A comparative study of two thienopyrimidine Schiff base probes for sequential monitoring of Ga3+ and Pd2.

Two Schiff base probes (S1 and S2) were prepared and synthesized by incorporating thienopyrimidine into salicylaldehyde or 3-ethoxysalicylaldehyde individually, with the aim of detecting Ga3+ and Pd2+ sequentially. Upon chelation with Ga3+, S1 and S2 exhibited fluorescence enhancement in DMSO/H2O buffer. Both S1-Ga3+ and S2-Ga3+ were quenched by Pd2+. The limit of detection for S1 in response to Ga3+ and Pd2+ was 2.86 × 10-7 and 4.4 × 10-9 M, respectively. For S2, the limit of detection for Ga3+ and Pd2+ was 4.15 × 10-8 and 3.0 × 10-9 M, respectively. Furthermore, the complexation ratios of both S1 and S2 with Ga3+ and Pd2+ were determined to be 1:2 through Job's plots, ESI-MS analysis, and theoretical calculations. Two molecular logic gates were constructed, leveraging the response behaviors of S1 and S2. Moreover, the potential utility of S1 and S2 for monitoring Ga3+ and Pd2+ in domestic water was verified.

Thienopyrimidine-derived multifunctional fluorescence sensor for the detection of Cu2+, Fe3+, and PPi in different solvents.

Hydrazine substituted thienopyrimidine, a new fluorophore, was used to synthesize a novel Schiff base R1 as a chemosensor via the condensation with p-formyltriphenylamine, and the structure was confirmed using nuclear magnetic resonance spectroscopy (NMR) and mass spectrometry (MS) analysis. When treated with Cu2+ in dimethylsulfoxide (DMSO)/H2O buffer, R1 showed a phenomenon of fluorescence quenching, which was reversible with the action of ethylenediaminetetraacetic acid (EDTA). When treated with Fe3+ in dimethylformamide (DMF)/H2O buffer, R1 exhibited the same phenomenon, but fluorescence was recovered with inorganic pyrophosphate (PPi) quantitatively. The complexation ratios for R1-Cu2+ and R1-Fe3+ were both 1:2, which were manifested by MS titrations and corresponding Job's plots. The limits of detection of R1 for Cu2+ and Fe3+ were 3.11 × 10-8 and 1.24 × 10-7 M, respectively. The sensing mechanism of R1 toward Cu2+ and Fe3+ was confirmed using density functional theory calculations and electrostatic potential analysis. Test strips of R1 were fabricated successfully for on-site detection of Cu2+ and Fe3+. In addition, R1 was applied to recognize Cu2+ and Fe3+ in actual water samples with satisfactory recovery.

The comparative study of two new Schiff bases derived from 5-(thiophene-2-yl)isoxazole as "Off-On-Off" fluorescence sensors for the sequential detection of Ga3+ and Fe3+ ions.

Two new Schiff bases, TIC ((E)-N'-(2-hydroxybenzylidene)-5-(thiophene-2-yl)isoxazole-3-carbohydrazide) and TIE ((E)-N'-(3-ethoxy-2-hydroxybenzylidene)-5-(thiophene-2-yl)isoxazole-3-carbohydrazide), have been designed and synthesized as chemosensors for distinct recognition of Ga3+ and Fe3+ ions. TIE demonstrated a prominent "turn on" response characterized by clear distinguished fluorescence when coordination with Ga3+ ions in the DMSO/H2O buffer solution. In comparison, TIC also showed "turn on" response of blue fluorescence which was more selective and sensitive than that of TIE due to the steric hindrance of ethoxy group of TIE. The newly formed complexes TIC-Ga3+ and TIE-Ga3+ may act as selective "turn-off" fluorescent probes towards Fe3+ ions. Limits of detection of TIC and TIE towards Ga3+ ions were 7.8809 × 10-9 M and 2.6277 × 10-8 M, respectively. Limits of detection of TIC-Ga3+ and TIE-Ga3+ towards Fe3+ ions were 8.6562 × 10-9 M and 3.3764 × 10-7 M, respectively. The molar ratio of the complex between the sensor and Ga3+ or Fe3+ ions were all 1:2 determined through Job's Plot, mass spectrometry, and theoretical calculations. Both sensors were utilized for the determination of target ions in environment water samples, and the portable paper sensors for detecting Ga3+ ions have been successfully developed.

A new Schiff base derived from 5-(thiophene-2-yl)oxazole as "off-on-off" fluorescence sensor for monitoring indium and ferric ions sequentially and its application.

A new Schiff base sensor (E)-N'-((8-hydroxy-2,3,6,7-tetrahydro-1H,5H-pyrido[3,2,1-ij]quinolin-9-yl)methylene)-5-(thiophen-2-yl)oxazole-4-carbohydrazide (TOQ) was synthesized and found to emit yellowish green fluorescence upon introduction of In3+. Furthermore, the resulting complex TOQ-In3+ was quenched selectively by Fe3+. The detection limits of TOQ for In3+ and Fe3+ were 1.75 × 10-10 M and 8.45 × 10-9 M, respectively. The complex stoichiometry of TOQ with target ions was determined to be 1:2 via Job's plot analysis, which further was verified by ESI-MS titration and theoretical calculations. Moreover, TOQ can be used for the determination of target ions in environmental water samples. A portable paper sensor of TOQ was successfully developed for detecting In3+ to assess its applicability.

A new sensor based on thieno[2,3-b]quinoline for the detection of In3+ , Fe3+ and F- by different fluorescence behaviour.

Based on thieno[2,3-b]quinoline-2-carbohydrazide and salicylaldehyde, a novel fluorescent probe (L) was designed and synthesized. L could be used as a multifunctional sensor to sequentially detect In3+ and Fe3+ through fluorescence enhancement and fluorescence quenching in DMF/H2 O buffer solutions. At the same time, L had good anti-interference ability, which could still detect In3+ and Fe3+ well in the presence of other metal ions. For F- , it could be detected by enhancing the fluorescence change caused by the introduction of Al3+ . When other anions were present, the detection of F- would not be interfered. The detection limits of In3+ , Fe3+ and F- were 1.16 × 10-10 M, 2.03 × 10-8 M and 7.98 × 10-9 M, respectively. The complexation model and sensing mechanism between L and In3+ , Fe3+ and F- were confirmed by calculating structural optimization and energy optimization using Gaussian 09 software.

A selective "turn-on" sensor for recognizing In3+ and Zn2+ in respective systems based on imidazo[2,1-b]thiazole.

A new simple and easily synthesized multitarget sensor, (E)-N'-(4-(diethylamino)-2-hydroxybenzylidene)imidazo[2,1-b]thiazole-6-carbohydrazide (X), was designed and synthesized using imidazo[2,1-b]thiazole-6-carboxylic acid and 4-(diethylamino)-2-hydroxybenzaldehyde. X could be used as a sensor to detect In3+ in DMF-H2O buffer solution and detect Zn2+ in EtOH-H2O buffer solution through fluorescence enhancement with detection limits of 1.02 × 10-9 M and 5.5 × 10-9 M, respectively. X exhibited an efficient "off-on-off" fluorescence behavior by cyclic addition of metal ions (In3+ and Zn2+) and EDTA. The stoichiometry between X and metal ions (In3+ and Zn2+) was 1 : 1. The binding mode and sensing mechanism of X with metal ions (In3+ and Zn2+) was verified by theoretical calculations using Gaussian 09 based on B3LYP/6-31G(d) and B3LYP/LANL2DZ basis, respectively. Moreover, X could be applied as a potential sensor for the quantitative detection of In3+ and Zn2+ with a satisfactory recovery and relative standard deviation (RSD) in real water samples.

Downregulation of CCL2 induced by the upregulation of microRNA-206 is associated with the severity of HEV71 encephalitis.

MicroRNAs (miRNAs) have been investigated widely as key regulators of gene expression in different diseases by affecting the miRNA­mediated regulatory function. Human enterovirus 71 (HEV71) can cause a series of human diseases, including encephalitis. Chemokine (C­C motif) ligand 2 (CCL2) is one of the important genes involved in regulating inflammation. However, the mechanisms underlying HEV71 encephalitis mediated by CCL2 remain to be elucidated. In the present study, reverse transcription­quantitative polymerase chain reaction analysis was used to determine the expression level of miR­206 and the mRNA expression of CCL2 in samples. Western blot analysis was used to detect the protein levels of CCL2. A luciferase assay was used to verify the miR­206 target site in CCL2. A CCK­8 assay and flow cytometry were used to determine cell proliferation and apoptosis. The results demonstrated that miR­206 was downregulated in severe HEV71 encephalitis. Using bioinformatics analysis, miR­206 was predicted to target the human CCL2 3'­untranslated region (3'­UTR). A dual­luciferase assay demonstrated that miR­206 downregulated the expression of CCL2 by directly targeting its 3'­UTR, whereas CCL2 3'­UTR mutations completely eliminated its interaction with miR­206. The expression levels of miR­206 and CCL2 were inversely correlated in cerebrospinal fluid. The expression of exogenous miRNA, which mimicked miR­206 miRNA, decreased the protein and mRNA levels of CCL2, whereas the suppression of endogenous miR­206 resulted in an increase of the protein and mRNA levels of CCL2. The present study also found that miR­206 promoted NPC cell proliferation and reduced the apoptosis of NPC cells via CCL2. The mechanism is likely to involve suppression of the expression of miR­206 and upregulation of the expression of CCL2, important in regulating the progress of HEV71 encephalitis. In conclusion, miR­206 may be useful in the prognosis and treatment of HEV71 encephalitis.

Preparation of Efficient BiOBr/MIL-88B(Fe) Composites with Enhanced Photocatalytic Activities.

In this study, a novel composite containing an iron based metal-organic framework (MOF) and BiOBr was successfully synthesized by a simple method, and was fully characterized by X-ray diffraction patterns, Fourier transform infrared spectra, UV-vis diffuse reflectance spectra, and transmission electron microscopy. Moreover, the photocatalytic activities of BiOBr/MIL-88B(Fe) composites and the pure materials were evaluated by measuring the degradation of Rhodamine B under visible light. The results show that the composite exhibits better photocatalytic activities than pure materials, which can be ascribed to the high adsorption capacity of MIL-88B(Fe) and the enhanced separation of photogenerated charge carriers from assembly of MIL-88B(Fe) on BiOBr. And the effects of various operating parameters such as catalyst dosage, medium pH, the mass ratio of BiOBr, and MIL-88B(Fe) and the dye initial concentration on the degradation of RhB have been studied.

Efficacy of high-dose methylprednisolone pulse therapy in the treatment of enterovirus 71 encephalitis.

To investigate the efficacy of high-dose methylprednisolone pulse therapy in the treatment of Enterovirus 71 (EV71) encephalitis. To determine whether high-dose methylprednisolone pulse therapy should be used, 80 cases of pediatric patients with EV71 encephalitis were randomly divided into steroid pulse therapy group and non-steroid pulse therapy group and their clinical information was compared using statistic analysis. There was no statistical difference in the duration of fever, duration of nervous system involvement, duration of hospital stay, blood pressure, and cure rates between the two groups (p>0.05). The heart rate, respiratory rate, white blood cell counts and blood glucose of the steroid pulse therapy group were significantly higher than those of the non-steroid pulse therapy group (p<0.05). High-dose steroid pulse therapy to treat EV71 encephalitis can't shorten the course or improve the prognosis of the disease. In contrast, it has side effects and might aggravate disease condition or interfere with disease diagnosis. Our study suggested that there is no beneficial effect to use high-dose steroid pulse therapy for the treatment of EV71 encephalitis.

A fluorescent sensor for Zn(2+) and NO2(-) based on the rational control of C[double bond, length as m-dash]N isomerization.

A new strategy for the ultrasensitive sensing of cations and anions based on the control of C[double bond, length as m-dash]N isomerization has been developed. Imine-derived ligand is non-fluorescent due to the C[double bond, length as m-dash]N isomerization process, whereas its ternary complex with ZnCl2 is moderately fluorescent because of the partial inhibition of C[double bond, length as m-dash]N isomerization. Such a ternary complex can give a remarkable fluorescence increase when it interacts with nitrite because of the much more efficient suppression of C[double bond, length as m-dash]N isomerization. This modulation process of C[double bond, length as m-dash]N isomerization can thus be used for the highly selective detection of Zn(2+) and NO2(-) in an aqueous solution.

A differentially selective probe based on diketopyrrolopyrrole with fluorescence turn-on response to Fe(3+), and dual-mode turn-on and ratiometric response to Au(3+), and its application in living cell imaging.

A diketopyrrolopyrrole-based probe DPP-PyR was able to recognize Fe(3+) and Au(3+) with fluorescent turn-on response via different emission modes with relatively low detection limit. Moreover, DPP-PyR exhibited preferential second mode of selectivity for Au(3+) as it ratiometrically displaced Fe(3+) from the [DPP-PyR+Fe(3+)] complex. Furthermore, the imaging experiments indicated that this probe was cell-permeable and could be used to detect Fe(3+) and Au(3+) ions within living cell. To the best of our knowledge, it was the first probe for detection Fe(3+) and Au (3+) at the same time ever reported.

A fluorescent sensor with a detection level of pM for Cd(2+) and nM for Cu(2+) based on different mechanisms.

A fluorescent sensor L, which showed turn-on response towards Cd(2+) with a detection limit of 1.9 × 10(-12) mol L(-1) in acetonitrile-H2O buffer solution based on the PET process and turn-off response toward Cu(2+) with a detection limit of 4.9 × 10(-9) mol L(-1) in pure water at pH 3.5 based on electrostatic effects, was developed.

A new diketopyrrolopyrrole-based probe for sensitive and selective detection of sulfite in aqueous solution.

A new probe was synthesized by incorporating an α,ß-unsaturated ketone to a diketopyrrolopyrrole fluorophore. The probe had exhibited a selective and sensitive response to the sulfite against other thirteen anions and biothiols (Cys, Hcy and GSH), through the nucleophilic addition of sulfite to the alkene of probe with the detection limit of 0.1 µM in HEPES (10 mM, pH 7.4) THF/H2O (1:1, v/v). Meanwhile, it could be easily observed that the probe for sulfite changed from pink to colorless by the naked eye, and from pink to blue under UV lamp after the sulfite was added for 20 min. The NMR and Mass spectral analysis demonstrated the expected addition of sulfite to the C=C bonds.

Synthesis of cyclic carbonates from CO2 and epoxides catalyzed by low loadings of benzyl bromide/DMF at ambient pressure.

An efficient, metal-free catalytic system for the conversion of CO2 and epoxides to cyclic carbonates under mild conditions with good-to-excellent yields (57-99%) was developed. A possible reaction mechanism involving the electrophilic activation of epoxides by benzyl cations and nucleophilic activation of CO2 by DMF is proposed.

A new fluorescence "off-on" chemodosimeter for L-cysteine based on water-soluble polythiophene.

A novel water-soluble cationic conjugated polymer, denoted as poly 2,5-[3-(1,1-dimethyl-4-piperidine methylene)thiophene] chloride（PDPMT-Cl was a novel fluorescent material. Fluorescence can be quenched by [AuCl4](-) effectively. On addition of l-cysteine (l-Cys) in [AuCl4](-)-PDPMT-Cl, fluorescence recovered. A new method to detect l-Cys was established successfully by designing a fluorescent "off-on" probe. The method showed good sensitivity and selectivity. Under optimized condition, the fluorescence intensity was linear to l-Cys concentration varying from 1.0 × 10(-8)M to 6.0 × 10(-5)M (γ=0.9982). The detection limit (3σ) was 1.39 × 10(-10)M. The method was successfully used for the determination of l-Cys in human serum and compound amino acid injection.

1-[(6-Chloro-pyridin-3-yl)meth-yl]-10-nitro-1,2,3,5,6,7,8,9-octa-hydro-5,9-methano-imidazo[1,2-a]azocin-5-ol.

In the title compound, C16H19ClN4O3, the cyclo-hexane ring displays a chair formation and the tetra-hydro-pyridine ring displays an envelope conformation with the methyl-ene C atom as the flap; the imidazolidine ring also displays an envelope conformation with a methyl-ene C atom as the flap. In the crystal, O-H⋯N hydrogen bonds between hy-droxy groups and pyridine rings link inversion-related mol-ecules into dimers. Weak C-H⋯O hydrogen bonds further link the dimers into supra-molecular chains running along the c axis.

Ultrasound-assisted production of biodiesel from soybean oil using Brønsted acidic ionic liquid as catalyst.

Biodiesel production from soybean oil with methanol was performed in the presence of a Brønsted acidic ionic liquid-based catalyst under ultrasound irradiation. The influences of various parameters on the transesterification reaction, including the amount of catalyst, the molar ratio of methanol to oil, the temperature and the ultrasound power, were investigated. The optimal conditions were: methanol/oil molar ratio of 9:1, 1.0 wt.% catalyst in oil, ultrasound power of 200 W, and reaction temperature of 60°C. Under these conditions, the conversion of triglycerides to fatty acid methyl esters was about 93.2% within the reaction time of 60 min.

Sonochemical decomposition of levofloxacin in aqueous solution.

The decomposition of levofloxacin was performed in an aqueous solution under ultrasound irradiation. The effect of operating conditions, including pH value, reaction time, initial concentration, and ultrasound power on the chemical oxygen demand (COD) removal rate was examined at room temperature (23 +/- 2 degrees C). Under a given condition (initial levofloxacin concentration = 20 mg/L, ultrasonic power = 400 W, and pH = 5.86), a 56.6% COD removal rate was obtained after 120 minutes of reaction time. It also was found that 5-day biochemical oxygen demand (BOD5) of the solution increased evidently after sonochemical treatment, and the ratio of BOD5/COD, which was a good measure for biodegradability, increased from 0 to 0.40, indicating that the biodegradability of the solution was enhanced. Based on the results, it is feasible that sonochemical oxidation can be used for the pretreatment of levofloxacin effluent before biological treatment processes.

Intensification of sonochemical degradation of antibiotics levofloxacin using carbon tetrachloride.

Sonochemical degradation of levofloxacin was investigated to assess the operational parameters and the impacts of rate enhancers (CCl(4)) and rate inhibitors (t-butanol). Different dosages of CCl(4), pH value of solutions, ultrasonic power, and initial concentration of levofloxacin which affected the degradation of levofloxacin were studied. The degradation rate of levofloxacin was accelerated with increased concentrations of CCl(4) via the accumulation of reactive chlorine species and the hindrance of ()OH radical combination reactions with atomic hydrogen. The addition of t-butanol at all test concentrations inhibited the degradation of levofloxacin regardless of the quantity of ()OH radicals in solution. It was also found that 5-day biochemical oxygen demand (BOD(5)) of the solution increased evidently after sonochemical treatment, and the ratio of BOD(5)/COD that was a good measure for biodegradability increased from 0 to 0.41, which indicated that biodegradability of the solution was obviously enhanced. Based on the results, it is feasible that sonochemical oxidation can be used for pretreatment of levofloxacin effluent before biological treatment processes.

Methyl 2-(p-toluene-sulfonamido)benzoate.

The title compound, C(15)H(15)NO(4)S, was prepared by simple condensation of methyl 2-amino-benzoate and 4-methyl-benzene-sulfonyl chloride. The dihedral angle between the benzene rings is 84.36 (6)°. The mol-ecular structure is stabilized by an intra-molecular N-H⋯O hydrogen-bonding inter-action involving the carbonyl group as acceptor, generating an S(6) graph-set motif.