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A novel colorimetric anion-chemosensor based on 1,10-phenanthroline-2,9-dicarbonyl-p-nitro-phenylhydrazine has been synthesized. Among the different anions tested, it shows the best selectivity towards AcO(-). The addition of acetate causes the color to change from yellow to red, which could be detected with naked eyes. The binding ability of chemosensor 1 with anions has been investigated through UV-vis spectral titrations. In addition, (1)H NMR experiment was carried out to explore the nature of interaction between chemosensor 1 and acetate., (Copyright © 2011 Elsevier B.V. All rights reserved.)

A sensitive colorimetric sensor (1) based on 4,5-dinitrobenzene-1,2-diamine was designed and synthesized. Binding of anions such as AcO(-), F(-) and H(2)PO(4)(-) results in a notable change in the visible region of spectrum (an approximately 90nm red shift), which can be detected by the 'naked-eye'. Furthermore, the binding ability was evaluated by UV-vis titration experiments as following: AcO(-)>F(-)>H(2)PO(4)(-)>>Cl(-), Br(-), I(-). The nature of the color change of 1 induced by AcO(-) was due to the intramolecular charge transfer (ICT) which was confirmed by X-ray crystal structure and (1)H NMR titration spectra.

A new and simple salicylaldehyde-based sensor 1 designed for fluoride sensing has been investigated in DMSO and even in the 9/1 DMSO/H(2)O (v/v) mixtures. The affinity constants of receptor 1 for anionic species in the 9/1 DMSO/H(2)O (v/v) reveal that it is sensitive to F. Also, the color changes induced by anions can provide a way of detection by 'naked-eye'. These result can be substantiated by the spectrum changes upon the addition of 25equiv. anions to 1 in the 9/1 DMSO/H(2)O solution. The further insights to the nature of interactions between the sensor 1 and F(-) were investigated by (1)H NMR titration experiments in 9/1 DMSO-d(6)/H(2)O (v/v). In addition, the proposed binding mode between 1 and F(-) was suggested.

A simple colorimetric and fluorescent anion chemosensor based on amide moieties, 6-nitro-1,4-dihydroquinoxaline-2,3-dione has been designed, synthesized and characterized by (1)H NMR, ESI-MS and elemental analyses. The strong basic anions such as F(-) and AcO(-) resulted in significant decrease in fluorescent emission intensity of the compound 1, accompanied synchronously with a dramatic color change from colorless to deep yellow in organic medium. (1)H NMR titration experiments shed light on the nature of the interactions between 1 and the anions.

Tris-hydrazone (1) functioned as a colorimetric chemosensor for a variety of anions such as F(-), AcO(-) and H(2)PO(4)(-). The anion binding could be easily detected by naked-eye according to color changes. The high binding ability of the receptor 1 to anions was further investigated by UV-vis absorption spectroscopy in DMSO. The results of job plot of the receptor 1 with different anions demonstrated that the stoichiometry of the complex between 1 and F(-) was 1:1 (1:anion) and the stoichiometry of the other complexes studied was 1:3 (1:anion).

The anion sensing ability of compound 1 based on a novel 2,4-dinitrophenylhydrazone derivative was studied through "naked-eye" experiment, UV-Vis spectral titration, and (1)H NMR titration. Sensor 1 was synthesized through a simple method with high yield. The solution of host 1 turned deep purple from light purple in the presence of the strong basic anions and turned yellow upon addition of the weak basic anions, respectively. The results could be explained on the basis of transfer of the tautomeric equilibrium of sensor 1 induced by anions with different basicity., (Copyright 2008 John Wiley & Sons, Ltd.)

A benzimidazole-based anion receptor 1 has been designed and synthesized. The structure of 1 is confirmed through single crystal X-ray diffraction analysis. Anion-binding studies carried out using (1)H NMR and UV-visible revealed that this compound exhibits selective recognition toward F(-) over other halide anions. The highest selectivity for F(-) among the halides is attributed mainly to the strongest hydrogen-bond interaction of the receptor with F(-); in addition, the higher match in geometry between the receptor and F(-) also plays a role in the selective recognition of the receptor for F(-). Receptor 1 (1 x 10(-5) M) shows dramatic color change from light-yellow to red in the presence of tetrabutylammonium fluoride (TBAF) (1 x 10(-5) M). Moreover, F(-)-induced color changes remain the same even in the presence of a large excess of Cl(-), Br(-), I(-)., (Copyright 2006 John Wiley & Sons, Ltd.)

A novel selective and sensitive colorimetric receptor 1 (1, 10-phenanthroline-2, 9-dialdehyde bis-(-p-nitrophenylureasemicarbo-hydrazone)) based on urea showing distinctive color fading phenomenon towards H2PO4− ion was reported. Fancifully, the recognition process of receptor 1 to H2PO4− was not interfered by the existence of others anions. We have probed the binding mechanism of 1-H2PO4− that H2PO4− ion induced competitive hydrogen binding process via intramolecular hydrogen-bond by UV-vis, fluorescence, 1H NMR titrations and ESI-MS experiments. [ABSTRACT FROM AUTHOR]

Three new selective anion receptors containing the (thio)urea binding sites were developed, Indole-3-formaldehyde phenyl-semithiocarbazone, Indole-3-formaldehyde nitrophenyl-semithiocarbazone, and Indole-3-formaldehyde nitrophenyl-semicarbazone, nominated as receptors 1, 2 and 3, respectively. Receptor 1 shows high selective recognition for F only, while both receptor 2 and receptor 3 containing a p-nitro group show high selective recognition for AcO. The high selective recognition of these receptors to anions is further investigated by X-ray crystallography diffraction, UV-vis, fluorescence analyses and H NMR. Furthermore, receptor 2 changes from yellow to orange, and receptor 3 darkens when acetate is added, providing a way of detection by 'naked-eye'. [ABSTRACT FROM AUTHOR]

novel artificial anion chemosensor 1 based on 2, 2′-di (4-nitrophenylurea-β- N-yl) -1, 1′-binaphthyl is designed and synthesized for sensing anions including halide ions and oxoanions. The fluorescent emission of the binaphthyl of receptor 1, forming the hydrogen bonding with anions as the sensing mechanism, is monitored in DMSO for detecting anions. In brief, while most of the anion chemosensors are switch-off fluorescent chemosensor, or non-fluorescent sensor, receptor 1 exhibits obviously the switch-on emission during the complexation with HPO. [ABSTRACT FROM AUTHOR]

An anion receptor was synthesized with ferrocene as binding frame. Anion recognition can be monitored by anion complexation-induced changes in UV-vis absorption spectra. Interaction between the receptor and acetate was described on the basis of 1H NMR experiments. [ABSTRACT FROM AUTHOR]

A carbazole-based neutral anion receptor 3 has been designed and synthesized. Anion binding studies carried out using 1H NMR and UV-visible reveal that this compound showed good selectivity for the iodide ion over other anions. The high selectivity for iodide ion among the anions is attributed mainly to the complementarity of the geometries between the receptor 3 and iodide ion. [ABSTRACT FROM AUTHOR]

A 3D supramolecular complex [Co(III)(Phen)2Cl2][DNQ]Cl·H2O (DNQ = 6,7-dinitroquinoxaline-2,3-dione) has been synthesized and determined by single-crystal X-ray analysis. Anion binding studies carried out using 1H NMR and UV-visible revealed that a genuine hydrogen bond interaction between anion receptor 2 and Cl- can be detected, but fluoride is deprotonating the anion receptor 2. X-ray analysis results show that it is not possible for the two amide nitrogen atoms of anion receptor to form hydrogen bonds to a chloride ion in the presence of small aliquots of water. [ABSTRACT FROM AUTHOR]

A novel selective and sensitive colorimetric receptor 1 (1, 10-phenanthroline-2, 9-dialdehyde bis-(-p-nitrophenylureasemicarbo-hydrazone)) based on urea showing distinctive color fading phenomenon towards H2PO4− ion was reported. Fancifully, the recognition process of receptor 1 to H2PO4− was not interfered by the existence of others anions. We have probed the binding mechanism of 1-H2PO4− that H2PO4− ion induced competitive hydrogen binding process via intramolecular hydrogen-bond by UV-vis, fluorescence, 1H NMR titrations and ESI-MS experiments. [ABSTRACT FROM AUTHOR]

A simple, novel anion receptor based on 4-hydroxy-3-(N-phenyl-thiourea-N′-nitrilo-methylidynyl)-azobenzene with hybrid –OH and thiourea binding sites was synthesized and characterized. Anion binding character was determined using visual inspection, UV–vis, fluorescence and 1H NMR analyses. The addition of F−, AcO− and H2PO4 − resulted in a marked red shift of the charge-transfer absorbance band (Δλ =140nm, from 340nm to 480nm) accompanied by a color change from light yellow to orange. [Copyright &y& Elsevier]

Abstract: Two novel highly sensitive colorimetric acetate anion receptors: 4-phenylazo-2-hydroxy-benzaldehyde 4-nitrophenylhydrazone (1) and 4-phenylazo-2-hydroxy-benzaldehyde 2,4-dinitrophenylhydrazone (2) based on azo derivative have been designed and synthesized. UV–vis experiments show that receptor 1 and receptor 2 can selectively recognize acetate in DMSO and even in 9/1 DMSO/H2O (v/v) mixtures. Meanwhile the color changes induced by anions can provide a way of detection by ‘naked-eye’. The further insights to the nature of interactions between receptor 1, 2 and AcO− have been investigated by 1H NMR titration experiments. [Copyright &y& Elsevier]

Abstract: A novel artificial anion receptor based on phenylhydrazone structure was designed, synthesized and characterized. The binding behavior of the receptor to various anions was investigated by UV–vis fluorescence analyses. In addition, 1H NMR experiments were carried out to explore the nature of interaction between receptor 1 and acetate. The processes of sensing can literally be seen through the ‘naked-eye’ for the sharp color changes from yellow to purple. [Copyright &y& Elsevier]

Abstract: A novel sensor for acetate containing thiourea and hydrazone structure has been synthesized. The anion recognition via hydrogen-bonding interactions could be monitored by anion complexation, which induced changes in UV–vis and fluorescence spectra. In particular, the recognition process could be easily detected by the ‘naked-eye’. Further insights to the nature of interactions between receptor 1 and AcO− were obtained by 1H NMR titration experiments. [Copyright &y& Elsevier]

Abstract: A novel and efficient receptor based on the phenylhydrazone derivatives is successfully developed and applied to the acetate anion recognition, indicating that the origin of special preference for acetate (AcO−) anion maybe the structure well matching between the host and the guest. The sensor changes its color so obviously on addition of the acetate ions and that may make the naked-eye recognition in DMSO and even in DMSO/H2O (95/5) solution come true. Also, the anion binding ability determinations were performed by UV–vis titration and 1H NMR titration experiments with different anions in the solutions mentioned. The fluorescence enhancement can also be observed after the host is coordinated with the AcO− anion and excited by light wavelength at 280nm. [Copyright &y& Elsevier]

Abstract: Tris–hydrazone (1) functioned as a colorimetric chemosensor for a variety of anions such as F−, AcO− and H2PO4 −. The anion binding could be easily detected by naked-eye according to color changes. The high binding ability of the receptor 1 to anions was further investigated by UV–vis absorption spectroscopy in DMSO. The results of job plot of the receptor 1 with different anions demonstrated that the stoichiometry of the complex between 1 and F− was 1:1 (1:anion) and the stoichiometry of the other complexes studied was 1:3 (1:anion). [Copyright &y& Elsevier]

Abstract: A novel and simple fluorescent receptor bearing thiourea moiety as recognition site was described. The recognition behavior of the receptor toward different anions was investigated in DMSO/H2O (95:5 v/v) and dry DMSO through two various channels: the colorless-yellow color change and a remarkable enhancement of the fluorescence. And the enhancement of the fluorescence was attributed to an anion-induced increase of the rigidity of the host molecule. [Copyright &y& Elsevier]

Abstract: A novel receptor based on phenylhydrazone derivative was developed and applied to the binding anion, showing a common preference for acetate (AcO−) ion, and the preference was related to structure matching between the host and the guest. The receptor exhibited a dramatic color change upon the addition of acetate ions so that we could finish anion recognition by naked eye without resorting to any spectroscopic instruments. The evaluation of the receptor interaction with anions was performed by UV–vis titration experiments with a variety of structurally different anions in DMSO, and the anion binding pattern of the chemosensor was hydrogen bond interactions. [Copyright &y& Elsevier]

Abstract: 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 NO− 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 10mg/L in pure aqueous solution. [Copyright &y& Elsevier]