The fabrication of advanced electromagnetic wave absorbents with wide bandwidth, robust absorption and small filling ratio remains a great challenge. In this work, the ternary composite aerogel of ...nitrogen-doped reduced graphene oxide/nickel ferrite@silicon dioxide modified by amino groups (NRGO/NiFe2O4@m-SiO2) was synthesized via the three-step route of solvothermal synthesis, Stöber method and hydrothermal self-assembly. Microscopic morphology characterization results indicated that the acquired binary and ternary magnetic composite aerogels exhibited a special three-dimensional porous network architecture. Moreover, the electromagnetic absorbing capacity of NRGO/NiFe2O4 composite aerogel could be obviously enhanced by coating SiO2 and modifying amino groups on the surfaces of SiO2. Remarkably, the as-fabricated NRGO/NiFe2O4@m-SiO2 composite aerogel possessed the broadest effective absorption bandwidth of 7.04 GHz (10.96–18.0 GHz) and robust absorbing intensity of −30.8 dB at 2.1 mm under a small filling ratio of 12.5 wt%. It was worth mentioning that the optimal minimum reflection loss could reach −56.0 dB when the matching thickness was increased to 3.4 mm. Besides, a minimum radar cross section value of −51.1 dB m2 could be achieved in the far-filed condition. The special porous network structure and magnetodielectric synergy in the ternary composite aerogel optimized the electromagnetic impedance, and notably enhanced the electromagnetic absorbing capacity. It was believed that this study would provide a novel approach for the construction of highly efficient carbon-based electromagnetic wave absorbers.
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•NRGO/NiFe2O4@m-SiO2 composite aerogel was constructed by a simple three-step route.•The ternary composite aerogel showed a three-dimensional porous network structure.•Electromagnetic absorption was enhanced by coating SiO2 and modifying amino groups.•Maximum absorption bandwidth reached up to 7.04 GHz, covering the whole Ku band.•Minimum radar cross section value was −51.1 dB m2 in the far-filed condition.
The goal of the present study was to explore, in our previously developed hybrid template, the effect of introduction of additional heterocyclic rings (mimicking catechol hydroxyl groups as ...bioisosteric replacement) on selectivity and affinity for the D3 versus D2 receptor. In addition, we wanted to explore the effect of derivatization of functional groups of the agonist binding moiety in compounds developed by us earlier from the hybrid template. Binding affinity (Ki) of the new compounds was measured with tritiated spiperone as the radioligand and HEK-293 cells expressing either D2 or D3 receptors. Functional activity of selected compounds was assessed in the GTPI3S binding assay. In the imidazole series, compound 10a exhibited the highest D3 affinity whereas the indole derivative 13 exhibited similar high D3 affinity. Functionalization of the amino group in agonist (+)-9d with different sulfonamides derivatives improved the D3 affinity significantly with (+)-14f exhibiting the highest affinity. However, functionalization of the hydroxyl and amino groups of 15 and (+)-9d, known agonist and partial agonist, to sulfonate ester and amide in general modulated the affinity. In both cases loss of agonist potency resulted from such derivatization.
Surface trap-mediated nonradiative charge recombination is a major limit to achieving high-efficiency metal-halide perovskite photovoltaics. The ionic character of perovskite lattice has enabled ...molecular defect passivation approaches through interaction between functional groups and defects. However, a lack of in-depth understanding of how the molecular configuration influences the passivation effectiveness is a challenge to rational molecule design. Here, the chemical environment of a functional group that is activated for defect passivation was systematically investigated with theophylline, caffeine, and theobromine. When N-H and C=O were in an optimal configuration in the molecule, hydrogen-bond formation between N-H and I (iodine) assisted the primary C=O binding with the antisite Pb (lead) defect to maximize surface-defect binding. A stabilized power conversion efficiency of 22.6% of photovoltaic device was demonstrated with theophylline treatment.
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•The hydroxyl and amino groups functionalized MCM-41 (MCM-NH2-OH) was synthesized.•MCM-NH2-OH exhibited a maximum adsorption capacity of 1664.9 mg·g−1 for Au(III).•Synergistic effect ...of –NH2 and –OH groups for Au(III) adsorption-recover in actual wastewater.
The recovery of Au(III) by adsorption has attracted extensive attention since it promotes solving the problems of environmental pollution and resource waste. Herein, we prepared the functionalized MCM-41 (MCM-NH2-OH) and explored the synergistic adsorption effects for Au(III). The adsorption capacity of MCM-NH2-OH reached 1664.9 mg·g−1, which was 15.98 times and 2.99 times higher than MCM-NH2 (104.2 mg·g−1) and MCM-OH (556.0 mg·g−1), respectively. The fitting kinetics experiments demonstrated that Au(III) adsorption by MCM-NH2-OH was conformed to the pseudo-second-order kinetic model. The adsorption rate of MCM-NH2-OH (2.62 × 10-2 g·mg−1·min−1) was 346.1 times higher than MCM-NH2 (7.57 × 10-5 g·mg−1·min−1). The adsorption mechanism and the role of –NH2 and –OH groups were investigated by XPS, XRD, and FTIR. More Au(III) can be adsorbed on –NH2 groups by electrostatic attraction and chelation that provided electron acceptor for –OH groups, which further enhanced the reduction of Au(III) to Au(0). Further, MCM-NH2-OH exhibited superior selectivity and reusability for Au(III). Therefore, the synergy between –NH2 and –OH groups is suitable for efficient adsorption-recover of gold applied in actual wastewater.
Temperature‐dependent dual fluorescence and switchable circularly polarized luminescence (CPL) are two highly pursued but challenging properties for small organic molecules (SOMs). We herein disclose ...a triarylborane π‐system based on a 2,2′‐diamino‐6,6′‐diboryl‐1,1′‐binaphthyl scaffold that can serve as a versatile building block for achieving these two properties by simply choosing different amino groups. BNMe2‐BNaph with less bulky dimethylamino groups displays temperature‐dependent dual fluorescence, and can thus be used as a highly sensitive ratiometric fluorescence thermometer. On the other hand, BNPh2‐BNaph with bulky diphenylamino groups exhibits intense fluorescence in both solution and in the solid state. A change of solvent from nonpolar cyclohexane to highly polar MeCN not only shifts the CPL position to much longer wavelength but also inverts the CPL sign. In addition, the complexation of BNPh2‐BNaph with fluoride greatly enhances the CPL intensity.
The combination of two donor–π‐acceptor subunits in the 2,2′‐diamino‐6,6′‐diboryl‐1,1′‐binaphthyl scaffold generates a versatile building block for organic fluorophores exhibiting temperature‐dependent dual fluorescence and switchable circularly polarized luminescence.
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•PSA modified hollow NH2-ZIF-8 (PHNZ) with high amino content was designed.•PSA hard template strategy was used to synthesis NH2-ZIF-8 rapidly.•The vesicle shape of PHNZ constructs ...low-resistance region to improve CO2 permeability.•CO2/N2 selectivity is improved by PSA layer and CO2 affinity of amino groups.
The amino functionalization of MOFs has been verified to be effective in improving the selective permeation of CO2. However, the introduction of amino groups into ZIF-8 by mixed ligands strategy is hard to achieve due to the high steric hindrance of benzene ring in 2-aminobenzimidazole ligand, resulting in insufficient content of amino groups. Therefore, in this work, polystyrene-acrylate (PSA) template is proposed to provide abundant adsorption and reaction sites for the rapid synthesis of NH2-ZIF-8 with high content of 2-aminobenzimidazole. Furthermore, the incomplete etching strategy is used to construct PSA modified hollow NH2-ZIF-8 nanospheres (PHNZ). Importantly, the thickness of PSA layer and the hollow size are adjusted by the etching time, as revealed by the SEM and TEM images. In this PHNZ, the modified PSA can provide good interface compatibility between PHNZ and Pebax matrix to enhance the CO2 selectivity, while the hollow structure can reduce the mass transfer resistance and improve the gas permeability. Moreover, the introduced amino groups can enhance the CO2 affinity of PHNZ and further improve the CO2/N2 selectivity of the PHNZ-based mixed matrix membranes (MMMs). Benefiting from the synergy of good interface compatibility and enhanced CO2 affinity from the amino groups, the PHNZ/Pebax MMMs present greatly improved CO2/N2 selectivity in contrast with pure Pebax and NH2-ZIF-8 based membranes. Besides, as the etching time increases, the PHNZ-2 and PHNZ-3 based MMMs present a higher CO2 permeability than that of NH2-ZIF-8 based MMM, revealing the significance of the hollow structure. The PHNZ-2/Pebax MMM with filler loading of 10 wt% expresses the best gas separation performance with the CO2 permeability of 121.9 Barrer and CO2/N2 selectivity of 96.6, respectively, showing an increase of 54.7 % and 98.0 % in contrast with pure Pebax membrane. Meanwhile, this CO2 separation performance is far beyond the Robeson upper bound in 2008 and close to the McKeown upper bound in 2019, demonstrating that the proposed PHNZ displays a promising and competitive potential in MMM based CO2 capture.
We report an amino‐functionalized indium‐organic framework for efficient CO2 reduction to formate. The immobilized amino groups strengthen the absorption and activation of CO2 and stabilize the ...active intermediates, which endow an enhanced catalytic conversion to formate despite the inevitable reduction and reconstruction of the functionalized indium‐based catalyst during electrocatalysis. The reconstructed amino‐functionalized indium‐based catalyst demonstrates a high Faradaic efficiency of 94.4 % and a partial current density of 108 mA cm−2 at −1.1 V vs. RHE in a liquid‐phase flow cell, and also delivers an enhanced current density of ca. 800 mA cm−2 at 3.4 V for the formate production in a gas‐phase flow cell configuration. This work not only provides a molecular functionalization and assembling concept of hybrid electrocatalysts but also offers valuable understandings in electrocatalyst evolution and reactor optimization for CO2 electrocatalysis and beyond.
The amino‐functionalized reconstructed indium‐organic framework electrocatalyst demonstrates a high activity for carbon dioxide electroconversion to formate in a gas‐phase flow cell.
Heavy metals in industrial wastewaters are posing a serious threat to the environment and to human health. Microalgae are increasingly being seen as potential solutions to this problem as they can ...remove pollutants through biosorption. This process offers certain advantages over other more traditional metal removal techniques as it is simple, inexpensive, eco‐friendly, and can be performed over a wide range of experimental conditions. Biosorption is possible due to the unique and complex structure of the microalgal cell wall. The variety of functional groups on the surface of the cell wall (such as carboxyl or amino groups) can act as binding sites for the heavy metals, thus removing them from the environment. This review focuses on the cell wall composition and structure of the most commonly used microalgae in heavy metal removal and shows the role of their cell wall in the biosorption process. This review also aims to report the most commonly used models to predict the velocity of microalgal biosorption and the removal capacities.
The structure and mechanism of umami taste receptor remain largely unclear, thus, far more research is necessary to increase the knowledge of tasty modalities. Umami/umami-enhancing peptides and ...their derivatives are widely distributed in foods and have been reported to play important roles in food taste through different modes of interactions with the umami receptors.
In this review, recognition of umami taste receptor, along with the structures and possible binding sites (orthosteric and allosteric sites) of umami/umami-enhancing peptides and their derivatives, was firstly described. The validation of the structural characteristics of umami and umami-enhancing substances and their binding sites to the receptors allows better understanding of the sensing mechanisms of umami taste.
There are several receptors responsible for the recognition of umami substances and each receptor may be activated through different mechanisms. Besides orthosteric sites, allosteric binding sites are also found and being emphasized as it may explain why complementary interactions among umami or umami-enhancing peptides and their derivatives as well as an increase in hydrophilicity of compounds may promote food acceptance. Unlike di-/tri-peptides, the spatial structure is the most critical factor for the taste modality of long-chain umami peptides besides amino acid composition. Quite a few of these peptides and derivatives can also act as taste enhancing agents. Multiple polar moieties in peptides and their derivatives may trigger the umami/umami-enhancing property. Maillard reaction and treatment with certain enzymes could facilitate the yield of umami/umami-enhancing peptide derivatives with increased hydroxyl or amino groups.
•Recognition of umami taste including receptors and their binding sites (orthosteric and allosteric binding sites).•The possible structure–taste relationship of identified umami peptides, umami-enhancing peptides and their derivatives.•The validation of possible binding sites of umami peptides, umami-enhancing peptides and their derivatives.•The contribution of peptide derivatives to the taste of foods and corresponding modification operations.
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