Chemosensors For Anions Research Articles

A terbium(III)-complex-based on-off fluorescent chemosensor for phosphate anions in aqueous solution and its application in molecular logic gates.

A new Tb(III) complex based on a tripodal carboxylate ligand has been synthesized for the selective fluorescent recognition of phosphate anions, including inorganic phosphates and nucleoside phosphates (e.g., ATP), in Tris buffer solution. The resulting L · Tb complex shows the characteristic emission bands centered at about 495 and 550 nm from the Tb(III)-centered (5)D4 excited state to (7)FJ transitions with J = 6 and 5, where the chelating ligand acts only as an "antenna". Upon the addition of phosphate anions to the aqueous solution of Tb(III) complex, significant "on-off" fluorescence changes were observed, which were attributed to the inhibition of the "antenna" effect between the ligand and Tb(III) after the incorporation of phosphate anions. Furthermore, this unique Tb(III) complex has been successfully utilized to detect phosphate anions with filter papers and hydrogels. Notably, the Tb(III) complex also can be used for the construction of molecular logic gates with TRANSFER and INHIBIT logic functions by using the above fluorescence changes.

A new highly selective fluorescent turn-on chemosensor for cyanide anion

A new simple molecule, 2-((2-phenyl-2H-1,2,3-triazol-4-yl)methylene)malononitrile (M1), was synthesized successfully by the Knoevenagel condensation reaction between 2-phenyl-1,2,3-triazole-4-carboxaldehyde and malononitrile. The receptor M1 is highly sensitive and selective to cyanide anion due to the nucleophilic addition of cyanide anion with M1. Distinct changes on UV–vis and fluorescence spectra can be detected with the addition of cyanide anion to the DMSO solution of M1. Optical properties of M1 were scarcely affected by the addition of other common background anions (F−,Cl−,Br−,I−,SCN−,OH−,CO42−,H2PO4−,SO42−,HSO4−,AcO−,andNO3−) under the same condition. The detection limit of CN− reaches ~1.43μM by M1 and the presence of background anions brought very slight interference for the detection of CN−.

UV-visible and (1)H-(15)N NMR spectroscopic studies of colorimetric thiosemicarbazide anion sensors.

Four model thiosemicarbazide anion chemosensors containing three N-H bonds, substituted with phenyl and/or 4-nitrophenyl units, were synthesised and studied for their anion binding abilities with hydroxide, fluoride, acetate, dihydrogen phosphate and chloride. The anion binding properties were studied in DMSO and 9 : 1 DMSO-H2O by UV-visible absorption and (1)H/(13)C/(15)N NMR spectroscopic techniques and corroborated with DFT studies. Significant changes were observed in the UV-visible absorption spectra with all anions, except for chloride, accompanied by dramatic colour changes visible to the naked eye. These changes were determined to be due to the deprotonation of the central N-H proton and not due to hydrogen bonding based on (1)H/(15)N NMR titration studies with acetate in DMSO-d6-0.5% water. Direct evidence for deprotonation was confirmed by the disappearance of the central thiourea proton and the formation of acetic acid. DFT and charge distribution calculations suggest that for all four compounds the central N-H proton is the most acidic. Hence, the anion chemosensors operate by a deprotonation mechanism of the central N-H proton rather than by hydrogen bonding as is often reported.

A highly selective fluorescent chemosensor for cyanide anions based on a chalcone derivative in the presence of iron(iii) ions, and its capacity for living cell imaging in mixed aqueous systems

A chalcone based chemosensor was reported, and its in situ formed complex can serve as a cyanide anion probe.

A fluorescent receptor for halide recognition: clues for the design of anion chemosensors.

The chemosensing properties of the polyaza-macrocycle 1-(6,7)-acridine-3,6,9,12-tetraaza-tridecaphane have been investigated by means of emission fluorescence spectroscopy, considering halide ions as substrates. As in the case of the free ligand, the fluorescence emission of the complexes is due to the acridinium species which are formed after photoinduced proton transfer reaction. The complexation constants have been obtained for the bi- and tri-protonated ligands in deoxygenated aqueous solutions. Two different emission behaviours have been observed varying the anion. Fluoride and chloride give rise to fluorescence enhancement whereas bromide and iodide strongly quench the emission. The macrocycle shows an unusual higher selectivity towards the chloride anion rather than fluoride. The fluorescence emission has been modelled considering a modified Stern-Volmer equation, taking into account the quenching effects of the largest anions, which can be considered negligible for fluoride and chloride anions. Ab initio calculations allow us to interpret the fluorescence emission of the complexes in terms of activation energy related to the proton transfer reaction responsible for the emission process.

A highly selective and turn-on fluorescence sensor for detection of cyanide.

2-Hydroxy-1-naphthaldehyde (receptor 1) serves as a selective chemosensor for cyanide anion (CN(-)). In the presence of CN(-), an enhanced fluorescent intensity and red shift were observed. The observed complexation between receptor 1 and CN(-) may cause from a formation of phenoxide anion by nucleophilic addition of the CN(-) to carbonyl group.

Synthesis and recognition properties of colorimetric anion chemosensor bearing 2,4-dinitrophenylhydrazone and indene-1,3-dione moieties

A new receptor named, 2-(2-(2,4-dinitrophenyl)hydrazono)2 H -indene-1,3-dione, used as a colorimetric sensor based on 2,4-dinitrophenylhydrazone derivative of ninhydrin was synthesized by simple step with good yields and characterized by IR and 1 H, 13 C NMR and MS spectroscopic techniques. The anion recognition properties were studied by UV-Vis spectroscopic technique. The results showed that the receptor had a higher affinity to F - , CN - , H 2 PO 4 - , CH 3 COO - and OH - , but showed no evident binding with Cl - , Br - and I - . Binding of the reseptor to anions such as CN - , AcO - , F - , H 2 PO 4 - and OH - exhibited an obvious color change from greenish yellow to purplish blue, which was possible to observe by the naked eye.

Fluorescent chemosensors for anions and contact ion pairs with a cavity-based selectivity.

The association of a concave macrocyclic compound to one or multiple fluorophores is an appealing strategy for the design of chemosensors. Indeed, as with biological systems, a cavity-based selectivity can be expected with such fluorescent receptors. Examples of calix[6]arene-based systems using this strategy are rare in the literature, and to our knowledge, no examples of fluorescent receptors that can bind organic contact ion pairs have been reported. This report describes the straightforward synthesis of fluorescent calix[6]arene-based receptors 4a and 4b bearing three pyrenyl subunits and the study of their binding properties toward anions and ammonium salts using different spectroscopies. It was found that receptor 4a exhibits a remarkable selectivity for the sulfate anion in DMSO, enabling its selective sensing by fluorescence spectroscopy. In CDCl3, the receptor is able to bind ammonium ions efficiently only in association with the sulfate anion. Interestingly, this cooperative binding of ammonium sulfate salts was also evidenced in a protic environment. Finally, a cavity-based selectivity in terms of size and shape of the guest was observed with both receptors 4a and 4b, opening interesting perspectives on the elaboration of fluorescent cavity-based systems for the selective sensing of biologically relevant ammonium salts such as neurotransmitters.

A single chemosensor for multiple target anions: The simultaneous detection of CN− and OAc− in aqueous media

A multifunctional fluorescent and colorimetric chemosensor 1 (Z)-1-((benzo[d]thiazol-2-ylimino)methyl)naphthalen-2-ol for the detection of both CN− and OAc− in aqueous solution has been developed. This sensor could simultaneously detect two anions through fluorogenic (CN−) and chromogenic (CN− and OAc−) methods. The sensor could function as a “turn-on” fluorescence receptor only to CN−. In addition, the sensor displayed an obvious color change from yellow to colorless upon selective binding with CN− through a nucleophilic addition mechanism. Moreover, the sensor also showed color change from yellow to orange upon deprotonation with OAc−. This is the first report that sensor 1 is able to detect simultaneously both CN− and OAc− by two different detection modes.

Octatosylaminophthalocyanine: A reusable chromogenic anion chemosensor

Detailed herein is the use of 2,3,9,10,16,17,23,24-octatosylaminophthalocyanine as a chromogenic chemosensor for anions. The host:guest complexes formed during the sensing event can be regenerated by acid treatment without loss of the sensing ability. This allows the phthalocyanine chemosensor to be reused. This system also responds in a colorimetric manner when exposed to the neutral solvent molecules, dimethyl sulfoxide and methanol. A single-crystal X-ray structure of the Pc 1:2 MeOH complex was obtained. It illustrates the main interactions between the host:guest species in the solid state. Fits of the binding curves are consistent with this stoichiometry predominating in the solution state.

Theoretical study of chemosensors for fluoride anion and optical properties of the derivatives of organosilicon 1,8-naphthalimide

The interactions between chemosensors, organosilicon 1,8-naphthalimide derivatives, and different (F−, Cl−, Br−, and AcO−) anions have been theoretically investigated using Density functional theory (DFT) approaches. Theoretical investigations have been performed to explore the optical and electronic properties of the colorimetric fluoride anion chemosensors. It turned out that the unique selectivity of chemosensors for F− is ascribed to their ability of the cleavage of OSi bond of the host sensors. The frontier molecular orbitals (FMOs) analyses have turned out that the vertical electronic transitions of chemosensors and their anions are characterized as intramolecular charge transfer (ICT). The study of substituent effects suggests that the substituted derivatives with nitrobenzene (1), anisole (2), benzo[c][1,2,5]thiadiazole (3), benzo[c]thiophene (4), and 2-phenylthiophene (5) fragments are expected to be promising candidates for colorimetric fluoride anion chemosensors.

Nitro substituted chalcone derivatives as quick-response chemosensors for cyanide anions

Three nitro substituted chalcone derivatives with diethylamino (1), carbazolyl (2) and pyrene (3) as terminal group have been synthesized via typical condensation reaction of 2-hydroxy-4-nitro-acetophenone with related aryl-aldehydes in good yields. Their crystal structure and recognition properties for cyanide anions have been investigated. The results indicated that all the compounds exhibit quickly obvious UV–vis absorption and fluorescence response to cyanide anions in aqueous solution. Especially, compound 1 with diethylamino as terminal group exhibits obvious fluorescence change from orange to green with fluorescence turn-on response upon the addition cyanide anions.

Rational design of organoboron derivatives as chemosensors for fluoride and cyanide anions and charge transport and luminescent materials for organic light-emitting diodes

The interactions between chemosensors, donor-π-acceptor (D-π-A) dipolar organoboron derivatives, and different (CN⁻, F⁻, Cl⁻, and Br⁻) anions have been theoretically investigated using DFT approaches. Theoretical investigations have been performed to explore the optical, electronic, charge transport, and stability properties of organoboron derivatives as charge transport and luminescent materials for organic light emitting devices (OLEDs). It turned out that the unique selectivity of organoboron derivatives for F⁻/CN⁻ is ascribed to the formation of chemosensors complexes. The frontier molecular orbitals (FMOs) and local density of states analysis have turned out that the vertical electronic transitions of absorption and emission for chemosensors and their F⁻/CN⁻ complexes are characterized as intramolecular charge transfer (ICT). The formation of complexes has effect on the distribution of FMOs and the flowing direction of electronic density for vertical transition. The study of substituent effects suggests that the derivatives with thiophene (2), furan (3), and 1H-pyrrole (4) fragments, are expected to be promising candidates for ratiometric fluorescent fluoride and cyanide chemosensors as well as chromogenic chemosensors, whereas derivatives with pyridine (5) and pyrimidine (6) fragments can serve as chromogenic chemosensors only. Furthermore, all the derivatives are promising luminescent and hole transport materials and 2, 3, 5, and 6 can serve as electron transport materials for OLEDs.

A ferrocene imidazolium-based macrocycle as an electrochemical chemosensor for halide anions

C4-H and C5-H protons of the imidazolium heterocycle have been exploited as a binding site for anion recognition in the design of two new redox-active imidazoliophane syn and anti isomers. The cooperative action of the two imidazolium motifs of the syn isomer is crucial for halide anion recognition. The integration of a ferrocene signalling unit at the C2 position of the imidazolium motif also facilitates the electrochemical sensing of anions by the syn isomer receptor.

Synthesis and evaluation of simple naked-eye colorimetric chemosensors for anions based on azo dye-thiosemicarbazones

A series of novel, highly selective azo dye-thiosemicarbazones based anion sensors (3e–f) have been synthesized from the condensation reaction between thiosemicarbazide and six different azo salicylaldehydes. The structure of the sensors was confirmed by spectroscopic methods. The selectivity and sensitivity in the recognition for acetate anion over other anions such as fluoride, chloride, iodide and dihydrogenphosphate anions were determined by naked-eyes and UV–vis spectra. The color of the solution containing sensor had an obvious change from light yellow to orange only after the addition of acetate anion in aqueous solution (water/dimethylsulfoxide, 7:3, v/v) while other anions did not cause obvious color change. The anion recognition property of the receptor via proton-transfer is monitored by UV–vis titration and 1H NMR spectroscopy. Under condition in aqueous solution of sensor 3e (water/dimethylsulfoxide, 7:3, v/v), linearity range for the quantification of acetate anion was 1–22μM and limit of detection (LOD) of acetate anion was 0.71μM.

Two fluorescence turn-on chemosensors for cyanide anions based on pyridine cation and the boronic acid moiety

Two chemosensors for cyanide anions based on N-methylpyridinium cation and the boronic acid moiety structures have been synthesized. Spectral shifts and intensity changes in acetonitrile allow for both absorption and fluorescence emission wavelength ratiometric and colorimetric sensing. The compounds are found to be able to recognize cyanide anion with obvious color change and fluorescence turn-on response due to the sensors' ability to bind the cyanide anion through boronic acid functional group.

Theoretical study on a chemosensor for fluoride anion-based on a urea derivative

The sensing mechanism of the N-Phenyl-N′-(3-quinolinyl)urea (PQU) chemosensor for fluoride anion has been investigated by density functional theory/time-dependent density function theory. The double intermolecular hydrogen bonds are formed between the three anions (X−F−, AcO−, Cl−) and the urea fragment of PQU. In the S0 states, the HbX− hydrogen bonds are slightly stronger than the HaX− hydrogen bonds and the fluoride-induced deprotonation occurs at the NHb position rather than at the NHa position. Consequently, the absorption peaks, including an intramolecular charge transfer transition and a ππ* transition, are significantly red-shifted. Thermodynamic calculations confirm that the deprotonation in the ground state is favorable in energy only when excess fluoride anion exists. Along with the S0 → S1 transition, the HaX− hydrogen bonds strengthen and the HbX− hydrogen bonds weaken. However, the emission spectra of [PQU-Hb]−, instead of [PQU-Ha]−, are observed upon addition of fluoride anion. © 2013 Wiley Periodicals, Inc.

Three hydroxy aurone compounds as chemosensors for cyanide anions

Three new 4-hydroxy aurone compounds 1–3 with dimethylamino (1), bromine (2) and cyano (3) as terminal group have been synthesized. Their photophysical properties as well as recognition properties for cyanide anions in acetonitrile and aqueous solution have also been examined. These compounds exhibit remarkable response to cyanide anions with obvious color and fluorescence change owing to hydrogen bonding reaction between cyanide anions and the O–H moiety of the sensors, which allows naked eye detection of cyanide anions.

Highly selective recognition of fluoride anion through direct deprotonation of intramolecularly hydrogen-bonded phenolic hydroxyl groups

Abstract A novel chemosensor for fluoride anion has been developed. This sensor, constructed by merging six phenolyl units into a hexaazatriphenylene (HAT) core, could recognize F− visually and spectroscopically with high selectivity over other anions, which was demonstrated by naked-eye experiment and UV–vis absorption spectroscopy study.

Rational design, green synthesis of reaction-based dual-channel chemosensors for cyanide anion

Abstract Chemosensors CF1 – CF3 were designed and synthesized via a simple green chemistry procedure. CF3 could instantly detect cyanide anion in aqueous solution by dual-channel model. The detection limit of CF3 for CN- is 10 nM. Test strips based on CF3 could act as a convenient and efficient CN − test kit.