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Thallium (Tl) is a highly toxic heavy metal, and its pollution and remediation in aquatic environments has attracted considerable attention. To reduce or remove Tl pollution in the environment, various strategies have been applied. Graphene oxide (GO) has abundant oxygen-containing functional groups, indicating its high application potential for pollution remediation via methods involving binding to metal ions or positively charged organic molecules or electrostatic interaction and coordination. However, the adsorption of Tl to GO occurs via physical adsorption, for which the adsorption efficiency is low. Therefore, herein, we report a new method to effectively remove Tl pollution in water. We combined GO with aza-crown ether, which enhanced the electronegativity and ability to bind metal ions. The functionalized graphene oxide (FGO) demonstrated high efficiency through a wide pH gradient of 5–10, with a dominant Tl(I) adsorption capacity (112.21 mg g−1) based on the Langmuir model (pH 9.0, adsorbent concentration of 0.8 g L−1). The adsorption of Tl(I) during removal fit a pseudo-second-order kinetic model well. The mechanisms of Tl removal involve physical and chemical adsorption. In summary, our study provides a new method for the detection and treatment of Tl-containing wastewater by using FGO.

Nd-based ternary catalysts are widely used for the polymerization of isoprene in rubber industry, however structure information during the polymerization of isoprene as well as the catalytic mechanism are still ambiguous. In this paper, the in situ XAFS technique was used to extract the local atomic structure around the Nd center of the catalyst consisting of Nd(vers)3, AlEt3, and Al(iBu)2Cl. Theoretical calculations were used to verify the structure changes in the alkylation process. Four catalysts with different alkylaluminums {AlEt3, Al(nOct)3, Al(iBu)3, and Al(iBu)2H} were, respectively, used for the polymerization of isoprene. The results demonstrate that the substitution of Nd–C for Nd–O bonds is reasonable in the alkylation step. The structural evolutions in the alkylation and chlorination steps, as well as in the polymerization processes of isoprene are all similar for these Nd-based ternary catalysts with different alkylaluminum components. In the polymerization process of isoprene, there are only about 2 Nd–Cl bonds at 2.85 A and 1–2 Nd–C bonds at 2.42 A around the Nd centers which are in a monomer state. The Nd–C bonds can be attributed to the contribution of isoprene. This highly-opened structure of the Nd active centers activates greatly the catalytic activity of the Nd-based ternary catalysts. A conjectural catalytic mechanism for the polymerization of isoprene has been deciphered on the basis of the in situ XAFS results. This study is expected to be helpful for the improvement and application of the Nd-based ternary catalysts.

Luteolin, 5,7,3′,4′-tetrahydroxylflavone, which is one of the most common dietary flavonoids, exists in many types of plants including fruits, vegetables and medicinal herbs. Spectroscopic studies (UV-visible, ESI-MS) and cyclic voltammetry (CV) were employed to study the relevant interaction of luteolin and Fe(III) in ethanol, as well as to evaluate the antioxidant activities of luteolin and its complexes against free radical-mediated damage, such as hydroxyl radicals (˙OH) and 1,1-diphenyl-2-picrylhydrazyl (DPPH) radicals. Luteolin can form a luteolin–Fe(III) complex with the ratio of 1 : 1 and coordinate to the Fe(III) ion at the 3′,4′-dihydroxyl group in ring B in the luteolin molecule. Luteolin strongly inhibits Fenton reaction via a combined effect of Fe(II) chelation and radical scavenging activities. The antioxidant activities of luteolin and its Fe(III) complex were evaluated by using the DPPH radical scavenging method. Luteolin shows better antioxidant activity than the luteolin–Fe(III) complex, which is also verified from the electrochemical point of view. The experimental results can be rationalized in terms of structural features governing antioxidant behavior i.e. substitution pattern of ring B in the luteolin molecule.

Six new coordination polymers, {[Zn2(Hpdtc)2(Hbpe)2]·5H2O} (1), [Zn2(pdtc)(bpe)1.5]n (2), [Zn(Hpztc)(Hbpe)(H2O)] (3), {[Zn2(pztc)(bpe)2(H2O]·9H2O}n (4), {[Cu2(pdtc)(bpy)(H2O)2]·3H2O}n (5) and {[Cu2(pdtc)(bpy)(H2O)2]·2H2O}n (6) [H4pdtc = pyridine-2,3,5,6-tetracarboxylic acid, H4pztc = pyrazine-2,3,5,6-tetracarboxylic acid, bpy = 4,4′-dipyridine, and bpe = 1,2-bis(4-pyridyl)ethene], have been synthesized under control by modifying the reaction conditions. Their structural diversities range from zero-dimensional (0D) (1, 3), two-dimensional (2D) (2, 5), to porous three-dimensional (3D) networks (4, 6). The pH values of the reagents of 1 and 3 are around 3, which results in the ligands of 1 and 3 being partly protonated. Both 1 and 3 show 0D structures. So we tried to modify the pH value to improve the structures. 2 and 4 were synthesized at higher pH values (5.8, 5.1). 2 and 4 have 2D layer structure and 3D pillar-layered framework, respectively. 5 and 6 were synthesized from the same reagents, 5 was synthesized at room temperature, while 6 was obtained under hydrothermal conditions. The coordination environment of Cu(II) centers in 6 is similar to 5 except that one oxygen atom from a water molecule for Cu1 in 5 is replaced by the oxygen atom from the pdtc4− ligand in 6, which results in different structures: 5 shows 2D network structure, 6 has a 3D porous framework. The PXRD, thermal stabilities and luminescent properties of these complexes were investigated in detail.

Expression of concern for 'Synthesis of a Fe 3 O 4 @P4VP@metal-organic framework core-shell structure and studies of its aerobic oxidation reactivity' by Zongcheng Miao et al. , RSC Adv. , 2017, 7 , 2773-2779, https://doi.org/10.1039/C6RA25820D., (This journal is © The Royal Society of Chemistry.)