RSC Advances

Li, Jie; Jia, Huichao; Lin, Jing; Luo, Han; Liu, Zhenya; Xu, Xuewen; Huang, Yang; Jin, Peng; Zhang, Jun; Abbas, Saleem; Tang, Chengchun

doi: 10.1039/c5ra11899apmid: N/A

Developing membranes with excellent mechanical strength and chemical stability is a practically important issue for efficient removal of pollutants from wastewater. In this work, we report on a free-standing membrane fabrication from an activated boron nitride (ABN) micro-ribbon. The membrane techniques we used, combine the intrinsic active adsorption competence of ABN and the mechanical advantages of conventional membrane filtration. The obtained membranes show an excellent removal ability of water pollutants through a simple filtration adsorption process. The examined pollutants include toxic metallic ions and organics. We showed that the dye (like methylene blue) removal ability significantly exceeded that of activated carbon by an order of magnitude at least; lead ions (Pb2+) in wastewater can be nearly fully removed, the starting 5 mg L−1 concentration was reduced to less than 0.01 mg L−1 after the 600 μm-thickness membrane adsorption filtration. Moreover, the membranes can be stacked together to further improve the adsorption capacity because of their high permeability. The excellent reusable performance of the filtration membranes was also confirmed. We believe that the reported work should open the way toward the practical application of ABN membranes in the field of wastewater purification.

Li, Shan; Chen, Tieqiao; Saga, Yuta; Han, Li-Biao

doi: 10.1039/c5ra16015dpmid: N/A

Chloroform-based Atherton–Todd-type reactions of alcohols and thiols with secondary phosphine oxides, generating phosphinothioates and phosphinates, respectively, are described. Various valuable phosphinothioates and phosphinates including those with functional groups are readily prepared under mild reaction conditions.

Xin, Linlin; Liu, Xuefeng

doi: 10.1039/c5ra10280dpmid: N/A

Black titanium dioxide (TiO2) inverse opals (BTIOs) were obtained by in situ H2 reduction of white TiO2 inverse opals (WTIOs). The combination of chemical hydrogenation and well-ordered inverse opal structure provides BTIOs with a better photocatalytic activity than the structure-related WTIOs, fragments of BTIOs, and P25 under visible light.

Duan, Yannan; Jana, Sadhan C.; Lama, Bimala; Espe, Matthew P.

doi: 10.1039/c5ra11769kpmid: N/A

Mechanically reinforced organic–inorganic hybrid silica aerogels are produced from simultaneous hydrolysis and condensation reactions of silane precursors – tetraethoxy silane (TEOS) and aminopropyltriethoxysilane (APTES) – and silane-modified polyurethane urea molecules each carrying multiple (≥3) reactive silane groups. In this manner, the post-gelation crosslinking reactions are avoided, the amount of polymer introduced into the aerogel structures is controlled, and the chain length between two crosslink points is tailored. The long chain polymer molecules introduce a certain degree of flexibility to the hybrid aerogel structures. The morphology, compressive properties, and surface area are obtained respectively using scanning electron microscopy, Instron tensile testers, and Brunauer–Emmett–Teller (BET) surface area analysis. The data on solid state 13C and 29Si NMR spectra reveal chemical reactions of the silane-modified polymers with the silica particle networks. Small angle X-ray scattering (SAXS) data are used to determine the fractal dimension of the silica networks. It is found that the self-crosslinkable multifunctional polyurethane urea chains form coatings on the silica networks and produce large enhancements in compressive modulus although with increases in shrinkage and bulk density.

Yuan, Guotao; Lu, Mengna; Fei, Jiuhui; Guo, Jun; Wang, Zuoshan

doi: 10.1039/c5ra10845dpmid: N/A

Core–shell structured Au@Cu2O nanocomposites with different morphologies were prepared by a facile solution route. X-ray diffraction (XRD) and transmission electron microscopy (TEM) results indicated that the obtained nanocomposite consisted of gold nanorod (NR) core and Cu2O shell, and both of them were in good crystallization. It was interested that the morphologies of the products could be tuned from octahedral to corner-truncated octahedral by changing the reductant. The results indicated that the reductant played a crucial role in determining the morphologies of as-prepared products. In addition, we investigated the photocatalytic properties of the products. It was found that both the core–shell structure and morphology of Au@Cu2O nanocomposites had great influence on the photodegradation of MO. As a result, the Au@Cu2O corner-truncated octahedral nanocomposites exhibited the best photocatalytic property. Our experimental results helped clarify the enhanced role of Au core and shape-dependent effect of Cu2O NPs, which contributed to pursue more efficient photocatalysts and other promising applications.

Diaz-Uribe, Carlos E.; Vallejo, William; Castellar, Wilmar; Trilleras, Jorge; Ortiz, Stephanie; Rodriguez-Serrano, Angela; Zarate, Ximena; Quiroga, Jairo

doi: 10.1039/c5ra13203gpmid: N/A

Chalcones constitute an important group of natural and synthetic products that have been screened due to their wide range of pharmacological applications. Herein, we studied the antioxidant activity of five newly synthetized (E)-1-(pyrrole-2-yl)-3-(aryl)-2-(propen-1-one) (PAPs) derivatives against singlet oxygen (1O2). The differences among the compounds are related to aryl substitution in the p-position where: 3a = C6H5, 3b = 4-H3COC6H4, 3c = 4-FC6H4, 3d = 4-ClC6H4, 3e = 4-BrC6H4. The PAPs were synthesized using a Claisen–Schmidt condensation reaction between 2-acetylpyrrole and aromatic aldehydes under ultrasonic irradiation (yields between 79–86%) and were characterized by IR, mass spectrometry, NMR and quantum chemical calculations. The total singlet oxygen quenching rate constants (kQ) of the PAPs were measured spectrophotometrically in ethanol at 25 °C and determined by using the Stern–Volmer model. As the character of the EWGs is increased from 3a to 3e, the kQ diminishes smoothly. The best quencher is found to be the 3a compound (where the aryl group is unsubstituted) with a kQ = 5.71 (±0.21) × 107 M−1 s−1, which is similar to those for other antioxidants e.g. flavonoids. These results suggest these compounds are efficient quenchers of singlet oxygen and their potential applicability in biological systems.

Kiran, G. Seghal; Priyadharshini, S.; Anitha, K.; Gnanamani, Elumalai; Selvin, Joseph

doi: 10.1039/c5ra10302apmid: N/A

Biofilm-forming pathogens are a potential threat to indwelling medical devices and infectious diseases. Management of device-associated Candida infections remains challenging with the existing drug discovery platforms. The available antifungal drugs are effective for the control of free-living pathogens but not effective on biofilm-forming pathogens. Thus an antifungal drug synergized with an antibiofilm agent would be an effective strategy to treat Candida biofilms. Mature C. albicans biofilms are anchored by a complex architecture in terms of distribution of fungal cells stabilized by exocellular polymeric substances. The findings of the present study provide a new insight on the possible development of enterococci probiotics and/or its exopolysaccharide (EPS) as synergistic with existing antifungal drugs to treat biofilm infections. The probiont Enterococcus faecalis MSI12 was picked from 142 seawater isolates screened for EPS production using a congo red plate assay. The probiotic characteristics of the isolate MSI12 were evaluated based on the temperature, pH, acid tolerance, autoaggregation, hydrophobicity and antioxidant activity. The biofilm disruption ability of the lyophilized EPS was determined in a microtitre plate assay using fluconazole as reference drug. Scanning electron microscope and confocal laser scanning microscope images were used for analysis of antibiofilm activity. The cell viability of E. faecalis MSI12 was very high at higher temperature, acidic pH, bile salt and salt concentration when compared to the reference strain Lactobacillus plantarum. Therefore the strain MSI12 might survive in the niche like human gut without prebiotics. The EPS from Enterococcus sp. MSI12 showed significant reduction of the treated Candida biofilm. The antibiofilm potential of EPS was much stronger than the standard antifungal drug fluconazole. This study revealed that biofilm disruption/control using a probiont EPS could deliver a synergistic approach as the probiotic strain can colonize in the host to prevent the formation of Candida biofilms.

Zhang, Ye; Qi, Zheng-Hang; Ruan, Gui-Yu; Zhang, Yi; Liu, Wei; Wang, Yong

doi: 10.1039/c5ra11488hpmid: N/A

A theoretical understanding of the Pd-catalyzed C(sp3)–H activation of aliphatic amines has been examined using the B3LYP density functional theory. The concerted metalation–deprotonation (CMD) mechanism is identified in the rate-determining steps of all possible reaction pathways. The rate- and regio-determining step of the catalytic cycle is deprotonation of the Cmethyl–H bond through a six-membered cyclopalladation transition state. According to the relative activation barriers, the Cmethyl–H activation is kinetically and thermodynamically more favorable than the Cethyl–H activation. More important, the only acetoxylation product is located, ignoring the diethyl-substituted or the dimethyl-substituted in the morpholine and not producing the lactone amines molecules, which is in good agreement with the experimental observations.

Feng, Jiangtao; Zhang, Qian; Wang, Jiajing; Yang, Honghui; Xu, Hao; Yan, Wei

doi: 10.1039/c5ra09062hpmid: N/A

In this article, the chemical oxidative approach was employed to synthesize bulk sponge-like polypyrrole; p-toluenesulfonate (pTSNa), sodium benzene-sulfonate (BSNa) and sodium nitrate (NaNO3) were chosen, respectively, as doping agents to modify the sponge polypyrrole. The microstructure, specific surface area and electrochemical activity of doped polypyrrole samples were characterized. Through repeated expansion and contraction tests, it was proved that the bulk polypyrrole samples exhibited excellent sponge property. To investigate the potential desalination ability, this type of sponge-characteristic polypyrrole was processed into electrodes, and applied in saline solution to remove sodium ions by the electrochemical approach. The results showed that the sponge polypyrrole performed wonderful desalination effect with above 20 mg Na+ for per gram polypyrrole.

Kahani, Seyed Abolghasem; Shahrokh, Mansoure

doi: 10.1039/c5ra09385fpmid: N/A

In this work, magnetic CuxNi1−x alloy nanoparticles were obtained from DCSs by a chemical reduction method. In this method magnetic CuxNi1−x alloy nanoparticles were prepared from [Cu(NH3)4][Ni(C2O4)2], [Cu(en)2][Ni(C2O4)2] and [Cu(py)4][Ni(C2O4)2] coordination complexes. Reduction of these complexes occurred in an ethanolic aqueous solution using hydrazine monohydrate. In order to characterization the synthesized compounds, we have used IR spectroscopy, EDX, SEM and XRD. The magnetic properties of the nanoalloys were measured using a Vibrating Sample Magnetometer (VSM). Magnetoimpedance (MI) measurements were performed using a Lock-in Amplifier (7265 Perkin Elmer) at a frequency of 250 kHz. These alloys demonstrate ferromagnetic behaviour which is due to the presence of nickel in the alloys. This property makes them excellent candidates for technological applications such as magnetic devices or sensors based on the MI effect. The powder X-ray diffraction patterns were analyzed using a Rietveld method. The analyses were carried out with the GSAS software package. The results of the Rietveld refinements show a good agreement between the observed pattern and the calculated values.