Simple Chemosensor Research Articles

A selective chemosensor via click chemistry for Cu2+ and Hg2+ ions in organic media

A simple chemosensor, 4-amino antipyrine linked bis-1,2,3-triazole, was synthesized via the “click” approach using the CuAAC method and characterized by FTIR, NMR, and ESI-MS spectroscopy, for the selective detection of Hg(ii) and Cu(ii) ions.

Direct fluorescence labelling of NO inside plant cells.

Nitric oxide (NO) plays a key role in regulating plant growth, enhances nutrient uptake, and activates disease and stress tolerance mechanisms in most plants. NO is marked as a potential tool for improving the yield and quality of horticultural crop species. Research on NO in plant species can provide an abundance of valuable information regarding this. Hence, we have prepared a simple chemosensor (NPO) for the detection of endogenous NO in chickpea saplings. NPO selectively interacts with NO as determined through a chemodosimetric method to clearly show both the colorimetric and fluorometric changes. After the interaction with NO, the colorless NPO turns yellow as observed by the naked eye and shows bright cyan-blue fluorescence under a UV lamp. The 1 : 1 stoichiometric ratio between NPO and NO is determined from Job's plot resulting in a stable diazeniumdiolate product. The interaction mechanism is well established by absorption, fluorescence titration, NMR titration, HRMS, and DFT calculations. This method has successfully been employed in the plant's root and stem systems to label NO. Confocal microscopy images might help us to understand the endogenous NO generation and the mechanism that happens inside plant tissues.

Reliable fluorescence technique to detect the antibiotic colistin, a possible environmental threat due to its overuse

Colistin, considered a drug of last resort as it is effective towards multidrug-resistant Gram-negative bacterial infections. Oral administration of colistin in the poultry industry is a common practice, not only to prevent and reduce bacterial infections, but also as a rapid-growth promoter. Long-term exposure to any antibiotic will eventually lead to the development of bacterial resistance towards all antibiotics through various mechanisms in the physiological system and environment. Chicken is the most consumed source of animal protein for humans throughout the world. In addition, the manure of poultry, containing traces of the used antibiotics, is being used in farming. Exposure to excess amounts of colistin causes a great concern not only to the humans but to the environment as a whole. In the present contribution, colistin has been detected in chicken hepatocyte cells through in vivo confocal microscopy. In addition, the amount of colistin in the chicken excrements has been estimated. A simple chemosensor NAF, a dye-based on napthaldehyde furfural, was developed for the detection of colistin, supplemented with experimental evidence and theoretical calculations.

A dual-channel chemosensor based on 2-hydroxy-5-methyl-1,3-benzenedialdehyde for fluorescence detection and colorimetric recognition of glutamic acid

A colorimetric and fluorescent dual-channel glutamic acid (Glu) chemosensor 4-methyl-6-aldehyde-6′-methoxy-2,2′-[ethylenediyldioxybis(nitrilomethylidyne)]diphenol (AMS) bearing an aldehyde group has been designed and synthesized. This structurally simple chemosensor displays rapid response and high selectivity for Glu over other common amino acids in DMF/H2O (9: 1, v/v, buffered by 0.2 M Tris-phosphate buffer at pH = 7.0) solution. The chemosensor interacted with Glu to form intermolecular hydrogen bonds with significantly quenched fluorescence, switching from bright green fluorescence to no fluorescence. Moreover, AMS can also successfully detect glutamic acid by absorption spectroscopy, which exhibited an UV–vis spectrum change, while its color changed from pale yellow to colorless under natural light. The experimental results of the competitive amino acids revealed that chemosensor is highly selective for recognizing Glu without the interference of other amino acids. Job's plot indicates that the binding stoichiometry between the chemosensor AMS and the targeted amino acid Glu is 1:1. Hence, our experimental findings very strongly suggest that AMS can be used as chemosensor for detecting Glu in future.

A Fluorene based Fluorogenic ''Turn-off'' Chemosensor for the Recognition of Cu2+ and Fe2+: Computational Modeling and Living-cell Application

Background: The traditional methods for the detection and quantification of Cu2+ and Fe3+ heavy metal ions are usually troublesome in terms of high-cost, non-portable, time-consuming, specialized personnel and complicated tools, so their applications in practical analyses is limited. Therefore, the development of cheap, fast and simple-use techniques/instruments with high sensitivity/selectivity for the detection of heavy metal ions is highly demanded and studied. Methods: In this study, a fluorene-based fluorescent ''turn-off'' sensor, methyl 2-(2-((((9H-fluoren-9- yl)methoxy)carbonyl)amino)-3- phenylpropanamido) acetate (probe FLPG) was synthesized via onepot reaction and characterized by 1H-NMR, 13C-APT-NMR, HETCOR, ATR-FTIR and elemental analysis in detailed. All emission spectral studies of the probe FLPG have been performed in CH3CN/HEPES (9/1, v/v, pH=7.4) media at rt. The quantum (Φ) yield of probe FLPG decreased considerably in the presence of Cu2+ and Fe3+. The theoretical computation of probe FLPG and its complexes were also performed using density functional theory (DFT). Furthermore, bio-imaging experiments of the probe FLPG was successfully carried out for Cu2+ and Fe3+ monitoring in living-cells. Results: The probe FLPG could sense Cu2+ and Fe3+ with high selectivity and sensitivity, and quantitative correlations (R2>0.9000) between the Cu2+/Fe3+ concentrations (0.0−10.0 equiv). The limits of detection for Cu2+ and Fe3+ were found as 25.07 nM and 37.80 nM, respectively. The fluorescence quenching in the sensor is managed by ligand-to-metal charge transfer (LMCT) mechanism. Job’s plot was used to determine the binding stoichiometry (1:2) of the probe FLPG towards Cu2+ and Fe3+. The binding constants with strongly interacting Cu2+ and Fe3+ were determined as 4.56×108 M-2 and 2.02×1010 M-2, respectively, via the fluorescence titration experiments. The outcomes of the computational study supported the fluorescence data. Moreover, the practical application of the probe FLPG was successfully performed for living cells. Conclusion: This simple chemosensor system offers a highly selective and sensitive sensing platform for the routine detection of Cu2+ and Fe3+, and it keeps away from the usage of costly and sophisticated analysis systems.

Luminescence turn-on response of naphthalene diimide based chemosensor with Formaldehyde: A novel stratagem for estimation of formaldehyde in storage fish samples

A new strategy has been developed for selective estimation of toxic Formaldehyde (FA) in storage fish samples by a simple chemosensor (BNDI) based on naphthalene diimide core in aqueous medium at neutral pH. The rapid “lightning–up” fluorescence feature of BNDI has been implied to detect and estimate aqueous FA selectively at very low concentration. The chemosensing properties of BNDI with aqueous FA have been established through a unique interaction pattern which is proven by different spectroscopic and theoretical analysis.

Optical Anion Receptors with Urea/Thiourea Subunits on a TentaGel Support.

Two simple chemosensors with urea (L1) and thiourea (L2) groups were synthesized and studied by different spectroscopic techniques. Both receptors can sense acetate (Ac–), dihydrogen phosphate (H2PO4–), and fluoride (F–) anions, accompanied by changes in UV–vis and 1H NMR spectra, and an optical response is observed as a color change of the solutions due to deprotonation and hydrogen-bonding processes. Also, L1 and L2 were supported on TentaGel resins (R1 and R2), and their fluoride-sensing properties in DMSO and water solutions were studied. Interestingly, R2 can sense fluoride ions in sample solutions of 100% water.

An AIE‐Active Tetraphenylethylene‐Based Cyclic Urea as a Selective and Efficient Optical and Colorimetric Chemosensor for Fluoride Ions

AbstractAnion sensing is a very challenging and important issue in many diverse fields, including biological, medical and environmental sciences. In this paper, we report the serendipitous synthesis of a tetraphenylethylene (TPE) bearing a cyclic urea (coded as: 1). This easy‐to‐make, simple chemosensor shows high selectivity towards fluoride (F−) ions. Importantly, this work demonstrates two important factors: firstly, the use of cyclic urea for ion sensing and secondly, the use of aggregation induced emission (AIE)‐ TPE signalling units. This selective fluoride sensing can be observed by the naked eye, UV‐vis absorption, fluorescence spectroscopy, and 1H‐NMR spectroscopy. Solutions of sensor 1 are fluorescent in DMSO with fluorescence quantum yield Φ=1.3 and upon addition of fluoride ions the emission is quenched with ΦF=0.07. Notably, other anions, such as CN−, AcO−, NO3−, H2PO4−, HSO4−, I−, OH−, ClO4−, SCN− and Cl−, do not show any quenching effect. The binding constant (K) between sensor 1 and fluoride was found to be 4.90×108 M−2 with a detection limit of 30 μM. We also studied AIE‐activity of 1 in THF/water mixture. As such the fluorescence quantum yield (ΦF) of 1 in pure THF solution shown to be 0.05 % which was enhanced 22‐fold to 1.98 and 6.65 % at fw=90 and 99 %, respectively. This is clear confirmation that compound 1 is AIE active due to decreased solubility and increased molecular self‐assembly as the water fraction is increased.

A simple chemosensor for ultrasensitive fluorescent “turn-on” detection of Fe3+ and alternant detection of CN-

ABSTRACTIt is worth noting that Fe3+ is paramagnetic in nature. Thus, in most of the cases, Fe3+ behave as fluorescent quencher which makes it difficult to develop a fluorescent ‘turn-on’ chemosensor. Therefore, it is still a big challenge to devise and synthesise a simple chemosensor that could selectively detect Fe3+ via fluorescent ‘turn-on’ response. In this paper, A simple fluorescence chemosensor T based on N,N-(3,3-dimethyl biphenyl)-bis(2-methoxyphenol) has been synthesised. T could selectively detect Fe3+ via fluorescent ‘turn-on’ response. Meanwhile, the fluorescent spectrum limit of T towards Fe3+ was 0.178 nM, the detection limit was much lowest than previously reported fluorescent chemosensor and has reached to ultrasensitive level. In addition, T could also alternately detect CN−. Intriguingly, IMPLICATION logic gate was successfully constructed. Finally, the test papers and films based on T were prepared, which could be used as a fluorescent display material for the detection of Fe3+ and CN−.

Pyrrole-quinazoline derivative as an easily accessible turn-off optical chemosensor for Cu2+ and resultant Cu2+ complex as a turn-on sensor for pyrophosphate in almost neat aqueous solution.

A simple chemosensor, 6-(1H-pyrrol-2-yl)-5,6-dihydro-benzo[4,5]imidazo[1,2-c]quinazoline (1), was synthesized via simple nucleophilic addition reaction coupled with Schiff base condensation. The probe 1 is aggregation-induced emission-active and could be used as an on-off fluorescence sensor toward Cu2+ in H2O/CH3CN (99.5%, v/v) solution. Furthermore, the resultant Cu2+ complex selectively responded to pyrophosphate (PPi) among various anions based on fluorescent on-off signal. In addition, the probe could be used for detecting Cu2+ and PPi in HeLa cells.

Visualisation of DCP, a nerve agent mimic, in Catfish brain by a simple chemosensor

A chemosensor, 3-aminophenol-based rhodamine conjugate (ARC) has been developed for visualisation of diethylchlorophosphate (DCP), mimic of a chemical warfare agent, in Catfish brain. The simple detection of DCP by “turn-on” fluorescence property of the chemosensor makes it unique for easy and rapid in vivo and in vitro detection of DCP with the detection limit of 5.6 nM.

2'-Deoxy-5-(hydroxymethyl)cytidine: estimation in human cancer cells with a simple chemosensor.

A pyrrole-based rhodamine conjugate (CS-1) has been developed and characterized for the selective detection and quantification of 2′-deoxy-5-(hydroxymethyl)cytidine (5hmC) in human cancer cells with a simple chemosensing method.

A pyrrole-containing hydrazone and its Cu2+ complex: an easily accessible optical chemosensor system for the successive detection of Zn2+/Cu2+ and pyrophosphate

A simple chemosensor, namely, ethyl 5-(isonicotinoylimino)methyl-2,4-dimethyl-pyrrole-3-carboxylate (1), was synthesized and characterized.

Quinoline containing acetyl hydrazone: An easily accessible switch-on optical chemosensor for Zn2 +

A simple chemosensor, namely, N-((quinolin-8-yl)methylene)acetohydrazide (1) was synthesized and used as an off–on fluorescence sensor, which exhibits high selectivity toward Zn2+ in aqueous media. The probe has large Stokes shift of >200nm, and its detection limit for Zn2+ is 89.3nM. The binding process was confirmed through UV–vis absorption analysis, fluorescence measurements, mass spectroscopy study, 1H NMR spectra and density functional theory calculation. The crystal structures of Zn2+, Ni2+, and Cu2+ complexes based on 1 were determined through X-ray crystallographic analysis. The fluorescent probe was then applied to monitor intracellular Zn2+ in HeLa cells.

A new unsymmetrical azine derivative based on coumarin group as dual-modal sensor for CN− and fluorescent “OFF–ON” for Zn2 +

A simple chemosensor YS based on coumarin group was designed and synthesized. Its structure was determined by single crystal X–ray diffraction analysis. In the presence of cyanide the sensor showed an immediate visible change in color from colorless to pale yellow by naked–eyes and produced a strong blue fluorescence rapidly in DMSO/H2O (3:7, v/v). The detection limit on fluorescence response of the sensor to CN− is down to 1.69×10−7M. In addition YS could show fluorescence turn–on response rapidly for Zn2+ over other metals ions such as Fe3+, Hg2+, Ag+, Ca2+, Cu2+, Co2+, Ni2+, Cd2+, Pb2+, Cr3+ and Mg2+ in aqueous solutions. Notably, this sensor served as a molecular switch, which was controlled by Zn2+ and EDTA cyclically. Test strips based on YS were fabricated, which could act as a convenient and efficient CN− and Zn2+ test kit. This chemosensor could achieve the detection of two ions, which need not depend on two different sensors.

A highly selective colorimetric and “turn-on” fluorimetric chemosensor for detecting CN− based on unsymmetrical azine derivatives in aqueous media

A novel highly selective chemosensor S1 for cyanide based on unsymmetrical azine derivative was successfully designed and synthesized, which showed both colorimetric and fluorescence turn-on responses for cyanide ions in aqueous. This structurally simple chemosensor could detect CN− anion over other anions in aqueous solution DMSO/H2O (v/v=3:2) undergo deprotonation reaction. Results showed that the chemosensor S1 exhibited 50 fold enhancement in fluorescence at 530nm and showed an obvious change in color from colorless to yellow that could be detected by naked eye under the UV-lamp after the addition of CN− in aqueous solution. Moreover, the detection limit on fluorescence response of the sensor to CN− is down to 6.17×10−8M by titration method. Test strips based on S1 were obtain, which could be used as a convenient and efficient CN− test kit to detect CN− in aqueous solution.

A highly selective colorimetric chemosensor for detection of iodide ions in aqueous solution

A simple chemosensor can be used as a colorimetric sensor for the highly selective and sensitive detection of iodide anions in aqueous solution.

A simple chemosensor for the dual-channel detection of cyanide in water with high selectivity and sensitivity

By a deprotonated mechanism, the simple chemosensorHYshowed high sensitivity and selectivity for cyanide in aqueous media.

Anthracene-Fe3+ ensemble based turn-on fluorescent probes for selective detection of fluoride

Abstract Two new and simple chemosensors, 1-(anthracen-9-ylmethyl)urea (3a) and 1-(anthracen-9-ylmethyl)thiourea (3b) bearing anthracene moiety, were synthesized from anthracen-9-ylmethanamine. Their UV–Vis absorption, fluorescence emission and potential application for the detection of ions were investigated. Of note is that their fluorescence emission excited with 370 nm could be quenched upon addition of Fe3+, whereby the highly selective recognition for Fe3+ was noticed. Furthermore, ensembles based on 3a-Fe3+ and 3b-Fe3+ complexes having the specific binding affinity for F− show rapid and selective detection of F− over other anions with a fluorescence turn-on mode.

Colorimetric and Optical Discrimination of Halides by a Simple Chemosensor.

A thiophene-based tripodal copper(II) complex has been synthesized as a new colorimetric and optical chemosensor for naked-eye discrimination of halides in acetonitrile and an acetonitrile-water mixture. The binding interactions of the new receptor with several anions were analyzed by UV-Vis titrations, electrospray ionization mass spectrometric (ESI-MS) experiments and density functional theory (DFT) calculations. The results from UV-Vis titrations indicate that the coordinative unsaturated copper(II) complex strongly binds a halide at its vacant copper(II) centre via a metal-ligand bond forming a 1:1 complex, exhibiting binding affinities in the order of fluoride > chloride > bromide > iodide. The interactions of the receptor with halides were further confirmed by ESI-MS, showing a distinct signal corresponding to a 1:1 complex for each halide, suggesting that the noncovalent interactions also exist in the gas phase. In addition, time-dependent DFT (TD-DFT) calculations were also carried out to understand the excited-state properties of the chemosensor complexes. A detailed analysis of the TD-DFT calculations shows a consistent red-shift in the first optically-allowed transition, consistent with the observed colorimetric experiments.