Study on the selectivity of anion receptors based on similar (thio)urea fragments.

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 (1)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'.

Colorimetric recognition of acetate anions in aqueous solution using charge neutral azo derivatives.

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/H(2)O (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 (1)H NMR titration experiments.

A novel acetate selective chromogenic chemosensor based on phenanthroline.

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.

A simple and neutral receptor acting as a sensitive and switch-on fluorescent chemosensor for H2PO4(-).

A novel artificial anion chemosensor 1 based on 2,2'-di(4-nitrophenylurea-ß-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 H(2)PO(4)(-).

An acetate sensor based on azo in aqueous media.

A colorimetric sensor 1,N,N'-di-(2-hydroxy-5-(phenldiazenyl)benzaldehyde)-1,3-diiminothiourea for acetate in DMSO and 9/1 DMSO/H(2)O (v/v) mixtures was designed and synthesized. The binding ability evaluated by UV-vis experiment reveals that sensor 1 can selectively recognize acetate. In addition, the color changes induced by anions can provide a way of detection by 'naked-eye'. The further insights to the nature of interactions between the sensor 1 and AcO(-) were investigated by (1)H NMR titration experiments in 9/1 DMSO-d(6)/H(2)O (v/v).

Ratiometric and selective fluorescent sensor for F(-) based on intramolecular charge transfer (ICT).

A simple colorimetric and ratiometric fluorescent anion sensor 1, was rationally designed and synthesized by facile one-step condensation on basis of the mechanism of intramolecular charge transfer (ICT). The sensor 1 shows more highly and selectively ability to F(-) that induced the color changes from little yellow to purple, absorption-transferred to long wavelength and emission-transferred to short wavelength. Accordingly, (1)H NMR analysis reveals that the F(-)-induced colorimetric and fluorometric responses of 1 are simply driven by hydrogen bonding interaction between the NH protons and F(-) ions.

A novel anthracene-based receptor: highly sensitive fluorescent and colorimetric receptor for fluoride.

A new highly sensitive colorimetric receptor 1 for fluoride based on anthracene-9,10-dicarbaldehyde bis-p-nitrophenylhydrazone was designed, synthesized and characterized. Experiments showed that the receptor 1 can selectively recognize the fluoride in DMSO and even in 95/5 DMSO/H(2)O (v/v) mixtures. The ability of recognition and the bond between receptor 1 and anions were determined using visual inspection, UV-vis and fluorescence analyses. In addition, (1)H NMR experiments were carried out to explore the nature of interaction between receptor 1 and fluoride. Finally, analytical application and detection of fluoride in toothpaste have been studied.

Design of two pyrazole-based sensors with similar configuration and different fluorescent response to anions.

Two simple fluorescent anion receptors based on 1-phenyl-3-methylpyrozole-5-one-4-one phenylhydrazone (L1) and 1-phenyl-3-methylpyrozole-5-one-4-one p-nitrophenylhydrazone (L2) were designed, synthesized and characterized with (1)H NMR, COSY spectrum, (13)C NMR, ESI-mass and elemental analyse. Interestingly, two receptors with similar configuration exhibited different anion binding behaviors in DMSO solution. The results of Job plots and ESI-mass spectrum indicate that L1 bind anions such as F(-), AcO(-), H(2)PO (4) (-) to form 2:1 host-guest complexation, while L2 bind anions to form 1:1 host-guest complexation in the solution.

A simple colorimetric sensor for biologically important anions based on intramolecular charge transfer (ICT).

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.

Colorimetric and fluorescent sensing of biologically important fluoride in physiological pH condition based on a positive homotropic allosteric system.

A novel positive homotropic allosteric system 1 based on 3-methylpyrozole-5-one-4-one-2',4'-dinitrophenylhydrazone was designed, synthesized and characterized. Colorimetric and fluorescent sensing of anions was achieved in physiological condition (pH 7.4), resulting from the positive homotropic allosterism of 1 induced by anions tested. In particular, the compound 1 exhibited a two-step response to the strong basic anions such as F(-). In the first step, the hydrazone form of 1 interacted with anions through hydrogen bonding with an obvious color change from yellow to orange upon addition of 0.3 equiv. of anions. In the second step, with further addition of anions, the hydrazone form of 1 was shifted to the azophenol form, whose anion binding was accompanied with an orange-to-purple color change. In addition, the receptor 1 exhibited a fluorescent enhancement response to anions exploiting two possible signaling transduction mechanisms: (1) inhibition of photoinduced electronic transfer (PET) and (2) binding-induced rigidity of the host molecule.

Anion recognition and sensing of ruthenium(II) and cobalt(II) sulfonamido complexes.

A series of artificial receptors, based on a sulfonamido system, have been designed and synthesized. The interaction of these receptors with biologically important anions was determined by UV-vis, (1)H NMR titration and electrochemical experiments. Results indicate that these receptors show high recognition abilities for fluoride (F(-)) or acetate (AcO(-)), moderate affinities for dihydrogen phosphate (H(2)PO(4)(-)) or hydroxyl (OH(-)) and almost no affinities for chloride (Cl(-)), bromide (Br(-)) or iodide (I(-)). (1)H NMR titration shows that the interaction between the receptors and anions depends on the hydrogen-bond formation. The Co(III)/Co(II) redox signals of receptor and disappear gradually when the fluoride or acetate anions are added. Moreover, visual color changes accompany guest binding, enabling this system to act as colorimetric anion sensors. The colorimetric properties of these sensors are ascribed to the hydrogen-bond formation and the colorimetric group quinoxaline.

Current development of Pd(II) complexes as potential antitumor agents.

Research has proven that the most effective and widely used metal-containing chemotherapy anticancer drugs are cisplatin ([cis-PtCl(2)(NH(3))(2)]) and many platinum complexes, however, these compounds have significant disadvantages including poor water solubility and serious side effects. Thus researches in order to overcome these shortcomings have never interrupted. Many non-platinum complexes have been synthesized and tested, in which some palladium complexes show significant antitumor activity in normal tumor cells and lower resistance of tumor cells to clinical treatments as well as lower side effects. Mononuclear palladium complexes with aromatic N-containing ligands, amino acid ligands, S-donor ligands, and P-containing ligands have respective qualities and properties due to the different structures and properties of the ligands; some dinuclear palladium complexes possess interesting steric structures and good antitumor activity; a try to modify natural medicines with Pd(2+) leads the research to a new route. In this review, medicinal chemistry, the development status and interactions of palladium complexes with DNA are discussed in order to provide guidance and determine structure and antitumor activity relationships for continuing studies of these systems.

A high selective anion colorimetric sensor based on salicylaldehyde for fluoride in aqueous media.

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 ON-OFF fluorescent chemosensor for biologically important anions based on amide moieties.

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.

A C3-symmetric colorimetric anion sensor bearing hydrazone groups as binding sites.

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).

Rational design of novel benzimidazole-based sensor molecules that display positive and negative fluorescence responses to anions.

Two novel and neutral benzimidazole derivatives-based anion receptors bearing a 1,10-phenanthroline fluorophore, N,N'-di-(2'-benzimidazolyl-methylene)-1, 10-phenanthroline-2,9-diamide (1) and N,N'-di-[2'-(benzimidazolyl-2'-) ethyl-]-1,10-phenanthroline-2,9-diamide (2), which exhibited turn-on and turn-off fluorescence responses to various anions, were rationally designed and synthesized and their fluorescent response toward anions was investigated in DMSO solution. In the process of anions binding, there were two different fluorescent responses in presence of anions: a quenching of the fluorescence emission for F- and AcO- and an enhancement of the fluorescence emission for Cl-, Br- and I-. Two different luminescent mechanisms of the receptors 1 and 2 resulting from various anions were exploited to rationalize quenching and enhancement of the fluorescence emission: a photo-induced electronic transfer mechanism (PET) and the increase of the rigidity of the host molecules, respectively. In particular, chloride could be recognized selectively from the anions tested according to changes of fluorescence spectrum.

A highly selective naked-eye colorimetric sensor for acetate ion based on 1,10-phenanthroline-2,9-dicarboxyaldehyde-di-(p-substitutedphenyl-hydrazone).

A new and simple colorimetric sensor with high selectivity for acetate ion based on 1,10-phenanthroline-2,9-dicarboxyaldehyde-di-(p-substitutedphenylhydrazone) receptor 2 has been synthesized. The selectively binding ability of receptor 2 to acetate ion over other anions tested was demonstrated by UV-vis absorption spectroscopy in DMSO. Comparing with other anions studied, the UV-vis absorption spectrum in dimethyl sulfoxide shows significant response toward acetate ion with high selectivity, and meanwhile dramatic color change is observed from yellow to green in the presence of acetate ion (5 x 10(-6)mol/L). Little UV-vis absorption spectrum change has occurred when receptor 2 was titrated with other different guest (F(-), Cl(-), Br(-), I(-), H(2)PO(4)(-) and OH(-)). In addition, the (1)H NMR spectrum titration shows deprotonation of the receptor in the presence of acetate ion.

Colorimetric recognizing of biologically important anions based on anion-induced tautomerism of the sensor.

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.

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 H(2)PO(4)(-) 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 simple and efficient colorimetric anion sensor based on a thiourea group in DMSO and DMSO-water and its real-life application.

An efficient colorimetric sensor with a thiourea moiety as binding sites and p-nitrophenylhydrazine as a signaling unit has been synthesized by only one single-step procedure. Selectivity for anions with the distinct geometry (tetrahedral, trigonal planar and spherical) has been investigated in dry DMSO and even in DMSO/H(2)O (95:5, v/v) solutions through the naked-eye experiment, UV-vis titration and (1)H NMR titration techniques. In particular, the fluoride of toothpaste can be detected qualitatively by the sensor 1.