, necessitating the development of effective and responsive techniques for its detection. Organic chromophores, particularly small molecules, have emerged as promising materials for sensing Hg2+ ions due to their high selectivity, sensitivity, and ease of synthesis. In this review article, we provide a systematic overview of recent advancements in the field of fluorescent chemosensors for Hg2+ ions detection, including rhodamine derivatives, Schiff bases, coumarin derivatives, naphthalene derivatives, BODIPY, BOPHY, naphthalimide, pyrene, dicyanoisophorone, bromophenol, benzothiazole flavonol, carbonitrile, pyrazole, quinoline, resorufin, hemicyanine, monothiosquaraine, cyanine, pyrimidine, peptide, and quantum/carbon dots probes. We discuss their detection capabilities, sensing mechanisms, limits of detection, as well as the strategies and approaches employed in their design. By focusing on recent studies conducted between 2022 and 2023, this review article offers valuable insights into the performance and advancements in the field of fluorescent chemosensors for Hg2+ ions detection. [ABSTRACT FROM AUTHOR]

Surface‐enhanced Raman scattering (SERS) has been visualized as a promising analytical technique in marked‐molecule detection for disease diagnosis, environmental pollution, and so on. Noble metal nanoparticles, especially gold nanoparticles (AuNPs), are commonly used to fabricate SERS substrates. Herein, we facilely fabricated a special platform to improve the dispersity and homogeneity of AuNPs. Practically, based on nano‐graphene oxide (GO), a special platform (s‐GO‐PEG‐R'hB) was prepared through GO functionalization with biocompatible poly(ethylene glycol) (PEG), acid‐activated fluorescence molecule (Rhodamine B lactam derivative, R'hB) and thiol sites with cysteamine. AuNPs were then in situ grown on s‐GO‐PEG‐R'hB sheets to provide GO/AuNPs nanocomposite (Au@s‐GO‐PEG‐R'hB) for use as an efficient SERS substrate, which can exert unique electromagnetic characteristics of AuNPs and improve its dispersity. With systematic morphology and composition characterizations, it was confirmed that uniform AuNPs were located on multi‐functionalized GO sheets in Au@s‐GO‐PEG‐R'hB as we designed. Au@s‐GO‐PEG‐R'hB performed well in SERS detection towards 4‐aminothiophenol (4‐ATP) and p‐phenylenediamine (PD), with preferable sensibility, stability and effectiveness. With well‐knit SERS results, it is indicated that Au@s‐GO‐PEG‐R'hB could take the advantages of inherent electrochemical properties of AuNPs and functionalized GO to be a potential substrate in SERS detection. Thus, it is foreseen that Au@s‐GO‐PEG‐R'hB can meet diverse SERS sensing demands in real life. [ABSTRACT FROM AUTHOR]

In this study, we synthesized a fluorescent material by modifying the C-2 amino group of carboxymethyl chitosan with a rhodamine B derivative, which was proposed and demonstrated using 1H NMR and FT-IR measurements. A series of experiments including selectivity, sensitivity, reversibility, pH, and water content were conducted to investigate the fluorometric and colorimetric properties of the grafted polymer. Utilizing a Fe3+-induced ring-opening mechanism of the rhodamine B spirolactam, we found that the grafted polymer exhibited a highly selective fluorescence response to Fe3+, with enhanced fluorescence at 583 nm compared to other tested metal ions and anions, accompanied by the characteristic absorption peak of rhodamine B that appeared at 561 nm with a noticeable color change from colorless to pink, facilitating visual observation. Additionally, the modified probe, composed of carboxymethyl chitosan, was easily regenerated through treatment with EDTA. [ABSTRACT FROM AUTHOR]

Triphenylmethyl‐based compounds such as rhodamines and fluoresceine representing an old and well‐known class of triphenylmethane dyes, are widely used in fluorescent labeling of bioimaging. Inspired by ultralong room temperature phosphorescence of triphenylphosphine derivatives, herein we report a methoxy substituted triarylmethanol ((4‐methoxyphenyl)diphenylmethanol, LJW‐1) exhibits ultralong room temperature phosphorescence (RTP) under ambient condition with afterglows of about 7 seconds. Its multiple C−H ⋅ ⋅ ⋅ π intermolecular interactions, C−H ⋅ ⋅ ⋅ O intermolecular interactions, hydrogen bond and π‐π interactions are beneficial for forming rigid environment in the aggregated state which is evidently an important factor in the appearance of excellent RTP. Different substituents on triarylmethanol result in compounds with different lifetimes varying from 7 μs to 818 ms. The substituent effects on the phosphorescence of triarylmethanol derivatives provide an efficient method for the design of organic RTP materials and may be enlightening the phosphorescence research of triarylmethanol derivatives. [ABSTRACT FROM AUTHOR]

The long-lived room-temperature phosphorescence (RTP) originating from thiophene boronate polyvinyl alcohol (PVA) has enabled the creation of metal-ion-responsive RTP films doped with spirolactam ring-containing rhodamine 6G (1). In this study, RTP-active PVA films, namely, TDB@PVA and ATB@PVA, were prepared through boronate esterification of thiophene-2,5-diboronic acid (TDB) and 5-acetylthiophene-2-boronic acid (ATB) with the diol units of PVA. The delayed emission properties were evaluated, revealing an emission band at 477 nm with a turquoise afterglow for TDB@PVA and at 510 nm with a green afterglow for ATB@PVA after UV light irradiation ceased. The photophysical properties were assessed using TD-DFT and DFT calculations at the B3LYP/cc-pVDZ level. N-(rhodamine-6G)lactam dye with a salicylimine unit (1) was doped into the RTP-based PVA films, producing a multicolored afterglow upon the addition of metal ions. This phenomenon is explained by a triplet-tosinglet Förster-type resonance energy transfer process from the cross-linked thiophene boronate in PVA to the metal-ion-activated colored form of 1. This photophysical feature finds applicability in encryption techniques. Notably, the reversible metal-ligand coordination of 1 in the PVA system enabled a write/erase information process. [ABSTRACT FROM AUTHOR]

Intracellular biothiols, including cysteine (Cys), glutathione (GSH), and homocysteine (Hcy), play a critical role in many physiological and pathological processes. Among them, GSH is the most abundant non-protein mercaptan (1–10 mM) in cells, and the change in GSH concentration level is closely related to the occurrence of many diseases, such as Parkinson's disease, Alzheimer's disease, and neurological diseases. Fluorescent probes have attracted much attention due to their advantages of high specificity, high sensitivity, high selectivity, low cost, and high quantum yield. Methods that use optical probes for selective detection of GSH in vitro and in vivo are in high demand. In this paper, we reviewed the most recent five years of research on fluorescence probes for the detection of GSH, including the specific detection of GSH, dual-channel identification of GSH and other substances, and the detection of GSH and other biothiols. According to the type of fluorophore, we classified GSH fluorescent probes into eight classes, including BODIPY, 1,8-Naphthalimide, coumarin, xanthene, rhodamine, cyanine, benzothiazoles, and others. In addition, we roundly discuss the synthesis, detection mechanism, photophysical properties, and biological applications of fluorescent probes. We hope that this review will inspire the exploration of new fluorescent probes for GSH and other related analyses. [ABSTRACT FROM AUTHOR]

The article focuses on recent advancements in chemistry, highlighting the development of new materials and chemical processes. Topics include the synthesis of insensitive energetic materials with enhanced detonation performance, the use of vanadium(V) complexes for syndiospecific ring-opening metathesis polymerization (ROMP) of cyclic olefins, and the exploration of metal-support interactions to enhance catalytic activity for hydrogen production.

Hydrazine, a compound known for its toxicity to human health and the environment, finds extensive use across various industries and potentially contributes to several diseases. Hence, the accurate measurement of hydrazine levels is paramount. This study introduces three new aggregation induced emissive luminogens (AIEgens) GBY-7, GBY-8, and GBY-9 crafted from benzofuran infused with a dicyanovinylidene group, tailored specifically for hydrazine monitoring. These probes feature a D–π–A core with a rotor, providing an optimal fluorescent base. Additionally, a potent electron-attracting nitrile group aids in the nucleophilic addition of N2H4 to form hydrazone, thereby blocking the intramolecular charge transfer (ICT) process and inducing optical signal modulation. Notably, luminogens GBY-8 and GBY-9 exhibit high selectivity in detecting hydrazine amidst competing amine-based compounds, showing detection limits of 0.00020 mM and 0.0043 mM, respectively. [ABSTRACT FROM AUTHOR]

The mechanochromic materials can respond to environmental changes by altering the optical properties of the system, which has garnered significant attention in recently. The utilization of these materials for the purpose of sensing tensile and compressive stress has been extensively documented. However, the mechanochromic polymer that can effectively discriminate hardness of inorganic particles is still rarely reported. In this article, a force‐sensitive organic polysiloxane was developed by introducing triethenyl‐substituted rhodamine derivatives crosslinker into the polymethylhydrosiloxane network through hydrosilylation addition reaction. The results demonstrated that the grinding of the crosslinked polysiloxane effectively facilitated the transmission of external force to the polymeric network, leading to an open ring isomerization of rhodamine accompanied by significant alterations in visible and fluorescent color. In addition, we found that the optical properties of the system showed distinct variations when the inorganic particles with different Moh's hardness were co‐ground with the polysiloxane. High Moh's hardness particles, such as Al2O3, could effectively trigger the mechanochromic behavior of the polymer, while Na2SO4 particles with low hardness failed to induce the corresponding change. Therefore, this organic polysiloxane could be used as a potential fluorescent indicator for hardness recognition. [ABSTRACT FROM AUTHOR]

The document is a contents list for the New Journal of Chemistry, a journal focused on new directions in chemistry. It includes various articles and papers on topics such as lithium-ion batteries, organic synthesis, photocatalysts, and nanocatalytic systems. The journal is published by The Royal Society of Chemistry and the Centre National de la Recherche Scientifique. [Extracted from the article]

Herein we have reported a fluorescent probe (MB-M) based on MB derivative for Cu2+ ions detection. The probe was well characterized by 1H NMR, 13C NMR and HR-MS spectrum. Probe MB-M showed naked-eyes recognition to Cu2+ as color change from colorless to indigo. The probe exhibited promising features such as high fluorescence and UV–vis selectivity, fast response (5 mint), workable at pH 2–7, and low limit of detection (LOD = 0.33 µM). Probe MB-M was also used for Cu2+ ions imaging in HepG-2 cells and detection in daily life (Test Strip and lake water). Moreover, non-covalent interaction (NCI) and quantum theory of atoms in molecules (QTAIM) analysis were used to study the interaction between MB-M and Cu2+ ions. By examining the electronic characteristics of the complex using natural bond orbital (NBO), electron density difference (EDD), and frontier molecular orbital (FMO) analysis, the sensitivity of MB-M towards Cu2+ ions were investigated. The results illustrated that the interactions between MB-M and Cu2+ ions involved chemisorption. [ABSTRACT FROM AUTHOR]

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Cancer cells are known to create an acidic microenvironment (the Warburg effect). At the same time, fluorescent dyes can be sensitive to pH, showing a sharp increase or decrease in fluorescence depending on pH. However, modern applications, such as confocal laser scanning microscopy (CLSM), set additional requirements for such fluorescent markers to be of practical use, namely, high quantum yield, low bleaching, minimal quenching in the cell environment, and minimal overlap with auto-fluorophores. R6G could be the perfect match for these requirements, but its fluorescence is not pH-dependent. We have attempted to develop an R6G conjugate with its FRET or PeT pair that would grant it pH sensitivity in the desired range (5.5–7.5) and enable the selective targeting of tumor cells, thus improving CLSM imaging. Covalent conjugation of R6G with NBD using a spermidine (spd) linker produced a pH-sensitive FRET effect but within the pH range of 7.0–9.0. Shifting this effect to the target pH range of 5.5–7.5 appeared possible by incorporating the R6G-spd-NBD conjugate within a "smart" polymeric micelle based on chitosan grafted with lipoic acid. In our previous studies, one could conclude that the polycationic properties of chitosan could make this pH shift possible. As a result, the micellar form of the NBD-spd-R6G fluorophore demonstrates a sharp ignition of fluorescence by 40%per1 pH unit in the pH range from 7.5 to 5. Additionally, "smart" polymeric micelles based on chitosan allow the label to selectively target tumor cells. Due to the pH sensitivity of the fluorophore NBD-spd-R6G and the selective targeting of cancer cells, the efficient visualization of A875 and K562 cells was achieved. CLSM imaging showed that the dye actively penetrates cancer cells (A875 and K562), while minimal accumulation and low fluorophore emission are observed in normal cells (HEK293T). It is noteworthy that by using "smart" polymeric micelles based on polyelectrolytes of different charges and structures, we create the possibility of regulating the pH dependence of the fluorescence in the desired interval, which means that these "smart" polymeric micelles can be applied to the visualization of a variety of cell types, organelles, and other structures. [ABSTRACT FROM AUTHOR]

• The lectin WSMoL inhibited the growth of C. neoformans B3501 and C. gattii R26. • Lectin treatment resulted in damage to the integrity of the lysosomes of yeast cells. • WSMoL also caused reduction of the mitochondrial membrane potential of C. neoformans B3501. • WSMoL inhibited biofilm formation by C. neoformans B3501. Moringa oleifera seeds contain a water-soluble lectin (WSMoL) that exerts antimicrobial effects against bacteria and Candida yeasts. In this study, we evaluated the activity of WSMoL against Cryptococcus neoformans (B3501 and H99) and Cryptococcus gattii (R265). Antifungal activity was evaluated by determining the minimum inhibitory concentration (MIC). Changes in the mitochondrial membrane potential of cells exposed to lectin were assessed using the fluorescent probe rhodamine 123. Moreover, the effect of WSMoL on the lysosomal membrane integrity was assessed via acridine orange staining. WSMoL exhibited an MIC of 6.25 µg/mL for all strains but did not exhibit any fungicidal activity. WSMoL caused lysosomal damage in C. neoformans B3501 and C. gattii R265 cells and reduced the mitochondrial membrane potential in C. neoformans B3501. Additionally, at concentrations of 25–400 µg/mL, WSMoL inhibited biofilm formation by C. neoformans B3501, the only isolate capable of producing biofilms. In conclusion, WSMoL exhibits antifungal activity, causing lysosomal and mitochondrial damage and inhibiting growth and biofilm formation in Cryptococcus yeasts. [ABSTRACT FROM AUTHOR]

This study aimed to investigate the potential of polycaprolactone–vitamin E TPGS (PCL-TPGS) micelles as a delivery system for oral administration of paclitaxel (PTX). The PCL-TPGS copolymer was synthesized using ring opening polymerization, and PTX-loaded PCL-TPGS micelles (PTX micelles) were prepared via a co-solvent evaporation method. Characterization of these micelles included measurements of size, polydispersity, and encapsulation efficiency. The cellular uptake of PTX micelles was evaluated in Caco-2 cells using rhodamine 123 (Rh123) as a fluorescent probe. Moreover, an everted rat sac study was conducted to evaluate the ex vivo permeability of PTX micelles. Additionally, a comparative pharmacokinetic study of PTX micelles versus the marketed formulation, Ebetaxel® (a Taxol generic), was performed after a single oral administration to rats. The results demonstrated that the micellar formulation significantly improved PTX solubility (nearly 1 mg/mL). The in vitro stability and release of PTX micelles in simulated gastric fluid (SGF) and simulated intestinal fluid (SIF) demonstrated that PTX micelles remained stable for up to 24 h and significantly slowed the release of PTX in both media compared to Ebetaxel®. The in vitro cellular uptake, ex vivo intestinal permeability, and in vivo pharmacokinetic profile demonstrated that PTX micelles enhanced the permeability and facilitated a rapid absorption of the drug. Conclusively, the PCL7000-TPGS3500 micelles exhibit potential as an effective oral delivery system for PTX. [ABSTRACT FROM AUTHOR]

A novel supramolecular system based on calix[4]arene linked with rhodamine B was designed and synthesized, incorporating different alkoxy side chains. All four supramolecular compounds (3a–3d) synthesized using this approach exhibited nematic-type liquid crystalline properties. Detailed analyses using polarizing optical microscopy, differential scanning calorimetry, the X-ray diffraction technique, and thermogravimetry were performed to investigate the microscopic, molecular arrangement pattern, and thermal behavior of the compounds. The well-known Schlieren and threaded-type texture pattern was observed in all four bi-substituted calixarene derivatives. They displayed unique texture patterns supporting the idea of a well-organized supramolecular structure. Additionally, these materials demonstrated enantiotropy-type mesophase with a wide temperature range and good thermal stability. Notably, they exhibited light-emitting properties in both solution and solid thin film states, showing the intriguing aggregation-induced emission effect. All four compounds adopted a cone conformation with two side substitution on the calix[4]arene rigid core. Compound 3c was utilized to stain nematode samples using a solution-state aggregation approach. The fluorescent supramolecule effectively allowed visualization and tracking of the staining patterns within the nematode organisms. This methodology enabled the examination of cellular and subcellular structures, further offering valuable insights into the behavior and morphology of nematodes. [ABSTRACT FROM AUTHOR]

Developing multifunctional nanomaterials with distinct photochemical properties, such as high quantum yield, improved photostability, and good biocompatibility is critical for a wide range of biomedical applications. Motivated by this, we designed and synthesized a dansyl‐tagged xanthate‐based capping agent (DX) for the synthesis of fluorescent silver nanoparticles (AgNPs). The capping agent DX was characterized by 1H and 13C‐NMR, LC–MS, and FT‐IR. The synthesized DX‐capped fluorescent AgNPs were thoroughly characterized by UV–visible spectroscopy, fluorescence spectroscopy, field emission scanning electron microscope (FE‐SEM), transmission electron microscope (TEM), dynamic light scattering (DLS), and zeta potential. The fluorescent AgNPs showed distinct surface plasmon resonance absorption at λmax = 414 nm, fluorescence at λmax = 498 nm, quantum yield = 0.24, zeta potential = +18.6 mV, average size = 18.2 nm. Furthermore, the biological activity of the fluorescent AgNPs was validated by its interaction with the most abundant protein in the blood, that is, BSA (Bovine serum albumin) and HSA (Human serum albumin) with binding constant of 2.34 × 104 M−1 and 2.14 × 104 M−1 respectively. Interestingly, fluorescence resonance energy transfer (FRET) was observed between the fluorescent AgNPs and BSA/HSA with a FRET efficiency of 77.23% and 56.36%, respectively, indicating strong interaction between fluorescent AgNPs and BSA/HSA. [ABSTRACT FROM AUTHOR]

Nucleophilic ring-opening of 1,6,10,14-tetraoxatetraspiro[2.1.25.1.29.1.213.13]hexadecane, a cyclooctane structure spiro-fused with four oxirane fragments, under the action of sodium azide was studied. Depending on the relative configuration of stereocenters in the starting compound, the reaction proceeded as an intramolecular transannular cyclization with the formation of a 9-oxabicyclo[3.3.1]nonane skeleton or as an independent nucleophilic opening of the oxirane rings, leading to tetraazido tetraols of the cyclooctane series. [ABSTRACT FROM AUTHOR]

In this investigation, we employed a straightforward hydrothermal method to synthesize various TiO2 nanostructures, including titanium nanoparticles (TNPs), titanium nanorods (TNRs), and titanium nanotubes (TNTs). Generally, TiO2 is a widely studied chemical compound in the materials research field, which finds applications in diverse areas such as photocatalysis and energy storage systems. Furthermore, these nanostructures hold immense potential for applications in dye degradation and supercapacitors. To characterize the synthesized photocatalysts, we employed techniques such as XRD, DLS, UV–Vis spectra, SEM, TEM, and electrochemical workstation. The as-synthesized photocatalysts demonstrated remarkable efficiency in degrading different concentrations of rhodamine B (RhB) and methyl orange (MO) dyes under direct sunlight while also exhibiting excellent electrochemical properties. For comparison, we included bulk TiO2 anatase powder in our study. In the case of supercapacitor application, TNRs exhibited the highest specific capacitance of 122 F g−1 at a current density of 0.5 A g−1, outperforming the 0-dimensional (0D) nanostructures and bulk TiO2 powder (TBP). Our results indicate that the 1-dimensional (1D) TiO2 nanostructures offer superior performance under optimal experimental conditions compared to the other forms of TiO2. [ABSTRACT FROM AUTHOR]

We synthesized a pyrene‐based sensitive fluorescent chemosensor, TPA‐Cl ((E)‐N,N,N‐trimethyl‐2‐oxo‐2‐(2‐(pyren‐1‐ylmethylene)hydrazinyl)ethan‐1‐aminium chloride), to detect hypochlorite in a perfect aqueous solution. TPA‐Cl showed high selectivity for hypochlorite through fluorescence color change from sky blue to blue. The detection limit for hypochlorite was calculated as 0.27 μM, which is a quite low value. Moreover, the presence of other anions or ROS hardly hindered the sensing of hypochlorite by TPA‐Cl. Furthermore, TPA‐Cl could be applied successfully as a test kit for the simple recognition of hypochlorite. Surprisingly, TPA‐Cl is the first pyrene‐based fluorescent chemosensor that can detect ClO− by using the TPA‐Cl‐coated test kit. Moreover, TPA‐Cl could achieve the quantification of ClO− in various environmental water samples. The hydrolytic cleavage and oxidation mechanism of TPA‐Cl by hypochlorite was elucidated through UV–vis and fluorescent spectroscopy, 1H NMR titration, ESI‐MS analysis and DFT calculation. [ABSTRACT FROM AUTHOR]

This study presents findings that suggest it is possible to fine‐tune and enhance the optical properties of anthraquinone (AQ) and its photocatalytic performance in the degradation of rhodamine B (RhB) at the molecular level through varying its keleton substituents. Specifically, the electron‐withdrawing substituent demonstrates a more pronounced improvement effect compared to the electron‐donating substituent. Out of the several compounds, 2‐carboxyanthraquinone (AQ−COOH) exhibits the highest photocatalytic activity. This is due to its ionization in water, generating H+ ions that enhance the destruction of RhB through photodegradation. After 30 min of exposure to visible light, the degradation rate of RhB reaches an impressive 99.9 %. It is noteworthy that a hydrochloric acid solution with a concentration of 0.5 mmol ⋅ L−1 has a considerable promoting impact on the photodegradation of RhB catalyzed by AQ−COOH, and that the total degradation of RhB can be accomplished in 15 min. In addition, AQ−COOH also has good applicability for the degradation of tetracycline, methylene blue, and methyl orange. As a recyclable solid catalyst, the catalytic activity of AQ−COOH remained mostly unchanged after being used five times. Additionally, AQ−COOH did not undergo degradation when exposed to visible light, indicating its excellent stability in the process of catalyzing RhB degradation. According to quenching experiments and EPR spectrum characterizations, the photo‐generated active species oxygen vacancies (h+), photogenerated electrons (e−), superoxide free radicals (O2⋅−), singlet oxygen (1O2) and hydroxyl radical (•OH) are involved in the hypothesized photo‐catalytic degradation mechanism. [ABSTRACT FROM AUTHOR]

A new ZnII coordination polymer (CP) based on 2,3‐pyrazine dicarboxylic acid (H2pzdc) and 4,4′‐bipyridine (bpy) (ZCP) was synthesized using a facile slow evaporation method. Single‐crystal X‐ray diffraction revealed that ZCP is a two‐dimensional porous CP, [Zn2(pzdc)2(bpy)(H2O)2]n, with van der Waals forces as the dominant interaction within its layers forming a 63 network. Employing energetic ultrasound irradiation, nanoscale ZCP (nZCP) was successfully synthesized and Eu3+ ions were incorporated within its host lattice (Eu@nZCP). The resulting platform exhibits superior fluorescence characteristics and demonstrates notable optical durability. Therefore, it was used as a dual detection fluorescent sensing platform for the detection of mercury and l‐cysteine (l‐Cys) in aqueous media through a turn‐off/on strategy. In the turn‐off process, the fluorescence emission of Eu@nZCP progressively quenches by the addition of HgIIvia a photo‐induced electron transfer (PET) mechanism. The fluorescence of Eu@nZCP is quenched to establish a low fluorescence background through the incorporation of HgII. This devised turn‐on fluorescent system is suitable for the recognition of l‐Cys (based on the strong affinity of l‐Cys to the HgII ion) through a quencher detachment mechanism. This method attained a relatively wide linear range, spanning from 0.001 to 25 µM, with the low detection limit of 5 nM for the sensing of HgII. Also, the corresponding limit of detection (LOD) for l‐Cys is 8 nM in a relatively wide linear range, spanning from 0.001 to 40 µM. [ABSTRACT FROM AUTHOR]

A sensitive and biocompatible N-rich probe for rapid visual uranium detection was constructed by grafting two trianiline groups to 2,6-bis(aminomethyl)pyridine. Possessing excellent aggregation-induced emission (AIE) property and the advantages to form multidentate chelate with U selectively, the probe has been applied successfully to visualize uranium in complex environmental water samples and living cells, demonstrating outstanding anti-interference ability against large equivalent of different ions over a wide effective pH range. A large linear range (1.0 × 10−7–9.0 × 10−7 mol/L) and low detection limit (72.6 nmol/L, 17.28 ppb) were achieved for the visual determination of uranium. The recognition mechanism, photophysical properties, analytical performance and cytotoxicity were systematically investigated, demonstrating high potential for fast risk assessment of uranium pollution in field and in vivo. [ABSTRACT FROM AUTHOR]

Mitochondria-targeted antioxidants (MTAs) have been studied quite intensively in recent years as potential therapeutic agents and vectors for the delivery of other active substances to mitochondria and bacteria. Their most studied representatives are MitoQ and SkQ1, with its fluorescent rhodamine analog SkQR1, a decyl ester of rhodamine 19 carrying plastoquinone. In the present work, we observed a pronounced antibacterial action of SkQR1 against Gram-positive bacteria, but virtually no effect on Gram-negative bacteria. The MDR pump AcrAB-TolC, known to expel SkQ1, did not recognize and did not pump out SkQR1 and dodecyl ester of rhodamine 19 (C12R1). Rhodamine 19 butyl (C4R1) and ethyl (C2R1) esters more effectively suppressed the growth of ΔtolC Escherichia coli, but lost their potency with the wild-type E. coli pumping them out. The mechanism of the antibacterial action of SkQR1 may differ from that of SkQ1. The rhodamine derivatives also proved to be effective antibacterial agents against various Gram-positive species, including Staphylococcus aureus and Mycobacterium smegmatis. By using fluorescence correlation spectroscopy and fluorescence microscopy, SkQR1 was shown to accumulate in the bacterial membrane. Thus, the presentation of SkQR1 as a fluorescent analogue of SkQ1 and its use for visualization should be performed with caution. [ABSTRACT FROM AUTHOR]

A series of stimuli-responsive fluorescent hydrogels were successfully synthesized via micelle radical copolymerization of hydrophilic acrylamide (AM), hydrophobic chromophore terpyridine-based monomer (TPY), and N-isopropylacrylamide (NIPAM). These hydrogels presented blue emissions (423–440 nm) under room temperature, which is caused by the π-π* transition of the conjugated structures. Once the ambient temperature was increased to 55 °C, the fluorescence color changed from blue (430 nm) to pink (575 nm) within 10 min, subsequently to yellow (535 nm), and eventually back to pink. The thermal-responsive properties are attributed to the transition of the TPY units from unimer to dimer aggregation via the intermolecular charge transfer complex at high temperatures. The hydrogels showed pH-responsive properties. The emission peak of the hydrogel exhibited a blue shift of ~54 nm from neuter conditions to acidic conditions, while a 6 nm red shift to an alkaline environment was observed. The hydrogels demonstrated an obvious change in fluorescence intensity and wavelength upon adding different metal ions, which is caused by the coordination between the terpyridine units incorporated on the backbones and the metal ions. As a consequence, the hydrogels presented a sharp quenching fluorescence interaction with Fe2+, Fe3+, Cu2+, Hg2+, Ni2+, and Co2+, while it exhibited an enhanced fluorescence intensity interaction with Sn2+, Cd2+, and Zn2+. The microstructural, mechanical, and rheological properties of these luminescent hydrogels have been systematically investigated. [ABSTRACT FROM AUTHOR]

Herein, we report the synthesis and characterization of a novel Schiff base ligand, (Z)-5-((pyren-1-ylmethylene)amino)-2,4-dihydro-3H-pyrazol-3-one (PMDP). The characterization of ligand PMDP was carried out using ESI-MS, 1H NMR, and UV–Visible spectroscopic techniques. As a probe, PMDP displayed a detectable, colorimetric colour shift in the presence of Cu2+ and Fe2+ ions. The solution was seen to have a light brown colour and to exhibit a fluorometric "turn off" response when Cu2+ and Fe2+ ions were present in a DMSO solution (HEPES 0.01 M, pH = 7.4) at room temperature. Job's plot revealed that the PMDP binding ratio to Cu2+ and Fe2+ ions was in 1:2 ratio. In contrast to the other metal ions (Cd2+, Mn2+, Co2+, Na+, Ni2+, Cu+, Fe3+, Hg2+, Mg2+, Zn2+, K+, and V5+), the synthesised probe showed exceptional sensitivity and selectivity for detecting Cu2+ and Fe2+ metal ions. The results indicate that the detection limits for Cu2+ and Fe2+ are 0.42 μM and 0.51 μM, respectively. Furthermore, PMDP was efficiently utilised for the quantitative analysis of Cu2+ and Fe2+ in real water samples, RGB colour values in smart phones, logic gate construction, and cell imaging in HeLa cells. [ABSTRACT FROM AUTHOR]

Various conjugates with rhodamines were prepared by starting with betulinic acid (BA) and platanic acid (PA). The molecules homopiperazine and piperazine, which were identified in earlier research, served as linkers between the rhodamine and the triterpene. The pentacyclic triterpene's ring A was modified with two acetyloxy groups in order to possibly boost its cytotoxic activity. The SRB assays' cytotoxicity data showed that conjugates 13–22, derived from betulinic acid, had a significantly higher cytotoxicity. Of these hybrids, derivatives 19 (containing rhodamine B) and 22 (containing rhodamine 101) showed the best values with EC50 = 0.016 and 0.019 μM for A2780 ovarian carcinoma cells. Additionally, based on the ratio of EC50 values, these two compounds demonstrated the strongest selectivity between malignant A2780 cells and non-malignant NIH 3T3 fibroblasts. A375 melanoma cells were used in cell cycle investigations, which showed that the cells were halted in the G1/G0 phase. Annexin V/FITC/PI staining demonstrated that the tumor cells were affected by both necrosis and apoptosis. [ABSTRACT FROM AUTHOR]

In the past, copper served as the material for conductive patches in antennas; however, its usage was constrained due to high costs, susceptibility to fading, bulkiness, environmental sensitivity, and manufacturing challenges. The emergence of graphene nanotechnology has positioned graphene as a viable alternative, offering exceptional electrical conductivity, strength, and adaptability. In this study, graphene is employed to fabricate conductive silver nanocomposites. The silver-graphene (Ag/GO) sample exhibits an electrical conductivity of approximately 21.386 S/cm−1 as determined by the four-point probe method. The proposed flexible antenna, characterized by four carefully selected cylindrical shapes, is used to construct the antenna patch for enhanced bandwidth and resonates at 2.47 GHz. It achieves remarkable performance characteristics, with a high gain of 11.78 dBi and a return loss greater than −20 dB. Safety considerations are addressed by evaluating the Specific Absorption Rate (SAR). For an input power of 0.5 W, the SAR is calculated to be 1.2 W/kg per 10 g of tissue, affirming the safety of integrating the suggested graphene flexible antenna into flexible devices. In this study, the bending of the antenna was assessed by subjecting the structure to bending at various radii and angles along both the X and Y axes. These findings underscore the promising utility of Ag/GO nanocomposites in the development of flexible antennas for wireless systems. [ABSTRACT FROM AUTHOR]

A highly efficient fluorescent sensor (S-DAC) was easily created by functionalizing the SBA-15 surface with N-(2-Aminoethyl)-3-Aminopropyltrimethoxysilane followed by the covalent attachment of 7-diethylamino 3-acetyl coumarin (DAC). This chemosensor (S-DAC) demonstrates selective and sensitive recognition of Fe3+ and Hg2+ in water-based solutions, with detection limits of 0.28 × 10–9 M and 0.2 × 10–9 M for Hg2+ and Fe3+, respectively. The sensor's fluorescence characteristics were examined in the presence of various metal ions, revealing a decrease in fluorescence intensity upon adding Fe3+ or Hg2+ ions at an emission wavelength of 400 nm. This sensor was also able to detect ferric and mercury ions in spinach and tuna fish. The quenching mechanism of S-DAC was investigated using UV–vis spectroscopy, which confirmed a static-type mechanism for fluorescence quenching. Moreovre, the decrease in fluorescence intensity caused by mercury and ferric ions can be reversed using trisodium citrate dihydrate and EDTA as masking agents, respectively. As a result, a circuit logic gate was designed using Hg2+, Fe3+, trisodium citrate dihydrate, and EDTA as inputs and the quenched fluorescence emission as the output. [ABSTRACT FROM AUTHOR]

In this paper, nitrogen-doped carbon dots (NCDs) were synthesized via a facile hydrothermal method using gum arabic (GA) and tris(hydroxymethyl)methyl aminomethane (tris) as precursors. The resultant NCDs show uniform size distribution and stable optical performance. Then a fluorescent signal quenching probe based on NCDs was proposed for the quantitative detection of mercury ions (Hg2+). The developed fluorescent nanoprobe based on NCDs demonstrated a good linear relationship in the range of 10 to 120 μM (R² = 0.99265) for toxic mercury(II), with a detection limit of 4.87 μM. Additionally, the present assay system could be efficiently used for the detection of Hg2+ in real water samples with a satisfactory recovery rate (96.11-104.04%). The metal-free NCDs, which exhibited little cytotoxicity, were successfully applied to in vitro fluorescence imaging of human triple negative breast cancer (TNBC) cells, achieving visualization of Hg2+ in cells. With good water solubility and biocompatibility, the nitrogen-doped carbon dots synthesized by this economical and ecologically friendly process are suitable for use in analytical testing and biological research. [ABSTRACT FROM AUTHOR]

The development of near‐infrared (NIR) fluorophores that have both excellent chemical stability and photostability, as well as efficient cell permeability, is highly demanded. In this study, we present phospha‐rhodamine (POR) dyes which display significantly improved performance for protein labeling. This is achieved by incorporating a 2‐carboxy‐3‐benzothiophenyl group at the 9‐position of the xanthene scaffold. The resulting cis and trans isomers were successfully isolated and structurally characterized using X‐ray diffraction. The HaloTag ligand conjugates of the two isomers exhibited different staining abilities in live cells. While the cis isomer showed non‐specific accumulation on the organelle membranes, the trans isomer selectively labeled the HaloTag‐fused proteins, enabling the long‐term imaging of cell division and the 5‐color imaging of cell organelles. Molecular dynamics simulations of the HaloTag ligand conjugates within the lipid membrane suggested that the cis isomer is more prone to forming oligomers in the membrane. In contrast, the oligomerization of the trans isomer is effectively suppressed by its interaction with the lipid molecules. By taking advantage of the superior labeling performance of the trans isomer and its NIR‐emissive properties, multi‐color time‐lapse super‐resolution 3D imaging, namely super‐resolution 5D‐imaging, of the interconnected network between the endoplasmic reticulum and microtubules was achieved in living cells. [ABSTRACT FROM AUTHOR]

A new structurally simple fluorescent CP probe based on chromone was designed and synthesized, and its structure was fully characterized using various analytical techniques. The CP probe displays a high selectivity and sensitivity for sensing Fe3+ with a "turn-off" fluorescence response over other metal ions in a DMSO/H2O (4:1, v/v) solution. The experiment results show that the CP probe is stable over a wide pH range of 2.0–12.0. The detection limit for Fe3+ was calculated to be 0.044 μmol•L−1. The molar ratio method indicated that the binding mode between the CP probe and Fe3+ is a 1:1 complex formation. HR-MS and density functional theory (DFT) calculations were also performed to further confirm the recognition mechanism. Both fluorescence imaging experiments and the MTT assay demonstrated that the CP probe was suitable for detecting intracellular Fe3+ and no significant cytotoxicity in living cells. [ABSTRACT FROM AUTHOR]

Iron ion is an essential metal ion that plays a crucial role in various metabolic processes in living organisms. It is involved in cellular metabolism, acts as a catalyst for enzymatic reactions, and functions as an oxygen carrier in hemoglobin. Insufficient levels of iron in the body can lead to adverse health conditions such as diabetes, anemia, liver and kidney damage, and heart diseases. Considering these factors, the development of an effective fluorescent probe for the detection of excessive Fe3+ levels is necessary to protect both environment and human health. Numerous fluorescent probes have been reported thus far for Fe3+ detection. However, the most of these probes rely on a single emission intensity alteration mechanism, such as photoinduced electron transfer (PET). In this study, we have developed fluorescent probes using chitosan functionalized with rhodamine B and coumarin derivatives, for efficient detection of Fe3+ and Zn2+ ions. The hybrid chitosan/rhodamine B (CS/RB) and hybrid chitosan/coumarin (CS/MCMC) fluorescent probes exhibit strong fluorescence intensity under ultraviolet light. When iron ions are introduced to CS/RB and CS/MCMC solution, they coordinate with weak-field ligands (such as N and O) in the structure of CS/RB through a high-spin method. This coordination leads to the self-assembly of Fe3+ on the CS/RB surface, generating single electrons and resulting in high paramagnetism, which in turn quenches the fluorescence. The quenching effect of Fe3+ on the CS/RB and CS/MCMC fluorescent probes enables efficient detection of Fe3+ ions. Importantly, this fluorescence quenching effect is specific to Fe3+ and is not affected by other metal ions. In summary, the developed fluorescent probes based on chitosan derivatives offer a promising approach for the sensitive and specific detection of iron ions in aqueous solutions. [ABSTRACT FROM AUTHOR]

A water‐soluble polymeric pyrene‐based polythioacetal (PTA‐Py) with thioacetal units in the main chain is simply synthesized by direct polycondensation of 3, 6‐dioxa‐1, 8‐octanedithiol, 1‐pyrene formaldehyde, and mPEG2k‐SH. The probe PTA‐Py shows a good fluorescence response to Hg2+ ions due to the Hg2+‐promoted deprotection reaction of thioacetal groups to regenerate the original 1‐pyrene formaldehyde compound. After adding Hg2+ to the PTA‐Py solution, the fluorescence intensity (FI) gradually increases with increasing concentrations of Hg2+. Compared with other metal ions, the probe exhibits high sensitivity, good selectivity, and rapid response to Hg2+. The low detection limits are 12.3 nm in ethanol‐PBS buffer and 13.3 nm in water, respectively. The results imply that the simply synthesized water‐soluble polymeric probe had potential applications in the rapid detection of Hg2+ ions in aqueous solutions. Moreover, the polymeric PTA‐Py shows high sensitivity for CH3Hg+ with detection limits of 26.5 nm in ethanol/PBS buffer. In addition, PTA‐Py can efficiently detect Hg2+ ions in HeLa cells. The results demonstrate that a valuable method is developed for biocompatible polymeric sensors for Hg2+ ions in biological and environmental samples. [ABSTRACT FROM AUTHOR]

Iodine, primarily in the form of iodide (I−), is the bioavailable form for the thyroid in the human body. Both deficiency and excess intake of iodide can lead to serious health issues, such as thyroid disease. Selecting iodide ions among anions has been a significant challenge for decades due to interference from other anions. In this study, we designed and synthesized a new pincer-type acridine–triazole fluorescent probe (probe 1) with an acridine ring as a spacer and a triazole as a linking arm attached to two naphthol groups. This probe can selectively recognize iodide ions in a mixed solvent of THF/H2O (v/v, 9/1), changing its color from colorless to light yellow, making it suitable for highly sensitive and selective colorimetric and fluorescent detection in water systems. We also synthesized another molecular tweezer-type acridine–triazole fluorescent probe (probe 2) that exhibits uniform detection characteristics for iodide ions in the acetonitrile system. Interestingly, compared to probe 2, probe 1 can be detected by the naked eye due to its circulation effect, providing a simple method for iodine detection. The detection limit of probe 1 is determined to be 10−8 mol·L−1 by spectrometric titration and isothermal titration calorimetry measurements. The binding stoichiometry between probe 1 and iodide ions is calculated to be 1:1 by these methods, and the binding constant is 2 × 105 mol·L−1. [ABSTRACT FROM AUTHOR]

The few commercially available chemosensors and published probes for in vitro Zn2+ detection in two-photon microscopy are compromised by their flawed spectroscopic properties, causing issues in selectivity or challenging multistep syntheses. Herein, we present the development of an effective small molecular GFP chromophore-based fluorescent chemosensor with a 2,2′-bipyridine chelator moiety (GFZnP BIPY) for Zn2+ detection that has straightforward synthesis and uncompromised properties. Detailed experimental characterizations of the free and the zinc-bound compounds within the physiologically relevant pH range are presented. Excellent photophysical characteristics are reported, including a 53-fold fluorescence enhancement with excitation and emission maxima at 422 nm and 492 nm, respectively. A high two-photon cross section of 3.0 GM at 840 nm as well as excellent metal ion selectivity are reported. In vitro experiments on HEK 293 cell culture were carried out using two-photon microscopy to demonstrate the applicability of the novel sensor for zinc bioimaging. [ABSTRACT FROM AUTHOR]

Fluorogenic dyes with high brightness, large turn‐on ratios, excellent photostability, favorable specificity, low cytotoxicity, and high membrane permeability are essential for high‐resolution fluorescence imaging in live cells. In this study, we endowed these desirable properties to a rhodamine derivative by simply replacing the N, N‐diethyl group with a pyrrole substituent. The resulting dye, Rh‐NH, exhibited doubled Stokes shifts (54 nm) and a red‐shift of more than 50 nm in fluorescence spectra compared to Rhodamine B. Rh‐NH preferentially exists in a non‐emissive but highly permeable spirolactone form. Upon binding to lysosomes, the collective effects of low pH, low polarity, and high viscosity endow Rh‐NH with significant fluorescence turn‐on, making it a suitable candidate for wash‐free, high‐contrast lysosome tracking. Consequently, Rh‐NH enabled us to successfully explore stimulated emission depletion (STED) super‐resolution imaging of lysosome dynamics, as well as fluorescence lifetime imaging of lysosomes in live cells. [ABSTRACT FROM AUTHOR]

By modifying the structure of pyridoxal phosphate, an "on–off" rhodamine fluorescent probe LPDQ with a new structure was synthesized. NMR, IR, and mass spectrometries characterized the structures of the probes. The LPDQ–Zn2+ system had been successfully constructed by the characteristic absorption peaks of the ultraviolet spectrum, and the experiments were carried out to investigate the ion fluorescence selectivity, cell imaging, reversibility, ion concentration, linear range, precision, and accuracy. The LPDQ reached the detection limit of 0.8 × 10−6 mol/l at 1 × 10−5–8.5 × 10−5 mol/l. The content of Zn2+ in the zinc gluconate sample was determined. According to the experimental data, the fluorescent probe LPDQ in this experiment has good performance and can be used to detect Zn2+ in water and oil paintings. [ABSTRACT FROM AUTHOR]

Triterpenoids widely exist in nature, displaying a variety of pharmacological activities. Determining triterpenoids in different matrices, especially in biological samples holds great significance. High-performance liquid chromatography (HPLC) has become the predominant method for triterpenoids analysis due to its exceptional analytical performance. However, due to the structural similarities among botanical samples, achieving effective separation of each triterpenoid proves challenging, necessitating significant improvements in analytical methods. Additionally, triterpenoids are characterized by a lack of ultraviolet (UV) absorption groups and chromophores, along with low ionization efficiency in mass spectrometry. Consequently, routine HPLC analysis suffers from poor sensitivity. Chemical derivatization emerges as an indispensable technique in HPLC analysis to enhance its performance. Considering the structural characteristics of triterpenoids, various derivatization reagents such as acid chlorides, rhodamines, isocyanates, sulfonic esters, and amines have been employed for the derivatization analysis of triterpenoids. This review comprehensively summarized the research progress made in derivatization strategies for HPLC detection of triterpenoids. Moreover, the limitations and challenges encountered in previous studies are discussed, and future research directions are proposed to develop more effective derivatization methods. [Display omitted] • Derivatization is a very significant step in HPLC detection of triterpenoids. • Enhancing performance of HPLC separation and sensitivity provides unique merits. • The derivatization sites of triterpenoids are mainly –OH and –COOH. • Derivatization reagents are acyl chlorides, rhodamines, sulfonic esters, amines, etc. [ABSTRACT FROM AUTHOR]

We prepared a rhodamine (RB)–perylene (Pery) compact electron donor/acceptor dyad (RB–Pery) to study the spin-orbit charge-transfer intersystem crossing (SOCT–ISC). The UV–vis absorption spectrum indicates a negligible electronic interaction between the donor and acceptor at ground state. However, the fluorescence of both the RB and Pery units are quenched in the dyad, which is attributed to the photoinduced electron transfer, supported by the electrochemical studies. Nanosecond transient absorption (ns-TA) spectra show delocalized triplet states, i.e., there is an excited-state equilibrium between Pery and the RB triplet states. The triplet state lifetime was determined as 109.8 μs. With intermolecular triplet–triplet energy transfer, monitored using ns-TA spectra, the triplet-state energy balance between RB and Pery in RB–Pery was confirmed. The proposed cascade photophysical processes of the dyad are 1RB*-Pery→RB–Pery+•→[3RB*-Pery↔RB-3Pery*]. Moreover, long-lived rhodamine radical cation (in milliseconds) was detected in both deaerated/aerated non-polar or low-polarity solvents (i.e., p-xylene, toluene). The potential energy curve of the dyad against the variation in the dihedral angle between the two units indicates large torsional freedom (53°~128°) in RB–Pery, which leads to inefficient SOCT–ISC; consequently, low singlet-oxygen quantum yields (ΦΔ = 2~8%) were observed. [ABSTRACT FROM AUTHOR]

Rapid detection and sensitive analysis of MMZ is of great importance for food safety. Herein, a fluorescent molecularly imprinted sensor based on upconversion nanoparticles (UCNPs) grafted onto covalent organic frameworks (COFs) was designed for the detection of MMZ. COFs with a high specific surface area and excellent affinity serve as substrates for grafting of UCNPs, which can inhibit the aggregation burst of UCNPs and improve the mass transfer rate of the sensor. Through a series of characterizations, it was found that the proposed UCNP-grafted COFs@MIP-based sensor had good optical stability, high adsorption efficiency, strong anti-interference ability, and high sensitivity owing to the integration of the advantages of UCNPs, COFs and MIPs. Under the optimal conditions, a good linear relationship was presented between the fluorescence intensity of UCNP-grafted COFs@MIPs and the methimazole concentration in the range of 0.05–3 mg L−1, and the detection limit was 3 μg L−1. The as-prepared UCNP-grafted COFs@MIPs were successfully applied for the detection of MMZ in actual samples, and the results were relevant with those determined by high-performance liquid chromatography. The sensor has good sensitivity, reusability, and high selectivity, which are highly valuable in the rapid analysis and detection of food safety. [ABSTRACT FROM AUTHOR]

The mercury ion (Hg2+) is a typical high-toxicity substance that can cause severe damage to the environment and human bodies. For the detection of Hg2+, there are still significant challenges in the detection range and limit of detection (LOD). In this study, three viologen-based fluorescent probes are developed, CdCl4(Btybipy) (1), ZnBr4(Btybipy) (2), CdBr4(Btybipy) (3) (Btybipy = bis-1-thiophen-3-ylmethyl-[4,4′]-bipyridinyl) through conventional solvent methods for detecting pH and Hg2+. Reversible discoloration and fluorescence response behaviour in the pH range of 4–12.8 is demonstrated by viologen-based fluorescent probes, which exhibit "ON–OFF–ON" signal changes. Compared with complex 1, it is surprising to find that complexes 2–3 display both fluorescence enhancement and fluorescence quenching simultaneously with the addition of different concentrations of Hg2+ (0–20 and 25–400 μM). There is broad linearity in the range of 0–20 and 50–300 μM with LODs of 2.14 and 3.13 nM, respectively. This occurrence of dual-signal modes is attributed to the participation of Br− and the thiophene S atom as dual chromophores in the coordination reaction of Hg2+. Dual-signal mode output, high sensitivity, wide detection range, and low LODs are exhibited by these fluorescent probes. The unique coordination reaction between Br− and the thiophene S atom with Hg2+ can provide a potential strategy for the exploitation of promising sensing platforms for monitoring Hg2+. [ABSTRACT FROM AUTHOR]

The mercury ion (Hg2+) is a typical high-toxicity substance that can cause severe damage to the environment and human bodies. For the detection of Hg2+, there are still significant challenges in the detection range and limit of detection (LOD). In this study, three viologen-based fluorescent probes are developed, CdCl4(Btybipy) (1), ZnBr4(Btybipy) (2), CdBr4(Btybipy) (3) (Btybipy = bis-1-thiophen-3-ylmethyl-[4,4′]-bipyridinyl) through conventional solvent methods for detecting pH and Hg2+. Reversible discoloration and fluorescence response behaviour in the pH range of 4–12.8 is demonstrated by viologen-based fluorescent probes, which exhibit "ON–OFF–ON" signal changes. Compared with complex 1, it is surprising to find that complexes 2–3 display both fluorescence enhancement and fluorescence quenching simultaneously with the addition of different concentrations of Hg2+ (0–20 and 25–400 μM). There is broad linearity in the range of 0–20 and 50–300 μM with LODs of 2.14 and 3.13 nM, respectively. This occurrence of dual-signal modes is attributed to the participation of Br− and the thiophene S atom as dual chromophores in the coordination reaction of Hg2+. Dual-signal mode output, high sensitivity, wide detection range, and low LODs are exhibited by these fluorescent probes. The unique coordination reaction between Br− and the thiophene S atom with Hg2+ can provide a potential strategy for the exploitation of promising sensing platforms for monitoring Hg2+. [ABSTRACT FROM AUTHOR]