The one-step synthetic strategy for the preparation of the hitherto unknown calix[3]carbazole from readily available starting materials is described. Calix[3]carbazole is obtained in 20% yield, and it could selectively bind the N(C2H5)4(+) cation (tetraethylammonium, TEA) via cation-π interactions. The experimental and modeling results indicate that calix[3]carbazole possesses a larger π-cavity as well as a better chromophoric property than the traditional phenol-based macrocycles, and thus is capable of binding to and optically responding to the relatively large guest TEA.
DNA three-way junctions (TWJ-DNA) are intermediate structures in DNA replication and/or recombination. They play very important roles in biological processes, but more subtle functions are still unknown due partially to the lack of a fluorescent ligand. In this study, a cationic calix[3]carbazole (2) has been synthesized and its properties of interacting with TWJ-DNA have been evaluated by UV/Vis and fluorescence spectroscopy, circular dichroism (CD), gel electrophoresis, and H NMR studies. The results show that 2 binds to the central hydrophobic cavity of TWJ-DNA. Moreover, it could selectively bind to TWJ-DNA over duplex and quadruplex DNA. Furthermore, 2 possesses the capability of serving as the TWJ-DNA probe as its trap-II excimer emission is turned on by TWJ-DNA.
Metallic group VIB transition metal dichalcogenides (1T-TMDs)
have
attracted great interest because of their outstanding performance
in electrocatalysis, supercapacitors, batteries, and so on, whereas
the strict fabrication conditions and thermodynamical metastability
of 1T-TMDs greatly restrict their extensive applications. Therefore,
it is significant to obtain stable and high-concentration 1T-TMDs
in a simple and large-scale strategy. Herein, we report a facile and
large-scale synthesis of high-concentration 1T-TMDs via an ionic liquid
(IL) assisted hydrothermal strategy, including 1T-MoS2 (the
obtained MoS2 sample was denoted as MoS2-IL),
1T-WS2, 1T-MoSe2, and 1T-WSe2. More
importantly, we found that IL can adsorb on the surface of 1T-MoS2, where the steric hindrance, π–π stacking,
and hydrogen bonds of ionic liquid collectively induce the formation
of the 1T-MoS2. In addition, DFT calculation reveals that
electrons are transferred from [BMIM]SCN (1-butyl-3-methylimidazolium
thiocyanate) to 1T-MoS2 layers by hydrogen bonds, which
enhances the stability of 1T-MoS2, so the MoS2-IL performs with high stability for 180 days at room temperature
without obvious change. Furthermore, the MoS2-IL exhibits
excellent HER performance with an overpotential of 196 mV at 10 mA
cm–2 in acid conditions.
Molybdenum
sulfide (MoS2) has extensively attracted
attention as a promising nonprecious metal catalyst for the electrochemical
hydrogen evolution reaction (HER). Nevertheless, synergistically enhancing
the intrinsic conductivity and active sites of MoS2 is
the pivotal challenge to build up its hydrogen production performance.
Herein, a facile ionic liquid-assisted hydrothermal and subsequent
annealing treatment strategy is first reported to synthesize W-doped
MoS2 nanosheets supported on carbon cloth (Mo1‑x
W
x
S
y
/CC). The experimental results prove that the substitutional
W doping can effectively activate the catalytic activity of the inert
basal plane of MoS2 due to the generation of sulfur vacancies.
Density functional theory calculations further confirm that W doping
and S vacancies reduce the band gap of MoS2 and promote
the adsorption of H atoms, thereby greatly improving the HER performance.
The synergistic effects of W doping and S vacancies endow this material
remarkable HER performance with a low Tafel slope of 49.3 mV dec–1 and an overpotenial of 165 mV for 10 mA cm–2 in 0.5 M H2SO4 solution. In short, our new
strategy provides a simple and efficient pathway to synthesize Mo1‑x
W
x
S
y
/CC, and it can be applied to the design of
other materials possessing multifarious merits.
Copper-based
materials have been extensively developed as electrocatalysts
for water oxidation due to their promising efficiency and large abundance.
Among them, copper telluride could be a potential electrocatalyst
but is rarely reported compared with other copper chalcogenides. In
this work, rationally designed copper telluride nanosheet arrays on
copper foil are fabricated via a facile ionic liquid (1-butyl-3-methylimidazole
chloride, [Bmim]Cl) assisted hydrothermal process. The ionic liquid
serves as the solvent and etching agent, promoting the progress of
reaction and affecting the morphology of products and the corresponding
oxygen evolution reaction (OER) performance. The resulting layer-structure
electrocatalysts provide a larger specific surface area and more exposed
surface atoms as well as a tight interface with good adhesion to the
substrate, thereby accelerating charge transfer and mass diffusion.
Based on the above-mentioned advantages, the copper telluride electrode
exhibits favorable catalytic OER activity and long-term stability
in alkaline media. This work not only expands the variety of OER electrocatalysts
but also provides a practicable approach to developing active and
stable non-noble materials toward electrochemical water-splitting
systems.
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