ChemCatChem
·
2018
·Vol. 10
·期 18
·4143-4153
·
IF 4.674
Xinyu Wang,Jing Lu,Yunlong Zhao,Xiaopeng Wang,Zhang Lin,Xueming Liu,Ronglan Wu,Chao Yang,Xintai Su
Graphical SuperHUMATE performance : A novel catalyst, carbon anchored nickel/heazlewoodite nanoparticles (Ni/Ni 3 S 2 @C nanosheets), was fabricated by facile pyrolysis of solid precursor with potassium humate as carbon source and sulfur source. The Ni/Ni 3 S 2 @C nanocatalyst exhibited superior catalytic performance towards 4-nitrophenol reduction with excessed sodium borohydride as reactant, which the K /m value up to 166 s −1 g −1 . A facile molten salt method was utilized for the synthesis of carbon anchored nickel/heazlewoodite nanoparticles (Ni/Ni 3 S 2 @C nanosheets) with potassium humate as the carbon and sulfur source and NaCl as template. The morphology, particle size and crystallinity of the products were characterized by various techniques containing TEM, FE-SEM and XRD. Furthermore, the mesoporous Ni/Ni 3 S 2 @C own easy accessibility of active sites and high surface area (149.04 m 2 g −1 ). Thus, the as-prepared Ni/Ni 3 S 2 @C exhibited prominent performance for catalytic reduction of 4-nitrophenol (4-NP). Catalytic reduction of other nitrophenols (NPs) were also tested which can prove that the catalyst own selectivity on reduction of NPs. For durability, the property of the catalyst does not decrease obviously after five cycles. More significant correlations concerning effect of activation parameters ( E a =37.21 kJ mol −1 ) on 4-NP reduction were scrutinized and discussed. Hence, we provide a facile method for fabrication of metal/metal sulfide@C which own better dispersity, small dimension and excellent catalytic performance for further studies.
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PHYSICAL CHEMISTRY CHEMICAL PHYSICS
·
2018
·Vol. 20
·期 38
·24796-24806
·
IF 3.906
Chensheng Ma,Chris Tsz-Leung Chan,Ruth Chau-Ting Chan,Allen Ka-Wa Wong,Bowie Po-Yee Chung,Wai-Ming Kwok
Apart from being an analogue of the prototype for photoinduced intramolecular charge transfer (ICT), 2-ethylhexyl 4-dimethylaminobenzoate (EHDMABA) is also one of the earliest patented and most commonly used sunscreen components. There is, however, little documented information about the photophysics and factors affecting the photophysics of this molecule. Such information is of importance for both the understanding of the ICT reaction and assessing the underlying process of photoprotection, especially in view of the “sunscreen controversy” that has arisen from the contrasting in vivo vs. in vitro photobiological results on this and related UV filters. We report herein a femtosecond broadband time-resolved fluorescence (fs-TRF), complemented by transient absorption (fs-TA) to allow a full probe of the excited state cascades for EHDMABA and two of its derivatives in solvents of varied properties. The results provide direct evidence for a nearly solvent independent inner sphere ICT reaction occurring on the sub-picosecond time scale, and an ensuing solvent dictated deactivation of the ICT state. The ICT state in the aprotic solvent acetonitrile decayed solely through the intrinsic intersystem crossing (ISC) to produce a potentially harmful triplet excited state. In the protic solvent, the solvation and formation of ICT-induced solute–solvent hydrogen (H)-bonding opened the originally inaccessible internal conversion (IC) channel of the ICT state, leading to the rapid reformation of the ground state molecule with a unitary efficiency in the aqueous solution. This H-bonding-mediated IC restrained or eliminated the intrinsic ISC, providing a mechanism at the molecular level for the benign dissipation of the electronic excitation. The precise rate of IC was observed to vary with the alkoxy substituent and its efficiency was affected by the H-bonding capacity of the solvent. The findings of this work demonstrate the pivotal role of the microenvironment and the direct participation of solvent molecules through H-bonding in drastically altering the nonradiative dynamics and promoting or inhibiting photostability and photoprotection. This may assist in developing next-generation UV filters and help in improving formulation design for the optimal efficacy of sunscreen products. The pronounced H-bonding-induced fluorescence quenching and variation in the fluorescence wavelength imply that these molecules may also serve as a sensitive fluorescence probe for the H-bonding properties of the microenvironment.
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ACS Applied Materials & Interfaces
·
2018
·
IF 8.097
Hui Peng,Rui Zhao,Jing Liang,Sihan Wang,Fei Wang,Jiezi Zhou,Guofu Ma,Ziqiang Lei
Two-dimensional conducting polymers nanosheet prepared by the soft-template-assisted technique in aqueous system still has rarely been reported, especially the formation of nanosheets structure by protonic acid assisted controlling the stability of the micelles method. Herein, a facile, one-step, bottom-up approach is developed to synthesize novel and uniform conductive poly(4-aminodiphenylamine) (P(4-ADPA)) nanosheets with controlled morphology via regulating the proton acid concentration during the self-assembly of surfactant lamellar micelles. The as-produced conducting P(4-ADPA) demonstrates a integral nanoframework structure with uniform and intertwined nanosheets, resulting in a satisfactory specific capacitance of 395 F g–1 at the current density of 0.5 A g–1. Furthermore, another pseudocapacitor electrode material, urchin-like W18O49, is selected as a negative electrode material to fabricate a novel P(4-ADPA)//W18O49 asymmetric supercapacitor, which extends the operating voltage window up to 1.5 V, provides an energy density of 24.4 W h kg–1 at a high power density of 1491 W kg–1, and possesses superlong-life of 92% capacitance retention after 10 000 cycles. Therefore, the present work will propose an affordable strategy to design novel conducting polymer nanosheets and open up the possibility of cheap conductive polymers to meet the demands of energy storage.
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CHEMICAL ENGINEERING JOURNAL
·
2018
·
IF 6.735
Nianbing Zhong,Ming Chen,Yihao Luo,Zhengkun Wang,Xin Xin,Bruce E. Rittmann
We present a novel UV–visible-light photocatalytic optical hollow-fiber in which a hollow optical fiber (HOF) and TiO 2 -based composite are coupled for enhancement of photocatalytic activity toward degradation of 4-chlorophenol (4-CP). A HOF was coated with a TiO 2 -based composite composed of Er 3+ :YAlO 3 /SiO 2 /TiO 2 (EYST) and acting as the photocatalytic element. The EYST coating showed good light-inducing capacity at the fiber-coating interface and high photocatalytic activity driven by UV–visible light. The photocatalytic activity of the fabricated photocatalytic HOFs was investigated for degradation of 4-CP in aqueous solution in the wavelength spectrum of 360–780 nm. Examined were the effects of the EYST coating gradient and reactor operating conditions (pH and temperature) on the degradation of 4-CP. The EYST-coated HOF significantly enhanced the 4-CP degradation, dechlorination, and mineralization, compared to pure TiO 2 -coated HOF and EYST-coated solid optical fibers. Specifically, high photocatalytic activity was obtained when the EYST coating thicknesses at the HOF’s incident end and HOF’s hemispherical end were 10 and 160 μm, the pH was 6.0, and temperature was 55 °C.
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JOURNAL OF FLUORESCENCE
·
2015
·Vol. 25
·期 5
·1183-1189
·
IF 1.927
Wu Fuyong,Xu Guangjun,Zeng Xi,Mu Lan,Redshaw Carl,Wei Gang
N , N ′-bis(4-methoxysalicylide)benzene-1,4-diamine ( S1 ) was synthesized from 4-methoxysalicylaldehyde and p -phenylenediamine and it was found to exhibit interesting aggregation-induced emission enhancement (AIEE) characteristics. In aprotic solvent, S1 displayed very weak fluorescence, whilst strong emission was observed when in protic solvent. The morphology characteristics and luminescent properties of S1 were determined from the fluorescence and UV absorption spectra, SEM, fluorescence microscope and grading analysis. Analysis of the single crystal diffraction data infers that the intramolecular hydrogen bonding constitutes to a coplanar structure and orderly packing in aggregated state, which in turn hinders intramolecular C-N single bond rotation. Given that the three benzene rings formed a large plane conjugated structure, the fluorescence emission was significantly enhanced. The absolute fluorescence quantum yield and fluorescence lifetime also showed that radiation transition was effectively enhanced in the aggregated state. Moreover, the AIEE behavior of S1 suggests there is a potential application in the fluorescence sensing of some volatile organic solvents.
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FLAVOUR AND FRAGRANCE JOURNAL
·
2014
·Vol. 30
·期 2
·179-187
·
IF 1.761
Zujin Yang,Zuobing Xiao,Hongbing Ji
Terpinen-4-ol has several biological properties, but its low stability and water-solubility limit its use. This study reports the formation of a solid terpinen-4-ol/ β -cyclodextrin ( β -CD) inclusion complex via lyophilization. Release experiments were performed at various temperatures (40, 60, 80, and 100°C) with humidity of 70%. The release of terpinen-4-ol was significantly increased with rising temperature. Avrami's equation was used to analyse release kinetics and a good fit was observed for terpinen-4-ol release. In addition, the complex enhanced antibacterial activity against Staphylococcus aurueus, Pseudomonas aeruginosa and Escherichia coli , with concentration ranging from 1.25 mg/ml to 5 mg/ml. To explain the experimental data, physico-chemical techniques have been utilized to investigate the inclusion complex of terpinen-4-ol with β -CD. Finally, the possible structure of the complex was proposed by quantum chemical calculations. The results indicated that enhanced thermal stability and antibacterial activity of terpinen-4-ol could be attributed to the weak interactions of hydrogen bonds between terpinen-4-ol and β -CD. Copyright © 2014 John Wiley & Sons, Ltd.
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MACROMOLECULES
·
2013
·
IF 5.521
Meihan Dan,Yang Su,Xin Xiao,Shentong Li,Wangqing Zhang
A new family of the thermo-responsive polymers based on poly[N-(4-vinylbenzyl)-N,N-dialkylamine] with the pendent amine group as well as the doubly thermo-responsive triblock copolymer were synthesized by reversible addition–fragmentation chain transfer (RAFT) polymerization. These polymers showed the lower critical solution temperature (LCST) and/or the upper critical solution temperature (UCST) in alcohol and in the alcohol/water mixture. The polymer molecular weight, the polymer concentration, the cosolvent/nonsolvent and the deuterated solvent affecting the LCST and/or UCST were investigated, and their great influence on the LCST/UCST was demonstrated. The origin of the phase transition of poly[N-(4-vinylbenzyl)-N,N-dialkylamine] at LCST upon heating was investigated and the possible reason was proposed. The doubly thermo-responsive triblock copolymer of PVMA53-b-PVEA108-b-PVMA53 underwent phase transition at two LCST temperatures. The PVEA108 block underwent the initial phase transition at the first LCST of 32.5 °C to form core–corona micelles, and then the subsequent phase transition of the PVMA53 block took place at the second LCST of 54.5 °C to produce corona-collapsed micelles. The proposed polymers based on poly[N-(4-vinylbenzyl)-N,N-dialkylamine] are anticipated to broaden the thermo-responsive polymer range and will be useful in polymer science.
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GREEN CHEMISTRY
·
2014
·Vol. 17
·期 2
·1269-1275
·
IF 6.852
Qingwen Tian,Lijian Huang,Wangen Zhao,Yanchun Yang,Gang Wang,Daocheng Pan
Aqueous solution deposition of metal chalcogenide semiconductor thin films is considered a green and low-cost approach. However, it is hard to find a general aqueous solution approach to deposit various kinds of high-quality metal sulfide thin films. Here, we describe a green and robust ammonium thioglycolate aqueous solution approach, and fifteen types of metal sulfide precursor solutions (metal = Cu, Zn, Sn, Ge, In, Sb, Mg, Cd, Mn, Bi, Fe, Ni, Li, Na, K) can be prepared using metal oxides or metal hydroxides as raw materials at room temperature under an air atmosphere. Moreover, elemental sulfur and selenium can also be highly dissolved. By this green route, high quality CZTS nanocrystal thin films can be deposited by directly coating the mixed Cu, Zn, and Sn precursor solutions without the need for complex nanocrystal synthesis. The remarkable power conversion efficiency of 6.62% was achieved, which is the highest value for aqueous solution deposited CZTSSe thin film solar cells.
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FLUID PHASE EQUILIBRIA
·
2014
·
IF 2.241
Chunlin Li,Qinbo Wang,Binwei Shen,Zhenhua Xiong,Chuxiong Chen
The solubility of 5,10,15,20-tetrakis(4-chlorophenyl) porphyrin manganese(III) chloride (abbreviated in p -ClTPPMnCl) in N , N -dimethylformamide (abbreviated in DMF) + water solvent mixtures at 293.2–353.2 K were measured. The effects of mass fraction of DMF in the solvent mixtures at 1.00–0.80 on the solubility were studied. The results show that the solubility decreases with the decreasing mass fraction of DMF at constant temperature, and increase with the increasing temperature at constant solvent composition. The experimental data were correlated with Apelblat equation, and the solubilities calculated by the model were in good agreement with experimental observations.
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REPRODUCTIVE BIOMEDICINE ONLINE
·
2015
·
IF 3.015
Fenju Qin,Jie Zhang,Linsen Zan,Weiqiang Guo,Jin Wang,Lili Chen,Yi Cao,Ouxi Shen,Jian Tong
The aim of the present study was to elucidate whether the GATA-4/SF-1 signalling pathway is involved in the inhibitory effects of melatonin on testosterone production in both the TM3 Leydig cell line and in C57BL/6J mice. In-vitro experiments demonstrated that melatonin treatment significantly reduced testosterone levels in cell culture medium ( P < 0.05 or P < 0.01); and decreased intracellular cyclic adenosine monophospha accumulation ( P < 0.05 or P < 0.01) and mRNA/protein expression of GATA-4 , SF-1 (NR5A1) , StAR , P450SCC (CYP11A1) and 3β-HSD ( P < 0.05 or P < 0.01). These effects were blocked by N-acetyl-2-benzyltryptamin, a melatonin receptor antagonist . Similar effects of melatonin on testosterone production ( P < 0.05 or P < 0.01) and down-regulation of transcription factors GATA-4 and SF-1 ( P < 0.01) were also observed in mice treated with intratesticular injections of melatonin. Overall, the data suggest that the inhibitory effects of melatonin on testosterone production are mediated via down-regulation of GATA-4 and SF-1 expression.
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CRYSTENGCOMM
·
2015
·Vol. 17
·期 13
·2690-2697
·
IF 4.034
Ke Tang,Jingcai Zhang,Wenzhi Wang,Shuping Wang,Jinxin Guo,Yanzhao Yang
A simple protocol has been reported here to successfully perform a controllable conversion between Ce(OH)4 nanorods [Ce(OH)4-NR] and Ce(OH)4 nanoflowers [Ce(OH)4-NF] based on a prolonged mechanical force-driven stirring process. Results show that the Ce(OH)4 nanostructures undergo a morphology transformation from the initial nanorods to irregular nanoflowers, then to nanoflowers emanating from one center only, by varying the stirring time before solvothermal reaction. The detailed study confirmed that the mechanical force significantly improved the mass transport of the solution and drove the seeds of Ce(OH)4-NR [seeds-NR] to generate the seeds of Ce(OH)4-NF [seeds-NF]. The final CeO2 products (CeO2 nanorods [CeO2-NR] and CeO2 nanoflowers [CeO2-NF]) that inherited the original morphology were obtained by annealing Ce(OH)4-NR and Ce(OH)4-NF, respectively. To further optimize the performance of the final products, Au/CeO2-NR and Au/CeO2-NF were synthesized by a simple oxidation–reduction process, which led to increased surface areas and promising potential in CO oxidation.
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ANALYTICA CHIMICA ACTA
·
2015
·
IF 4.513
Jing Luo,Jiaojiao Cong,Jie Liu,Yahan Gao,Xiaoya Liu
In this work, a novel and convenient strategy was developed to prepare molecularly imprinted polymers (MIPs) on the surface of graphene sheet. In this route, vinyl group functionalized graphene (GR/NVC) was first prepared by immobilizing 4-vinylcarbazole onto the surface of graphene via π–π interaction. The subsequent grafting copolymerization of methacrylic acid and ethylene glycol dimethacrylate in the presence of 4-nitrophenol (4-NP, template molecule) was carried out at GR/NVC surface, leading to the formation of GR/MIPs composite. The GR/MIPs composite was characterized by FTIR, fluorescence, TGA, SEM and AFM, and was used to fabricate electrochemical sensor for the detection of 4-NP. The electrochemical behavior of GR/MIPs sensor for 4-NP was investigated by cyclic voltammetry (CV) and differential pulse voltammetry (DPV). The effects of the preparation conditions, such as concentration of the NVC and template, the solution pH, and incubation time, were also optimized. Under optimized conditions, the DPV current response of GR/MIPs sensor was nearly 12 times than that of the GR/NIPs sensor. It also should be noted that as compared to traditional MIP, shorter response time and much higher current response were demonstrated. In addition, the GR/MIPs sensor could recognize 4-NP from its structural analogs, indicating the excellent selectivity of the GR/MIPs sensor. The peak current is linearly proportional to the concentration of 4-NP ranging from 0.01 μM to 100 μM and 200 μM to 1000 μM with a significantly low detection limit of 5 nM, a wider response range and lower detection limits as compared to most of the previously reported electrochemical sensors for 4-NP. Furthermore, the GR/MIPs sensor exhibits good stability with adequate reproducibility and has been successfully used to determine 4-NP in water samples.
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