No abstract

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.