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Cooperation between organelles is essential to maintain the normal operation of the cell. A lipid droplet (LD), a dynamic organelle, is specialized in lipid storage and can interact physically with mitochondria in several cell types. However, an appropriate method for in situ studying the interaction relationships of mitochondria-LDs is still lacking. Herein, a charge-dependent strategy is proposed for the first time by considering adequately the charge difference between mitochondria and LDs. According to the novel strategy, we have developed a unique fluorescent probe Mito-LD based on the cyclization and ring-opening conversion. Mito-LD could simultaneously stain mitochondria and LDs and emit a red and green fluorescence, respectively. More importantly, with the probe Mito-LD, the in situ interaction relationships of mitochondria-LDs were investigated in detail from LD accumulation, mitochondrial dysfunction, lower environmental temperatures, and four aspects of apoptosis. The experimental results showed that mitochondria played an important role in LD accumulation, and the numbers and size of LDs would increase after mitochondrial dysfunction that may be due to excess liposomes. In addition, as an energy storage organelle, LDs played an important role in helping to coordinate mitochondrial energy supply in response to cold. In addition, the Mito-LD revealed that the polarity of mitochondria was higher than that of LDs. In a word, the probe Mito-LD could serve as a potential tool for further exploring mitochondria-LD interaction mechanisms, and importantly, the charge-dependent strategy is valuable for designing robust new probes in imaging multiple organelles.

The development of sensitive, cheap, and portable methods for detecting nitroaromatics explosives has a profound significance and value for public health and environmental protection. For this purpose, a new D-π-A barbituric acid derivative CB-CYH with aggregation-induced emission (AIE) behavior was synthesized, which can interact with picric acid through photoinduced electron transfer (PET). Scanning electron microscopy (SEM) and dynamic light scattering (DLS) indicate that the enhanced emission of the compounds is related to the formation of nano-aggregates. It is well known that an important source of mechanochromic fluorescence (MCF) characteristic materials is the compound with AIE characteristics. The chemosensing test paper prepared by aggregated nanoparticles based on AIE properties is often subjected to external friction or squeeze during transportation or storage, resulting in changes of their optical properties, and destruction of test paper followed. Therefore, the development of compounds with AIE properties and stable optical properties in the presence of external stimuli is particularly important for chemosensing test paper. Molecular dynamics simulation (MDS) shows that the presence of hydrophobic cycloalkyl group in CB-CYH, which caused the molecules to be closely interspersed with each other; hence, it is difficult to change the microstructure and stacking mode of molecules by external stimulation simultaneously; the optical properties are not changed by external stimuli. Therefore, the test paper based on the AIE effect of CB-CYH was developed as chemosensing test paper for the detection of nitroaromatics.

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. A chemically crosslinked cellulose ester films 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 modified could be recycled and exhibited constant adsorption performance for five successful runs.

Two barbituric acid derivatives CB-Ph and CB-Me were synthesized, both of which show a strong aggregation induced emission (AIE) effect. It was found that these two compounds show almost the same absorption and emission spectra. As a result, they show the same yellow color in daylight and the same yellow-green color under UV at 365 nm. Upon grinding, CB-Ph exhibits superior mechanochromic fluorescence (MCF) properties, with its fluorescence color from yellow-green (555 nm) to brown (580 nm) and its emission intensity decreases by 93%. However, neither the fluorescence peak wavelength nor the intensity of CB-Me shows observable changes after being ground, indicating no MCF effect. The X-ray diffraction (XRD) data indicate that the CB-Ph powder changes from the crystalline to amorphous state after being ground, whereas CB-Me remains in its crystalline state. Molecular dynamics simulation (MDS) shows that CB-Ph takes a 3D conformation due to three phenyl groups on the periphery of the molecule, which hinders the molecules from aggregating closely and results in the change of the microstructure by external force stimuli. However, CB-Me aggregated more closely due to its better planarity and hydrophobic n-hexane group, which make it difficult to change the microstructure upon being ground. Based on the unique optical properties of CB-Ph and CB-Me, a new data encryption-decryption technology is developed. CB-Ph is used as cryptographic ink due to its excellent MCF effect upon grinding. CB-Me is used as a camouflage material as it shows the same color as CB-Ph in the daylight and under UV-365 nm; furthermore, its colors remain unchanged after being ground.

Visualizing cholesterol (CL) fluctuation in plasma membranes is a crucially important yet challenging task in cell biology. Here, we proposed a new imaging strategy based on permeability changes of plasma membranes triggered by different CL contents to result in controllable spatial distribution of single fluorescent probes (SF-probes) in subcellular organelles. Three spatial distribution-controllable SF-probes (PMM-Me, PMM-Et, and PMM-Bu) for imaging CL fluctuation in plasma membranes were rationally developed. These SF-probes target plasma membranes and mitochondria at normal CL levels, while they display solely staining in plasma membranes and mitochondria at increased and decreased CL levels, respectively. These polarity-sensitive probes also show distinct emission colors with fluorescence peaks of 575 and 620 nm in plasma membranes and mitochondria, respectively. Thus, the CL fluctuation in plasma membranes can be clearly visualized by means of the spatially distributed and two-color emissive SF-probes.

A new carbazole-based naked-eye colorimetric and fluorescent sensor CPPB with aggregation induced emission (AIE) effect was successfully synthesized. The solid powder of CPPB emitted intense yellow fluorescence, and its emission wavelength and fluorescence intensity in DMSO/H2O solution varied with the percentage of water (fw). Nano-aggregates of CPPB molecules were prepared by increasing fw of DMSO/H2O solution, and the optimal aggregation state of CPPB was reached in 99% aqueous DMSO solution with the maximum fluorescence intensity. Moreover, CPPB displayed high selectivity and sensitivity toward cyanide anions (CN−) in 99% aqueous DMSO solution even in the presence of other competitive anions (CN−, F−, Cl−, AcO−, NO3−, I−, CO32−, HCO3−, HSO3−, SO42−, S2−, HS−, OH−, H2PO4− and HPO42−) and the reactive oxygen species (H2O2, O2·−, 1O2, t-BuOOH and ·OH). The sensing mechanism for CN− was confirmed by optical spectral studies, 1H NMR titration, HRMS spectra, Job's plot analyses and DFT calculations. Sensor CPPB for CN− detection revealed extremely low detection limit (67.4 nM), high anti–interference ability, wide pH response range (3.0–10.0) as well as the immediate response (15 s). Furthermore, the CPPB-based test strips were applied to detect CN− qualitatively and quantitatively in 100% aqueous solution.

A new dibenzothiophene-based barbituric acid derivative (DTB) with an aggregation induced emission (AIE) effect was synthesized as a naked-eye colorimetric and fluorescent probe for CN−. The UV-vis spectra and fluorescence spectra of DTB in a DMSO/H2O mixture changed with different water fractions (fw). Nano-aggregates of DTB were formed with the strongest fluorescence emission when fw reached 99%. Furthermore, DTB expressed good selectivity and high sensitivity for CN− in 99% aqueous DMSO solution. The sensing mechanism of DTB for CN− was confirmed by 1H NMR titration, HRMS spectra, Job's plot and DFT calculations. Furthermore, DTB detected CN− with a low detection limit (21.6 nM), wide pH range (4–10), high anti-interference ability and fast response time (10 s). Moreover, DTB-based test strips were prepared for CN− detection, and DTB could detect CN− in real water samples.

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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 (fw = 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.

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.

Herein, an environmentally friendly electrochemical approach is reported that takes advantage of the captodative effect and delocalization effect to generate nitrogen-centered radicals (NCRs). By changing the reaction parameters of the electrode material and feedstock solubility, dearomatization enabled a selective dehydrogenative C-N versus N-N bond formation reaction. Hence, pyrido[1,2-a]benzimidazole and tetraarylhydrazine frameworks were prepared through a sustainable transition-metal- and exogenous oxidant-free strategy with broad generality. Bioactivity assays demonstrated that pyrido[1,2-a]benzimidazoles displayed antimicrobial activity and cytotoxicity against human cancer cells. Compound 21 exhibited good photochemical properties with a large Stokes shift (approximately 130 nm) and was successfully applied to subcellular imaging. A preliminary mechanism investigation and density functional theory (DFT) calculations revealed the possible reaction pathway.

Among the natural polymers able to form edible films, starch and gelatin (Gel) are potential sources. Corn starch is a polysaccharide widely produced around the world, and gelatin differs from other hydrocolloids as a fully digestible protein, containing nearly all the essential amino acids, except tryptophan. Based on this, with advantages such as abundance, relatively low cost, biodegradability, and edibility, studies considering alternative systems for food protection that utilize biopolymers have increased significantly in recent years.; Results: A novel macromolecular crosslinker starch-BTCAD-NHS (starch-butanetetracarboxylic acid dianhydride-N-hydroxysuccinimide, SBN) was successfully prepared to modify gelatin film. Compared with the blank gelatin films, the resulting SBN-Gel films exhibited improved surface hydrophobicity, higher tense strength and elongation-at-break, lower Young's modulus values, greater opacity, poorer water vapour uptake properties and better anti-degradation capacity.; Conclusion: The modified gelatin film material with advanced properties obtained in this work was safe, stable eco-friendly and biorefractory, and was an ideal choice to form packaging in the food industry. Also, the crosslinking SBN-Gel coating was effective in reducing corruption and extending the shelf life of peeled apple substantially. © 2018 Society of Chemical Industry.; © 2018 Society of Chemical Industry.

An electrospun membrane (CB-PS) was prepared by electrospinning technique from a solution of aggregation induced emission (AIE) active compound 5-(N-carbazole styryl)-1,3-dimethyl-barbituric acid (CB) and polystyrene (PS) in DMF/THF. The membrane was electrospun upon amino-functionalized glass [G-NH2], producing a fluorescent sensor [CB-PS]/[G-NH2] for detecting picric acid (PA). The AIE-active compound were highly photostable and the sensor [CB-PS]/[G-NH2] exhibited high selectivity and sensitivity for the detection of PA over nitroaromatics (NACs) in aqueous phase. The quenching constant (KSV) to PA was obtained to be 3.29 × 104 M−1 in aqueous phase with a limit of detection (LOD) up to 228 ppb. Selectivity study demonstrates that common interferents have an insignificant effect on the emission intensity of the fluorescent nanofibers in aqueous phase, while reusability study indicates that the fluorescent nanofibers can be regenerated. Real water sample was also tested, and negligible matrix effect on explosives detection was observed. The fluorescence quenching by PA can be attributed to the photo-induced electron transfer (PET) in the quenching process. This research provides new insights into the application of AIE-active materials in fluorescent nanofibrous explosive sensor.

A double-layered sensor was prepared by an electrospinning method using pyrene, polystyrene, and gelatine to prepare a pyrene-polystyrene/gelatin/glass device for the determination of nitroaromatic...

Nanocomposites have attracted more attention due to their extensive applications. However, it is still a huge technological challenge in fabrication of transparent hybrid materials because of nanoparticle aggregation resulting from their high specific surface energies. In this paper polymerizable molecule was controlled chemically grafted onto ZnS nanoparticles to obtain polymerizable-group-capped nanoparticles that can copolymerize with a mixture of acrylic monomers of N,N-dimethylacrylamide (DMA) and 2-hydroxyethyl methacrylate (HEMA) or glycidyl methacrylate (GMA) or methyl methacrylate (MMA) to prepare transparent high refractive index (RI) nanocomposite hydrogels. The dispersion homogeneity of the nanoparticles in the nanocomposites was studied by dynamic mechanical thermal analysis (DTMA), transmission electron microscopy (TEM), scanning electron microscopy (SEM), and energy dispersive X-ray mapping analysis (EDX). Moreover, the nanocomposites were characterized by transmittance, mechanical properti...

A hyperbranched porous polymer P based on adamantane and pyrene was synthesized through the Sonogashira coupling reaction. The three-dimensional rigid molecular skeleton of adamantane makes polymer P porous. Compound M, which acts as the block moiety between two adamantane groups in polymer P, was also synthesized for the control experiment. Compared with M, the characteristics of P changed remarkably with it exhibiting different emission behaviors and performances for the detection of DNT. In saturated DNT vapor, the quenching efficiency (ηEP) of film P (82%) was remarkably superior compared with that of film M (22%). In addition, a series of films with different thicknesses and different amounts of polymer P were prepared. Results showed that the quenching efficiencies did not change with an increase in the film thickness.

The functionalized cellulose ester MCN was firstly synthesized and used to cross-link gelatin by amidation between -NH2 in gelatin and active ester groups in MCN to form a composite polymer network Gel-MCN, which was confirmed by Van Slyke method, FTIR, XRD and TGA-DTG spectra. The model drug omeprazole was loaded in Gel-MCN composites mainly by electrostatic interaction and hydrogen bonds, which were certified by FTIR, XRD and TGA-DSC. Thermal stability, anti-biodegradability, mechanical property and surface hydrophobicity of the composites with different cross-linking extents and drug loading were systematically investigated. SEM images demonstrated the honeycomb structural cells of cross-linked gelatin networks and this ensured drug entrapment. The drug release mechanism was dominated by a combined effect of diffusion and degradation, and the release rate decreased with cross-linking degree increased. The developed drug delivery system had profound significance in improving pesticide effect and bioavailability of drugs.

A novel hydrophilic polymer based on hydroxyl group grafted onto the side chain of polymer was successfully synthesized. Due to the hydrophilic of hydroxyl groups, the hydrophilic polymer overcame the drawback of fluorescent conjugated polymer insoluble in water. Polymer chains evenly distributed in aqueous solution and possessed the signal amplification effect in the aqueous phase. The hydroxyl groups in polymer could effectively absorb nitroaromatics (NACs) by hydrogen bonding interaction between NACs and hydroxyl groups. When the TNT and DNT concentration was 1.08 × 10 −4 mol/L and 1.44 × 10 −4 mol/L respectively, the quenching efficiency ( η EP ) of polymer reached 93% and 91%. The limit of detection of the polymer to DNT and TNT solution are 7.4 × 10 −7 mol/L and 1.1 × 10 −6 mol/L, respectively. Fluorescence quenching studies demonstrated that the hydrophilic polymer was highly sensitive towards NACs. Moreover, the excellent property of selectivity indicated the hydrophilic polymer might be a promising sensor in the monitoring field of the underwater hidden explosives and water environmental quality.

Two phenylcarbazole-based dimers, namely, 9,9'-diphenyl-9 H ,9' H −3,3'-bicarbazole ( 1 ) and 9,9'-bis(4-bromophenyl)−9 H ,9' H −3,3'-bicarbazole ( 2 ), have been obtained through the oxidation of 9-phenylcarbazole and 9-(4’-bromophenyl) in the presence of FeCl 3 , respectively, which show strong photoluminescent properties with the fluorescence quantum yields of 0.2 and 0.21 based on the reference of Quinin sulfate, respectively. The maximal emission peak of compounds 1 and 2 were observed at 465 and 413 nm in the solid state, respectively, revealing that the luminescent properties were tuned by the substituent group. The title compounds were characterized by FI-IR, UV–vis, 1 H-NMR, 13 C-NMR, 1 H− 13 C NMR, mass spectra, elemental analysis (EA) and single-crystal X-ray diffraction. Both compounds 1 and 2 crystallize in space group P -1, and supramolecular hydrogen bondings and stacking interactions between aromatic rings are observed. Compounds 1 and 2 display trans- and cis- formation structures, respectively. Two compounds show high thermal stabilities, in which the decomposition temperature is 414 and 363 °C for 1 and 2 , respectively.

Carbazole-based linear conjugated polymer (P 1 ) and hyperbranched conjugated polymer (P 2 ), were successfully synthesized with high molecular weights and good solubilities through Sonogashira coupling reactions. Compared with P 1 , the charactyeristics of P 2 were remarkably changed by exhibiting outstanding thermal stabilities and different emission behaviors. In this work, a superquenching effect was observed in the TNT-detection process by using P 2. The calculated Stern-Volmer quenching constant revealed that P 2 was more sensitive than P 1 towards TNT in solution, owing to the hyperbranched structure of P 2 had multiple exciton migration channels and diffusion pathways via numerous branches in the two-dimensional (2D) space. Simultaneously, quenching efficiency of P 2 was higher than that of P 1 , due to hyperbranched structure of P 2 had multiple exciton migration channels.

In recent years, many types of food-packaging films and composites have been prepared using gelatin because of its good film-forming ability, non-toxic nature and cost-effectiveness. However, the relatively weak thermal stability, poor mechanical properties and easily-degradable quality limit the potential application of gelatin as a practical material. Microcrystalline cellulose (MCC), which comprises one of the most abundant biomass resources, has been regarded as a safe and reliable food additive because it has the same ingredients as the cellulose in people's daily intake. Food-packaging films with the excellent properties provided by gelatin and oxidized-cellulose represent a topic of great interest.; Results: MCC was modified by 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO)-mediated oxidation and chosen as the base of the macromolecule cross-linker (TMN). After modification of gelatin film by TMN, the minimum amount of free -NH2 in solution was 4.8 × 10-4 mol g-1 ). The thermal property obviously increased (from 322.31 o C to 352.63 o C) and was crucial for usage in the food industry. The highest water contact value 123.09° (η = 25%) indicated a better surface hydrophobicity. The higher Eab (58.88%) and lower Em (77.16%) demonstrated that a more flexible and shatter-proof material was obtained. Water vapor uptake studies suggested increased moisture absorption and greater swelling ability.; Conclusion: The film material obtained in the present study was safe, stable, eco-friendly and biorefractory and could also be decomposed completely by the environment after disposal as a result of the properties of the ingredients gelatin and cellulose. The incorporation of a cellulosic cross-linker to gelatin-based films was an ideal choice with respect to developing a packaging for the food industry. © 2016 Society of Chemical Industry.; © 2016 Society of Chemical Industry.

Functionalization of microcrystalline cellulose (MCC) with 1,2,3,4-butanetetracarboxylic acid dianhydride (BTCAD) was obtained by esterification reaction. A novel macromolecule cross-linker, MCC-BTCAD-NHS (MBN), was successful prepared through amidation between N-hydroxysuccinimide (NHS) and MCC-BTCAD to modify gelatin films. The reaction between gelatin and MBN was confirmed by the residual free amino test, FTIR, elemental analysis, and XRD spectra. The results indicated that the addition of MBN into gelatin decreased the film degradation ratio and increased its thermal stability, flexibility, hydrophobicity, light barrier performance, and water adsorption ability. In addition, SEM images further proved the successful cross-linking reaction. The particular gelatin film material with excellent performance ended up the limitation of blending modification method for gelatin with natural macromolecule and extended its application in many fields.

Efficient migration of excitons in conjugated polymers is important for sensor devices. In this study, we make use of pyridine and styrene as the sensing units to design the two-dimensional hyperbranched conjugated polymer P 2 (poly(2,3,5,6-styrylpyrazine)s) and the one-dimensional linear conjugated polymer P 1 (poly(2,5-styrylpyrazine)s) along with their two corresponding model compounds ( M 1 , M 2 ) to study the orbital energies of LUMO (the lowest unoccupied molecular orbital) and HOMO (the highest occupied molecular orbital). Interestingly, comparing with the Stern-Volmer constants ( K sv ) of P 1 ( K sv = 2.49 × 10 4 M −1 ), P 2 shows excellent sensibility ( K sv = 6.84 × 10 4 M −1 ) in the presence of TNT (2,4,6-trinitrotoluene), indicating that super quenching effect may get involved in P 2 . The superior fluorescent quenching performance of P 2 could be explained by the following theories: (i) hyperbranched conjugated polymers afford multi-dimensional transport pathways for excitons to migrate; (ii) The LUMO of P 2 is closer to that of TNT molecules; (iii) Quenching speed is positively correlated with the rate of electron transfer. In addition, the fluorescence lifetimes of the polymers are almost constant as the TNT concentration increased, indicating that the sensing mechanism could be static quenching.

Three new metal coordination complexes, namely [Co(IPA)(4PBI)]·H2O (1), [Cd(IPA)(4PBI)(H2O)] (2) and [Cd(TPA)(4PBI)(H2O)] (3) [4PBI = 2-(pyridine-4-yl)-(1H)-benzoimidazole, IPA = isophthalate and TPA = terephthalate], were obtained under hydrothermal conditions by reacting cobalt and cadmium salts with 4PBI and IPA or TPA. Complexes 1–3 were structurally characterized by X-ray single-crystal diffraction, EA, IR and PXRD. All of these complexes display low dimensional features with one-dimensional (1D) motifs. Complex 1 is a 1D tape-like structure containing bi-nuclear units, which is further extended into a 3D supramolecular architecture through intermolecular hydrogen bonds and stacking interactions. Complex 2 shows a 1D structural motif, which is further assembled into a 3D supramolecular architecture by hydrogen bonds and packing interactions. Complex 3 is also a 1D chain. Through intermolecular hydrogen bonds and π⋯π packing interactions, a 3D supramolecular network is also generated for 3. The luminescent properties of complexes 2 and 3 were investigated in the solid state at room temperature. Additionally, thermogravimetric analysis (TGA) of 1–3 has been discussed in details.

Four barbituric derivatives (1–4), were synthesized with obvious aggregation induced emission (AIE) or aggregation induced emission enhancement (AIEE) behaviors. The optical properties in different states and the mechanisms of the enhanced emission of 1–4 were investigated. We found that there were a large number of globular or blocky nanoparticles with average diameters from 229 to 394 nm in tetrahydrofuran (THF)/water solutions when the water fraction (fw) was 90%. The single crystal data of 2 and 4 reveal that multiple intermolecular interactions restrict the intramolecular motions, and promote the formation of a herringbone arrangement (4), thus permitting intense emission in the aggregate state. In addition, the frontier molecular orbital energy and band gap calculated by density functional theory (DFT) are consistent with the experimental results. Compound 4 is cell-permeable: upon entering the live cells, the dye molecules can accumulate in the lysosomes and turn on the fluorescence.

Intelligent responsive materials with switchable wettability surfaces are of great importance in the field of oil/water separation. Here, a distinctive pH-responsive bio-based oil/water separation material was prepared. A low-cost titanium dioxide (TiO

Three new nonplanar barbituric derivatives, named as TTB, TTTB, and TOB, were synthesized. The D-π-A type conjugated compounds showed obvious intramolecular charge transfer (ICT) property, which was evidenced by theoretical calculations and spectral analyses. All of them exhibited aggregation induced emission (AIE) when formed nanoaggregates. These nanoaggregates also showed reversible mechanofluorochromism (MFC). Their red light emission became deep red after grinding and then recovered with dichloromethane fuming. Hence, a strategy to fabricate mechanofluorochromic nanoaggregate phosphors via nonplanar π-skeleton and steric effect was demonstrated, and these nanophosphors possess potentials for mechanosensors and anticounterfeiting technology.

Barbituric acid derivatives with typical aggregation induced emission (AIE) are reported. Their emission wavelengths varied with water fraction of their solution. UV–visible absorption spectroscopy and theoretical calculations revealed the intramolecular charge transfer (ICT) possibility from donor to acceptor and the mechanism was confirmed as a restriction of intramolecular motion (RIM). The AIE properties were affected by the different substituents on barbituric acid. When the molecular volume increased, the AIE effect decreased. Fluorescent quenching mechanism was applied to detect nitroaromatic explosives. For 2,4,6-trinitrophenol (PA), one of the derivatives 5-(4-diphenylamino styrene)-1,3-diphenyl-barbituric acid in THF/H2O mixture (1:9, v/v), showed amplified fluorescence quenching with a maximum Stern–Volmer quenching constant of 4.1 × 104 M−1. The solid phase paper test based on 5-(4-diphenylamino styrene)-1,3-diphenyl-barbituric acid also showed a superior sensitivity toward PA both in vapor and solution.

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 Ksv 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.

Based on dibenzothiophene fluorophore, a new colorimetric and fluorescent sensing material 2-(dibenzothiophenyl-4-ethenylidenyl)-1,3-indanedione (DTI) was developed, which was a favorable turn-off fluorescent sensor of monitoring CN– ion at extremely low detection limit (0.14 μM) in 99 % aq. DMSO solution. The response mechanism of DTI towards CN– could put down to nucleophilic attack of cyanide group (CN–) toward the double-bond between the dibenzothiophene and the 1,3-indanedione units, which breaking intramolecular charge transfer (ICT) process. This mechanism was proposed by 1H NMR, Job’s titration and DFT calculation, leading to a significant fluorescence attenuation and a visual color change. The absorption and emission experiments demonstrated that it showed highly sensitive, selective and good stability for CN– in DMSO/H2O (1:99, v/v). Moreover, DTI displayed high effectiveness in monitoring the CN– in test strips achieved to conveniently determinate CN– by naked-eye without any instruments.

Conjugated polymer P, which was synthesized by introducing 9,9-diphenylfluorene and thiophene units into the backbone of poly(fluorenylene ethynylene), showed high sensitivity in detecting nitroaromatics. A double-layer sensor, named P-PS/GEL, was prepared by electrospinning technique using polymer P, polystyrene (PS), and gelatin (GEL). A nanofibrous membrane from the mixture of PS and P as the top layer (P-PS) served as the sensing layer for detecting nitroaromatics (NACs). A gelatin nanofibrous membrane as the bottom layer (GEL) served as porous scaffold for the top layer. Therefore, apart from transferring into the top layer directly from above, the NACs molecules could also approach the top sensing layer through the bottom porous layer. This double-layer conformation greatly improved the permeability of the P-PS layer. As a result, the double-layer sensor exhibited a greater quenching efficiency (Q f) of 75 % than that of the single-layer P-PS (55 %). Importantly, the sensor showed good reversibility of quenching process after being exposed to saturated DNT vapor for 6 cycles.

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.

A phenylamine-oligothiophene-based fluorescent sensor 2TBEA was reported. This sensor exhibited highly selective, sensitive and rapid detection of Hg(2+) ion in THF/H2O (7/3, v/v) solution through fluorescence quenching. The detection was unaffected by the coexistence of other competitive metal cations including Na(+), K(+), Ag(+), Ca(2+), Fe(3+), Al(3+), Co(2+), Cu(2+), Ni(2+), Zn(2+), Pb(2+), Cd(2+), Fe(2+) and Cr(3+). A1:1 binding ratio for 2TBEA - Hg(2+) was demonstrated by Job's plot and mole-ratio curves. The coordination process was chemically reversible with EDTA. The detection limit was evaluated to be as low as 6.164×10(-8)M.

A novel sensing material (Gel-P) based on conjugated carbazole polymer grafted onto gelatin was successfully synthesized by spin-coating way. The grafting reaction between gelatin and Polymer P was confirmed by ATR-FTIR spectra of Polymer P and the content of residual amino group in gelatin solution. After UV irradiation for 30 min, the fluorescence intensity of Gel-P only reduced by 7.6%, while the polystyrene film doped with polymer P (Ps + P) decreased by 32.4%, indicating higher capability in inhibiting photobleaching for Gel-P due to the presence of tryptophan in gelatin and the fixation effect of gelatin molecules to polymer chains via hydrogen bonds between amino and hydroxyl. Exposed to saturated DNT vapor, the Gel-P sensor exhibited a high quenching efficiency (Qf) of 60% after 50 s and the fluorescence of P in Gel-P film was completely quenched for 300 s owing to the plenty of NH2 and OH groups in gelatin, which could effectively absorb nitroaromatics (NACs) by hydrogen bonding interaction between NACs and gelatin. After being exposed to saturated DNT vapor for 300 s, the Gel-P sensor showed good reversibility of quenching process.

A functionalized glass sensor (G-P) was prepared for detecting nitroaromatic compounds (NACs) by chemically immobilizing a conjugated polymer P on the surface of a glass slide. The monolayer film sensor had several advantages: the signal amplification effect of conjugated polymers, no leakage of sensing materials in solution, and good permeability for the analytes. Fluorescence quenching studies demonstrated that the sensor was highly sensitive to NACs. When the DNT concentration was 1.03 × 10–7 mol/L, the quenching efficiency (1–I/I 0) of G-P reached 52.8%. Moreover, the excellent properties of reversibility, selectivity and sensitivity indicated the glass G-P might be a promising sensor in the field of explosives detection.

A dicyanoisophorone-based turn-on chemodosimeter 1 has been designed and synthesized to detect Cu2+ in aqueous media via selective hydrolysis reaction of the picolinate moiety accompanied with generating the fluorophore. The probe 1 exhibited remarkably selective fluorescence enhancement with a 164 nm Stokes shift and highly significant color change to Cu2+ over other metal ions. The limit of detection of probe 1 was calculated as low as 0.2 μM for Cu2+. The probe 1 was also successfully applied to fluorescence imaging of Cu2+ in HeLa cells.

A fast-responsive fluorescent phenylamine-oligothiophene sensor 3TDDA was reported. This sensor exhibited highly selective and sensitive detection of Hg(2+) ion in aqueous solution (THF/CH3CN/H2O, 45/50/5, v/v) through fluorescence quenching. The detection was not affected by the coexistence of other competitive metal ions such as Na(+), K(+), Ag(+), Ca(2+), Fe(3+), Al(3+), Co(2+), Ni(2+), Zn(2+), Pb(2+), Cd(2+), Fe(2+) and Cr(3+). A stoichiometric ratio (1:1) of the sensor and Hg(2+) was determined by a Job's plot and mole-ratio curves. The binding of sensor 3TDDA and Hg(2+) was also chemically reversible with EDTA. The detection limit was calculated as low as 4.392×10(-7) M.

N-hydroxysuccinimide-activated furandicarboxylic acid (NHS-FDCA), a novel cross-linker, was synthesized to modify gelatin films. The properties of cross-linked gelatin solution was also explored, which showed residual-free amino and viscosity reached best level when mol(NHS-FDCA)/mol(–NH2) ≥1.5. A more homogeneous film was observed by SEM and DSC results exhibited higher decomposition temperature (T d) compared with original films. The degradation test verified better compatibility of modified gelatin films. Finally, the optimization experiment was carried out via free-NH2 and viscosity test.

Glycidyl trimethyl ammonium chloride-modified chitosan (GMAC-m-CS) was synthesized through nucleophilic substitution of GMAC on CS in isopropanol dispersed system, which was characterized by FTIR and 1H NMR methods. The interaction between GMAC-m-CS and surface active ILs −1-dodecyl (tetradecyl and hexadecyl)-3-methylimidazolium bromide (CnmimBr, n = 12, 14, 16) was studied by surface tension and conductivity methods. The amount of CnmimBr adsorbed on GMAC-m-CS increases first with raising temperature, and then decreases, which reaches the largest amount at 30°C. The amount increases with the increase of alkyl chain length. The surface tension reducing capabilities of GMAC-m-CS/CnmimBr systems increase with temperature, however, decrease with the increase of GMAC-m-CS concentration. The aggregation processes of C14mimBr in solutions without GMAC-m-CS and with high concentration of GMAC-m-CS were entropy driven; however, it is enthalpy driven in solutions with low concentration of GMAC-m-CS. Based on the analysis of properties of GMAC-m-CS/CnmimBr, the interaction model of GMAC-m-CS/ILs was proposed.

In this work, a series of 2-(2-hydroxyphenyl)benzothiazole (HBT) derivatives with an aggregation-induced emission–excited state intramolecular proton transfer (AIE-ESIPT) dual mechanism was synthesized. We systematically investigated their optical properties in solution, aqueous suspension, and the solid state. The fluorescence properties of these five compounds were highly dependent on the solvent environment. Particularly, DMSO and DMF were found to significantly promote deprotonation of the phenolic hydroxyl and favor fluorescence emission from the phenolic anion. The Keto or Enol forms generally could be transformed to phenolic anions with the aid of base in solution. The results from aggregation-induced emission enhancement (AIEE) and red-shifted AIE clearly illustrated the evolution process of the fluorescence spectra, indicating that the three luminescent species in the solution were transformable. The systematic investigation demonstrated that the desired fluorescence could be generated for HBT derivatives by varying the solvents or adding additives, such as base or water, to the solution. Because of the synergistic effect of AIE and ESIPT, these fluorophores exhibited high solid-state quantum yields and large Stokes shifts. These dyes also featured high photostability and tunable emission spectra covering most of the visible light region. Single crystal studies and theoretical calculations elucidated the luminescent properties. When loaded on filter paper, the HBT-based dyes exhibited high-efficiency fluorescence visualization and reversible solid-state luminescence switching under alternating amine and acid vapor treatments. These dyes were used on banknotes for anti-counterfeiting measures, demonstrating the practical applications of these molecules as security inks.

Two barbituric acid derivatives of the similar color and fluorescence have been synthesized with aggregation induced emission (AIE) behaviour. Among them, CB-Ph exhibits crystallization-induced emission enhancement (CIEE) induced by ethanol. Molecular dynamics simulations show that the conformation of CB-Ph in the aggregated state is propeller-like, which prevents strong interaction between molecules and is beneficial to produce CIEE effect. Under the stimulation of dichloromethane (DCM), the solid CB-Ph changes from crystalline to amorphous, resultantly, the emission color of CB-Ph changes from yellow (554 nm) to orange (590 nm) and the emission intensity decreases by 91%. Furthermore, it was found that the emission color and intensity of CB-Ph can be restored by fumigation with ethanol. The crystalline state and amorphous state of CB-Ph can be converted into each other by the treatment with DCM and ethanol. CB-Me takes similar molecule structure to CB-Ph and shows the same emission wavelength with CB-Ph. However, it shows no change in emission color or intensity by the treatment with DCM or ethanol. Based on these two compounds, a new data encryption-decryption techniques developed, in which based on CIEE effect of CB-Ph is used as password ink due to CIEE effect and CB-Me is used as camouflage material without CIEE property.

Intelligent responsive materials with switchable wettability surfaces are of great importance in the field of oil/water separation. Here, a distinctive pH-responsive bio-based oil/water separation material was prepared. A low-cost titanium dioxide (TiO2) and environmentally friendly chitosan (CS) were used to combine with stearic acid (SA) to form the superhydrophobic TiO2@SA/CS coating. The coated materials (cotton fabric, sponge and filter paper) can be converted from superhydrophobicity to superhydrophilicity under ammonia treatment, and the superhydrophobicity can be restored again after heating treatment. The stimuli-responsive surface of the material was applied for the separation of oil/water/oil ternary mixtures and for the effective separation of various surfactant-stabilized water-in-oil emulsions and oil-in-water emulsions before and after wettability conversion. These results may provide a new prospect for the development of intelligent responsive oil/water separation materials with controllable wettability.

Fluorescent conjugated polymers are widely used for trace detection of explosives due to their super-quenching effect. In this work, a hyper-branched conjugated polymer P2 and a linear conjugated polymer P1 were synthesized. Compared with P1, P2 showed the superior sensitivity toward 2,4,6-trinitrophenol (PA). The Stern-Volmer constants (Ksv) of P2 (1.56 × 104 M−1) was 2.7 times higher than that of P1 (0.57 × 104 M−1), and the LODs to PA of P2 (8.8 μM) was 3.2 times lower than that of P1 (24 μM). These data indicated the enhanced super-quenching effect in P2. Due to the electrons transfer among the conjugated backbone of polymer, the super-quenching effect of P1 with one-dimensional (1D) configuration may be defined as “length quenching”, while that of P2 with two-dimensional (2D) configuration can be defined as “Area quenching”. The 2D conjugation nature of P2 provided multi migration channel for excitons, which resulted in the remarkably enhanced super-quenching.

Six different barbituric acid derivatives using ethyl, propyl, butyl, pentyl, hexyl and heptyl groups as hydrophobic substituents were prepared. Molecular dynamics simulation was carried out to study the effect of different carbon chain lengths on the aggregation-induced emission process. Among the compounds, the CB-5 containing a hexyl substituent exhibited the strongest Aggregation induced emission (AIE) effect, not the CB-6 with longest carbon chain. The aggregates of CB-5 was used to detect the 2, 4, 6-trinitrotoluene (TNT) in aqueous media, exhibiting a maximum quenching constant of 3.1 × 105 M−1. The paper sensor based on CB-5 showed a superior sensitivity toward TNT both in vapor and solution. This provided a clear strategy for designing compounds that utilize the hydrophobic interaction of long-chain alkyl chains to enhance the AIE effect.