doi: 10.1002/asia.201300131

A novel kind of macrocyclic-host-functionalized periodic mesoporous organosilica (PMO) with excellent and reversible recognition of Pb^II was developed. The macrocyclic host molecule cis-dicyclohexano[18]crown-6, with strong affinity to Pb^II, was carefully modified as a bridged precursor to build the PMO material. To break down the limit of the functionalization degree for PMOs incorporated with large-sized moieties, a site-selective post-functionalization method was proposed to further decorate the external surface of the PMO material. The selective recognition ability of the upgraded PMO material towards Pb^II was remarkably enhanced without destroying the mesoporous ordering. Solid-state ¹³C and ²⁹Si NMR spectroscopy, X-ray photoelectron spectroscopy (XPS), XRD, TEM, and nitrogen adsorption–desorption isotherm measurements were utilized for a full characterization of the structure, micromorphology, and surface properties. Reversible binding of Pb^II was realized in the binding–elution cycle experiments. The mechanism of the supramolecular interaction between the macrocyclic host and metal ion was discussed. The synthetic strategy can be considered a general way to optimize the properties of PMOs as binding materials for practical use while preserving the mesostructure.

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doi: 10.1002/asia.201300279

Lithium-ion batteries (LIBs) represent the state-of-the-art technology in rechargeable energy-storage devices and they currently occupy the prime position in the marketplace for powering an increasingly diverse range of applications. However, the fast development of these applications has led to increasing demands being placed on advanced LIBs in terms of higher energy/power densities and longer life cycles. For LIBs to meet these requirements, researchers have focused on active electrode materials, owing to their crucial roles in the electrochemical performance of batteries. For anode materials, compounds based on Group IVA (Si, Ge, and Sn) elements represent one of the directions in the development of high-capacity anodes. Although these compounds have many significant advantages when used as anode materials for LIBs, there are still some critical problems to be solved before they can meet the high requirements for practical applications. In this Focus Review, we summarize a series of rational designs for Group IVA-based anode materials, in terms of their chemical compositions and structures, that could address these problems, that is, huge volume variations during cycling, unstable surfaces/interfaces, and invalidation of transport pathways for electrons upon cycling. These designs should at least include one of the following structural benefits: 1) Contain a sufficient number of voids to accommodate the volume variations during cycling; 2) adopt a “plum-pudding”-like structure to limit the volume variations during cycling; 3) facilitate an efficient and permanent transport pathway for electrons and lithium ions; or 4) show stable surfaces/interfaces to stabilize the in situ formed SEI layers.

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doi: 10.1002/asia.201300149

Surface-tethered polymers, or “polymer brushes”, are emerging as key elements in the context of regulating the surface characteristics of materials. Their properties, such as biocompatibility, antifouling, colloidal stability, wettability, and corrosion resistance, play a vital role in ascertaining their potential applications. The availability of straightforward procedures for polymer brush synthesis, which are applicable to a wide range of monomers and are adaptable to a range of substrates, is a clear advantage over other surface-modification strategies. Herein, the important advancements that are pertinent to the fabrication of polymer brushes are outlined. Furthermore, an exhaustive up-to-date overview of the developments in different application domains, including smart drug-delivery systems, biosensing, antifouling, stimuli-responsive surfaces, and ion-conducting membranes, that benefit from the developments in the field of polymer brushes, is presented.

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Convenient preparations of 3,4-dichloropyrrole and 3,4-difluoropyrrole are reported. 2,3,17,18-Tetrahalohexaphyrins were synthesized and meso-reduced hexaphyrins were obtained by reduction of tetrabromo- and tetrachloro[28]hexaphyrin with NaBH₄ as the first example of phlorin-type hexaphyrin.

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doi: 10.1002/asia.201300078

Porous hybrid Cu₂O/polypyrrole nanoflakes have been synthesized from solid CuO nanoplate templates through the pyrrole-induced reductive transformation reaction at elevated temperature. The conversion mechanism involves the reductive transformation of CuO to Cu₂O and the in situ oxidative polymerization of pyrrole to polypyrrole. In addition, the morphology of the as-converted nanohybrids depends on the shape of the CuO precursors. The strategy enables us to transform single-crystalline CuO nanosheets into hollow hybrid Cu₂O/polypyrrole nanoframes. The ability to transform CuO and an organic monomer into porous hybrid materials of conducting polymer and Cu₂O with macrosized morphological retention opens up interesting possibilities to create novel nanostructures. Electrochemical examinations show that these porous hybrid Cu₂O/polypyrrole nanostructures exhibit efficient catalytic activity towards oxygen reduction reaction (ORR), excellent methanol tolerance ability, and catalytic stability in alkaline solution, thus making them promising nonprecious-metal-based catalysts for ORR in alkaline fuel cells and metal–air batteries.

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This study shows that graphene-like nanosheets of MoO₃ can be prepared by a variety of chemical methods besides ultrasonication. The prepared few-layer materials exhibit good photocatalytic activity for the degradation of dyes. Composites of MoO₃ nanosheets with a conducting borocarbonitride show excellent performance as supercapacitor electrodes.

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Transition metal-doped graphene hybrids were prepared by exfoliation of metal-doped graphite oxide precursors in either H₂ or N₂ atmosphere. Characterizations of the materials suggest that the H₂ exfoliated materials had higher C/O ratios in general. The electrocatalytic activities of the transition metal-doped graphene hybrids were reflected in an enhancement of the kinetics of oxygen reduction under alkaline conditions, which is important for renewable energy applications such as fuel cells. It was found that hybrid materials exfoliated in N₂ atmosphere exhibited greater electrocatalytic activities than those exfoliated in H₂ atmosphere.

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The current fabrication strategy for colloidal PbSe semiconductor nanocrystals (NCs) frequently involves acutely toxic reagents and tedious reaction procedures, and is plagued by products with poorly controlled size and morphology. Herein, a facile and phosphine-free method for synthesizing PbSe NCs is reported by the reaction of elemental Se and PbCl2 that involves only oleylamine as both ligand and reaction medium. This method results in monodispersed PbSe NCs with well-controlled size and morphology. In addition, the obtained NCs display strong optical limiting effects, and thus hold potential for the development of nonlinear optical devices.