Bromide selective fluorescent anion receptor with glycoluril molecular scaffold

Glycoluril based fluorescent anion receptor has been designed and synthesized. Anion binding studies carried out using fluorescence spectroscopy and ¹H NMR revealed that this compound displays good affinities for bromide ion.     

基于咪唑的荧光传感器对磷酸二氢根离子的高选择性识别

设计并合成了基于咪唑基团的高选择性的荧光传感器, 分别利用荧光和紫外-可见光谱研究了其对阴离子的识别. 结果显示, 该类荧光传感器只在H₂PO₄^-离子存在下发生显著的荧光猝灭现象, 并且产生一个新的荧光发射峰, 因此可用于乙腈溶液中H₂PO₄^-的快速有效检测.     

Chiral tripode approach toward multiple anion sensing with lanthanide complexes

A chiral tripodal ligand was demonstrated to form a series of lanthanide complexes exhibiting multiple anion-sensing profiles, which incorporated a fluorescent quinoline and a stereo-controlled substituent in a tetradentate skeleton. This mainly gave 1:2 (lanthanide cation/ligand) complexes with lanthanide triflates but 1:1 complexes with lanthanide nitrates. Since addition of external guest anion dynamically changed the preferred stoichiometry, the chiral lanthanide complexes exhibited anion-responsive fluorescence, luminescence, and circular dichroism spectral characteristics as multiple anion-sensing probes.     

Unprecedented intramolecular cyclization of pyridinium to pyrido[1,2-a]benzimidazole: a novel chemodosimeter for fluoride ions

Pyridinium 1a underwent an efficient intramolecular cyclization initiated by fluoride ions to form highly fluorescent 1,3,4-triphenylpyrido[1,2-a]benzimidazole, providing a novel chemodosimeter for fluoride ions detection.     

A fluorescence-active 1,3-bis(isothiouronium)-derived naphthalene exhibiting versatile binding modes toward oxoanions in aqueous MeCN solution: new methodology for sensing oxoanions

A unique binding property of the PET (photoinduced electron transfer) sensor 1 is described, in which a naphthalene moiety at the 1,3-positions is attached by isothiouronium units that serve as anion-binding units. Fluorescence emission (λ_max=339 nm) was significantly switched on at an excitation wavelength of 279 nm upon recognition of anion in 6% (v/v) H₂O/MeCN solution at 25 °C. Titration curves with HPO₄²⁻ and AcO⁻ differ greatly; that with HPO₄²⁻ shows a stoichiometric 2:1 host-to-guest binding, whereas that with AcO⁻ shows a biphasic 1:1 and 1:2 host-to-guest binding, reflecting principally the charged shapes of the oxoanions. This finding is attributable to the plural built-in isothiouronium units with a high anion-binding ability, and suggests a new way to develop fluorescent sensors for oxoanion recognition.     

A Multi-armed Neutral Receptor for α,ω-Dicarboxylate Anions

A multi-armed neutral anion receptor (1) bearing multiple amide and thiourea binding sites was synthesized. Receptor 1 forms 1:2 complexes with dicarboxylate anions, and the sensitivity for recognition of dicarboxylate depends strongly on the chain length of these dicarboxylate anions. Addition of the anions caused a considerable change in the absorbance and fluorescent intensity of the host solution and a consequent visible color change.     

含双蒽基团酰胺受体分子的合成及阴离子识别研究

合成了一种新型的带有双蒽基团的酰胺阴离子受体B.用荧光光谱、紫外-可见吸收光谱以及核磁共振氢谱研究了B与Cl^-,Br^-,I^-及对硝基酚氧阴离子的相互作用.结果表明,B与Cl^-,Br^-,I^-等阴离子无识别作用,而与对硝基酚氧阴离子有较好的选择性识别能力,其络合比为1∶1.利用荧光发射强度和吸光度的变化分别计算出主体B与客体相互作用的络合常数KS分别为(1.24±0.07)×10⁵和(1.27±0.18)×10⁵,并对主体分子B与客体之间的相互作用进行了讨论.     

Anion detection by aggregation-induced enhanced emission (AIEE) of urea-functionalized tetraphenylethylenes

Substituted tetraphenylethylenes (TPEs) have been prepared that feature four alkyl or aryl urea groups arrayed along the periphery. Exposure of these TPEs to monovalent anions (halide, carboxylate, nitrate, and azide) resulted in enhanced fluorescence emission attributed to aggregation of the TPE molecules via urea-anion hydrogen bonding. Emission enhancement correlated with anion basicity, with fluoride ion eliciting the largest fluorescence response. Increased fluorescence emission could also be detected visually in solutions viewed under UV light. This study demonstrates the feasibility of TPE-based fluorescent anion sensors/detectors, and it is envisioned that additional design modifications may afford anion-selective fluorescent sensors.     

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 new terpyrrolic analogue of dipyrrolylquinoxalines: an efficient optical-based sensor for anions in organic media

The synthesis and X-ray structural characterization of a new terpyrrolic analog of dipyrrolylquinoxaline (DPQ) is described that contains two pyrrole anion recognition groups bridged by a central 1,2-linked pyrrole. Relative to the ‘parent’ DPQ system, this new terpyrrolic scaffold acts as an improved colorimetric and fluorescent sensor for halide and dihydrogen phosphate anions in organic media. This enhancement is particularly dramatic in the case of H₂PO₄⁻ (studied as its tetrabutylammonium salt); in CH₂Cl₂ it is bound with an affinity constant, K, of 17,500 M⁻¹ by the terpyrrole of this report vs. 80 M⁻¹ in the case of DPQ. The present findings thus support the emerging notion that a range of pyrrole-based anion recognition and sensing systems may be produced by replacing the central quinoxaline spacer in DPQs by other bridging subunits and that these new receptors may have properties that differ dramatically from their DPQ ‘parents’.     

Novel thiophene based colorimetric and fluorescent receptor for selective recognition of fluoride ions

A colorimetric anion sensor 2,2′-(1E,1′E)-(thiophene-2,5-diylbis(methan-1-yl-1-ylidene)) was synthesized and characterized by various spectroscopic techniques. Anion binding studies were carried out using UV-visible spectrophotometric titrations and emission spectra studies, revealed that the receptor exhibits selective recognition toward F⁻over other anions. The selectivity for F⁻among the halides is attributed mainly to the hydrogen-bond interaction of the receptor with F⁻. Receptor 1 showed color change from fluorescent green to orange in the presence of tetrabutylammonium fluoride with 1:1 stoichiometry. Receptor 1 exhibits remarkably enhanced fluorescence intensity.     

Synthesis of Schiff Base Bearing Phenolic Hydroxy Group and Its Anion Recognition

A new anion receptor bearing phenolic hydroxy group based on 3,5-ditertbutylsalicylaldehyde-p-nitrophenylhydrazone (1) was designed and synthesized. Upon addition of AcO^- and F^-, the receptor exhibited visible color changes from deep yellow to purple. However, no obvious color changes were observed on addition of the other anions tested (H₂PO₄^-, Cl^-, Br^-, I^-). The binding properties of the receptor with anions such as AcO^- and F^- were investigated by UV-Vis and fluorescent titrations. The result indicated that the receptor 1 had a higher affinity to AcO^- and F^- and a 1:1 host-guest complex was formed through H-bond interactions between 1 and anions.     

Coumarin-based tripodal chemosensor for selective detection of Cu(II) ion and resultant complex as anion probe through a Cu(II) displacement approach

In this paper, a novel tripodal fluorescent receptor based on naturally occurring coumarin was synthesized and its ionic recognition properties were fully investigated by spectroscopic techniques. As revealed by the results, tripodal 1 exhibits excellent selectivity toward copper(II) by forming a 1:1 complex with triazole N as the main binding sites. And the resulted 1·Cu²⁺ complex shows recognition ability toward H₂PO₄^? by metal displacement approach. The recognition mechanism was further investigated by computer calculation.     

微波消解－离子色谱法测定染料中痕量阴离子

建立了染料痕量阴离子的微波消解离子色谱方法。对离子色谱的干扰,pH对分离效果影响,淋洗液的选择对保留时间的影响,流速对峰高、峰面积、分离度和理论谈板数的影响进行了研究。结果表明：六种阴离子具有良好的线性关系,相关系数为0.9991-0.9999,检出限为0.0002-0.0032mg/L,加标回收率为97.6%-101.4%,阴离子精密度＜0.03%-2.55%,仪器定量和定性精密度＜3.0%,本方法精密、准确、快速,对氮杂BODIPY荧光染料2,6－位置引入卤素的含量测定具有实际应用价值。     

Cyanine dye-based chromofluorescent probe for highly sensitive and selective detection of cyanide in water

Cyanine dye Cy5 was used to be a probe for highly selective detection of trace cyanide in water by using a convenient two-phase strategy. The detection limit of both the fluorescent and colorimetric assay for cyanide is below 1.9 μM, the maximal allowance level for drinking water set by the World Health Organization.     

A ratiometric fluorescent chemosensor, 1,10-phenanthroline-4,7-dione, for anions in aqueous-organic media

A new fluorescent chemosensor, 1,10-phenanthroline-4,7-dione (1), which is capable of the ratiometric sensing of anions in aqueous MeCN, was developed. Chemosensor 1 recognized an anion via two NH groups in the molecule, and showed a much higher affinity for F⁻ than that of 4-quinolone, which binds to an anion at one NH group of the molecule. Upon binding to F⁻, the intensity of the emission band ascribed to the complex of 1-F⁻ was drastically enhanced, while the emission intensity of unbound 1 gradually decreased. The changes in these two emission bands enabled the successful ratiometric sensing.     

Ratiometric dual fluorescent receptors for anions under intramolecular charge transfer mechanism

A series of the intramolecular charge transfer (ICT) dual fluorescent receptors with anion binding site in the electron acceptor were designed and synthesized. These receptors exhibited dual fluorescence in acetonitrile and the charge transfer (CT) emission energy was found to correlate linearly with the Hammett constant of the substituent existing in the electron acceptor, which is the basis for anion sensing. Dual fluorescence of these receptors was found to be sensitive to the presence of anions such as fluoride and acetate and the receptors can be employed as ratiometric fluorescent sensors for anions.     

A novel calix[4]arene fluorescent receptor for selective recognition of acetate anion

A novel bridged fluorescent calix[4]arene with 1,8-diaminoanthracene and glycine at the upper rim has been prepared, which exhibited selective recognition towards AcO⁻ over other anions such as F⁻, Cl⁻, Br⁻, , , I⁻ and by fluorescence spectroscopy and ¹H NMR method.     

Anthracene derivatives bearing two urea groups as fluorescent receptors for anions

For the recognition and sensing of anionic analytes, comparative studies were carried out on the anion bindings of pyrophosphate, H₂PO₄⁻, and dicarboxylates to the anthracene derivatives bearing two urea groups on the 1,8 and 9,10-positions as fluorescent chemosensors for anions. Their binding properties were compared using fluorescence and ¹H NMR, and the results were rationalized with an ab initio study.     

Supramolecular Functions Related to the Redox Activity of Transition Metals

Abstract

The combination of the properties of different subunits in a multicomponent system may give rise to a function which is defined supramolecular. The presence of transition metals in one or more subunits may induce inter-component processes related to their redox and electron transfer (eT) properties, which trigger the supramolecular function (SF). The following examples are considered: (1) a receptor for transition metals is covalently linked to a fluorescent fragment; following recognition, a metal-to-fluorophore eT process quenches the fluorescence. SF: fluorosensing. (2) an azacyclam macrocycle, hosting the Ni^II/Ni^III redox couple, is covalently linked to a photoactive fragment: the Ni^III state quenches the neighboring fluorophore through an eT mechanism, the Ni^II state does not. SF: redox switching of a fluorescent signal. (3) a Cu^II ion is coordinated by two 2,2′-bipyridine molecules, each bearing a cyclam subunit containing a nickel centre; when nickel is in the divalent state, an inorganic anion X^? (N₃ ^?,NCO^?,NCS^?) is bound to Cu^II; on oxidation, X^? moves to the Ni^III centre. SF: electrochemically triggered translocation of X^? from copper to nickel and vice versa.