Highly selective binding of basic amino acids, i.e. lysine, arginine, and histidine, by a negatively charged carboxylatopillar[5]arene (CP5A) is reported. And the complexation behavior of the CP5A host towards lysine metabolites including cadaverine (Cad), acetyl-l-lysine (AcLys) and trimethyl-l-lysine (TMLys) is also described.
Highly effective binding of neutral dinitriles by simple alkyl-substituted pillar[5]arenes and the formation of interpenetrated geometries are reported. The resulting host-guest complexes represent one of the most efficient recognition motifs based on pillararenes.
The complexation of neutral 1,4-dihalobutanes with simple pillar[5]arenes was investigated. The results indicate the formation of interpenetrated complexes, where the dispersive interactions dominate the complex stability. Typically, 1,4-diiodobutane displays the strongest binding strength with ethylpillar[5]arene [K(a) = (1.0 ± 0.1) × 10(4) M(-1)], up to 120 fold as compared with 1,4-difluorobutane.
The binding behavior of substituted 1,4-bis(pyridinium)butane derivatives (X-Py(CH(2))(4)Py-X, X = H, 2-methyl, 3-methyl, 4-methyl, 2,6-dimethyl, 4-pyridyl, and 4-COOEthyl) 1(2+)-7(2+), with negatively charged carboxylatopillar[5]arene (CP5A) has been comprehensively investigated by (1)H NMR and 2D ROESY and UV absorption and fluorescence spectroscopy in aqueous phosphate buffer solution (pH 7.2). The results indicated that the position of the substituents attached on pyridinium ring dramatically affects the association constants and binding modes. 3- and 4-Substituted guests (1(2+), 3(2+), 4(2+), 6(2+), 7(2+)) form [2]pseudorotaxane geometries with CP5A host, giving very large association constants (>10(5) M(-1)), while 2,6-dimethyl-substituted 5(2+) forms external complex with relatively small K(a) values [(2.4 ± 0.3) × 10(3) M(-1)] because the 2,6-dimethylpyridinium unit is too bulky to thread the host cavity. Both of the binding geometries mentioned above are observed for 2(2+), having one methyl group in the 2-position of pyridinium. Typically, the association constant of [2]pseudorotaxane 1(2+)⊂CP5A exceeds 10(6) M(-1) in water, which is significantly higher than those of previously reported analogues in organic solvents. The remarkably improved complexation of bis(pyridinium) guests by the anionic host was due to electrostatic attraction forces and hydrophobic interactions.
Phase evolution of hybrid metal oxides derived from MOF-74 nanowires was investigated systematically, and NiO/NiCo2O4(1 : 1) nanowires with hollow structure exhibited excellent performance in energy storage.
Owing to their nonemissive characteristics, electrochromic materials
promise distinct advantages in developing next-generation eye-friendly
information displays. Yet, it remains a challenge to manipulate the
structure of the materials to achieve a strong memory effect with
high optical contrast, which is of importance for displaying images
with essentially zero energy consumption. Here, we design a mixed
crystalline WO
x
thin film implanted with
massive oxygen deficiencies based on a conventional reactive magnetron
sputtering process. The obtained WO
x
film
exhibits high dual-band optical modulation in both visible (VIS, 99.0%
in 633 nm) and near-infrared (NIR, 94.2% in 1300 nm) regions as well
as an exceptional memory effect (the colored transmittance increases
only by 0.04% at 633 nm after 50 days). The enhanced electrochromic
performance can be attributed to dense Li+-ion binding
sites as well as the trapping effect provided by the massive internal
oxygen deficiencies. The strategy in this work bestows the WO
x
thin film a promising candidate for developing
electrochromic information displays and other energy-efficient devices
as well.
Oil spills in the deep-sea environment such as the 2010 Deep Water Horizon oil spill in the Gulf of Mexico release vast quantities of crude oil into the sea-surface environment. Various investigators have discussed the marine transport and fate of the oil into different environmental compartments (air, water, sediment, and biota). The transport of the oil into the atmosphere in these previous investigations has been limited to only evaporation, a volatility dependent pathway. In this work, we studied the aerosolization of oil spill matter via bursting bubbles as they occur during whitecaps in a laboratory aerosolization reactor. By evaluating the alkane content in oil mousse, crude oil, the gas phase, and particulate matter we clearly demonstrate that aerosolization via bursting bubbles is a solubility and volatility independent transport pathway for alkanes. The signature of alkane fractions in the native oil and aerosolized matter matched well especially for the less volatile alkanes (C20-C29). Scanning electron microscope interfaced with energy dispersive X-ray images identified the carbon fractions associated with salt particles of aerosols. Theoretical molecular dynamics simulations in the accompanying paper lend support to the observed propensity for alkanes at air-salt water interfaces of breaking bubbles and the produced droplets. The presence of a dispersant in the aqueous phase increased the oil ejection rate at the surface especially for the C20-C29 alkanes. The information presented here emphasizes the need to further study sea-spray aerosols as a possible transport vector for spilled oil in the sea surface environment.
Although photoelectrochemical synthesis of NH 3 is considered as an ecofriendly and sustainable process under ambient conditions, stable and highly efficient catalysts for the N 2 reduction reaction are still lacking because of the chemically inert nature of the triple bonds in elemental nitrogen and the competitive reaction of water reduction. In this paper, a photoelectrochemical N 2 reduction reaction route is proposed through combining black silicon and Ag nanoparticles using a simple deposition method. The synergetic effect of Ag nanoparticles and black Si significantly enhances the activity for the ammonia evolution reaction. The obtained Ag/bSi photocathode reaches a high Faraday efficiency of 40.6% and an NH 3 yield of 2.87 μmol h −1 cm −2 at −0.2 V versus the reversible hydrogen electrode in 0.1 M Na 2 SO 4 .
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