[en] A fluorescent sensor based on phenylamine-oligothiophene derivative 3TEA was reported. This sensor showed highly selective and sensitive detection of Hg²⁺ ion in THF/H₂O (7/3, v/v) solution through fluorescence quenching. The detection was unaffected by other competitive metal ions. The detection limit was found to be as low as 3.952×10⁻⁷ M estimated by the titration method. The recognition process is reversible and confirmed by EDTA experiment. The turn-off fluorescence behavior of mercury interaction with 3TEA has been found to be so fast that it can be used for its qualitative as well as quantitative estimation. - Highlights: • A highly sensitive and selective fluorescence chemosensor 3TEA was reported. • 3TEA features high sensitive with the detection limit for Hg²⁺ ions was as low as 3.952×10⁻⁷ M. • 3TEA can detect Hg²⁺ ion on-line and in real time.

[en] A chemically crosslinked cellulose ester films (MCC-CAD-GA) based on cellulose (MCC), citric acid anhydride (CAD) and L-glutamic acid (L-GA) was successfully prepared via amidation for the adsorption of Cd²⁺, Co²⁺, Ni²⁺, Pb²⁺ and Cu²⁺ ions with lower concentration from water. The obtained composites were characterized by FTIR, XRD, elemental analysis and SEM. The results showed that the thermal stability and mechanical strength of MCC-CAD-GA films were enhanced. The adsorption parameters, such as temperature, contact time, adsorbent dose, pH, and initial metal ion concentration were optimized. The adsorption capability of the composite for heavy metal ions was substantially and synergistically improved by adding L-GA into MCC-CAD. The composite films could be recycled and exhibited constant adsorption ability for five successful runs. In addition, the adsorption behavior followed the pseudo-second order kinetic model, and the adsorption isotherms were well described by the Langmuir model. All the results suggested that the MCC-based composite films could be considered as a promising candidate for heavy metal ions treatment.

[en] Highlights: • There exhibited evidentwavelength-tunable emission. • THF/H 2 O solutions, their emission color can change from green to orange. • Solid-state and their emission color can change from yellow to light red. • When DNT or PA was added, the color observed with the naked eye changes from orange to colorless. Three D-π-A barbituric acid derivatives were synthesized through the knoevenagel reaction between 1,3-dicyclohexylbarbituric acid and different aldehydes (N-Ethyl-3-carbazolecarboxaldehyde, 4-Dimethylaminobenzaldehyde and 4-(N,N-diphenylamino) benzaldehyde), which were named as CB, NB and TNB, respectively. The optical analyses showed the three compounds exhibited evident aggregation-induced emission (AIE) properties in THF/water. TNB emitted the strongest intensity in the aggregate state. The results of molecular dynamics simulation (MDS) showed that TNB has the highest binding energy in the solid state, which may rationalize the stronger emission intensity of TNB. NB exhibited noticeable mechanochromic fluorescence (MCF) performance, with the powder color changing for orange to yellow-brown after being ground. Both NB and TNB exhibited photostability under excitation within 1800 s. Additionally, TNB aggregates exhibited obvious fluorescence quenching to 2, 4-dinitro-toluen (DNT) and trinitrophenols (PA). The K_sv of TNB for DNT, PA were 2.8 × 10⁵ M⁻¹ and 3.4 × 10⁵ M⁻¹ respectively, and the corresponding limits of detection (LOD) were 0.367 μM and 0.296 μM, respectively.

[en] Highlights: • Polymerizable-group capped ZnS was synthesized and copolymerized with acrylic monomers to prepare high refractive index nanocomposite hydrogels. • The uniform dispersibility of ZnS in the nanocomposite hydrogel was confirmed. • The nanocomposite hydrogel contact lens with high RI was fabricated and characterized. • High RI nanocomposite hydrogel contact lens with ultra high loading ZnS nanoparticles. - Abstract: Refractive index (RI) is an important parameter for contact lens biomaterials. In this paper, a novel polymerizable-group capped ZnS nanoparticle (NP) was synthesized by chemical link between hydroxyl group on the surface of ZnS (ME-capped) and isocyanate group of polymerizable molecule of 2-isocyanatoethyl methacrylate. Then the ZnS NP copolymerized with monomer of 2-hydroxyethyl methacrylate (HEMA) and N,N-dimethylacrylamide (DMA) to prepare high refractive index hydrogel contact lens with high content of inorganic ZnS NP. Increasing polymerizable-group capped ZnS content in the hydrogels improved its RI value and mechanical properties, however decreased slightly its transmittance, equilibrium (ESR) and lysozyme deposition on the hydrogel surface. The ZnS-containing hydrogels possessed good cytocompatibility and in vivo biocompatibility in rabbit eyes, demonstrating a potential application as high RI ocular refractive correction biomaterial.

[en] Highlights: • Visualization of AIE process was illustrated by molecular dynamics simulation. • Long alkyl and cyclohexane substituents are introduced into the AIE molecule as hydrophobic groups. • Hydrophobic groups enhances the AIE fluorescence stability in the aggregate state in water. • The CSB-2 still exhibited a superior performance in detecting TNT in aqueous media after placed for a week. Since the aggregation induced emission (AIE) phenomenon was reported, many research groups have used this unique AIE effect to develop chemo- or bio-sensors for detecting ions, gases, explosives, proteins, and enzymes. Most of these sensors work in their aggregate state, therefore, fluorescence stability has become one of the important problem, and unfortunately, as far as we know, there is no paper to discuss what factors can improve the fluorescence stability of AIE compounds in the aggregate state, if the fluorescence stability of the sensors are poor, there will seriously affect the detection result. In this article, we found that compounds with hydrophobic long alkyl substituents can maintain stable fluorescence intensity for a long time in the aggregate state. In addition, cyclohexane is introduced as a hydrophobic substituent. Therefore, the fluorescence stability of the aggregates also increased by 90% within 1800s. The aggregation solutions of CB-3 and CSB-2 were left for two weeks, and no significant changes were found in the fluorescence intensity. Molecular dynamics simulation (MDS) shows that the presence of hydrophobic substituents in compounds cause the molecules to be closely interspersed with each other, hence, making it difficult to change the optical properties, microstructure and stacking mode of the AIE aggregates by external stimulations. The introduction of hydrophobic substituents improves the fluorescence stability of AIE compounds, and makes the AIE phenomenon more valuable in the fields of biological/chemical sensing and imaging.

[en] Four new barbituric derivatives that bears the furan and thiophene and the 1,3-dimethyl barbituric acid moiety, has been synthesized. These D-π-A type conjugated compounds showed obvious intramolecular charge transfer (ICT) properties, which were evidenced by theoretical calculations and spectral analysis. The compounds exhibited Aggregation induced emission (AIE) characteristic. TOB-1 and FTB-1 were quite weakly emission in pure THF, while a significant AIE effect was observed in water/THF (f_w = 70% and 90%) mixtures with a large AIE factor of 40.5 and 46.8. Barbituric acid derivatives with thiophene electron donating group possess the distinct mechanofluorochromic (MFC) behavior. The original powder of FTB-1, BFTB-2 and TFTB-4 could emit strong orange-yellow (614 nm), orange-red (663 nm) and yellow (571 nm) light under UV irradiation, while the fluorescence color changed into orange (629 nm), red (691 nm) and orange yellow (583 nm) emission after grinding, respectively, a red shift of 15, 28 and 12 nm was observed, respectively. Among them, the emission color of compound BFTB-2 can be observed by naked eyes. Such mechanochromism was reversible upon the treatment of grinding and fuming with CH₂Cl₂. The XRD studies of the powders showed that the MFC behavior of FTB-1 and BFTB-2 might be switched reversibly under the stimulus of external force because of the decrease in crystallinity. The resultant red shift of TFTB-4 was attributed to the planarization induced by grinding.