A disulfide-bridged bispillar[5]arene was synthesized via efficient oxidation of thiol-pillar[5]arene. The resulting disulfide-bridged bispillar[5]arene was successfully applied in constructing linear supramolecular polymers which were confirmed by concentration-dependent 1H NMR spectroscopy, 2D DOSY and viscosity measurements. Such supramolecular polymers manifested redox responsiveness and were fabricated into water dispersible nanospheres with high fluorescence properties.

Cysteine (Cys), homocysteine (Hcy), and glutathione (GSH) are interconnected and play essential roles for regulating the redox balance of biological processes. However, finding a simple and effective method for the simultaneous determination for these three biothiols in biological systems is always a challenge. In this work, we report a method for the simultaneous quantitative determination of three biothiols in a mixture using a monochlorinated boron dipyrromethene (BODIPY)-based fluorometric sensor. At a specified period of time, after reacting with excess sensor, Hcy and GSH form predominantly sulfur-substituted BODIPY, while Cys generates sulfur-amino-diBODIPY due to a fast substitution–rearrangement–substitution reaction. A significant difference in polarities of these respective major products simplifies their separation by TLC, thus leading to the simultaneous determination of Cys, Hcy, and GSH readily. The sensor was successfully applied for the simultaneous quantitative detection of three biothiols in human serum, and the results were in good agreement with those obtained via high performance liquid chromatography (HPLC).Keywords: BODIPY; cysteine; glutathione; homocysteine; serum

We reported a BODIPY-based fluorescent probe for the simultaneous detection of GSH and Cys/Hcy. The nitrothiophenol moiety of the probe serves not only as a leaving group for the thiol-substitution reaction, but also a fluorescence quencher to provide a low emission background. The electron-withdrawing imidazolium group drastically increases reactivity of the Cys/Hcy-induced substitution–rearrangement reaction. The imidazolium group can further be replaced by GSH and resulted in a bithioether-product (λabs = 568 nm, λem = 588 nm), which showed distinct photophysical properties from the amino-product (λabs = 443 nm, λem = 530 nm) in the case of Cys/Hcy. It is noted that they exhibited great differences in absorption spectra of more than 120 nm. Thus, the simultaneous detection of GSH and Cys/Hcy can be achieved at different excitation wavelengths. The probe can quantitatively determinate the amount of Cys, Hcy and GSH in certain concentration ranges. We also found that the probe could detect GSH and Cys in living cells from different emission channels.

We report a facile method for the quantitative detection of cysteine (Cys), homocysteine (Hcy) and glutathione (GSH) in a mixture. BODIPY-based sensors 1 and 2 are synthesized, and the diverse reactivities of 1 and 2 in the presence of a mixture of biothiols lead to distinct absorption spectra at a specified period of time. With a spectral analysis, we are capable of distinguishing three biothiols and achieving the quantitative determination of Cys, Hcy and GSH in a mixture.

Correction for ‘Colorimetric sensors with different reactivity for the quantitative determination of cysteine, homocysteine and glutathione in a mixture’ by Li-Ya Niu et al., RSC Adv., 2015, 5, 13042–13045.

We reported a new monofunctionalized pillar[5]arene bearing imidazolium moiety that formed stable [1]pseudorotaxane even at high concentration (100 mmol/L) in chloroform. The self-assembly was detailed investigated by multiple methods, including varying concentration 1H NMR, 2D COSY NMR, 2D NOESY NMR, viscosity measurements, 2D DOSY NMR, and HR-ESI-MS analysis. [1]Rotaxane was obtained efficiently through photo thiol-ene reaction which further confirmed the formation of [1]pseudorotaxane.A new monofunctionalized pillar[5]arene bearing imidazolium moiety that formed stable [1]pseudorotaxane even at high concentration (100 mmol/L) was reported. [1]Rotaxane was obtained efficiently through thiol-ene reaction from [1]pseudorotaxane which further confirmed the formation of [1]pseudorotaxane.

The introduction of hydroxy group to the 3- or 5-position of 4,4-difluoro-4-bora-3a,4a-diazaindacene (BODIPY) results in unexpected tautomerization to BDPONa with interesting structural and photophysical properties. The core of BDPONa is an anion with sodium cation as counter-ion. BDPONa displays strong fluorescence in organic solvents.We reported a BODIPY analogue with interesting structural and photophysical properties.

Water-dispersible nanospheres of hydrogen-bonded supramolecular polymers have been prepared for the first time by using the miniemulsion method. Nanospheres containing chromophores with high fluorescence quantum yields were fabricated to mimic the natural light-harvesting system.

We report a photoresponsive monofunctionalized pillar[5]arene based on stiff stilbene. The Z isomer, Z-1, tends to form self-complexing [1]pseudorotaxanes and [c2] daisy chains, whereas the E analog, E-1, forms supramolecular polymers.

A McMurry coupling reaction was used for the efficient synthesis of a bis(m-phenylene)-32-crown-10 based cryptand Z-3 with high yield. This photoresponsive cryptand formed host–guest complexes with paraquat derivative 4 and 2,7-diazapyrenium derivative 5. Z-3, and E-3 exhibited similar binding affinity to the small guest 4, while dramatic changes were observed in the binding affinity to the large guest 5.

Compounds comprising one or two quadruply hydrogen bonding units, 2-ureido-4[1H]-pyrimidinone (UPy) and tris(tetraethylene glycol monomethyl ether) moieties, were reported to form highly stable hydrogen-bonded assemblies in water. Compound 1, containing one UPy, assembles into vesicles, and compound 2, containing two UPy units, forms micelles. The aggregates disassemble reversibly when the solution pH is raised to 9.0 or above. The results demonstrate the utility of hydrogen bonding to direct the self-assembly of small-molecule building blocks in aqueous media.

Biological thiols, including cysteine (Cys), homocystein (Hcy) and glutathione (GSH), play crucial roles in maintaining the appropriate redox status of biological systems. An abnormal level of biothiols is associated with different diseases, therefore, the discrimination between them is of great importance. Herein, we present two fluorescent sensors for selective detection of biothiols based on our recently reported intramolecular displacement mechanism. We expanded this mechanism to commercially available chromophores, 4-chloro-7-nitro-2,1,3-benzoxadiazole (NBD-Cl) and heptamethine cyanine dye IR-780. The sensors operate by undergoing displacement of chloride by thiolate. The amino groups of Cys/Hcy further replace the thiolate to form amino-substituted products, which exhibit dramatically different photophysical properties compared to sulfur-substituted products from the reaction with GSH. NBD-Cl is highly selective towards Cys/Hcy and exhibits significant fluorescence enhancement. IR-780 showed a variation in its fluorescence ratio towards Cys over other thiols. Both of the sensors can be used for live-cell imaging of Cys. The wide applicability of the mechanism may provide a powerful tool for developing novel fluorescent sensors for selective detection of biothiols.

Biological thiols, including cysteine (Cys), homocysteine (Hcy) and glutathione (GSH), play important roles in maintaining the appropriate redox status of biological systems. The discrimination between them is of great importance because of their different biological roles. Herein, we present a new near-infrared (NIR) fluorescent sensor Cy-NO2 for selective detection of Cys over Hcy/GSH. The nitrothiophenol group is introduced to quench the fluorescence through photo-induced electron transfer (PET). The sensor undergoes displacement of nitrothiophenol with thiol to turn on the fluorescence. The amino groups of Cys/Hcy further replace the thiolate to form amino-substituted products, which exhibit dramatically different photophysical properties compared to the sulfur-substituted product from the reaction with GSH. By means of more rapid intramolecular displacement of sulfur with the amino group of Cys than Hcy, the discrimination of Cys is achieved. Moreover, Cy-NO2 was successfully applied for bioimaging Cys in living cells.

Control over structural transformations in supramolecular entities by external stimuli is critical for the development of adaptable and functional soft materials. Herein, we have designed and synthesized a dipyridyl donor containing a central Z-configured stiff-stilbene unit that self-assembles in the presence of two 180° di-Pt(II) acceptors to produce size-controllable discrete organoplatinum(II) metallacycles with high efficiency by means of the directional-bonding approach. These discrete metallacycles undergo transformation into extended metallosupramolecular polymers upon the conformational switching of the dipyridyl ligand from Z-configured (0°) to E-configured (180°) when photoirradiated. This transformation is accompanied by interesting morphological changes at nanoscopic length scales. The discrete metallacycles aggregate to spherical nanoparticles that evolve into long nanofibers upon polymer formation. These fibers can be reversibly converted to cyclic oligomers by changing the wavelength of irradiation, which reintroduces Z-configured building blocks owing to the reversible nature of stiff-stilbene photoisomerization. The design strategy defined here represents a novel self-assembly pathway to deliver advanced supramolecular assemblies by means of photocontrol.

Dynamic covalent bonds supplied by reversible anthracene dimerization were combined with pillar[5]arene/imidazole host–guest interactions to construct double-dynamic polymers. Heating such polymers (in solution or as a gel) led to depolymerization by dissociation of either the host–guest complexes alone or the complexes and the anthracene dimers, depending on the extent of heating. The polymers reformed readily upon cooling or irradiation.

Entrapment within surface-crosslinked micelles (SCMs) enhanced the emission of conventional hydrophobic fluorescent dyes, endowed them with excellent water solubility and membrane permeability, and greatly expanded the Stokes shifts without any covalent structural modification of the dyes.

We report a turn-on fluorescent sensor based on nitrothiophenolate boron dipyrromethene (BODIPY) derivatives for the discrimination of cystein (Cys) from homocystein (Hcy) and glutathione (GSH). The sensor was applied for detection of Cys in living cells.

•Indicators based on BODIPY and di-2-picolyamine derivatives were designed.•12 cross-reactive BODIPY indicators provide facile identification of the heavy metal ions.•The collected images were digitized for the semi-quantitative discriminations.•Array technologies and pattern-recognition were combined.A BODIPY(4,4-difluoro-4-bora-3a,4a-diaza-s-indacene)-based fluorometric sensor array has been developed for the highly sensitive detection of eight heavy-metal ions at micromolar concentration. The di-2-picolyamine (DPA) derivatives combine high affinities for a variety of heavy-metal ions with the capacity to perturb the fluorescence properties of BODIPY, making them perfectly suitable for the design of fluorometric sensor arrays for heavy-metal ions. 12 cross-reactive BODIPY fluorescent indicators provide facile identification of the heavy-metal ions using a standard chemometric approach (hierarchical clustering analysis); no misclassifications were found over 45 trials. Clear differentiation among heavy-metal ions as a function of concentration was also achieved, even down to 10−7 M. A semi-quantitative interpolation of the heavy-metal concentration is obtained by comparing the total Euclidean distance of the measurement with a set of known concentrations in the library.A BODIPY-based fluorometric sensor array has been developed for the highly sensitive detection of eight heavy metal ions at micromolar concentration. 12 cross-reactive BODIPY fluorescent indicators provide facile identification of the heavy metal ions using a standard chemometric approach (hierarchical clustering analysis); no misclassifications were found over 45 trials. Clear differentiation among heavy metal ions as a function of concentration was also achieved, even down to 10−7 M.

A fluorometric paper-based sensor array has been developed for the sensitive and convenient determination of seven heavy-metal ions at their wastewater discharge standard concentrations. Combining with nine cross-reactive BODIPY fluorescent indicators and array technologies-based pattern-recognition, we have obtained the discrimination capability of seven different heavy-metal ions at their wastewater discharge standard concentrations. After the immobilization of indicators and the enrichment of analytes, identification of the heavy-metal ions was readily acquired using a standard chemometric approach. Clear differentiation among heavy-metal ions as a function of concentration was also achieved, even down to 10−7 M. A semi-quantitative estimation of the heavy-metal ion concentration was obtained by comparing color changes with a set of known concentrations. The sensor array was tentatively investigated in spiked tap water and sea water, and showed possible feasibility for real sample testing.Highlights► Fluorometric indicators were synthesized combining the BODIPY and multipyridyl receptors. ► Chemometric analysis was successfully applied. ► Heavy-metal ions were discriminated at their wastewater discharge standard concentrations. ► Indicators were immobilized and a simple paper-based sensor was designed.

We report a ratiometric fluorescent sensor based on monochlorinated BODIPY for highly selective detection of glutathione (GSH) over cysteine (Cys)/homocysteine (Hcy). The chlorine of the monochlorinated BODIPY can be rapidly replaced by thiolates of biothiols through thiol–halogen nucleophilic substitution. The amino groups of Cys/Hcy but not GSH further replace the thiolate to form amino-substituted BODIPY. The significantly different photophysical properties of sulfur- and amino-substituted BODIPY enable the discrimination of GSH over Cys and Hcy. The sensor was applied for detection of GSH in living cells.

We have developed a new class of benzothiazolium hemicyanine Cu(II) complex based colorimetric and fluorometric dual-modal chemosensor for the toxic cyanide anion in 100% water solution. This dual-modal response was achieved by the removal of Cu(II) ions from sensor complex in the presence of cyanide to recover the internal charge transfer (ICT) character of the hemicyanine dye. The novel sensor shows good sensitivity with μM-level detection limit, and displays high selectivity to cyanide in the presence of other common interference anions.

Entrapment within surface-crosslinked micelles (SCMs) enhanced the emission of conventional hydrophobic fluorescent dyes, endowed them with excellent water solubility and membrane permeability, and greatly expanded the Stokes shifts without any covalent structural modification of the dyes.

We report a photoresponsive monofunctionalized pillar[5]arene based on stiff stilbene. The Z isomer, Z-1, tends to form self-complexing [1]pseudorotaxanes and [c2] daisy chains, whereas the E analog, E-1, forms supramolecular polymers.

We report a turn-on fluorescent sensor based on nitrothiophenolate boron dipyrromethene (BODIPY) derivatives for the discrimination of cystein (Cys) from homocystein (Hcy) and glutathione (GSH). The sensor was applied for detection of Cys in living cells.

Water-dispersible nanospheres of hydrogen-bonded supramolecular polymers have been prepared for the first time by using the miniemulsion method. Nanospheres containing chromophores with high fluorescence quantum yields were fabricated to mimic the natural light-harvesting system.