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Although significant progress has been made in the synthesis of covalent organic frameworks (COFs) in recent years, the construction of hierarchical pores in such materials remains a great challenge. Herein, we report a facile synthesis of hierarchically porous COFs (HP-COFs) under mild conditions in ionic liquids 1-alkyl-3-methylimidazolium tetrafluoroborates ([Cnmim][BF4], n = 4, 6, 10). It has been found that apart from the inherent micropores, a large mesoporous structure has been produced in the COFs in which the size of pores can be simply tuned by adjusting the alkyl chain length of the ionic liquids. These mesopores have been confirmed by N2 sorption and electron microscopy techniques. Importantly, this approach is applicable for the preparation of various HP-COFs, such as imine and hydrazone based COFs, which are quite difficult to acquire through traditional methods. In addition, these HP-COFs show highly effective catalytic performance for C–C bond formation, especially for large size molecule based C–C coupling reactions in comparison with uni-pore COFs. [ABSTRACT FROM AUTHOR]

CdTe quantum dots (QDs) capped by 1-ethyl-3-methylimidazolium mercaptopropionate ([emim]MP) and the reduced graphene oxide (RG) modified by the amine-terminated ionic liquid ([amim]Br) were synthesized in this work. The coordinating interface interactions between QD and RG render the nanocomposite the excellent electrochemical performances as revealed by cyclic voltammetry, chronocoulometry, and electrical impedance spectroscopy. Based on the experimental results obtained from amimRG, CdTe@MP-amimRG, CdTe@[bmim]MP-amimRG, and CdTe@[emim]MP-amimRG nanocomposites, it is proposed that the synergistic effects between imidazolium rings and graphene are responsible for the enhanced performances. Taking the CdTe@[emim]MP-amimRG nanocomposite as the electrochemical sensor of puerarin, the proposed method demonstrates the linear range over 0.01–4.0 μmol L −1 with the detection limits of 6 nmol L −1 in the aqueous solution (S/N = 3). Moreover, the sensor exhibits fast response time (2s), high sensitivity (74.57 μA μmol L −1 cm −2 ), as well as reproducibility (RSD ≤ 8%), and can maintain the stability at 4 °C for two weeks. [ABSTRACT FROM AUTHOR]

Abstract: The dependences of the absorption spectra of chrome azurol S (CAS) and Al3+–CAS complexes on the concentration of ionic liquids (ILs), 1-alkyl-3-methylimidazolium bromide ([C n Mim]Br, with n =8, 10, 12), were measured at 298.15K in aqueous solutions with pH=5.6. It is found that ILs can induce the significant red-shifts of the wavelength at the absorption maximum (λ max) of Al3+–CAS complex from 545 to 646nm for [C8Mim]Br, and to 642nm for [C12Mim]Br and [C16Mim]Br, respectively. Accompanying the red-shifts, the absorbance at λ max, and thereby molar absorptivity (ɛ), changes markedly with the IL concentration, and consequently the effect of ILs on the absorbance at λ max is systematically investigated in this work. Along with the experimental results of resonance light scattering, the sensitization mechanism is analyzed from the aggregation of the ILs and the interactions of ILs with CAS and Al3+–CAS complexes. It is shown that the hydrophobic interactions of IL subaggregates with CAS in Al3+–CAS complex are the crucial factor for the sensitization. [Copyright &y& Elsevier]

Abstract: Methyl orange (MO) exhibits a sensitive spectral signature to the polarity of medium environment. Using MO as the spectroscopic probe, this paper reports the results of studies on the aggregation of 1-alkyl-3-methylimidazolium-based ionic liquids (ILs, [C n mim]Br, n =8, 10, 12, and 16) in aqueous solutions. Along with the results obtained from the measurements of electrical conductivity and resonance light scattering (RLS), this investigation shows the characteristics of the IL aggregation and the properties of the bulk phase prior to the aggregation, and hence reveals the aggregation differences between surface active [C n mim]Br and traditional surfactants. It is shown that hydrogen bonds play a dominant role in the aggregation of ILs in addition to Coulombic and hydrophobic interactions. Compared with traditional cationic surfactant, IL displays the stronger aggregation due to the formation of the hydrogen bonded network. Also, such hydrogen bonded network results in the loose arrangements of imidazolium rings in the subaggregates of [C n mim]Br (n <10). When the mid-wavelength absorption band is just beginning to appear as the band of absorption maximum, the corresponding concentration is indicative of the formation of the perfect aggregates, and is in agreement with the critical aggregation concentration (CAC) of the ILs except [C8mim]Br. Moreover, it was found that the polarity in the core of the perfect IL aggregates is similar to the polarity within micelles of traditional cationic surfactant with the same alkyl chain length. [Copyright &y& Elsevier]

[Display omitted] • A crosslinking Sb-NC/PoMXene network with fully-active species is designed. • The network greatly enhances ion/electron transport and alleviates volume variation. • Interweaved polar interfaces benefit rich binding/catalytic sites to polysulfides. • Long cyclability is achieved for 700 cycles with capacity retention over 99%. The performances of lithium-sulfur batteries (LSBs) depend heavily on sulfur hosts with the desired properties including excellent electronic conductivity, high sulfur loading, strong polysulfide capture, and active catalytic centers. Here, we demonstrate 2D partially oxidized Ti 3 C 2 T x MXene (PoMXene) can be cross-linked by Sb, N co-implanted carbon (Sb-NC) through Ti-O-Sb bond to synthetize Sb-NC/PoMXene. It is shown that the nanostructuring Sb-NC/PoMXene provides fast ion/electron transport channel and robust 3D architecture to alleviate volume variations. Significantly, the interweaved polar interfaces benefit rich binding sites from Sb nanoparticles, N atoms, TiO 2 and Ti 3 C 2 T x towards polysulfides, and the Sb-NC could catalytically accelerate redox kinetics, thus efficiently suppressing polysulfide shuttle. As a result, the Sb-NC/PoMXene/S hybrids represent high capacity (1148.4 mAh g−1 at 0.1C) and long cyclability (570.6 mAh g−1 after 700 cycles at 2C). When the sulfur loading is increased to 4 mg cm−2, the thick cathode still maintains a high areal capacity of 3.8 mAh cm−2 with a decay of only 0.10% per cycle over 100 cycles at 0.2C. The studies pave a novel pathway to design nanostructured electrodes and promote catalytic performances in LSBs. [ABSTRACT FROM AUTHOR]

The development of a simple, template-free, and one-step strategy to synthesize nanostructured Au architectures with fascinating morphology is highly desirable and technically important due to their valuable applications in varied fields. In this work, the “green” strategy of “tunable ionic liquids-water (ILs-H 2 O) interfacial synthesis” developed previously by us is utilized for feasible synthesis of gold needle mushroom-like micro/nanostructures at the 1,3-dibutylimidazolium bis(trifluoromethylsulfonyl)imide ([C 4 bim][Tf 2 N]) - water interface and ambient conditions. The as-obtained gold needle mushrooms (AuNMs) have been characterized and analyzed systemically by scanning electron microscopy, X-ray powder diffraction, energy-dispersive X-ray spectroscopy, and transmission electron microscopy. It is shown that the as-prepared AuNMs can be used as substrates to perform surface enhanced Raman scattering (SERS) investigation with striking SERS sensitivity. By employing ILs with different alkyl chain lengths of the imidazolium cations and/or different nature of anions, Au nanomaterials with diverse morphologies can be easily prepared at different ILs-H 2 O interfaces. Based on the analysis of the control experiments, the growth and formation of AuNMs at the [C 4 bim][Tf 2 N]-H 2 O interface have been discussed. [ABSTRACT FROM AUTHOR]