Reaction mechanism of “amine–borane route” towards Sn, Ni, Pd, Pt nanoparticlesLidor-Shalev, Ortal; Zitoun, David
doi: 10.1039/c4ra11483cpmid: N/A
The understanding of the chemical reaction yielding nanomaterials is often based on basic assumptions and novel syntheses are usually presented without knowledge on their reaction mechanism. Herein, the chemical reduction of metal precursors by Lewis complexes of amine–borane is fully investigated, reaction and mechanism, for the synthesis of metallic nanoparticles (NPs). In this study, Sn NPs are obtained by the chemical reduction of tin acetylacetonate complex [Sn(acac)2] using dimethylamine–borane (DMAB) as a reducing agent. The reaction yields single crystalline Sn NPs independently of the use of surfactant. The size of the NPs can be adjusted by regulating the complex/DMAB ratio. The use of DMAB as a reducing agent is extended to the synthesis of Ni, Pd, Pt and Sn/Pd NPs. We investigate the synthetic mechanism by using 11B-NMR and calorimetric analytical tools. The mechanism is found to be specific to the acetylacetonate complexes and involves the reaction of borane on the ligand.
Optically active helical polyacetylene/Fe3O4 composite microspheres: prepared by precipitation polymerization and used for enantioselective crystallizationChen, Huaiyu; Li, Lei; Liu, Dong; Huang, Huajun; Deng, Jianping; Yang, Wantai
doi: 10.1039/c4ra12267dpmid: N/A
This article reports the first coordination–precipitation polymerizations for preparing chiral, magnetic composite microspheres consisting of helical substituted polyacetylene and Fe3O4 nanoparticles. The microspheres were obtained in high yield (>85%) and characterized by XRD, FT-IR, SEM, TEM, CD and UV-vis absorption techniques. TEM and SEM images showed that the microspheres were approx. 600 nm in average diameter and possessed a spherical morphology with a rough surface. CD and UV-vis absorption spectra demonstrated that the polyacetylene chains constructing the microspheres adopted helical structures of a predominantly one handed screw nature, which enabled the microspheres to show remarkable optical activity. The microspheres also performed desirable magneticity. They were further used as chiral selectors efficiently inducing enantioselective crystallization of d- and l-alanine as model chiral enantiomers. Moreover, the microspheres can be easily restored under the assistance of an external magnetic field. The coordination–precipitation polymerizations provide a versatile platform for preparing advanced chiral and non-chiral, magnetic hybrid microspheres.
Magnetic activated carbon prepared from rice straw-derived hydrochar for triclosan removalLiu, Yuchen; Zhu, Xiangdong; Qian, Feng; Zhang, Shicheng; Chen, Jianmin
doi: 10.1039/c4ra11815dpmid: N/A
Recently, considerable attention has been given to the hydrothermal liquefaction (HTL) of waste rice straw for the production of bio-oil and hydrochar. However, hydrochar material could not be directly applied in the environmental field, due to its limited porosity and surface area. In order to improve the porosity and adsorption capacity of rice straw-derived hydrochar, it was activated and magnetized to a magnetic activated carbon. The activation condition for hydrochar was firstly considered, due to the negative effect of the magnetic medium. Results suggested that the as-prepared magnetic activated carbon possessed a large surface area (around 674 m2 g−1), and exhibited both a high adsorption capacity and a fast adsorption rate for triclosan (TCS) removal. In addition, magnetic activated carbon can be easily recovered from aqueous solutions by an external magnetic field. Overall, the waste rice straw-derived hydrochar can be transformed to a highly efficient magnetic adsorbent for TCS removal.
The indium(iii) chloride catalyzed synthesis of sulfur incorporated 3-acylcoumarins; their photochromic and acetate sensing propertiesPrakash Rao, H. Surya; Desai, Avinash
doi: 10.1039/c4ra09228gpmid: N/A
The synthesis and evaluation of the photochromic properties of 3-acylcoumarins are very important as they exhibit selective sensing properties. We found that InCl3 efficiently catalyzes the condensation of 2-hydroxybenzaldehydes and β-keto esters to provide near quantitative yields of 3-acylcoumarins. The 3-(phenylsulfanyl/phenylsulfinyl/phenylsufonyl)propanoyl coumarins with an electron-donating NMe2 group at the C7 position were prepared to evaluate the influence of sulfur on the emission and acetate ion sensing properties. Our studies revealed that 7-(diethylamino)-3-(3-(phenylsulfanyl/phenylsulfinyl/phenylsufonyl)propanoyl)-2H-chromen-2-one exhibits excellent fluorescence emission in hexane and ethyl acetate (Φ ≈ 80%). The 3-acylcoumarin with sulfone in the C3-acyl side-chain detects acetate anions selectively and this property can be conveniently followed by fluorescence emission spectroscopy.
Synthesis, antimalarial activity, heme binding and docking studies of 4-aminoquinoline–pyrimidine based molecular hybridsKumar, Deepak; Khan, Shabana I.; Tekwani, Babu L.; Ponnan, Prija; Rawat, Diwan S.
doi: 10.1039/c4ra09768hpmid: N/A
A series of novel 4-aminoquinoline–pyrimidine hybrids was synthesized and evaluated for their antimalarial activity. Several compounds showed potent antimalarial activity against both CQ-sensitive and CQ-resistant strains of P. falciparum with no cytotoxicity against Vero cell lines. The selected compound 7f, when evaluated for in vivo activity showed mild suppression of parasites in the P. berghei-mouse malaria model. The heme binding studies were conducted to determine the probable mode of action of these hybrids. Compound 8d formed a stable 1 : 1 complex with hematin suggesting that these hybrids act on a heme polymerization target. The binding of most active hybrids was studied by molecular docking analysis in the active site of Pf-DHFR-TS. The top scoring compounds with low binding energy, interact in the active site of Pf-DHFR-TS in a similar way to the natural protein substrate dihydrofolate. The pharmacokinetic properties of the most active compounds were also assessed using ADMET prediction.
Synthesis of a novel CuI/CuII-containing sandwich-type cluster and its catalytic electron transfer propertyXue, Xiaolong; Zhao, Xiaofang; Zhang, Deshun; Han, Zhangang; Yu, Haitao; Zhai, Xueliang
doi: 10.1039/c4ra08145epmid: N/A
A novel six-metal sandwich-type heteropolyanion [Na2CuICuII(OH2)Cu2II(B-α-SbW9O33)2]9− (1) has been synthesized in good yield from a one-pot hydrothermal reaction and characterized by IR, XPS, XRD and TG. Single-crystal X-ray analysis reveals that compound H9[Na2CuICuII(OH2)Cu2II(B-α-SbW9O33)2]·9H2O (H9-1) crystallizes in tetragonal system with space group of P4̄21m and consists of a 2D inorganic network based on Cu–O–W linkages among polyanionic clusters. A structural feature is that the six-metal {Na2Cu4} central belt of the anion contains the mixed valence states of CuI/CuII group. This compound shows excellent catalytic activity for effectively promoting the inorganic electron transfer (redox) reaction of ferricyanide to ferrocyanide by thiosulphate with high rate constant value in aqueous solution. In addition, compound (H9-1) also exhibits an inhibition effect for the organic photodegradation reaction of Rhodamine B (RhB).