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In this study, the fluorescence properties of Co(II) Schiff base complex (Co(II) complex) were examined. The sensor properties of the Co(II) complex nitroaromatic compounds [(DNB, TNT, DNT, 2-NP, 4-nitrophenol (NP), 2,4-dintrophenol (DNP) and 1,3,5-trinitrophenol (TNP) e.g.,] were investigated by fluorescence spectroscopy. Compound has high sensitivity for the sensing of 1,3,5-trinitrophenol (TNP) (K sv: 4.74 × 104 M−1) with low LOD of 0.034 μM. It was revealed that the complex ([CoLCl(H 2 O) 2 ]∙2H 2 O) exhibited strong fluorescence properties. Additionally, the synthesized Co(II) complex was utilized for fluorescence quenching-based TNP detection in water solution with high selectivity and sensitivity. The stoichiometry of the compound and TNP was found to be 1:1 (ligand/TNP) via fluorescence titrations (Job's plot). • The Co(II) Schiff base complex exhibited strong fluorescence properties. • The sensor properties of the Co(II) complex nitroaromatic compounds were investigated by fluorescence spectroscopy. • Utilized for fluorescence quenching-based TNP detection in water solution with high selectivity and sensitivity. • Fluorescence signal of Co(II) complex exhibited a strong linear relationship within the range of 5.0–40.0 μM of TNP. • Compound has highest sensitivity for the sensing of 1,3,5-trinitrophenol (TNP) (Ksv: 4.74 × 104 M-1) with low LOD of 0.034 μM. [ABSTRACT FROM AUTHOR]

[Display omitted] • Synthesis of benzothiazole functionalized tetraphenylethylene (TPE-BTH) is achieved. • TPE-BTH showed turn-off fluorescence response towards TNP and DNP. • TPE-BTH exhibited lower LOD for TNP of 7.28 × 10-8 M. • TPE-BTH displayed lower LOD towards DNP 1.23 × 10-8 M. • Molecular simulation was employed to investigate the interaction between TPE-BTH and TNP and DNP. The detection of nitroaromatic compounds (NACs) such as 2,4,6-trinitrophenol (TNP) and 2,4-dinitrophenol (DNP) is critical for environmental monitoring and security, due to their extensive use in explosives and the associated health risks. However, current methods for detecting these compounds face challenges in sensitivity, specificity, and practicality. In this study, a new benzothiazole functionalized tetraphenylethylene molecular scaffold (TPE-BTH) have been successfully synthesized and characterized for its potential in explosive sensing. The TPE-BTH compound exhibits distinct UV–Visible and fluorescence emission behaviors in different solvent polarities. A remarkable feature of TPE-BTH is its pronounced fluorescence quenching upon the addition of 2,4,6-trinitrophenol (TNP) and 2,4-dinitrophenol (DNP) in a dichloromethane solution, highlighting its sensitivity and potential utility in explosive detection. The detection limits for TNP and DNP were determined to be remarkably low at 7.28 × 10-8 M and 1.23 × 10-8 M, respectively. Through theoretical investigations, we explored the interaction mechanisms between TPE-BTH and TNP, uncovering the roles of internal hydrogen bonding within picric acid and π-π interactions as well as dipole interactions between the molecules. Additionally, 1H NMR was utilized to elucidate the interaction mechanisms between TPE-BTH and TNP. The development of TPE-BTH as a molecular scaffold for NAC detection significantly contributes to the field of explosive sensing and environmental monitoring. [ABSTRACT FROM AUTHOR]

Sensing nitroaromatic explosives has gained significant attention due to both increased terrorist threats and a need for environmental protection. In this regard, a fluorescent chemosensor, 1-benzyl-3,5-di(thiophen-2-yl)pyrazin-1-ium bromide (BTPyz), was synthesized and characterized via spectroscopic methods. The photophysical properties were investigated using absorption and emission spectral analysis. As a fluorescent chemosensor, BTPyz exhibited a selective response towards 2,4,6-trinitrophenol (TNP) with a detection limit of 11.6 nM and quenching constant (KSV) of 3.8 × 104 M−1. The fluorescence quenching mechanism was attributed to ground-state charge-transfer complex formation and resonance energy transfer, as evident from Uv-visible, fluorescence and NMR spectroscopy, single-crystal XRD studies, and density functional theory calculations. BTPyz was also employed for the contact mode detection of TNP on paper strips. The detection of TNP in real water and soil samples demonstrated BTPyz to be a promising detection tool toward environmental specimens. [ABSTRACT FROM AUTHOR]

An unexpected promoting effect of KBr, used as a diluting salt, on the degradation of picric acid (PA) was observed during in situ diffuse reflectance infrared Fourier-transform (DRIFT) spectroscopy experiments performed here under accelerated ageing conditions—at 80 °C and under an inert or oxidative atmosphere. While the formation of potassium picrate was excluded, this promoting effect—which is undesired as it masks the possible effects of test conditions on the ageing process of the material—was assumed to favor a first step of the decomposition mechanism of PA, which involves the inter- or intramolecular transfer of hydrogen to the nitro group, and possibly proceeds up to the formation of an amino group. An alternative diluting salt, ZnSe, which is much less commonly used in infrared spectroscopy than KBr, was then proposed in order to avoid misleading interpretation of the results. ZnSe was found to act as a truly inert diluting salt, preventing the promoting effect of KBr. The much more chemically inert nature (towards PA) of ZnSe compared to KBr was also confirmed, at much higher temperatures than DRIFT experiments, by dynamic differential scanning calorimetry (DSC) runs carried out on pure PA (i.e., PA without salt) and PA/salt (ZnSe or KBr) solid mixtures. [ABSTRACT FROM AUTHOR]

Two simple, sensitive, and fast visible spectrophotometry techniques for quantifying modafinil in marketed dosage form have been proposed. The method A was focussed on the complexation involving charge transfer with picric acid to give pale yellow colored chromogen which shows absorption maxima at 450 nm. In the concentration range of 5-40 µg mL-1 Beer's law is obeyed with a correlation value of 0.999. The method B depends on the oxidative coupling process with MBTH in the presence of FeCl3 in acidic pH to give green colour chromogen which shows absorption maxima at 657 nm. In the concentration range of 10-50 µg mL-1, Beer's law was obeyed with a correlation value of 0.999. The developed methodologies have been statistically verified for use in quality control laboratories for pharmaceuticals. [ABSTRACT FROM AUTHOR]

CeO2 nanoparticle-loaded chitosan-bocglycine zinc complex was synthesized and characterized by UV–Visible, FT-IR, Powder XRD, and SEM–EDX analysis. From the XRD analysis, the crystal structure was studied and the approximate nanoparticle size of the CeO2 was calculated to be 22 nm. The UV–Visible spectrum has detected the presence of CeO2 nanoparticles by appearing corresponding intense peaks. The stretching frequency of the Ce-O bond was detected by the FT-IR peak at 720 cm−1. The SEM graph showed spherical morphology and uniform distribution of nanoparticles of both pure CeO2 and CeO2 nanocomposites. The photocatalytic degradation of picric acid (PA) with a nanocomposite as photocatalyst combined with Fenton’s process was studied under UV light (254/365/395 nm), visible, and sunlight at different pH values (2.5, 7, and 10.5). It is observed that the degradation of PA (pH2.5) under sunlight was very high and reached 100% within 35 min. The experiment was also repeated with pure photocatalyst (CeO2-loaded chitosan-bocglycine zinc complex), Fenton’s reagent (Fe2+/H2O2), and combined with both under sunlight at a pH value of 2.5, a time interval of 40 min. The experimental results confirmed that under sunlight the degradation of picric acid (pH2.5) with pure photocatalyst is reached up to 20%, with Fenton’s reagent, it is reached up to 45% but when photocatalyst and Fenton’s reagent both are combined, it is reached up to 100%. It is concluded that the degradation of PA was more efficient under sunlight with a combination of both our prepared photocatalyst and Fenton’s reagent. [ABSTRACT FROM AUTHOR]

Hydrogen-bonded organic frameworks (HOFs), as a newly developed porous material, have been widely used in various fields. To date, several organic building units (OBUs) with tri-, tetra-, and hexa-carboxylic acid synthons have been applied to synthesize HOFs. To our knowledge, di-carboxylic acids have rarely been reported for the construction of HOFs, in particular, di-carboxylic acid-based HOFs with fluorescence sensing properties have not been reported. In this study, a rare example of a di-carboxylic acid-based, luminescent three-dimensional hydrogen-bonded organic framework has been successfully constructed and structurally characterized; it has a strong electron-rich property originated from its organic linker 9-phenylcarbazole-3,6-dicarboxylic acid. It represents the first example of HOF-based sensors for the highly selective and sensitive detection of PA (Picric acid) with reusability; the LOD is less than 60 nM. This work thus provides a new avenue for the fabrication of fluorescent HOFs sensing towards explosives. [ABSTRACT FROM AUTHOR]

The chemical analysis that is frequently employed for the evaluation of the freshness of fish includes (i) the quantification of trimethylamine (TMA) and (ii) the estimation of the K-Index, based on the ratio between the concentrations of adenosine triphosphate (ATP) and its breakdown products. TMA is quantified using a colorimetric reference method (AOAC), while the K-Index is usually determined by HPLC. The present work proposes a method for the above freshness biomarkers based on HR 1H-NMR as an alternative method able to assess both indexes simultaneously on aqueous fish extracts. To validate the proposed 1H-NMR method, a large set of validation checks has been addressed, such as accuracy, precision, specificity, limits of detection, linearity, and range of linearity and quantification according to EuroChem guidelines. The results show that the methodology satisfies all the validation requirements at the same level as the most frequently used methods, with the advantage of being faster and more repeatable, avoiding the use of solvents, such as toluene and formaldehyde, or dangerous reagents such as picric acid. [ABSTRACT FROM AUTHOR]

A series of new oxoquinoline‐imidazole derivatives (IMD1‐IMD4) was prepared, and they were characterized by analytical and spectral data. Further, they were employed as effective fluorescence signaling switches through "OFF‐ON" and "ON‐OFF" by an ESIPT (excited‐state intramolecular proton‐transfer) mechanism. The OFF‐ON green fluorescence exhibited by IMD1 selectively at 486 nm with Zn2+ and F− is the basis for the determination of Zn2+ and F− ions by way of detection limits of 5.28×10−9 M and 1.74 ×10−10 M, respectively. In contrast, IMD3 being fluorescent active (ON) with blue emission at 464 nm selectively exhibits quenching in fluorescence intensity in the presence of Fe3+ and picric acid (PA) at pH 7.4. This quenching property of IMD3 leads to the rapid determination of Fe3+ and picric acid (PA) selectively with a limit of detection of 3.28×10−9 M and 1.63×10−10 M, respectively. Experimental findings have been well‐complemented by Density Functional Theory (DFT) studies. The activity of the synthesized oxoquinoline‐imidazole compounds (IMD1 and IMD3) was demonstrated on HeLa (Henrietta Lacks, a human cell line) and breast cancer cells for the detection of Zn2+ and Fe3+ ions, respectively. [ABSTRACT FROM AUTHOR]

Given the significance of uric acid and creatinine in clinical diagnostic, disease prevention and treatment, a multifunctional electrochemical sensor was proposed for sensitive detection of uric acid and creatinine. The sensitive detection of uric acid was realized based on the unique electrochemical oxidation of nanoporous gold (NPG) towards uric acid, showing good linearity from 10 μM to 750 μM with a satisfactory sensitivity of 222.91 μA mM−1 cm−2 and a limit of detection (LOD) of 0.06 μM. Based on the Jaffé reaction between creatinine and picric acid, the sensitive detection of creatinine was indirectly achieved in a range from 10 to 2000 μM by determining the consumption of picric acid in the Jaffé reaction with a detection sensitivity of 195.05 μA mM−1 cm−2 and a LOD of 10 μM. For human urine detection using the proposed electrochemical sensor, the uric acid detection results were comparable to that of high-performance liquid chromatography (HPLC), with a deviation rate of less than 10.28% and the recoveries of uric acid spiked in urine samples were 89~118%. Compared with HPLC results, the deviation rate of creatinine detection in urine samples was less than 4.17% and the recoveries of creatinine spiked in urine samples ranged from 92.50% to 117.40%. The multifunctional electrochemical sensor exhibited many advantages in practical applications, including short detection time, high stability, simple operation, strong anti-interference ability, cost-effectiveness, and easy fabrication, which provided a promising alternative for urine analysis in clinical diagnosis. [ABSTRACT FROM AUTHOR]

Four fluorimetric probes had been developed to rapidly detect 2,4,6-trinitrophenol (TNP). They were designed and synthesized on the basis of 1,3,4-thiadiazole framework combining calculation with experiment. Among them, SK-1 displayed strong blue emission with fluorescence quantum yield as high as 63.6% in solution. Further evaluation demonstrated that SK-1 displays good selectivity and high sensitivity for rapid and visual detection of TNP. It brought significant changes in both colour and fluorescence emission spectrum. The detection limit was as low as 38 nM. Quenching mechanism was confirmed as photo-induced electron transfer (PET) by nuclear magnetic titration and DFT calculations. What's more, application in real water samples and solid phase paper tests illustrated the practical significance of detection of TNP in both vapor and solution. [ABSTRACT FROM AUTHOR]

A propylimidazole functionalized coumarin derivative (IPC) was fabricated for the first time and applied as a dual responsive fluorescent chemoprobe for sensitive and selective recognition of picric acid (PA) and Fe3+. Strong fluorescence quenching phenomena of the IPC were observed in H2O/ACN (5/95, v/v) medium (λem=408 nm) upon the additions of Fe3+or PA. The fabricated dual responsive IPC offered good selectivity and sensitivity with the low limit of detection values (0.92 µM for PA and 0.22 µM for Fe3+) lower than the acceptable amounts of Fe3+ and PA by the international official authorities. The validation study for the chemoprobe IPC for PA and Fe3+ was also performed. The interaction phenomena of IPC with PA and Fe3+ based on the findings of a range of experiments were considered and DFT computations were done to verify their recognition mechanisms. The sensing phenomena of IPC towards PA (1:1) and Fe3+ (3:1) were confirmed by the MALDI TOF–MS, FT–IR, 1H–NMR titration and Job's methods. Furthermore, the compound IPC was effectively applied as a fluorescent sensor for Fe3+ and PA detection in real natural spring water samples. [ABSTRACT FROM AUTHOR]

Picric Acid Disposal Microscopy Listserver I Good afternoon, we have found a bottle of old picric acid, which someone may have been using for microscopy purposes a long time ago. Obviously, the wise lab manager checks the picric acid bottle periodically (which can vary with lab usage of picric in etchants) to make sure that the picric acid remains wet. In 1894, Russian scientists manufactured artillery shells using picric acid salts, and picric acid-based explosives were used in WWI. From George Vander Voort: Picric Acid - Hazards and Safe Usage: Picric acid (2,4,6-trinitrophenol, [(NO SB 2 sb )3C SB 6 sb H SB 2 sb OH]) is widely used in metallography labs for common steel etchants known as picral, a 4% solution in ethanol; Vilella's reagent, 1 g picric acid and 5 mL HCl and 100 mL ethanol; and alkaline sodium picrate (2 g picric acid, 20 g NaOH, 100 mL water), for coloring M3C and M6C carbides, as well as several other formulations. Histology labs use picric acid as a mordant for staining and it is an ingredient in Bouin's fixative, a favorite for investigators of ovarian tissue. [Extracted from the article]

Picric acid (PA) is an important industrial feedstock and hence the release of industrial effluents without proper remediation results in its buildup in soil and water bodies. The adverse effects of PA accumulation in living beings necessitate the development of efficient methods for its detection and quantification. Herein, we describe pyrene-based fluorescent sensors for PA, where pyrene is appended with electron-withdrawing groups, malononitrile, and 2-(3-cyano-4,5,5-trimethylfuran-2(5H)-ylidene) malononitrile (DCDHF). These molecules displayed the typical emission of pyrene monomers, as well as a broad red-shifted emission resulting from an intramolecular charge transfer (ICT) in the excited state. Both the emissions displayed a turn-off response to PA with high selectivity and sensitivity and the lowest limit of detection was estimated as 27 nM. To prove the feasibility of on-site detection, test paper strips were prepared, which could detect PA up to 4.58 picograms. Using a combination of experimental and theoretical studies the mechanism of the detection was identified as primary/secondary inner filter effect, oxidative photoinduced electron transfer, or a combination of both depending on the excitation wavelength. Interestingly, the contribution of each of these mechanisms to the total quenching process varied with a change in the excitation wavelength., (© 2024 Wiley-VCH GmbH.)

Frederick Crace-Calvert (1819-1873), an English chemist, carried extensive research on a wide variety of subjects (inorganic, organic, and biochemistry, materials science, coal chemistry, manufacture of steel, etc.). During his study of lead and its derivatives he found that lead behaved in a completely different manner when submerged in distilled water or in common (saline) water. He discovered four new lead oxides, three crystalline (one olive, one red and one pink, and a fourth one, amorphous and of a fine red color); he studied the action of ammonia on the hydrate of lead protoxide and the nitrates of lead at different temperatures and synthesized a variety of salts in which one equivalent of lead oxide was gradually substituted by one of ammonia. Together with Johnson they discovered that the higher the purity of metal, the higher the amount of corrosion by sulfuric acid. They developed a series of new alloys in which the components were present in defined proportions and studied the physical and chemical properties of metals alloys, and amalgams (thermal expansion, thermal conductivity, specific gravity, and the action of acids). Crace-Calvert developed a very efficient method for decreasing the amount of sulfur in coke, based on the action of sodium chloride, a discovery that was applied by the French and English metallurgical industry to produce a better-quality iron, at substantial savings. He analyzed rust and concluded that the main atmospheric factor causing rust was CO2 and not oxygen or water vapor. He also studied the therapeutic properties of picric acid and his finding that this acid turned the skin and eyes yellow, temporarily.

Nitroaromatic effluents are common wastes generated from different industrial activities. These wastes can cause various environmental problems due to their toxicity on living organisms and difficulties to decompose either chemically or biologically. However, picric acid (2,4,6-trinitrophenol, TNP) could be used as a sole carbon, nitrogen, and energy source by a few bacterial cells. In this study, a bacterial strain isolated from the Red Sea, Jeddah, Saudi Arabia, has been shown to utilize picric acid as a sole carbon and nitrogen source at a relatively high concentration. The growth medium altered from yellow into the orange-red color (hydride-Meisenheimer complex) after 48 h of incubation as detected using High-Performance Liquid Chromatography (HPLC). The stoichiometric release of 0.285 mol of nitrite showed strong evidence that the picric acid was completely mineralized. Molecular identification using 16S rRNA analysis indicated that the isolated strain is Enterococcus thailandicus RF1 (Genbank Accession No. MN960654). This strain is capable of utilizing TNP aerobically at pH 7.0 and 30 °C with nitrite release. Furthermore, Enterococcus thailandicus RF1 cells were immobilized by adsorption on polyurethane foam and TNP degradation was enhanced and increased to 1.12-folds of free cells. The immobilized cells were found to be used efficiently for bioremediation of TNP from wastewaters.

The development of inexpensive, equipment-free, portable, and user/environmentally-friendly analytical devices that can be efficiently utilized for on-site detection of PA is still a great challenge. To address these unmet demands, we have developed a smartphone-based disposable sensing bioplatform through immobilization of chlorophyll in a cotton thread for fluorescent monitoring of picric acid (PA). The fluorescence quenching of chlorophyll upon increasing the PA concentration based on the inner filter effect was considered as the sensing strategy in the developed sensor. The fabricated thread-based microfluidic sensing bioplatform was further coupled with a compact, low cost, portable, and 3D-printed all-in-one smartphone-based analytical device (ASAD) that is able to thoroughly perform all analytical steps of PA determination in environmental samples, including sample preparation (mixing and centrifuging/separating) and analyzing steps. The satisfactory results achieved by the fabricated ASAD-based wicking sensing platform with good linearity (5.0–100.0 μM), detection limit (1.0 μM), and selectivity toward PA show its great potential to be widely exploited for easy, ultra-low-cost, sensitive, selective, and smart detection of PA, particularly at point-of-use applications, where are often far from well-equipped centralized laboratories.

A new anthracene-based metal–organic framework (MOF, named as CUST-607), [Cd3(H2O)(H3L)2(dia)2]·4DMA·10H2O (dia = 9,10-bis(1H-imidazol-1-yl)anthracene, H3L = 4,4′,4′′-[1,3,5-benzenetriyltris(carbonylimino)]tris(benzoate)), was synthesized by a solvothermal method. Through single X-ray diffraction analysis, CUST-607 displays a three-dimensional multihole network with the triclinic space group of P1¯ and (3,3,4,5)-connected nodes. Gas adsorption and desorption experiments show that CUST-607 has a microporous structure with a large surface area of 702.15 m2 g−1. CUST-607 also exhibits selective and strong adsorption of CO2 with a 40 kJ mol−1Qst value. Luminescence sensing experiments show that CUST-607 has a high selectivity for detecting nitroaromatic explosives, particularly for 2,4,6-trinitrophenol. The quenching constant Ksv is 1.43 × 105 M−1, higher than that of most reported MOFs. In addition, the CUST-607 fluorescence sensor exhibits high recyclability in detecting nitrobenzene and 2,4,6-trinitrophenol and can be used as potential sensors in practical applications. [ABSTRACT FROM AUTHOR]

A zeroth-order, non-diffracting Bessel beam, generated by picosecond laser pulses (1064 nm, 10 Hz, 30 ps) through an axicon, was utilized to perform pulse energy-dependent (12 mJ, 16 mJ, 20 mJ, 24 mJ) laser ablation of silver (Ag) substrates in air. The fabrication resulted in finger-like Ag nanostructures (NSs) in the sub-200 nm domain and obtained structures were characterized using the FESEM and AFM techniques. Subsequently, we employed those Ag NSs in surface-enhanced Raman spectroscopy (SERS) studies achieving promising sensing results towards trace-level detection of six different hazardous materials (explosive molecules of picric acid (PA) and ammonium nitrate (AN), a pesticide thiram (TH) and the dye molecules of Methylene Blue (MB), Malachite Green (MG), and Nile Blue (NB)) along with a biomolecule (hen egg white lysozyme (HEWL)). The remarkably superior plasmonic behaviour exhibited by the AgNS corresponding to 16 mJ pulse ablation energy was further explored. To accomplish a real-time application-oriented understanding, time-dependent studies were performed utilizing the AgNS prepared with 16 mJ and TH molecule by collecting the SERS data periodically for up to 120 days. The coated AgNSs were prepared with optimized gold (Au) deposition, accomplishing a much lower trace detection in the case of thiram (~50 pM compared to ~50 nM achieved prior to the coating) as well as superior EF up to ~108 (~106 before Au coating). Additionally, these substrates have demonstrated superior stability compared to those obtained before Au coating. [ABSTRACT FROM AUTHOR]

If fixation is not adequate, the other processes that follow such as dehydration, clearing, infiltration, embedding, microtomy and staining, will also be inadequate. A poorly processed tissue will make it difficult for the Pathologist/Histoscientist to render a proper diagnosis. This article is aimed at elucidating more on fixatives and fixation process in histopathology. The information presented in this review was gathered primarily from an extensive literature search on PubMed, Scopus and Textbooks. Fixatives in histopathology can be grouped into simple and compound fixatives. Simple fixative is a solution or gas which contains only one active ingredient or that has a singlechemical solution. Examples include; Formaldehyde, Glutaraldehyde, Mercuric Chloride, Potassium Dichromate, Picric Acid, Osmium Tetroxide, Acetic Acid, Ethanol, Acetone and Chromic Acid. When two or more simple fixatives are combined in a solution, the resulting solution is called a compound fixative. This can be further divided into Microanatomical and cytological fixatives. Examples of a micro-anatomical fixatives include; 10% formal-saline, Heidenhain's Susa, Boiun's fluid, Formol Sublimate. Cytological fixatives are grouped into cytoplasmic and nuclear fixatives. Fixation terminates any ongoing biochemical reactions, and also increases the mechanical strength or stability of the treated tissues. To accomplish this, tissue samples are usually immersed immediately in a fixative fluid. The fixatives employed prevent autolysis and putrefaction from taking place. Fixatives are integral substances used in histopathology to forestall the actions of autolysis and putrefaction in tissue samples. [ABSTRACT FROM AUTHOR]

In this study, Cu20-polyoxotungstate [Cu20Cl(OH)24(H2O)12(P8W48O184)]25− supported on a magnetic substrate was used as a high-performance green method for the reduction of nitrophenol compounds such as 4-nitrophenol (4-NP) and 2,4,6-trinitrophenol (2,4,6-TNP). [Fe3O4@SiO2-NH2-Cu20P8W48] as heterogeneous magnetic nanocatalyst was synthesized and characterized by FT-IR, SEM, TEM, VSM, and TGA. This nanocatalyst has an excellent efficiency in the reduction of nitrophenol compounds to aminophenol compounds. The UV-Vis absorption spectrum is used at different times to evaluate the progress of the reaction. Under optimal conditions, 100% conversion and selectivity in reduction of 4-NP and 2,4,6-TNP to 4-AP and 2,4,6-TAP were obtained, respectively. In addition, after the reaction, the [Fe3O4@SiO2-NH2-Cu20P8W48] was recovered using an external magnetic field and used for the next cycle. The results showed that the nanocatalyst can perform eight consecutive cycles without any significant decrease in efficiency. In the end, according to the results, the proposed mechanism for this reaction was reported. [ABSTRACT FROM AUTHOR]

It is an attractive but challenging proposition to develop effective fluorescent sensors for detecting specific organic compounds. In this study, we designed and synthesized three Zn(II) complexes, namely [Zn(3N3PY)2](NO3)2·3.5CH3OH (1), [Zn(3N3PY)(BIN)]·1.5DMF (2) and [Zn(3N3PY)(BIN)0.5(HCOO)] (3) (H2BIN = 2,2′-biisonicotinic acid, HCOO− = formate), using a D–π–A ligand 4′-(4-(1H-1,2,4-triazol-1-yl)phenyl)-2,2′:6′,2′′-terpyridine (3N3PY) with mononuclear, one-dimensional (1D) chain and dinuclear structures, respectively. The three-dimensional (3D) supramolecular assemblies were achieved by the linkage of the Zn(II) complexes through π–π and hydrogen bonding interactions. The assemblies demonstrated intense luminescence and exhibited an excellent ability for sensing specific organic molecules namely 2,4,6-trinitrophenol (TNP), 4-methylbenzaldehyde (4-MB) and decabromodiphenyl oxide (DBDPO). [ABSTRACT FROM AUTHOR]

The charge transfer interactions between the seproxetine (SRX) donor and π-electron acceptors [picric acid (PA), dinitrobenzene (DNB), p-nitrobenzoic acid (p-NBA), 2,6-dichloroquinone-4-chloroimide (DCQ), 2,6-dibromoquinone-4-chloroimide (DBQ), and 7,7′,8,8′-tetracyanoquinodi methane (TCNQ)] were studied in a liquid medium, and the solid form was isolated and characterized. The spectrophotometric analysis confirmed that the charge–transfer interactions between the electrons of the donor and acceptors were 1:1 (SRX: π-acceptor). To study the comparative interactions between SRX and the other π-electron acceptors, molecular docking calculations were performed between SRX and the charge transfer (CT) complexes against three receptors (serotonin, dopamine, and TrkB kinase receptor). According to molecular docking, the CT complex [(SRX)(TCNQ)] binds with all three receptors more efficiently than SRX alone, and [(SRX)(TCNQ)]-dopamine (CTcD) has the highest binding energy value. The results of AutoDock Vina revealed that the molecular dynamics simulation of the 100 ns run revealed that both the SRX-dopamine and CTcD complexes had a stable conformation; however, the CTcD complex was more stable. The optimized structure of the CT complexes was obtained using density functional theory (B-3LYP/6-311G++) and was compared. [ABSTRACT FROM AUTHOR]

Haloperidol (HPL) is a typical antipsychotic drug used to treat acute psychotic conditions, delirium, and schizophrenia. Solid charge transfer (CT) products of HPL with 7,7,8,8-tetracyanoquinodimethane (TCNQ) and picric acid (PA) have not been reported till date. Therefore, we conducted this study to investigate the donor–acceptor CT interactions between HPL (donor) and TCNQ and PA (π-acceptors) in liquid and solid states. The complete spectroscopic and analytical analyses deduced that the stoichiometry of these synthesized complexes was 1:1 molar ratio. Molecular docking calculations were performed for HPL as a donor and the resulting CT complexes with TCNQ and PA as acceptors with two protein receptors, serotonin and dopamine, to study the comparative interactions among them, as they are important neurotransmitters that play a large role in mental health. A molecular dynamics simulation was ran for 100 ns with the output from AutoDock Vina to refine docking results and better examine the molecular processes of receptor–ligand interactions. When compared to the reactant donor, the CT complex [(HPL)(TCNQ)] interacted with serotonin and dopamine more efficiently than HPL only. CT complex [(HPL)(TCNQ)] with dopamine (CTtD) showed the greatest binding energy value among all. Additionally, CTtD complex established more a stable interaction with dopamine than HPL–dopamine. [ABSTRACT FROM AUTHOR]

A new RP-HPLC method was developed and validated to achieve the separation and quantification of the organic explosive compounds such as pentaerythritol tetranitrate (PETN), 1-methyl-2,4,6-trinitro toluen (TNT), picric acid, 1,3,5,7-tetrazocine (HMX), cyclorimethylenetrinitramine (RDX), 2,4,6 Tri nitro phenyl methyl nitramine (Tetryl), 1-methyl-2,4-dinitro toluen (DNT), ethylene glycol dinitrate (EGDN), and trinitroglycerine (TNG) in this study. The mobile phase composition (IPA percentage in water) and the flow rate was optimized for the separation of the organic explosive compounds. Theoretical plate number (N), capacity factor (k'), resolution (Rs) were used to determine the optimum chromatographic conditions. The most favorable conditions were detected as 22% IPA in water, a flow rate of 1.7 mL/min. Under optimum chromatographic conditions, separation was completed within 18 min. The linear ranges were 6.5-100 and 10-0.625 mg/L (R2 = 0.998-0.999) for investigated explosives. Mean recoveries were found to be in the range of 95.3%-103.3%. LOD and LOQ were ranged between 0.09-1.32 mg/L and 0.31-4.42 mg/L, respectively, for investigated explosives. The obtained results showed that the new method was very suitable for the separation of the resolution of organic explosive compounds with C18 columns. TNT and RDX seized from terrorists were found to be in 372.99 mg/L and 79.55 mg/L, respectively. [ABSTRACT FROM AUTHOR]

Multidentate organic ligand with bridged and chelated functions is firstly developed to build cluster-based metal–organic framework. N-donating multidentate ligand 4-phenyl-2,6-bis(2′-pyrazinyl)pyridine (PBPP) is deliberately selected to construct a unique metal–organic framework {[WS4Cu4I4[Ni(PBPP)2]]2·DMF]}n (1) (DMF = N,N′-dimethylformamide). X-ray structure analysis reveals that 1 exhibits a 2D (6,3) graphene-like network, fabricated by rare pentanuclear [WS4Cu4]2+ building clusters, Ni2+ building metals, bridged and chelated PBPP and terminal I−. 1 has good water stability and luminescence. More importantly, the detection performance of 1 is explored through luminescence quenching effect, which reveals that 1 can detect 2,4,6-trinitrophenol (TNP) with high sensitivity and selectivity. The sensing mechanism has also been studied. [ABSTRACT FROM AUTHOR]

In the present study, Graphene Oxide (GO) was prepared by the modified Hummer's method. Further, different wt% of reduced Graphene Oxide (rGO) decorated TiO2 (TiO2-rGO) nanocomposites were synthesized using non-toxic sodium L-ascorbate as a reducing agent. The structure, morphology, optical and chemical composition of the composites were investigated with analytical techniques such as XRD, FESEM, HRTEM, UV –Vis DRS, FTIR, XPS and Raman spectroscopy. The zeta potential study reveals that the surface charge of the materials is negative and the value increases with the increase in the rGO content which proves residual acid groups on rGO and by the decoration of rGO surface with TiO2. The photocatalytic activity of the composites was tested for the degradation of nitrophenols [Mononitrophenol (MNP), Dinitrophenol (DNP) and Picric Acid (PA)] in the presence of the Fenton's reagent with UV light (wavelengths 254 and 390 nm), visible light and sunlight at different pHs (3,7 and 10). In the presence of Fenton's reagent, the catalyst TiO2-rGO 1% exhibited 100% degradation of nitrophenols in UV light of wavelength 254 nm within 15 min whereas with sunlight the catalysts, TiO2-rGO 5% and TiO2-rGO 10% exhibited 100% degradation of nitrophenols within 15 min and 18 min, respectively, at pH 3. Thus, the combined catalysts could have much impact on the photocatalytic degradation of water-borne organisms in the future. [ABSTRACT FROM AUTHOR]

A simple one-step solid-state pyrolysis method has been employed to synthesize highly crystalline nitrogen-doped carbon dots using adipic acid and urea as carbon and nitrogen sources. The prepared carbon dots displayed UV emission (λex = 290 nm and λem = 370 nm) and blue fluorescence emission (λex = 360 nm and λem = 420 nm). These crystalline nitrogen-doped carbon dots exhibited a quantum yield of 6% with tryptophan as standard at 370 nm emission and 14% with quine sulfate as standard at 420 nm emission. The synthesized carbon dots were spherical, having a mean particle diameter of 2.56 ± 0.57 nm. The prepared carbon dots have large functional groups on their surface, which renders excellent water solubility to them. Carbon dots was used as selective and sensitive turn off sensor for detection of picric acid Metanil yellow with the linear response for picric acid ranging from 2 μM to 22 μM and 2–45 μM with a detection limit of 0.06 μM and 0.45 μM and for Metanil yellow ranging from 1 μM to 30 μM with a detection limit of 0.32 μM. The mechanism for detecting metanil yellow is proposed to be the inner filter effect. At the same time, it is both the inner filter effect and FRET for picric acid. The actual sample application of carbon dots as a nanosensor was tested to detect metanil yellow as an adulterant in turmeric powder. [ABSTRACT FROM AUTHOR]

The effluents generated from synthesis and processing plant of Picric acid is reported to be carcinogenic and hence needs to be treated to reduce its concentration below safe discharge limit. Present paper deals with studies on mineralization of Picric acid by adopting photochemical and electrochemical processes and the efficacy of these processes. In both these processes, effect of Fenton reagent is also studied. In photo chemical process, further effect of TiO2 photo catalyst with different particle size has also been studied. The treated solution was characterized by using UV-Visible spectrophotometer, High Performance Liquid Chromatography (HPLC) and Total Organic Carbon (TOC) analyzer. The observed results have been interpreted and reported in the present paper. Crucial process parameters in all these processes viz. pH, concentration of oxidizer and catalyst are optimized to achieve picric acid mineralization in reasonable time. It was observed that the time required to bring down the concentration of Picric acid from 100 ppm to less than 1 ppm using photo chemical method was 2 hours whereas this time was reduced to 1 hour using Fenton reagent in photo chemical process. In photo catalysis process carried out using TiO2 catalyst, it was observed that TiO2 nano-particles are more efficient compared to that of commercially available micron size TiO2 powder. To prevent the problem of difficulty in recovery of TiO2 powder after treatment, nano particle TiO2 beads blended in Polysulfone were also used. These beads were advantageous in terms of recovery and its performance was comparable to commercial TiO2 powder. In case of electrochemical treatments at optimised process parameters, picric acid was found completely mineralised to bring its concentration less than 1 ppm using Electro-Fenton reaction picric where as under Electro-peroxide reaction picric acid is mineralised up to 3 ppm after 3 hrs. After studying these processes, it is observed that electro-chemical process is more users friendly and economical; however, photo-Fenton process is more effective in achieving complete mineralization of Picric acid in reasonable time. [ABSTRACT FROM AUTHOR]

Naphthalimide‐hydroxyquinoline based conjugates (NQ1 and NQ2) were synthesized for the detection of nitroaromatics in HEPES buffer/DMSO (9/1, v/v, pH=7.4) and Fe3+/Pd2+ in CH3CN solvent. The NQ1 and NQ2 were characterized using NMR (1H, 13C, COSY) and IR spectroscopies. Theoretical studies revealed that 8‐HQ moiety in NQ1 and NQ2 placed at orthogonal position with respect to naphthalimide core to minimize steric crowding. The energy gap between HOMO and LUMO for NQ1 and NQ2 were found to be −3.1 eV. The emission spectrum of NQ1 and NQ2 showed decrease in the emission intensity at 450 nm upon addition of picric acid (PA) and trinitrotoluene (TNT) whereas addition of 2‐nitroaniline caused quenching with concomitant red‐shift of the emission band in 90 % HEPES buffer‐DMSO. The detection limit of NQ1 for PA, TNT and 2‐NA detection was calculated as 8.7×10−6 M, 2.2×10−5 M and 1.8×10−5 M. The complexation of NQ1 with PA, TNT and 2‐NA was further supported by Job's plot, dynamic light scattering studies and NMR titrations. We successfully utilized NQ1 and NQ2 for the detection of PA, TNT and 2‐NA in real soil samples with excellent recovery. NQ1 also showed quenching of the emission intensity at 450 nm upon addition of Fe3+ and Pd2+ ions in CH3CN. Thus, NQ1 showed solvent‐dependent dual chemosensor type behavior. The functioning of NOR gate has been achieved using Fe3+/NACs with NQ1. [ABSTRACT FROM AUTHOR]

The one‐pot three‐component domino reaction of 2‐acetylphenothiazine, 4‐Cl/4‐Me benzaldehyde and malononitrile afforded 3‐amino‐4′‐chloro/4′‐methyl‐5‐(10H‐phenothiazin‐2‐yl)‐[1,1′‐biphenyl]‐2,4‐dicarbonitriles in good yields. These phenothiazine‐tethered biaryls exhibited strong red fluorescence under UV lamp in solid state and green fluorescence in DMSO. These probes were sensitive towards multi‐analytes like Fe3+, Cu2+, picric acid and 4‐nitrophenol with good lower limit of detection. [ABSTRACT FROM AUTHOR]

Water-soluble isonicotinamide-stabilized fluorescent gold nanoclusters (AuNCs) were synthesized in one step and used as fluorescent probes for the sensitive and selective determination of 2,4,6-trinitrophenol (TNP). The AuNCs were characterized by transmission electron microscopy, X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy and fluorescence spectroscopy. The fluorescence of the isonicotinamide-stabilized AuNCs was quenched by TNP that follows a linear relationship with the TNP concentration from 0.2 to 20 µM. The sensor provides a low detection limit of 0.06 µM. By using absorption spectroscopy, fluorescence spectroscopy and fluorescence lifetime, the fluorescence quenching mechanism was demonstrated to be due to the inner filter effect between AuNCs and TNP. The sensor was successfully employed for TNP determination in water samples. [ABSTRACT FROM AUTHOR]

We report a simple route to design highly sensitive triangular silver nanoplates (TSNPs)-based SERS substrate for the trace-level detection of explosive molecules. The size-dependent localized surface plasmon resonance (LSPR) tunability for the synthesis of TSNPs is achieved by controlling reaction kinetics and seed volume in a modified seed-mediated approach. The computed extinction spectra of TSNP, using the finite-difference time-domain (FDTD) method, are in excellent agreement with the experimental results, therefore assisting further in the investigation of the plasmonic properties of TSNP. The higher electric field enhancement offered by TSNP is systematically investigated by performing the FDTD simulations for various sizes and corner rounding of TSNP. The FDTD results show that the dipolar plasmon resonance wavelength, size, and corner rounding of TSNP are the principal contributing factors for designing the high-performance SERS substrate. Herein, we have used a portable Raman system for the SERS-based detection of three important explosive molecules: picric acid (PA), ammonium nitrate (AN), and 2, 4-dinitrotoluene (DNT). The TSNP-based SERS substrates display excellent intensity enhancement factors of ~ 107 for rhodamine 6G (R6G) and PA and ~ 105 for AN. The high sensitivity of SERS substrate with limit-of-detection (LOD) of value 2.3 × 10−11 M for PA and 3.1 × 10−8 M for AN and effective batch-to-batch reproducibility for DNT, thus offering its potentials for field detection of explosive molecules at trace-level. [ABSTRACT FROM AUTHOR]

The aim is study biochemical markers of connective tissue metabolism in children with musculoskeletal disorders and their association with dental caries of temporary teeth. There were examined 232 children at the age of 5 (202 children with musculoskeletal disorders and 30 conditionally healthy children without somatic pathology). Among children with musculoskeletal disorders 68 (33.66%) had flat feet, 59 (29.21%) – postural impairment and 75 (37.13%) – combined pathology of the musculoskeletal sestem. For further research, the children were divided into three groups, 30 people in each. Group І included children with pathology of the musculoskeletal system, dental caries, without oxyproline in urine; group ІІ – with pathology of the musculoskeletal system, dental caries and oxyproline in urine; group ІІІ – with dental caries and without oxyproline in urine. Urinary excretion of glycosaminoglycans using a nephelometric test with cetylpyridinium chloride was determined. The concentration of creatinine in urine was measured in units of weight in the formation of a chromogenic complex of a solution of picric acid with creatinine in an alkaline medium. Dental status was assessed in terms of caries prevalence, deft index and severity of dental caries. The prevalence of caries of temporary teeth in 5-years old children with musculoskeletal disorders was on average 90.6±2.05%, deft index ─ 6.62±0.20, being significantly higher than in children without somatic pathology (respectively 70.83±4.45% and 5.15±0.34, р<0.001). Oxyprolin was detected only in the urine of children with combined pathology of musculoskeletal system (on average 3.53±0.11 units). The excretion rates of glycosaminoglycans in children with pathology of the musculoskeletal system, dental caries and oxyproline in urine (gr.ІІ) were two times higher than the reference range (415.37±15,09 CPCh units / 1 g creatinine, р<0.001). In the absence of oxyproline in urine, both in somatically healthy children (gr. ІІІ) and in children with pathology of the musculoskeletal system (gr. І), the levels of excretion of glycosoaminoglycans were within the reference range (respectively 198.83±10.71 and 203.87±12.52 CPCh units / 1 g creatinine. The levels of daily excretion of creatinine were within the normal range in children of gr. ІІІ (1.17±0.13 g/day; in children of gr. І they were 2.85 times lower (0.41±0.05 g/day, p<0.001); in children of gr. ІІ – 6.5 times lower (0.18±0.02 g/day р<0.001). In children of gr. ІІ, a negative correlation was found between the levels of creatinine and oxyproline (τ= -0.68, p<0.05). The absence of oxyproline in the urine of children of gr. І and ІІІ indicates the absence of collagen decay in their bodies. In children with pathology of the musculoskeletal system against the background of undifferentiated connective tissue dysplasia (gr. ІІ), a strong, positive correlation was found between the deft index and levels of urinary excretion of oxyproline (τ= +0.77, p<0.05) and glycosaminoglycans (τ= +0.90, p<0.05), which indicates that the development of dental caries depends on the severity of the pathology of the musculoskeletal system [ABSTRACT FROM AUTHOR]

Bright luminescent hydrophobic carbon dots receive significant attention on account of their potential utility in bio‐imaging, sensors, and creating a full range of colors in displays. Herein, the solvothermal one‐pot synthesis of nitrogen and sulfur‐doped hydrophobic carbon dots (HCDs) from a single precursor, is reported. These HCDs exhibit good dispersibility in different organic solvents and show blue fluorescence in solid and solution states. Notably, HCDs show green color room temperature phosphorescence emission centered at 515 nm with a long average lifetime of 1.1 ms and an ultralong lifetime of 334 ms at 77 K. An intense white light with Commission international de d'Eclairage chromaticity coordinate of (0.32, 0.34) is generated by a simple mixing of HCDs with rhodamine 6G in the solution state. Furthermore, these HCDs are explored for the rapid detection of extremely hazardous and strong explosive picric acid in a non‐aqueous solution with a limit of detection of 3.2 µm and good selectivity. [ABSTRACT FROM AUTHOR]

• Quinoline-based fluorescent turn-off sensor QN has been synthesized to detect PA. • The sensor displays fluorescent intensity at 504 nm. • The sensor exhibits high sensitivity and selectivity towards PA, even among other interfering species. • The detection limit of the sensor QN towards PA was calculated to be 9.33 × 10−6 M. • The binding mechanism was confirmed through 1H NMR titration, FT-IR studies, and DFT studies. A simple turn-off quinoline-based fluorescent chemosensor, 1-(6-amino-2-methyl-4-phenylquinolin-3-yl)ethan-1-one (QN) has been developed, synthesized, and characterized by various spectroscopic methods. This probe is selective for the sequential recognition of picric acid (PA), using a fluorescent turn-off method. QN exhibits a broad emission band at 504 nm, but fluorescence quenching occurs upon the addition of picric acid over other nitro compounds. The binding stoichiometric ratio between QN and picric acid was calculated to be 1:1 through Job's plot analysis, and the binding constant was determined. The limit of detection towards picric acid was found to be 9.33 µM. Further, the mechanistic approach for binding has been investigated by spectroscopic methods like 1H NMR titration, FT-IR studies, and density functional theory (DFT) studies. [Display omitted] [ABSTRACT FROM AUTHOR]

[Display omitted] • Kitchen waste okra peels derived synthesis of nitrogen doped carbon dots (N-CDs) as a fluorescent probe. • N-CDs a fluorescent probe shows sensitivity towards Cr6+ and Mn7+ metal ions with instant decolourisation of Mn7+. • The developed fluorescent probe shows sensitivity and selectivity towards 4-nitroaniline (4-NA) and picric acid (PA). • The developed method has good effectivity for real water sample with good recovery rate. • The circular economy based reactivated carbon as an adsorbent for removal of model pollutant dyes. The present study explores the kitchen waste okra peels derived synthesis of nitrogen doped carbon dots (N-CDs) via simple carbonization followed by reflux method. The synthesized N-CDs was characterized using, TEM, XPS, FTIR, XRD, Raman, UV–Visible and Fluorescence Spectroscopy. The N-CDs emits bright blue emission at 420 nm with 12 % of quantum yield as well as it follows excitation dependent emission. Further, the N-CDs were employed as a fluorescence sensor for detection of hazardous metal ions and nitro compounds. Among various metal ions and nitro compounds, the N-CDs shows fluorescence quenching response towards Cr6+, and Mn7+ metal ions as well as 4-nitroaniline (4-NA) and picric acid (PA) with significant hypsochromic and bathochromic shift for Mn7+, 4-NA and PA respectively. The developed fluorescent probe shows relatively low limit of detection (LOD) of 1.46 µg/mL, 1.05 µg/mL, 2.1 µg/mL and 2.2 µg/mL for the above analytes respectively. The N-CDs did not show any significant interference with coexisting ions and successfully applied for real water sample analysis. In addition, circular economy approach was employed for adsorption of dyes by reactivating leftover waste carbon residue which was obtained after reflux. Thus, the kitchen waste valorization and circular economy approach based N-CDs have potential applications in the field of detection of emerging pollutants, and environmental remediation. [ABSTRACT FROM AUTHOR]

2,4,6 - Trinitrophenol, commonly known as picric acid, is a powerful explosive that has been used historically in military ammunition. Picric acid is extremely toxic and sensitive to friction and heat; thus, it is prone to accidental detonation at high temperatures. It is critical to detect and separate picric acid from the impacted areas. In the present study, we designed and developed a fluorescent copolymer (P1) for temperature-dependent picric acid detection. The solvatochromic and aggregation-induced emission (AIE) properties of P1 were utilized to detect picric acid at a high temperature of 40 °C (high alert level) by turn-off emission. Additionally, a polymeric thin film (F1) was fabricated by immobilizing P1 onto the surface of quartz slide. Notably, F1 retained its emissive properties across a range of temperatures (both relatively low and high alert levels), facilitated by its AIE characteristics. The portable film, F1, displayed a nanomolar sensitivity toward picric acid, making it suitable for on-site detection in aqueous media (neutral pH). Furthermore, F1 demonstrated efficient separation of picric acid from nitroaromatic explosive mixtures with a separation efficiency of 70 % over four cycles. Importantly, F1 exhibited practical utility in detecting and separating picric acid in real samples, highlighting its potential for environmental monitoring applications. [Display omitted] • A maleimide-based fluorescent polymeric probe was developed for picric acid detection. • The temperature-dependent turn-off fluorescence detection of picric acid was observed. • The polymeric film showed nanomolar sensitivity toward picric acid at various temperatures. • The polymeric film demonstrated an efficient picric acid separation from polluted areas. [ABSTRACT FROM AUTHOR]

Both 1 and 2 can achieve highly selective and sensitive fluorescence burst detection of the pesticides DTF and TNP in the environment. [Display omitted] • Two new coordination polymers were designed and synthesized. • Advantages of the application of CPs for chemical sensing analytical methods are summarized comprehensively. • Hirsfeld d norm surface of carboxylate are mainly covered by H···O/O···H, C···H/H···C and H···H interactions. Two thermally and water stable zinc-based coordination polymers (CPs) [Zn 2 (bb)(AZA) 2 ] n (1) and [Zn 2 (bb)(PA) 2 ] n (2) (bb = 4,4′- bis (imidazolyl) biphenyl, H 2 AZA=Azelaic acid and H 2 PA=Heptanedioic acid) were synthesized by a hydrothermal method and were structurally characterized through X-ray single-crystal diffraction, X-ray powder diffraction, elemental analysis, thermogravimetric analysis, infrared spectroscopy, ultraviolet spectroscopy, and other tests. Both of CPs 1 and 2 have 2D layered networks. Notably, CP 1 behaves as a multi-responsive fluorescent sensor toward dinotefuran (DTF) and 2,4,6-trinitrophenol (TNP) with high sensitivity, selectivity, and stability based on high fluorescence quenching efficiency. The detection limits for dinotefuran (DTF) and 2,4,6-trinitrophenol (TNP) were determined to be 1.99 ppm and 3.19 ppm, respectively. Additionally, the color of the test paper remained unchanged under natural light. Furthermore, the possible sensing mechanisms have been discussed in detail, and are supported by PXRD analysis, UV–vis spectroscopy, and density functional theory (DFT). [ABSTRACT FROM AUTHOR]

An orange light emitting 'off–on-off' fluorogenic probe for consecutive detection of Al3+ ions and 2,4,6-trinitrophenol having detection and quantification limit in the nM range. [Display omitted] • A fluorogenic sensor (HNMN) has been introduced to detect Al3+ ions and picric acid (PA). • A paper strips-based test kit has been fabricated to detect Al3+ ions and PA. • The LOD and LOQ values are found to be 8.6 nM and 28.4 nM respectively in the DMF medium. • Demonstrate a facile approach to design highly red-shifting fluorosensors from the non-fluorophore moieties. • Could be avoided false signaling during the detection of target analytes. A simple, orange light emitting 'off–on-off' fluorogenic sensor, (E)-4-(((2-hydroxy-4-nitrophenyl) imino) methyl) naphthalene-3-ol (HNMN), has been introduced for the successive recognition of Al3+ ions and 2, 4, 6-trinitrophenol respectively, utilizing the photoluminescence 'off–on-off' mechanism. A significant enhancement in the photoluminescence of HNMN is found at 558 nm, attributed to the chelation of Al3+ ions, resulting in a visible orange-colored photoluminescence under a handy 365 nm UV light illumination. Among the different tested nitroaromatic compounds (NACs), 2, 4, 6-trinitrophenol, namely picric acid (PA), selectively quenches the orange photoluminescence caused by Al3+ on the HNMN complex. The stoichiometric ratio for the complex formation between HNMN and aluminum ion is determined to be 1:1, with an estimated limit of detection (LOD) and quantification (LOQ) found to be 8.6 nM and 28.4 nM respectively in DMF medium. Different spectroscopic analyses have elucidated the mechanistic features of identifying Al3+ ions. A test kit–based experiment is performed with the HNMN- coated filter paper to detect Al3+ ions and PA sequentially & selectively. Based on the chemical inputs and optical output, we have framed the INHIBIT molecular logic circuit. The present report evokes a facile approach for the design and molecular development of highly red-shifting fluorosensors from the non-fluorophore moieties to avoid false signaling during the detection of target analytes. [ABSTRACT FROM AUTHOR]

[Display omitted] • New Zn(II) carboxylate complex containing 2-aminopyridine ligand was synthesized and structurally characterized. • FT-IR, UV–visible, fluorescence spectroscopy; single crystal XRD studies were performed. • DNA binding ability of the complex was assessed using absorption and emission spectral studies. • Sensing ability of the complex towards nitroaromatic compounds were explored by fluorescence quenching measurements. • Selective sensing of picric acid in presence of other nitroaromatics explored. • Theoretical studies (DFT) carried out to ascertain complex's preferential binding towards nitroaromatics, especially picric acid revealing involvement of π-stacking and spodium bonding interactions. A mononuclear zinc(II) carboxylate complex containing 4-hydroxybenzoic acid and N -donor 2-aminopyridine was synthesized in aqueous methanol and comprehensively characterized by elemental, spectroscopic, and single-crystal X-ray diffraction analyses. The complex crystallized in monoclinic space group P 2 1 / c having a distorted square pyramidal structure. Spectral and X-ray diffraction analyses confirm the molecular composition of the complex. The complex has shown strong fluorescence emission, acts as a selective and sensitive chemosensor for nitroaromatics. The complex is able to selectively detect picric acid in the presence of other nitroaromatics. Density Functional Theory (DFT) calculations further elucidate the complex's preferential binding towards nitroaromatics, revealing the involvement of π-stacking and spodium bonding interactions. This work not only expands the understanding of zinc(II) carboxylate complexes in supramolecular chemistry but also highlights their promising applications in environmental monitoring and biological studies due to their significant fluorescence quenching in the presence of nitroaromatics and moderate DNA binding affinity. [ABSTRACT FROM AUTHOR]

A nine-metal Zn(II)-Nd(III) nanoring with a diameter of about 2.3 nm was constructed for the rapid and ratiometric fluorescence detection of explosive 2,4,6-trinitrophenol at the ppm level. [Display omitted] • 2,4,6-Trinitrophenol (TNP) is detected firstly by a NIR luminescent high-nuclearity d-4f nanomolecular sensor. • The ratiometric fluorescence detection of TNP is fast and reliable. • The ratiometric fluorescence detection of TNP is highly sensitive and selective. Rapid and quantitative detection of 2,4,6-trinitrophenol (TNP) is very crucial for homeland security, military application, and environment protection. Herein, a nine-metal Zn(II)-Nd(III) nanoring 1 with a diameter of 2.3 nm was constructed by the use of a long-chain Schiff base ligand, which shows ratiometric fluorescence response to TNP with high selectivity and sensitivity. The fluorescence sensing behavior of 1 to TNP is expressed by a first-order equation I 1060nm / I 560nm = -0.0128*[TNP] + 0.9723, which can be used to quantitatively analyze TNP concentrations in solution. The limits of detection (LODs) to TNP based on the ligand-centered (LC) and Nd(III) emissions of 1 are 5.93 μM and 3.18 μM, respectively. The fluorescence response mechanism to TNP is attributed to the competitive absorption effect and photoinduced electron transfer (PET). The luminescence quenching of 1 is dominated by static process. [ABSTRACT FROM AUTHOR]

The recognition of nitroexplosives is a pivotal area of research, vital for homeland security and environmental safety. This critical review aims to succinctly outline the key characteristics of luminescent Zn(II) Schiff base complexes, highlighting their design, synthesis, and sensing abilities, with a specific emphasis on their role in nitroexplosives detection. [Display omitted] • Discussion on different luminescent chemosensors for the detection of nitroexplosives. • Brief discussion on the advantages of using zinc(II) Schiff base complexes as chemosensors. • Brief discussion on different synthetic strategies of the zinc(II) Schiff base complexes. • Highlights on their sensing mechanism. In this review, we briefly summarize the key aspects of the synthetic strategies for zinc(II) Schiff base complexes, focusing on their photophysical properties such as the origin of luminescence, intensity, lifetime, and quantum yield. Additionally, we discuss the advantages of using luminescent zinc(II) complex-based sensors, the factors underlying their effectiveness as chemosensors for explosive detection, their mechanisms of action, and future outlooks and concerns. Most of the zinc(II) Schiff base complexes reported to date function as turn-off luminescent chemosensors for nitroexplosives. Some zinc(II) complexes discussed in this review demonstrate very high selectivity and sensitivity, with limits of detection (LOD) in the ppb or nM range for picric acid. Additionally, certain zinc(II) complexes can detect picric acid in the solid state through a visible color change observable to the naked eye under ambient light. [ABSTRACT FROM AUTHOR]

[Display omitted] • Simple and cost-effective synthesis of MoS 2 @MWCNTs by wet chemical method. • The MoS 2 @MWCNTs has improved surface area attributed in its surface imperfections and defects. • The MoS 2 @MWCNTs selectively detects picric acid (PA) in the presence of common water and structurally analogues interferants. • The synthesized electrocatalyst shows lower LoD with wide linear range. • The recyclability, reproducibility, repeatability experiments prove efficacy of electrocatalyst and applied for real samples. Nitrophenols are industrially versatile yet environmentally detrimental compounds. Herein, we have synthesised molybdenum sulphide based dichalcogenide supported multiwalled carbon nanotubes i.e. MoS 2 @MWCNTs electrocatalyst by simple wet chemical method for PA determination. The successful decoration of MoS 2 over MWCNTs were confirmed by various characterizations techniques including scanning electron microscopy (SEM) shows MoS 2 layers grown on MWCNTs and having average size is –80 nm. Energy dispersive X-ray analysis (EDAX) reveals elements are homogenously distributed in nanocomposite. High resolution-transmission electron microscopy (HR-TEM) shows increase in average diameter after decoration of MoS 2 over MWCNTs from 30 nm to 70 nm. The Fourier transform infrared (FT-IR) analysis suggests the presence of Mo-S stretching frequency at 605 cm−1 in addition to hydroxyl, carbonyl, C–C, C–O stretching frequencies are also observed. In Raman spectrum from apart D and G bands, the characteristic intense bands E 2g 1 and A 1g of MoS 2 were pointed towards presence of molybdenum and sulphur. The X-ray diffraction (XRD) confirms synthesised electrocatalyst is in hexagonal crystal structure with P63/mmc space group. The X-ray photoelectron spectroscopy (XPS) reveals that for Mo 3d is found to be two characteristics peaks at 231.2 eV and 233.2 eV corresponds to Mo4+ 3d 3/2 and 3d 5/2 respectively. The peak at 229 eV corresponds to S 2s. Whereas, the signal appears at 162.7 eV, 165 eV, 169 eV and 170 eV shows sulphur is in 2S 3/2 and 2S5 /2 states. Electrochemical performance was examined by cyclic voltammetry (CV) tests. The Electrocatalyst is highly selective, having appreciable anti-interference property, lower limit of detection (LoD), i.e., 0.5 μM with wide linear range. The low R ct and high k⁰ pointed that MoS 2 @MWCNTs performed better towards electrochemical detection of PA. [ABSTRACT FROM AUTHOR]

In order to design organic small molecule fluorescent materials with multiple sensing, a bibranched -NH2 modified cyanostilbene derivative (AM) was synthesized. It exhibits solvent and aggregation-induced emission effects, with a solid-state quantum yield of 28%, which is seven times higher than that in THF. The synthesized sample AM demonstrated high sensitivity to trace water via a fluorescence “turn-off” response, achieving a low detection limit of 0.41 µM in THF and 0.80 µM in EtOH. AM also exhibits a “turn-off” response to picric acid, attributed to the photo-induced electron transfer effect it induces. The recognition of picric acid by AM demonstrates specificity and resistance to interference from nitro explosives, with a detection limit of 300 ppb and a linear relationship (R2 = 0.9981) at the range of 0–4 equivalents AM. Such acid recognition can facilitate the design of qualitative test papers and safety inks. Additionally, AM can function as a temperature sensor with a linear relationship (R2 = 0.9976) within the temperature range of 25–110 °C. Leveraging these unique characteristics, a series of methods were proposed for the direct quantitative determination of trace water in nonaqueous solvents, picric acid, and temperature. [ABSTRACT FROM AUTHOR]

[Display omitted] • Simple V-shaped pyrene-based probe (py- o ) with aggregation-induced emission for PA detection. • Qualitative and quantitative detection of PA in real water. • Naked-eye detection of PA in solid State by TLC plates. The detection of nitroaromatic explosives in real samples is essential for environmental monitoring because of their strongly powerful nature and wide applications in industries. Aggregation-induced emission enhancement (AIEE) active fluorescent probe has been widely employed to detect nitroaromatic explosives. Hereby, a simple V-shaped bispyrene-based fluorescent probe (called py- o ) with AIEE properties was designed and synthesized, which was fully charactered by 1D NMR, ESI, FTIR, and 2D NOESY spectra. The py- o displayed bright blue-green fluorescence excimer emission at 480 nm in DMF/H 2 O (v/v 1:1). It is observed that the fluorescence excimer emission of py- o at 480 nm was quenched by PA in solution with a quenching constant of 5.45 × 104 M–1, and the limit of detection was approximately 0.139 μM. The details of the sensing mechanism were explained using 1H NMR titrations, Job's plot and Bensi-Hildebrand methods, which revealed a 1:1 binding ratio via the π-π interactions between PA and py- o . Meanwhile, it exhibited outstanding anti-interference ability in the detection of PA when interfering analytes were added under the same conditions. Furthermore, low-cost thin-layer chromatography (TLC) plates coated with py- o were developed as fluorescent tools for naked-eye detection of PA in the solid state. Therefore, this work provides a new method for constructing an AIEE fluorescent probe for the detection of nitroaromatic explosives to utilize in environmental monitoring. [ABSTRACT FROM AUTHOR]

[Display omitted] • The N-CQDs are synthesized using o-phenylenediamine as carbon and nitrogen source. • N-CQDs can selectively recognize PA and its homologous (DNP and NP) in the presence of other analytes. • A linear correlation is observed between PA concentration (0 ∼ 10.0 μmol/L) and N-CQDs fluorescence intensity (0.05 mg/mL) at 556 nm, and the detection limit is ∼ 70 nmol/L. • The Stern-Volmer graphs lack sufficient linearity, confirming the static quenching interaction between N-CQDs and PA. • The N-CQDs are successfully applied to determine PA content in simulated and real samples quantitatively. Nitrogen doping carbon quantum dots (N-CQDs) are synthesized using o-phenylenediamine as a carbon and nitrogen source via the water hydrothermal method. The size of the obtained N-CQDs is about 5.51 nm, and FTIR results show that their surface contains many –OH and –NH 2 groups. N-CQDs can selectively recognize PA and its homologous (DNP and NP) in the presence of other analytes (including TNT, Tetryl, PETN, RDX, HMX, NC, NG, DNT, NT, NB, DNP, NP, BP, PC, AN, Ca2+, Cl-, Mg2+, Na+, H 2 O 2). A linear correlation is also observed between PA concentration (0 ∼ 10.0 μmol/L) and N-CQDs fluorescence intensity (0.05 mg/mL) at 556 nm. The linear curve is y = -3.64 × 107x + 404.91, and the detection limit is ∼ 70 nmol/L. The Stern-Volmer graphs lack sufficient linearity, confirming the static quenching interaction between N-CQDs and PA. Finally, the N-CQDs are successfully applied to determine PA content in simulated and real samples quantitatively. [ABSTRACT FROM AUTHOR]

A pyridine functionalized pyrimidine-based system, H2P was successfully synthesized, characterized, and evaluated for its remarkable selective characteristics towards Zn2+ and ATP ions. The chemical sensing capabilities of H2P were demonstrated through absorption, fluorescence, and NMR spectroscopic techniques. The probe exhibited outstanding sensitivity when interacting with the ions, demonstrating relatively strong association constants and impressively low detection limits. The comprehensive binding mechanism of H2P with respect to Zn2+ and ATP ions was investigated using a combination of analytical methods, including Job's plot, NMR spectroscopy, mass spectrometry, and density functional theory (DFT) experiments. The interesting sensing ability of H2P for Zn2+/ATP ions was harnessed for live cell bioimaging and other diverse on-site detection purposes, including paper strips, cotton swabs, and applications involving mung bean sprouts. Further, the fluorescent probe demonstrated its effectiveness in detecting Zn2+ and ATP within live cells, indicating its significant potential in the realm of biological imaging applications. Moreover, the molecular configuration of the zinc complex (H2P–Zn 2 Cl 4), derived from H2P , was elucidated using X-ray crystallography. This complex exhibited intriguing multifunctional attributes, encompassing its capability for detecting picric acid and for reversible acid/base sensing responses. The enhanced conducting behavior of the complex as well as its resistance properties were investigated by performing I – V characteristics and electrochemical impedance spectroscopic (EIS) experiments respectively. [Display omitted] • A simple pyridine-appended pyrimidine bis hydrazone was synthesized. • The probe exhibited remarkable sensing capability towards Zn2+ and ATP ions. • Multifunctional features of the zinc complex are discussed. • Bio-imaging and on-site detection applications are presented. [ABSTRACT FROM AUTHOR]