Yun-Bao Jiang

A highly selective charge transfer fluoroionophore for Cu2

A dual fluorescent charge transfer fluoroionophore (1) with its ionophore incorporated in the electron acceptor was developed and was found to show a highly selective fluorescent response to Cu2+ with a dramatic enhancement in its CT emission.

A simple visual sensor with the potential for determining the concentration of fluoride in water at environmentally significant levels

We have developed a simple and robust fluorescence based boronic-acid molecular sensor for determining the concentration of fluoride in water at environmentally significant levels. The simplicity of the method and the ability to measure fluoride in water between 0.1 and 1.5 ppm is particularly noteworthy given the WHO requirements for detecting levels of fluoride in drinking water below 1.5 ppm.

A ratiometric luminescent sensing of Ag+ ion via in situ formation of coordination polymers

A ratiometric luminescent sensing of Ag(+) ion is developed via the Ag(I)-NCys coordination polymeric luminophore in situ formed in aqueous solution upon mixing Ag(+) ion with the designed fluorescent thiol ligand NCys.

Effect of cyclodextrin inclusion complex formation on the twisted intramolecular charge transfer (TICT) of the included compound: the p-dimethylaminobenzoic acid-β-cyclodextrin system

Abstract The effect of cyclodextrin inclusion complex formation on the twisted intramolecular charge transfer (TICT) of the included compound was examined using the TICT-typical dual fluorescence for the p-dimethylaminobenzoic acid (DMABOA)-β-cyclodextrin (β-CD) system in buffered (pH 4.12 and 8.00) and unbuffered (pH 5.06) solutions. The host-to-guest ratio of the DMABOA-β-CD inclusion complex is evaluated to be 1 : 1 in the three solutions from an analysis of the fluorescence intensity data by two methods. Enhanced LE (locally excited state) and TICT emissions and Ia/Ib ratio, a blue-shifted TICT fluorescence band and a stronger excitation wavelength dependence of the TICT fluorescence for DMABOA in the β-CD inclusion complex are observed. The correlation of the Ia/Ib ratio with the medium polarity is opposite in the inclusion complex to that observed in organic solvents. The TICT fluorescence of the DMABOA-β-CD inclusion complex with DMABOA in the basic form shows a stronger excitation wavelength dependence than that with DMABOA in the acidic form. A decreased pKa of DMABOA in the β-CD inclusion complex is determined. This is taken as evidence that the Me2N group of the DMABOA molecule in the β-CD cavity. TICT is shown to be viscosity dependent in the cyclodextrin inclusion complex. The dependence of the TICT fluorescence of DMABOA in the inclusion complex on the polarity, viscosity and excitation wavelength is discussed in detail with regard to the dynamic scheme of the TICT model and the structural characteristics of the ground and excited states.

Ratiometric Fluorescent Chemosensor for Hg2+ Based on Heptamethine Cyanine Containing a Thymine Moiety

Based on a T-Hg(2+)-T binding mode, a sensitive ratiometric fluorescent chemosensor for aqueous Hg(2+) was developed with a heptamethine cyanine chromophore containing a thymine moiety.

Highly selective iodide-responsive gel–sol state transition in supramolecular hydrogels

We demonstrate for the first time a highly selective anion-responsive reversible gel–sol state transition in a supramolecular hydrogel of Ag(I)-glutathione (GSH) coordination polymers, which allows for facile and selective visual recognition of I−via naked eyes even in a strongly colored and/or fluorescent background. Such a strategy overcomes the drawback of spectral interferences which are often encountered in conventional colorimetric and fluorimetric means. It was rationalized that I− functioned as a depolymerizing agent for the Ag(I)-GSH supramolecular hydrogels. A feasible quantitative assay for I− was established that afforded satisfactory results for simulated wastewater samples. We believe that this strategy can in principle be applicable to other species by following a smart gel–sol state transition in designed supramolecular hydrogel.

Metal-Metal-Interaction-Facilitated Coordination Polymer as a Sensing Ensemble: A Case Study for Cysteine Sensing

A detailed investigation of the absorption and CD signals of Ag(I)-cysteine (Cys) aqueous solutions at buffered or varying pH has allowed us to suggest that coordination polymers are formed upon mixing Ag(I) and Cys bearing a Ag(I)-Cys repeat unit. The formation of the coordination polymers are shown to be facilitated by both the Ag(I)···Ag(I) interaction and the interaction between the side chains in the polymeric backbone. The former allows for an immediate spectral sensing of Cys with enantiomeric discrimination capacity with both high sensitivity and selectivity, and the contribution of the side-chain/side-chain interaction serves to guide extended sensing applications by means of modulating this interaction. With our preliminary data on the corresponding Cu(I)-Cys and Au(I)-Cys systems that exhibited similar spectral signals, we conclude that the M(I)-SR coordination polymers (M = Cu, Ag, or Au) could in general function as spectral sensing ensembles for extended applications. This sensing ensemble involves the formation of coordination polymers with practically no spectral background, thus affording high sensing sensitivity and selectivity.

p-dimethylaminobenzamide as an ICT dual fluorescent neutral receptor for anions under proton coupled electron transfer sensing mechanism

Abstract The intramolecular charge transfer (ICT) dual fluorescence of p -dimethylaminobenzamide (DMABA) in acetonitrile was found to show highly sensitive response to HSO 4 − over several other anions such as H 2 PO 4 − ,AcO − and ClO 4 − . In the presence of bisulfate anion the dual fluorescence intensity ratio and the total intensity of DMABA decreased while the dual emission band positions remained unchanged. Absorption titration indicated that a 1:1 hydrogen bonding complex was formed between bisulfate anion and DMABA, which gave a binding constant of 2.02×10 4 mol −1 l that is two orders of magnitude higher than those for other anions. The obvious isotopic effect observed in the fluorescence quenching [ K SV ( HSO 4 − )/K SV ( DSO 4 − )=1.63 ] suggests that the hydrogen atom moving is an important reaction coordinate. It was assumed that the dual fluorescence response was due to proton coupled electron transfer mediated by hydrogen bonds within the 1:1 HSO 4 − -DMABA hydrogen-bonding complex.

The Development of Boronic Acids as Sensors and Separation Tools

Synthetic receptors for diols that incorporate boronic acid motifs have been developed as new sensors and separation tools. Utilizing the reversible interactions of diols with boronic acids to form boronic esters under new binding regimes has provided new hydrogel constructs that have found use as dye-displacement sensors and electrophoretic separation tools; similarly, molecular boronic-acid-containing chemosensors were constructed that offer applications in the sensing of diols. This review provides a somewhat-personal perspective of developments in boronic-acid-mediated sensing and separation, placed in the context of the seminal works of others in the area, as well as offering a concise summary of the contributions of the co-authors in the area.

Assembly of N-hexadecyl-pyridinium-4-boronic acid hexafluorophosphate monolayer films with catechol sensing selectivity

The highly water insoluble N-hexadecyl-pyridinium-4-boronic acid hexafluorophosphate is synthesised and investigated for sensor applications. This amphiphilic molecule is immobilised by evaporation of an acetonitrile solution at a basal plane pyrolytic graphite (HOPG) electrode surface and is shown to provide a monolayer film. By varying the amount of deposit partial or full coverage can be achieved. The N-hexadecyl-pyridinium-4-boronic acid hexafluorophosphate monolayer acts as an active receptor for 1,2-dihydroxy-benzene (catechol) derivatives in aqueous media. The ability to bind alizarin red S is investigated and the Langmuirian binding constant determined as a function of pH. It is shown that the immobilised boronic acid monolayer acts as sensor film for a wider range of catechols. A comparison of Langmuirian binding constants for alizarin red S (1.4 × 105 mol−1 dm3), catechol (8.4 × 104 mol−1 dm3), caffeic acid (7.5 × 104 mol−1 dm3), dopamine (1.0 × 104 mol−1 dm3), and L-dopa (8 × 103 mol−1 dm3) reveals that a combination of hydrophobicity and electrostatic interaction causes considerable selectivity effects.