Anion recognition based on phenolic hydroxyl group in competitive media

Two novel artificial receptors, one containing phenolic hydroxyl group and diamide (1), the other only containing diamide (2), were designed and synthesized. The binding ability evaluated by UV–vis and fluorescence titration experiments in dry DMSO revealed that compound 1 could selectively recognize AcO^?. In particular, the binding ability can also be detected in the DMSO/H₂O solution by UV–vis. The interference experiment result showed that the binding ability was not influenced by the existence of other anions. In contrast, there were no detectable interaction between receptor 2 and anions. The further insights to the nature of interaction between receptor 1 and AcO^? were investigated by ¹H NMR titration experiments and theoretical investigation, which demonstrated receptor 1 complexed AcO^? through the synergistic hydrogen bonding interaction of OH and NH.     

Acenaphthenequinone based simple colorimetric anion sensor with only one binding site

Quinonehydrazone compound 1 was designed to be a simple chromogenic anion sensor with one anion binding site. The sensor 1 was easily obtained in 83% yield by the condensation of acenaphthenequinone with 4-nitrophenylhydrazine in ethanol solution. In DMSO, sensor 1 could high selectively and visually detect anions with strong basicity (e.g., AcO^?, F^? and H₂PO₄ ^?) from chloride, bromide, and iodide ions with weak basicity.     

Synthesis of Novel Anionic Receptors with （Thio）urea and Amide Binding Sites and the Recognition Properties for Anions

IntroductionSincemoreandmoreanionsplayanimportantroleinbiologicalandchemicalprocesses ,thedesignandsynthe sisofreceptorsforon lineandrealtimedetectionofbio logicallyimportantanions ,andforenvironmentalmonitor ingofharmfulanionpollutantshaveattractedparticularat tentioninsupramolecularchemistry .1Thebasicstrategyfortheconstructionofanion bindingreceptorsistoexploitthereceptorsthathaveelectrostatic ,2 hydrogenbonding ,3orLewisacidiccentralinteraction .4 Amongavarietyofnon covalentinteractions ,h…     

A highly selective fluorescent sensor for fluoride anion based on pyrazole derivative: Naked eye “no–yes” detection

A new pyrazole-based fluorescent sensor, 5-amino-3-(5-phenyl-1H-pyrrol-2-yl)-1H-pyrazole-4-carboxamide (compound 1), was studied for fluoride anion (F^?) detection in organic or water-containing solution. This compound displayed both changes in UV–vis absorption and fluorescence emission spectra upon addition of F^?. With increasing of F^?, blue emission intensity increases drastically and reaches saturation with 607-fold enhancement at 424 nm. The results indicate that compound 1 has highly selectivity for fluoride detection over other anions, such as Cl^?, Br^?, I^?, HSO₄^?, H₂PO₄^? and AcO^? in DMSO or aqueous DMSO solutions. ¹H NMR titration and other experiments confirm that the sensing process is mainly from the deprotonation of the pyrazole–NH in compound 1.     

Anion Recognition Using Novel and Colorimetric Tweezer Receptors:1,3-Phenylenedi(carbonylhydrazone) in Aqueous-organic Binary Solvents

本文设计合成了2种新型的间苯二甲酰腙类钳形受体。在DMSO和DMSO-H2O混合溶液中,通过紫外可见光谱分别考察了受体分子3a对F-, Cl-, Br-, I-, AcO-, HSO4-, H2PO4-和ClO4-的相互作用。结果表明,在DMSO溶液中,受体3a对F-,CH3COO-和H2PO4-有显著识别效果,溶液颜色由无色变为黄色,实现裸眼检测。在15%H2O-85%DMSO含水体系中,3a可高选择性识别CH3COO-。1H NMR滴定表明过量F-的加入使受体分子3a发生脱质子作用,探讨了主客体之间的作用机理。并直接用于水相中无机醋酸盐的直接显色检测。     

Novel Hydrazone‐Based Tripodal Sensors: Single Selective Colorimetric Chemosensor for Acetate in Aqueous Solution

A series of novel tripodal colorimetric anion sensors based on hydrazone CHN NH groups have been synthesized and their recognition behavior with anionic guests has been studied. In DMSO solutions, sensors 1 and 2 show colorimetric responses for F⁻, H₂PO⁻₄ and AcO⁻, while in DMSO/H₂O (9:1, V/V) solutions, sensor 1 shows single selectivity for AcO⁻. ¹H NMR titration confirms that the tripodal sensors could bind anions through the collaboration of three hydrazone groups and anions residing in the central cavity of the sensors.     

Synthesis of a Phenylhydrazone‐based Colorimetric Anion Sensor with Complementary IMP/INH Logic Functions

A dinitrophenyl hydrazone colorimetric anion sensor (receptor 1 ) was synthesized and its recognition properties towards various anions were investigated by naked eye observation and spectroscopic methods, namely UV‐vis and ¹H NMR titrations in DMSO. The addition of AcO^?, F^? and H₂PO₄^? to receptor 1 resulted in marked red shift of the charge‐transfer absorbance band (Δλ=91 nm, 407 nm to 498 nm) concomitant with a 'naked‐eye' detectable colour change from yellow to pink. However, both the colour and spectral changes were reversible by the addition of cations (M^II) of 3d^5‐10 as well as Cd^II, Hg^II, Mg^II and Ca^II. Subsequently, complementary IMP/INH logic functions based on colour and spectral switching (ON/OFF) were affirmed. The sensor can, thus be utilized as a colorimetric molecular switch modulated by F^?/M^II.     

一种三足型比色传感器对阴离子的颜色响应

A thiourea-based tripodal colorimetric anion sensor was synthesized. Its binding abilities with AcO^- and halide anions in DMSO were studied by UV-Vis spectra. The sensor showed different color responses to these anions. The association constants and different stoichiometries were deduced by nonlinear least-square curve fitting or linear fitting.     

Color responses of novel receptors for AcO and a test paper for AcO in pure aqueous solution

An efficient AcO⁻ sensor L which contains 1,10-phenanthroline-based and nitrophenylhydrazine-based groups, and its water-soluble Ru(II) complex were synthesized, characterized and studied in this Letter. Via UV-vis experiments and ¹H NMR titration in DMSO solution, it was found that there were potential hydrogen bonds between the NCH and AcO⁻ after the deprotanation of two -NH during the reaction of L or its Ru complex with anions. Furthermore, an easy-to-prepare test paper was developed to detect AcO⁻ at 10 mg/L in pure aqueous solution.     

Pyrrole-based tetra-amide for hydrogen pyrophosphate (HP2O73−) and F− ions in sol-gel medium

A simple pyrrole-based tetra-amide 1 shows selective fluorescence sensing of HP₂O₇^3? over a series of other anions in CH₃CN by exhibiting excimer emission at ~450 nm. In DMSO:CHCl₃ (1:5 v/v), compound 1 forms gel that undergoes disintegration to sol in the presence of basic anions such as F^?, AcO^? and H₂PO₄^?. However, the gel state of 1 under a particular condition is observed to be selective to F^? over AcO^? and H₂PO₄^? anions. The recognition properties of the receptor have been studied by fluorescence, UV–vis and ¹H NMR spectroscopic methods.     

Novel N,N＇-Diacylhydrazine-Based Colorimetric Receptors for Selective Sensing of Fluoride and Acetate Anions

Three novel and simple N,N＇-diacylhydrazine-based colorimetric receptors have been prepared. The binding properties of the receptors to anions such as F^-, Cl^-, Br^-, AcO^-, HSO4^- and HEPO4^- in acetonitrile solution were examined by UV-Vis spectroscopy methods, which show high sensitivity and selectivity to F^- and AcO^- over other anions. The results indicated that a 1 ： 1 stoichiometry complex was formed between the receptors and the anions, while ^1H NMR titrations confirmed hydrogen binding interaction between the receptors and the anions.     

5-(1H-Indol-3-yl)-pyrazolyl derivatives as colorimetric sensor for anions

The synthesis, characterisation and binding and deprotonation studies with anions for four 5-(1H-indol-3-yl)-pyrazolyl derivatives (2–5) have been described. It is worthy to mention that sensor 2 shows a drastic change in absorption spectrum (ca. 335 nm) and colour (colourless to blue) upon addition of F^? in DMSO solution due to the deprotonation of indole –NH proton, as confirmed by ¹H NMR titration. Sensor 4 recognizes F^? and CN^? ions by deprotonation mechanism with visible colour change of the solution in a similar manner to that of 2. However, in contrary to 2 and 4, sensor 3 binds with F^?, CN^?, H₂PO₄ ^?, AcO^? and PhCOO^? ions exploiting hydrogen-bonding interaction with the shifting of absorption band to longer wavelength and subsequent colour change of the solution. Compound 5 recognizes F^? without any visual colour change and its binding is studied by ¹H NMR titration to acquire the important information about the nature of binding between F^? and 5.     

Salicylaldehyde-indole-2-acylhydrazone: a simple,colorimetric and absorption ratiometric chemosensor for acetate ion

A simple anion receptor (i.e. salicylaldehyde-indole-2-acylhydrazone) was synthesised and its recognition properties were investigated by naked-eye observation, UV–vis titration spectra, ¹H NMR spectroscopy and DFT calculations. The obtained results indicated that this receptor could realise the selective colorimetric sensing and absorption ratiometric response towards AcO^?  in CH₃CN–DMSO medium, by virtue of threefold intermolecular hydrogen bonding interactions formed with phenolic OH, indole NH and amide NH.     

Triphenylamine-based simple chemosensor for selective fluorometric detection of fluoride, acetate and dihydrogenphosphate ions in different solvents

Triphenylamine-based new chemosensors 1 and 2 have been designed and synthesized for fluorometric detection of anions. The urea-amide conjugates in 1 and 2 are involved in binding of anions via hydrogen bonding. UV?Cvis and fluorescence titration experiments revealed that the sensor 1 has the selectivity for acetate (AcO^?), dihydrogenphosphate (H₂PO₄ ^?) and fluoride (F^?) over the other anions examined in the present study, in CHCl₃. In comparison, receptor 2 is non responsive for the same anions under similar conditions. In more polar solvent CH₃CN containing 0.1% DMSO, the receptor 1 shows a greater selectivity towards fluoride. The color of the solution of 1 is changed from colorless to light yellow and finally to yellowish brown only in the presence of fluoride in CH₃CN containing 10% DMSO. In pure DMSO and CH₃CN solvents, almost colorless solution of 1 is transformed into blood red and reddish brown in the presence of 30 equivalent amounts of F^?, respectively.     

Two Thiourea-based Colorimetric Sensors for Anions: Structure and Binding Study

Two colorimetric thiourea-based chemsensors with two relatively rigid arms, 2A and 2B, were synthesized. Their binding abilities with halide anions, AcO^?, [Formula: See Text] were studied by UV-Vis spectroscopy in DMSO. The two sensors showed a notable selective color response to F^? anion from colorless to green-yellow in recognition. The structures of the two sensors and their binding behaviors are discussed. The association constants were calculated by nonlinear fittings of 1:1, 1:2 or 1:1 to 1:2.     

Highly selective probe of a copper(II) complex based on a coumarin derivative for hydrogen sulfide detection

Abstract

A fluorescent probe 1 containing copper(II) had been designed and synthesized based on a coumarin derivative. The molecular structure of probe 1 was characterized by ¹H NMR, HRMS, IR, and elemental analysis. The interactions of 1 with biologically important anions and amino acid were determined by UV–Vis, fluorescence, and HRMS titration experiments. Results indicated that probe 1 showed the highest binding ability for HS^? among studied anions (AcO^?, H₂PO₄^?, F^?, Cl^?, Br^?, and I^?) and cysteine in pure dimethyl sulfoxide (DMSO) and HEPES buffer solution. As we expected, the response of UV–Vis spectra in aqueous solution was stronger than that of pure DMSO solvent. In addition, the binding ability for HS^? was not hindered by the existence of other anions. HRMS titration experiment showed that the interacted mechanism was that the copper(II) ion in 1 was captured by HS^? and then free ligand released. Furthermore, the detection limit of probe 1 with HS^? was carried out through UV–Vis titration showing 1 to be highly sensitive for HS^?.     

Electroanalytical and spectral investigation of organic receptors as colorimetric and absorption ratiometric anion chemosensor

Colorimetric receptors R1 and R2 have been designed and synthesized by Schiff base condensation and characterised by standard spectroscopic techniques. Anion binding ability of the receptors have been investigated quantitatively through optical, electrochemical and ¹HNMR titration studies. UV-vis spectra of receptor R1 and R2 exhibited a significant red shift for F^? and AcO^? ions with a visual color response. Receptor R1 exhibited selective response towards AcO^? ion in the presence of HEPES buffer media. Incremental color change of receptor R2 with the higher equivalence of AcO^? ions clearly represent the ratiometric response. Cyclic voltammetric studies of R1 and R2 exhibits shift in oxidation and reduction peak with successive addition of AcO^? ions indicating the anion induced oxidation of -NH and reduction of the keto group and nitro species. Electrooptical and ¹H NMR titration studies of R2 collectively reflects the anion induced change of chromophore from C=N to N=N indicative of azo-hydrazone tautomeric signaling in the presence of AcO^? ions. Lower detection limit of 2.1 and 0.41 ppm achieved with sodium salt of AcO^? ion with R1 and R2 reflects their utility as colorimetric chemosensor.     

Determination Limit of Fluorescence Turn‐On Probes for the Acetate Anion

Three fluorescent turn‐on probes containing 3,6‐dichloro‐9H‐carbazole as carbazyl part have been designed and synthesized. Among studied anions F^?, AcO^?, H₂PO , Cl^?, Br^? and I^?, AcO^? showed the strongest binding ability with all probes. The strong basic anions, such as AcO^?, H₂PO , and F^?, induced a significant red‐shift in absorption and a concomitant increase in fluorescent emission of the probes caused by photoinduced electron transfer (PET). The determination limit of probe 3 (Scheme 1) toward AcO^? is 3.0×10^?7 M . ¹H‐NMR Titration experiments shed light on the nature of the interaction between the probes and the anions. Theoretical investigation further illustrated the possible binding mode in these host? guest interactions and the roles of molecular frontier orbitals in molecular interplay.     

Rational design of a colorimetric and ratiometric fluorescent chemosensor based on intramolecular charge transfer (ICT)

A simple colorimetric and ratiometric fluorescent anion sensor 1, 3,6-dichloro-1,8-dinitrocarbazole, was rationally designed and synthesized on basis of the mechanism of intramolecular charge transfer (ICT). In DMSO solutions of 1, the presence of AcO⁻, F⁻ and H₂PO₄⁻ gave birth to the formation of a 2:1 host-to-guest complex, which was synchronously accompanied by a ‘naked-eye’ color change from light yellow to purple, a red-shift of the absorption spectrum and a blue-shift of the emission spectrum.     

A novel colorimetric and fluorometric anion sensor based on BODIPY-calix[4]pyrrole conjugate

A novel fluorescent anion sensor 1 based on boradiazaindacenes (BODIPY) derivative was synthesized and its absorption and fluorescence properties were investigated in various solvents. 1 exhibited a red shift of absorption spectrum and fluorescence quenching in varying degree in the presence of F^?, AcO^?, H₂PO₄ ^? and Cl^? due to multiple hydrogen bonding interactions between these anions and calix[4]pyrrole receptor. As an anion sensor in the visible region, 1 displayed the similar selectivity and sensitivity toward anions compared to the parent calix[4]pyrrole. However, 1 can be used as an effective dual responsive optical sensor for F^? via chromogenical and fluorogenical signals.