Presence Of Picric Acid Research Articles

A Straight Green Fluorescent N,N‐Dimethylbenzamine ‐ Carbazole Probe for Recognition of Explosive Picric Acid

AbstractThe sensor 4‐(9H‐carbazol‐9‐yl)‐N,N‐dimethylbenzenamine, CNDMA a green fluorescent ligand developed for selective sensing of picric acid in DMSO/H2O (1 : 9) over different other nitroaromatic compounds. The sensing mechanism involves emission quenching significantly in the presence of picric acid with a color change from green to non‐fluorescent yellow. The sensing process drives through electrostatic and Hydrogen bonding interaction with formation of an Electron Donor‐Acceptor complex. In addition, inner filter effect also play role on the fluorescence quenching. The fluorescence quenching is a mixed‐type of both static and dynamic quenching process. The binding nature was figured out using the 1H NMR and FTIR titration studies. In addition the sensor showed good quenching efficiency and quenching constant with a lowest detection limit (LOD) of 5.09×10−8 M (R=0.99964) at 358 nm. Test strip experiment is demonstrated to understand the practical feasibility of the sensor.

Sensing of picric acid using an AIEE active “Turn Off” fluorescent probe derived from hydroxy naphthaldehyde and benzyloxy benzaldehyde

A novel Schiff base with AIEE characteristics has been developed and used as a chemosensor for picric acid in aqueous media. The Schiff base 1-((E)-((E)-(4-(benzyloxy) benzylidene) hydrazono) methyl) naphthalen-2-ol [BBHN] with strong fluorescence emission was obtained by the simple condensation of 1-(hydrazonomethyl)naphthan-2-ol and 4-benzoxy benzaldehyde. The characterization of BBHN was done using Fourier Transfer Infra-Red, UV–visible, Magnetic Resonance (1H and 13C) spectroscopy, and HRMS. The sensing behaviour of BBHN aggregates towards nitro explosive was then investigated. The aggregates of BBHN showed a quick, highly selective, and sensitive fluorescence ‘Turn Off’ response towards picric acid (PA) in an aqueous medium among various other nitroaromatics. The limit of detection was 4.04 µM with 2.03 × 106 M−1 as the quenching constant. The fluorescence “Turn Off” response in the presence of PA is mainly due to π-π interactions, and non-covalent hydrogen bonding interactions. Moreover, steady-state fluorescence lifetime measurement and Stern − Volmer plots reveal that the fluorescence quenching followed mixed quenching strategies.

Imidazole-Based Metal–Organic Framework for the “On1–Off–On2” Fluorescence-Based Detection of Picric Acid and the Adsorption of Congo Red

An imidazole-functionalized metal–organic framework (MOF), {[Ba2L (H3CCOO) (DMF)2] (DMF)}n, denoted as HBU-168, has been synthesized and characterized by single-crystal X-ray diffractometry. The synthesized MOF exhibits ligand-based luminescence, which can be attributed to coordination effects. Due to its excellent fluorescence performance, HBU-168 can be used to detect nitroaromatic compounds (NACs) and metal ions selectively and sensitively. The most striking properties of HBU-168 are the distinct red shift (∼34.8 nm) observed in the presence of picric acid (PA) with a Stern–Volmer constant (KSV) of 4.17 × 104. The mechanism of the change in luminescence in the presence of PA is determined by experiments and density functional theory calculations. The results indicate that the electron transfer between PA and the MOF has a reduction in the frontier orbital energy gap. Subsequently, HBU-168 is used to prepare a light-emitting-diode-based sensor (denoted HBU-168-LED), which can detect PA rapidly and visually. In addition, we find that HBU-168 can be used to detect metal ions, particularly magnesium ions. The metal detection mechanism is based on the turn-on fluorescence of HBU-168 caused by weak interactions between the MOF and metal ions. Finally, HBU-168 is found to be a good adsorbent for Congo red, achieving a removal efficiency of 98.89%. Therefore, the multifunctional HBU-168 MOF is a promising luminescent sensor and adsorbent.

Highly effective detection of picric acid by a Ca(II)-Framework with adjustable crystal morphology and size

It is of great significance to synthesize photo-functional metal-organic frameworks (MOFs) for specific identification of pollutants and to control the morphology of MOFs for practical applications. In this article, a Ca(II)-organic framework [HBU-170, H3L ​= ​4, 4′, 4'' - (1H-imidazole-2, 4, 5-triyl) tribenzoic acid] with controllable morphology and size, was successfully synthesized under solvothermal conditions by regulating pH and characterized. With the decrease of pH value, the size of crystals is getting larger and the appearance changes from spherical to the flowers “blossomed” gradually. For the best crystallinity and better thermal stability, HBU-170–25 was selected as the volunteer for fluorescent detections. To investigate the concentration effect of detection, two groups of nitro aromatic compounds are used as additive agent. The most striking properties of HBU-170–25 are the distinct red shift and fluorescence changes observed in the presence of picric acid. The limit of detection (LOD) is calculated to be 19.06 ​μM (based on the linear regression in the range of 65.420–310.345 ​μM). The fluorescence quenching rates of picric acid is 6.7 × 103 in the linear range of 65.420–310.345 ​μM. According to the quenching efficiency, HBU-170–25 represents the better detection ability in the lower concentration. Moreover, the results of actual sample analysis indicate that HBU-170–25 owns the potential of application in the tests of actual samples.

AIE-active phenothiazine based Schiff-base for the selective sensing of the explosive picric acid in real water samples and paper-based device

A highly selective and sensitive AIE fluorescent chemosensor based on phenothiazine and ethylene diamine was synthesized (DPTZ-SB) for the exclusive detection of picric acid (PA). Interestingly, DPTZ-SB can sense PA exclusively over five other competitive explosives, due to the specific complexation ability of DPTZ-SB towards PA. For the better mechanistic understanding, Stern-Volmer, Modified Stern-Volmer and Job’s plot were employed, which showed the limit of detection and binding constant to be 0.2 ppb and 4.05 × 1010 M−1, respectively, and the stoichiometric ratio of DPTZ-SB:PA as 1:2. The values are promising as compared to the AIE fluorophores reported for PA sensing recently. The sensing mechanism was elucidated using DFT studies and 1H NMR titration experiment, which revealed the active involvement of the imine groups of the Schiff base in the complexation process. Furthermore, in order to broaden the applicability, the probe DPTZ-SB was applied in real water samples obtained from the local river, lake and tap water. Interestingly, a paper based fluorescent sensor was devised by embedding DPTZ-SB on the filter paper and was analyzed by a handheld UV lamp. Under UV light illumination, the paper-based sensor exhibited prominent fluorescence quenching in the presence of PA, which can be conveniently visualized. Moreover, the color-scanning application available in smart phones was coupled with the paper-based sensor to quantitate the scanometric assays. On a parallel note, DPTZ-SB showed excellent aggregation induced enhanced emission (AIEE) property. In fact, a 9.4-times enhancement in the photoluminescence (PL) intensity was noted for a 90:10 H2O:DMF of DPTZ-SB as compared to that in pure DMF. Therefore, the multifaceted applicability of the Schiff base has been explored, particularly in the fields of PA explosive detection device in real life samples and AIEE.

Fluorimetric quantification of picric acid in aqueous medium via smartphone and invisible ink applications using pyrene based sensor

• Simple imidazole-pyrene based sensor for quantification of picric acid in aqueous medium. • The fluorescent probe became non-fluorescent in presence of picric acid. • Addition of picric acid caused bare-eye color change from colorless to yellow. • Colorimetric detection of picric acid using smartphone ‘Color detector App’. • Detection of picric acid by the means of invisible ink applications. A simple imidazole-pyrene based sensor (1) has been developed by simple one step reaction and characterized by using common spectroscopic techniques. When various nitroaromatic compounds were incorporated to CH 3 CN:H 2 O (1:2, v/v) solution of 1 , the fluorescent probe turned non-fluorescent in presence of picric acid, upon irradiation at 310 nm. This was accompanied by negligible changes with other molecules along with fluorescent color change from bluish-green to colorless in case of picric acid. Also, the fluorimetric sensing of picric acid was done using smartphone and invisible ink applications. The sensor has been found efficient for the recognition of picric acid in aqueous medium.

Sensing and formation of a stable gel in the presence of picric acid by a low-molecular-weight-gelator

In this work, a set of amide-based compounds, L1-L3, have been studied. These compounds are decorated with various H-bonding functional groups while the presence of aromatic rings not only promote π‒π stacking but also made these molecules electron-rich. All three compounds were utilized for the sensing of electron-deficient nitro-explosives. These compounds were found to be highly selective for the nanomolar sensing of picric acid (PA). Out of three compounds, L3 acted as a low-molecular-weight-gelator and formed a more stable and stronger gel in the presence of PA. The resultant PA@L3−gel was studied by the SEM, powder XRD and rheological techniques while further supported by the molecular docking studies. These results illustrate that doping of L3 with PA not only enhances several noteworthy interaction avenues but also the stability of the resultant PA@L3−gel when compared to L3−gel.

Photoactivatable carbon dots as a label-free fluorescent probe for picric acid detection and light-induced bacterial inactivation.

The zero-dimensional carbon nanostructure known as carbon dots showed attractive attributes such as multicolour emission, very high quantum yield, up-conversion, very good aqueous solubility, eco-friendliness, and excellent biocompatibility. These outstanding features of the carbon dots have raised significant interest among the research community worldwide. In the current work, water-soluble nitrogen, silver, and gold co-doped bimetallic carbon dots (BCDs) were prepared using the one-pot hydrothermal method with citric acid as a sole carbon source. As prepared BCDs showed size in the range of 4-8nm and excitation-independent emission behaviour with maximum emission observed at 427nm. Additionally, these BCDs showed a very high quantum yield value of 50% and fluorescence lifetime value of 10.1ns respectively. Interestingly, as prepared BCDs selectively sense picric acid (PA) by exhibiting "selective fluorescence turn-off" behaviour in the presence of PA with a limit of detection value (LOD) of 46nM. Further, as prepared BCDs were explored for photodynamic therapy to inactivate bacterial growth in the presence of light (400-700nm) by generating singlet oxygen. Thus as prepared BCDs offer lots of potentials to use a nanoprobe to detect picric acid in an aqueous medium and to design next-generation antibacterial materials.

Unique carbazole – N,N-dimethylanline linked chalcone a colorimetric and fluorescent probe for picric acid explosive and its test strip analysis

A unique carbazole-N,N-dimethylbenzamine chalcone probe was designed for a selective, sensitive fluorescent detection of threatening explosive Picric acid. The fluorescence of the novel ligand (E)-3-(4-(dimethylamino)phenyl)-1-(9-ethyl-9H-carbazol-6-yl)prop-2-en-1-one (CCNDA) quenches at 541 nm selectively with picric acid in pool of different nitroaromatic compounds (NACs). The sensor emits a green fluorescence which gradually quenches on addition of increasing concentration of picric acid to a pale yellow solution. The fluorescence quenching is attributed to the involvement of Intramolecular Charge Transfer through electrostatic and H-bonding interaction with picric acid. A lowest recognition limit of about 7.84 × 10−8 M was achieved using our sensor CCNDA. The three dimensional emission spectral behavior of the ligand CCNDA in presence of picric acid was also studied. Test strip experiment was done to find the practical applicability of the sensor.

Visual sensing of picric acid in 100% aqueous media based on supramolecular polythiophene assemblies with colorimetric and fluorescent dual response

A colorimetric and fluorometric dual probe based on a water-soluble polythiophene derivative (PMTPBA) was designed and synthesized. It can be applied to determination of picric acid (PA) in 100% aqueous solution. The approach relies on the formation of supramolecular polythiophene assemblies in the presence of PA through electrostatic, charge transfer and π-π stacking interactions. This probe could be utilized for the rapid and visual detection of PA both in aqueous solution and solid support with high specificity and sensitivity. The detection limit of this sensor is as low as 5.0 × 10-8 mol/L.

A simple and ubiquitous device for picric acid detection in latent fingerprints using carbon dots.

This work addresses the synthetic optimization of carbon dots (CDs) and their application in sensing picric acid from latent fingerprints by exploiting a smartphone-based RGB tool. The optimization of the synthesis of CDs is investigated towards achieving shorter reaction time, better product yield and fluorescence quantum efficiency. Precursors such as citric acid and thiourea were chosen for the synthesis of CDs. Among the various synthetic methodologies, it is found that the pyrolysis method offers ∼50% product yield within 15 min. The morphology and optical properties of the prepared CDs are characterized using the typical microscopic and spectroscopic techniques, respectively. The synthesized CDs exhibit quasi-spherical shape with an average particle size of 1.7 nm. The excitation dependent emissive properties of CDs are investigated by time resolved fluorescence spectroscopy. Furthermore, the excellent fluorescence properties (φ = 11%) of CDs are explored as a fluorescent fingerprint powder for the identification of latent fingerprints on various substrates. In addition, the presence of picric acid in latent fingerprints was detected. Furthermore, this study is extended to perform real time detection of fingerprints and harmful contaminants in fingerprints by utilizing a smartphone-based RGB color analysis tool. Based on these investigations, the prepared CDs could be a prospective fluorescent material in the field of forensics.

Sensing of Zn(II) and nitroaromatics using salicyclaldehyde conjugated lysozyme-stabilized fluorescent gold nanoclusters

This manuscript presents new applications of the red-emitting lysozyme-stabilized gold nanoclusters (Lyso-AuNCs) in the field of fluorescent sensing. With the addition of salicylaldehyde (SA) to the solution of Lyso-AuNCs, the red-emission turned immediately to yellow, and the emission band at 650 nm was blue-shifted and enhanced significantly at 498 nm due to the formation of imine linkage between the –CHO group of SA and the –NH2 groups of the lysozyme coated on the surface of AuNCs. The nano-assembly SA conjugated Lyso-AuNCs (SA_Lyso-AuNCs) was applied as a nanoprobe for the fluorescent detection of metal ions and nitroaromatics. With the addition of Zn2+, the probe SA_Lyso-AuNCs showed selective turn-on fluorescence enhancement at 452 nm due to the complexation-induced aggregation of the nanoclusters, and the titration experiment inferred that the Zn2+ ions can be detected down to 1.37 × 10−7 M. In contrast, when the nitroaromatics were added to the probe SA_Lyso-AuNCs, selective fluorescence quenching of the probe was observed at 650 nm and 498 nm in the presence of picric acid (PA) and para-nitrophenol (p-NP). The limit of detection of nitroaromatics PA and p-NP can be detected down to 2.90 × 10−7 M and 3.59 × 10−7 M, respectively. Finally, the practical utility of the probe SA_Lyso-AuNCs was validated by quantifying PA and p-NP in the real water samples.

A novel fluorescent triazole trindane-coumarin receptor for the selective detection of nitroaromatics

A new fluorescent triazole trindane-coumarin based chemosensor (L1) was designed, synthesized by click chemistry and applied for the detection of various nitroaromatic compounds, such as 1-chloro-4-nitrobenzene, 4-nitrotoluene, 3-nitrotoluene, m-dinitrobenzene, nitrobenzene, 2-nitrotoluene and 1-chloro-2-nitrobenzene, picric acid and p-nitrophenol. Among the tested nitroaromatics, L1 shows selective turn-off fluorescence in the presence of picric acid and p-nitrophenol due to the energy transfer mechanism in aqueous DMSO medium. Without any noticeable interference from the other tested nitroaromatics, sensor L1 can be applied to detect picric acid and p-nitrophenol down to micromolar range. Further, the practical utility of L1 was validated by monitoring the concentrations of picric acid and p-nitrophenol in the real environmental water samples.

A Fluorescent Chemosensor with a Hybridized Local and Charge Transfer Nature and Aggregation‐Induced Emission Effect for the Detection of Picric Acid

AbstractA novel fluorescent molecule TPA‐CO, which exhibited a hybridized local and charge transfer (HLCT) nature and aggregation‐induced emission (AIE) effect, was developed and utilized as a chemosensor for the detection of picric acid (PA) in both organic solution and water. It was found that TPA‐CO exhibited apparent fluorescent quenching along with the color change to yellow upon the addition of PA. Notably, more sensitive detection was achieved in the H2O: THF (9:1) medium, with the LOD almost two third lower than that in pure THF. Such more sensitive response in aqueous solution was accomplished by the synergy of HLCT and AIE effects in TPA‐CO nanoparticles, which facilitated both highly efficient fluorescence in the absence of PA and rapid quenching rate in the presence of PA, respectively. Therefore, it is proposed an effective design strategy by integrating HLCT and AIE effects for developing PA chemosensors.

Gel Formed by Self-Assembly of a Urea-Modified Monopyrrolotetrathiafulvalene Derivative Displays Multi-Stimuli Responsiveness and Absorption of Rhodamine B.

A new monopyrrolotetrathiafulvalene-based derivative containing a urea group was designed, synthesized and thoroughly characterized. It proved to be a non-gelator in a single solvent even when heated or sonicated. However, it could self-assemble in a CHCl3 (CH2 Cl2 )/n-hexane mixture to form a thermo-responsive supramolecular organogel. SEM, FT-IR spectroscopy, UV/Vis absorption spectroscopy, and SAXS revealed that in the organogel system, the gelators self-assembled into supramolecular networks with a J-type aggregation mode under the joint effect of π-π stacking, intermolecular hydrogen-bonding, and van der Waals forces. Interestingly, the gel phase was shown to undergo reversible gel-sol transformation induced by Fe3+ -Vitamin C (Vc), trifluoroacetic acid-triethylamine (TFA-TEA) and picric acid (PA)-NaOH. In particular, in the presence of picric acid, the experimental results proposed that charge transfer occurred from the electron-donor gelator to the electron-acceptor picric acid due to the possibility of complex formation. Furthermore, the formed organogel could behave as the matrix for encapsulating cationic fluorescent dye from wastewater, and the adsorption efficiency was directly proportional to the concentration of the gelator.

Imine polymers containing chiral nanohoops in the backbone obtained through [2 + 2] cyclocondensation

ABSTRACTA simple method for synthesis of polymers containing shape persistent imine macrocycles as nanohoops in the main chain is studied. It is based on the cyclocondensation reaction carried out in solution and room temperature of triphenylamine‐based tetraaldehyde compounds with (R,R)‐trans‐1,2‐diaminocyclohexane. The pristine polymer P1 bearing long alkyl groups is soluble during the synthesis but becomes insoluble after precipitation due to the strong and multiple CH/π and π‐π stacking intermolecular interactions from arene–arene species and entanglement and interpenetrating of flexible alkyl groups inside of rigid macrocycle hollow. Polymer without any solubilizing groups (P2) separates during the polymerization as an insoluble material. Both polymers are amorphous and have good thermal and environmental stability. They have a low surface area because discrete nanovoids introduced by macrocycles are disconnected in the amorphous polymers and non‐accessible for gas adsorption. Polymers have inherent luminescent properties due to triphenylamine groups and chirality derived from (R,R)‐conformation of the cyclohexane skeleton. In presence of picric acid (PA), the polymer fluorescence in solid state or suspension is strongly quenched, thus the polymers can work as efficient fluorescent probes toward nitrophenolic compounds. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2018, 56, 2565–2573

Preparation and electrochemical properties of cobalt-phthalocyanine-decorated Fe3O4 nanoparticles

Phthalocyanines (Pcs) have been known for excellent electron transfer properties owing to their extended [Formula: see text]-conjugated structures. In addition, functionalized iron oxide nanoparticles (Fe[Formula: see text]O[Formula: see text] NPs) have attracted considerable interest owing to their unique spectral and electronic properties. Hence, it can be reasonably expected that Fe[Formula: see text]O[Formula: see text] NPs decorated with Pc molecules could provide a useful electrocatalytic system. Herein, we present the preparation and electrochemical properties of cobalt-phthalocyanine (CoPc)-decorated Fe[Formula: see text]O[Formula: see text] NPs (CoPc@Fe[Formula: see text]O[Formula: see text]. The Fe[Formula: see text]O[Formula: see text] NPs were first coated with a silica layer to produce SiO[Formula: see text]@Fe[Formula: see text]O[Formula: see text]. Subsequently, CoPc with a siloxane end group (CoPc-TEOS) was anchored to the outer surface of the SiO[Formula: see text]@Fe[Formula: see text]O[Formula: see text]. The CoPc@Fe[Formula: see text]O[Formula: see text] thus prepared was fully analyzed using various characterization methods. Distinctive electrochemical responses of CoPc and CoPc@Fe[Formula: see text]O[Formula: see text] in the presence of picric acid were observed, demonstrating the potential application of the current approach to electrochemical catalysis.

Aggregation induced emission enhancement behavior of conformationally rigid pyreneamide-based probe for ultra-trace detection of picric acid (PA)

In this study, we designed and prepared pyrene-based dipodal probes with a range of molecular flexibility for picric acid (PA) detection. These probes commonly contain a central rigid core, but probe 1 contains relatively short linkers/spacers compared to probes 2 and 3. The dipodal probes produced dominant pyrene excimer fluorescence in an aqueous solution, and aggregation-induced emission enhancement (AIEE) was observed. The fluorescence emission of probe 1 was significantly quenched only by the presence of PA, while probes 2 and 3 were responsive to 4-nitrophenol or 2,4-dinitrophenol as well as PA. Of the three dipodal probes, the highest binding strength was observed for probe 1 with PA, which gave an association constant of Ka = 3.96 × 107 M−1.1H NMR measurements and DFT calculations indicate that, upon addition of PA, these dipodal probes formed individual probe-PA complexes via π–π interactions between the pyrene ring and PA in an aqueous solution. This complex formation enabled energy transfer from electron-rich pyrene to electron-poor PA upon excitation, leading to fluorescence quenching. Probe 1 provided ultra-trace detection of PA in water, with observed and calculated limit of detections (LOD) of 1 nM and 0.13 pM, respectively, one of the lowest values reported. Effective fluorescence quenching was also obtained using probe 1-coated filter paper or TLC plate with PA solution/vapor, suggesting the significant potential of this sensing system in real-time applications. These studies were supported by FE-SEM, TEM, and UV-visible, fluorescence, NMR and DFT calculations.

Rhodamine appended hexaphenylbenzene derivative: through bond energy transfer for sensing of picric acid

A rhodamine appended hexaphenylbenzene based derivative 5 has been designed and synthesized, which displays through bond energy transfer in the presence of picric acid in MeOH and serves as a "turn on" sensor for picric acid.

Efficient Fluorescence Quenching of tert-butyl substituted Phthalocyanines with Picric Acid

Two tert-butyl substituted phthalocyanines(Pcs), in metal-free and metallated forms, were synthesized and the fluorescence responses toward various nitro derivatives, including picric acid(PA), 2,4-dinitrotoluene(DNT), 1,4-dinitrobenzene(DNB), 4-nitrotoluene(NT), nitrobenzene(NB), 1,4-benzoquinone(BQ), and nitromethane(NM) were investigated. Among the various nitro derivatives, current Pc derivatives exhibited efficient and exclusive fluorescence quenching in the presence of picric acid, which was readily observed by a naked eye. Quenching efficiency was estimated by the Stern-Volmer relationship, in which quenching constant, KSV, was calculated to be in the range of 10 4 M -1 . It was also found out that the aggregational behaviors of these Pcs are heavily dependent on the nature of solvent systems, subsequently affecting the quenching efficiency.