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In this study, the homopolymerization of 2,2‐dimethyltrimethylene carbonate (DTC) and its copolymerizations with e‐caprolactone (CL) were carried out in detail using the isothiourea‐based Lewis pairs comprised 2,3,6,7‐tetrahydro‐5H‐thiazolo(3,2‐a)pyrimidine and magnesium halides (MgX₂) with benzyl alcohol (BnOH) as the initiator. The copolymerization of DTC and CL via one‐pot addition produced randomly sequenced copolymers. On the other hand, a well‐defined linear poly(e‐caprolactone)–block–poly(2,2‐dimethyltrimethylene carbonate) (PCL‐b‐PDTC) diblock copolymer was prepared by simple sequential ring‐opening polymerization of CL and DTC. In addition, poly(ω‐pentadecalactone)–block–PDTC diblock copolymer was successfully prepared by the same strategy. Moreover, PDTC–poly(ethylene glycol) (PEG)–PDTC triblock copolymer was synthesized in the presence of PEG 2000. The effects of different polymerization conditions on the polymerization reactions have been systematically discussed. The resulting polymers were characterized by the ¹H and ¹³C NMR spectra, gel permeation chromatography (GPC), differential scanning calorimetry (DSC), and matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometry (MALDI‐ToF MS). The block copolyester structures were confirmed by the ¹³C NMR spectroscopy and DSC characterizations. These results indicated that the supposed mechanism was a dual catalytic mechanism. The proposed mechanism involved activation of the monomer via coordination to the MgX₂, and the initiator alcohol was deprotonated by base. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019, 57, 2349–2355

Although lots of work has reported the structural variations of starch in microwave treatment, most of them are detected in the environment with non-constant microwave power and inhomogeneous heating, and the results are always in poor repeatability. In this study, the equipment with constant microwave power (CPM) and homogeneous heating was designed. And the phase transition of multi-scale structure of rice starch (30% moisture content) caused by CPM treatments with two heating modes, namely rapid microwave heating (RWH) and slow microwave heating (SWH) were investigated systematically. SEM results showed that the surface of starch granules after CPM treatment were rough and broken, and the damage caused by RWH was more distinct than that by SWH. SAXS, XRD and 13C NMR results revealed that the CPM treatment decreased the degree of crystallinity and content of double helices of starch. Moreover, the influence of RWH on the variation of starch granules was greater than that of SWH, which can be attributed to the intensive friction and collision as well as the rapid evaporation of water in RWH treatment. Specifically, it exhibited greater destruction on the linkage of starch and the internal crystalline region in RWH treatment than SWH treatment, thereby resulting in more obvious damages on the lamellar and morphological structure of rice starch. In conclusion, CPM equipment has improved the problems of uneven heating and poor experimental repeatability. After CPM treated starch, the molecular structure of starch was destroyed, which provides a useful method to modify properties of starch.

PtxFe/C/N-GC electrocatalysts were prepared using a composite of Hofmann-like Pt/Fe-based metal–organic frameworks and two-dimensional oxidized graphene. The PtxFe/C/N-GC-700 composite (annealed at 700 °C) exhibited an enhanced mass activity in the electrocatalytic methanol oxidation reaction, which was ten times higher than that of commercial Pt/C (20%) catalysts.

Tetraphenylethylene (TPE) foldamers with double hairpin-turn linkers showing an aggregation-induced emission (AIE) effect have been synthesized for the first time. A crystal structure of a foldamer-TNT complex has been obtained, enabling unprecedented direct observation of the interactions between TNT molecules and the chromophores of the foldamer. Instead of π-π stacking interactions, which have often been considered to be the key mechanism in the binding of TNT by chromophoric receptors, strong n-π interactions between the nitro groups of TNT and the aromatic rings of the foldamer have been found. Exceptionally, by addition of 1 % NaF to a suspension of the foldamer in H2 O/THF (95:5), the fluorescence quenching efficiency by TNT vapor significantly increased from about 20 % to more than 90 %. Even after diluting TNT-saturated air at 25 °C by a factor of 2×104 , an obvious quenching response was observed, indicating that ultratrace TNT vapor (down to 3.4 fg per mL of air) could be detected.

A new [3 + 3] trimeric macrocycle, based on tetraphenylethylene having an aggregation-induced emission effect, could form a interdigitation molecular cage with a big void by host–guest interactions. The cage could accommodate two TNT molecules and detect TNT at the 1.7 fg level per mL of air. Moreover, the cage could give permanent pores that had a BET surface area of 347 m2/g and could adsorb 7.8 wt % CO2 with high CO2/N2 selectivity up to 32 (273 K, 1 bar).

In this study, three isothioureas (ITUs), 2,3,5,6-tetrahydroimidazo[2,1-b]thiazole (ITU 1), 2,3,6,7-tetrahydro-5H-thiazolo-[3,2-a]pyrimidine (ITU 2) and 3,4,7,8-tetrahydro-2H,6H-pyrimido[2,1-b][1,3]thiazine (ITU 3) were prepared. These ITUs coupled with magnesium halides (MgX2) as the cocatalysts, cooperatively promoted the ring-opening polymerization (ROP) of several common lactones (including δ-valerolactone, e-caprolactone, e-decalactone and even of macrolactone ω-pentadecalactone) and 2,2-dimethyltrimethylene carbonate. These cocatalysts were found to exhibit suitable activities and ITU 2 emerged as the most active organic component. The order of activities for the magnesium halides was found to be lying in the following order: MgI2 > MgBr2 > MgCl2. The polymerizations attained high conversions (>90%) under optimal conditions, and produced linear polyesters having predictable molecular weights, narrow polydispersity indices (PDIs < 1.20) and defined end groups, which were derived from the benzyl alcohol initiator. The resulting polymers were characterized using GPC, IR, DSC, NMR and MALDI-ToF mass. The kinetic and chain extension experiments showed that the ITUs/MgX2-cocatalyzed ROPs of e-caprolactone proceeded a living polymerization characteristics. Furthermore, the proposed polymerization mechanism was supposed to be a dual catalytic mechanism, and involved the activation of monomers through coordination to Lewis acids, while the initiator was activated by bases.

A set of new metal coordination polymers constructed from a novel semi-rigid aromatic carboxylate ligand, namely, [M(L)(4PBI)(H2O)]n (M = Ni, Co and Cu for 1, 2 and 3, respectively) and [Cd(L)(4PBI)]n (4) (H2L = 3-(1-carboxyethyl) benzoic acid; 4PBI = 2-(pyridin-4-yl)-(1H)-benzoimidazole), have been synthesized by the hydrothermal reaction, which were characterized by element analyses, FT-IR, UV–Vis diffuse reflection spectra, X-ray single-crystal diffraction, powder X-ray diffraction, and thermogravimetric analyses (TGA). Complexes 1, 2 and 3 are iso-structural. They form a one-dimensional (1D) linear chain structure connected by semi-rigid aromatic anion and further assemble into a three-dimensional (3D) supramolecular framework by π⋯π stacking and hydrogen bonding interactions. Complex 4 possesses two bi-nuclear units and displays two-dimensional (2D) layer which can further extend to a 3D supramolecular architecture via hydrogen bonding and weak packing interactions. Moreover, the luminescent property of complex 4 was investigated in the solid state at room temperature.

Three new metal coordination complexes, namely, [Co(BPO)2(H2O)4](BS)2(H2O)2 (1), [Co(BPO)2(H2O)4](ABS)2(H2O)2 (2), [Co(BPO)2(H2O)4](MBS)2(H2O)2 (3) [BPO=2,5-di(pyridin-4-yl)-1,3,4-oxadiazole, BS=benzenesulphonate, ABS=4-aminobenzenesulphonate, MBS=4-methylbenzenesulphonate] were obtained under hydrothermal conditions. Complexes 1–3 were structurally characterized by single-crystal X-ray diffraction, powder X-ray diffraction, IR and thermogravimetric analyses (TGA). All of them display a zero-dimensional motif, in which strong intermolecular hydrogen bonding interactions (O–H···O/N) and packing interactions (C–H···π and π···π) make them achieve a three-dimensional supramolecular architecture. The primary catalytic results of these three complexes show that high efficiency for the green synthesis of a variety of 3,4-dihydropyrimidin-2(1H)-ones was observed under solvent free conditions through Biginelli reactions. The present catalytic protocols exhibit advantages such as excellent yield, easy isolation, eco-friendly conditions, and short reaction time.

A neutral chiral receptor based on TPE cyclohexylbisurea was synthesized and could discriminate the enantiomers of many different kinds of chiral reagents, including chiral acidic compounds, basic compounds, amino acids, and even neutral alcohols. The (1)H NMR spectra disclosed that the ability of chiral recognition could be ascribed to the multiple hydrogen bonds and CH-π interactions between the TPE urea receptor and the enantiomer of the chiral guest, which led to the selective aggregation of the receptor with one of the two enantiomers. This result exhibited a great potential in enantiomer discernment and high-throughput analysis of enantiomer composition of these chiral analytes by one chiral AIE molecule.

We report three self-assembled iron complexes that comprised an anti-parallel open form (o-Lanti ), a parallel open form (o-Lsyn ), and a closed form (c-L) of diarylethene conformers. Under kinetic control, FeII 2 (o-Lanti )3 was isolated, which exhibited a dinuclear structure with diamagnetic properties. Under light-irradiation control, FeII 2 (c-L)3 was prepared and exhibited paramagnetism and spin-crossover behaviour. Under thermodynamic control and in the presence of indispensable [FeIII (Tp*)(CN)3 ]- , FeII 2 (o-Lanti )3 and FeII 2 (c-L)3 transformed into tetranuclear FeIII 2 FeII 2 (o-Lsyn )2 , which exhibited complete spin-crossover behaviour at T1/2 =353 K.

A tetraphenylethylene (TPE) derivative bearing two dimethylformamidine units was synthesized. The dihydrogen chloride salt of this TPE derivative was soluble in water and showed almost no emission. By addition of phosphate anions, the dihydrogen chloride salt could be transformed into the monohydrogen chloride salt, which was barely soluble and emitted strong fluorescence through aggregation-induced emission (AIE), while many other anions could not bring about a fluorescence enhancement. Meanwhile, the dihydrogen chloride salt and monohydrogen chloride salt could be reversible transformed by addition of acid and base alternately in the presence of phosphate anion, which led to fluorescence turn-on and turn-off. Therefore, the TPE dimethylformamidine holds potential for selectively sensing phosphate anions in water and use as fluorescence pH switch. This study provided a new approach to AIEgen sensors by using formamidine groups.

A new imidazolium macrocycle based on tetraphenylethylene (TPE) has been synthesized. This positively charged macrocycle showed a typical aggregation-induced emission (AIE) effect but fluorescence emission could not be induced by common inorganic anions in aqueous solution, including pyrophosphate bearing four negative charges. However, in the presence of a half equivalent of zinc(II) ions, the addition of pyrophosphate anions could arouse a strong fluorescence while other common inorganic anions gave almost no response. The macrocycle has an inherent cavity with the correct size for binding a pyrophosphate anion, so that the pyrophosphate anion can be easily aggregated together with the macrocycle and a zinc cation, which selectively triggers a turn-on fluorescence.

The identification of explosives is critical for analyzing the background of terrorism activities and the origin of pollution aroused by the explosives, but it is a challenge to discriminate the explosives with a very similar structure. Herein we report a series of TPE-based macrocycles with an AIE effect for the 0.2-4 ppb level detection of TNT among a number of nitro-aromatic compounds through fluorescence quenching in natural water sources, whereas the contact mode approach using portable paper sensors exhibited a high sensitivity for the detection of TNT at 1.0 × 10(-13) M level. The reliability of the quantitative analysis has been confirmed by HPLC. Our findings demonstrate that the TPE-based macrocycles have great potential as excellent sensors for TNT. Moreover, it was found for the first time that the macrocycles could selectively recognize nitroaromatics explosives bearing methyl group through a CH3-π interactions, and even exhibit a sole selectivity for TNT among the very difficultly differentiating nitroaromatics including trinitrophenol and trinitrobenzene.

Anthocyanins and flavonols are important flavonoid metabolites in grapes, making a dominant contribution to the color, the mouth feel and even the flavor of grapes and wines. The accumulation of these flavonoids in grapes is greatly influenced by a many, diverse but interacting factors, of which variety and climate are among the most important ones. In the present study, the anthocyanin and flavonol profiles of four grape varieties (Vitis vinifera L.), Cabernet Sauvignon, Carmenere, Syrah and Merlot, from five major wine regions in China were examined for two consecutive years (2006 and 2007). The results showed that the total anthocyanin content of the berry skins in these cultivars tended to increase from east to west in China, yet the proportion of the acylated anthocyanins displayed the opposite trend. It seemed possible that the western grape regions, with their high altitude and low annual rainfall, had an advantage in producing high level of anthocyanins. In addition, a high proportion of trihydroxylated flavonols were always found in the western region grapes, whereas dihydroxylated flavonols were more prominent in the lower altitude eastern regions. This suggested that the relative amounts of these flavonoid compounds may depend on their corresponding cultivar characteristics, while the amounts are more affected by the environmental factors where they were growing.

A novel imidazolium macrocycle based on bridged tetraphenylethylene (TPE) was synthesized. Because it bears the bridged TPE units, this macrocycle not only displays an aggregation-induced emission (AIE) effect but also exhibits monomer emission, which is very rare in AIE compounds. With aggregation of the macrocycle, the aggregate emission increases while the monomer emission decreases. It was found that this imidazolium macrocycle can form a stable 2:1 complex with C60, which gives rise to quenching of both the aggregate emission and the monomer emission. Unexpectedly, the aggregate emission exhibited a higher quenching efficiency than the monomer emission, probably because one adsorbed C60 molecule could affect more macrocycle molecules in the aggregate.

In this study, a screening and confirmation method for the determination of l-hydroxyproline (Hyp) as a target compound in milk and dairy products using high-performance liquid chromatography with tandem mass spectrometry was developed. The samples were lyophilized after acidic hydrolysis, followed by cleanup with graphitized carbon black to remove pigments. Hyp was separated by a hydrophilic interaction chromatographic column and analyzed by high-performance liquid chromatography with tandem mass spectrometry working with multiple reaction monitoring mode using an electrospray ionization interface in a positive-ion mode. Average recoveries in spiked milk and dairy products ranged from 68.0 to 101.1% with relative standard deviations between 2.0 and 11.7% (n = 7). A reagent-matched standard calibration curve was used for quantification of Hyp, with linear correlation coefficient (R(2)) > 0.99 in the concentration range of 0.1-100 μg/mL. The LOQs were from 0.25 to 5 mg/kg, which were usually sufficient to verify the Hyp in samples. The confirmation concentration of Hyp ranged from 10 to 50 mg/kg.

Proximally dietherified calix[4]arene at lower rim was selectively nitrated to give mononitrocalix[4]arene, dinitrocalix[4] arene, and trinitrocalix[4]arene, respectively, under different reaction conditions. These three nitrocalix[4]arenes could be purified in good yield just by recrystallization, which provided a concise approach to inherently chiral calixarene. It was disclosed by crystal structure of trinitrocalix[4]arene that R-enantiomer and S-enantiomer of it could form a self-included dimer by NO2–HAr hydrogen bond and CH3–Pi interaction in the cavity of the calixarene. In the presence of optically pure (1S,2S)-1,2-diphenyl-1,2-ethanediamine, (1R,2R)-1,2-cyclohexanediamine, cinchonidine, or cinchonine, the two enantiomers of trinitrocalix[4]arene could be discriminated by 1H NMR spectrum.

It was found for the first time that neutral amphiphilc tetraphenylethylene (TPE) derivatives showed an enhanced monomer emission and a decreased aggregate emission when they were included in the cavity of γ-cyclodextrin. This result provided a new insight into the aggregation-induced emission (AIE) effect.

Five new coordination complexes, [CdI2(3-PyBim)](H2O)3 (1), [Cd(SO4)(3-PyBim)(H2O)4] (2), [CdCl2(4-PyBim)2(H2O)2] (3), [CdBr2(4-PyBim)2(H2O)2] (4) and [CdI2(4-PyBim)2(H2O)2] (5) [3-PyBim=2-Pyridin-3-yl-1H-benzoimidazole, 4-PyBim=2-Pyridin-4-yl-1H-benzoimidazole], were obtained under hydrothermal conditions and characterized by single crystal X-ray diffraction, IR, elemental analysis, and powder X-ray diffraction. All of the complexes have mononuclear structures. Among the crystal structures of these complexes, there exist a variety of intermolecular hydrogen bonding interactions and π⋯π interactions, which further extend to a 3-D supramolecular architecture. The solid state photoluminescent properties of 1–5 vary with the electronegativity of the coordination anion. Additionally, the thermogravimetric analyses of these complexes are discussed.

Due to frequent soil Cd contamination and wide use of butachlor in China, there is a need to assess their combined toxicity to soil microorganisms. The combined effects of cadmium (Cd, 10 mg kg −1 soil) and herbicide butachlor (10, 50, and 100 mg kg −1 soil) on enzyme activities and microbial community structure in a paddy soil were assessed using the traditional enzyme assays and random amplified polymorphic DNA (RAPD) analysis. The results showed that urease and phosphatase activities were significantly reduced by high butachlor concentration (100 mg kg −1 soil). When the concentrations of Cd and butachlor added were at a ratio of 1:10, urease and phosphatase activities were significantly decreased whereas enzyme activities were greatly improved at the ratio of 1:5, which indicated that the combined effects of Cd and butachlor on soil urease and phosphatase activities depended largely on their addition concentration ratios. Random amplified polymorphic DNA (RAPD) analysis showed loss of original bands and appearance of new bands when compared with the control soil. Random amplified polymorphic DNA fingerprints suggested substantial differences between the control and treated soil samples, with apparent changes in the number and size of amplified DNA fragments. The addition of high concentration butachlor and the combined impacts of Cd and butachlor significantly affected the diversity of the microbial community. RAPD analysis in conjunction with other biomarkers such as soil enzyme parameters would prove a powerful ecotoxicological tool. Further investigations should be carried out to understand the clear link between RAPD patterns and enzyme activity.

Three new metal coordination polymers, namely, [Co(DPP)2(H2O)2]·(BS)2·2H2O (1), [Co(DPP)2(H2O)2]·(ABS)2·2H2O (2) and [Co(DPP)2(MBS)2] (3) [DPP = 1,3-di(pyridin-4-yl)propane, BS = phenyl sulfonic acid, ABS = p-aminobenzene sulfonic acid, MBS = p-methylbenzene sulfonic acid] were obtained under hydrothermal conditions. Complexes 1–3 were structurally characterized using X-ray single-crystal diffraction, XRD and IR spectroscopy. Both complexes 1 and 2 display a 1D tape structure. Meanwhile, complex 3 exhibits a 2D layer and further stacks via C–H⋯π interactions to generate a three-dimensional supramolecular architecture. These three metal coordination polymers have been applied as catalysts for the green synthesis of a variety of 3,4-dihydropyrimidin-2(1H)-ones under solvent-free conditions through the Biginelli reaction. Interestingly, the catalysis products have been obtained in high yields under eco-friendly synthesis conditions.

Three new metal coordination polymers constructed from adipic acid and 2-(pyridin-3-yl)-(1H)-benzimidazole ligands, [M(ADP)(3PBI)2(H2O)2]·2H2O (M = Ni and Co for 1 and 2, respectively) and [Cd(ADP)(3PBI)(H2O)] (3) [ADP = adipic acid dianion; 3PBI = 2-(pyridin-3-yl)-(1H)-benzimidazole], have been synthesized by hydrothermal reactions and were characterized by X-ray single-crystal diffraction, elemental analyses, IR, powder X-ray diffraction, and thermogravimetry. Complexes 1 and 2 are isostructural. Both form a 1-D linear chain structure, which is further assembled into a 3-D supramolecular framework by π⋯π stacking and hydrogen bonding interactions. Complex 3 possesses a binuclear unit and displays a 2-D layer which is further extended to a 3-D supramolecular architecture via hydrogen bonding and other weak packing interactions. The luminescent properties of 3 were investigated in the solid state at room temperature.

Tetraphenylethylene pillar[6]arenes with an AIE effect were synthesized for the first time. The fluorescence of the pillar[6]arenes could be quenched much more and much faster by TNT than by other nitroaromatics including 2,4,6-trinitrophenol, which could be used to detect TNT in air.