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A series of heterobimetallic (Au⋯Ag interlocking and Au⋯Cu interlocking) [2]catenanes were studied using DFT and TD-DFT methods to explore the relationship between their structures and properties. In order to fully investigate the influence of metal type in these [2]catenanes and compare the similarities and differences between these heterobimetallic and homometallic catenanes, the results were also compared with our previously studied homometallic Au⋯Au interlocking [2]catenane molecules. The results display that the steric hindrance increases with the increase of the number of monomers, and thus the distances between the center and the edge of the rings become longer, demonstrating a trend of outward expansion. As the size of the ring becomes larger, the total weak interaction increases and shows increasingly dispersed distribution. The value of the dispersion interaction energy increases with the overgrowth of the size of molecular systems and correspondingly the energy level of the frontier orbital decreases and the energy gap becomes bigger when two hexamers interlock. Compared with the Au⋯Ag interlocking [2]catenanes, the Au⋯Cu interlocking [2]catenanes present red-shifted absorption spectra, which is consistent with their smaller energy gap. The hole–electron analysis results indicate that the S0 → S1 excitations are almost unidirectional charge transfer excitations due to the significant separation of holes and electrons, while for the high-energy excited states, local excitations occupy a dominant position. Through the study of the specific proportion of charge transfer on each fragment in the main transition process, we found that for heterometallic [2]catenanes, the Cu atom in the Au⋯Cu interlocking [2]catenanes has a greater influence on the electronic structure. As for homometallic [2]catenanes, the effects of Au atoms in the two rings are equivalent on the electronic structure. [ABSTRACT FROM AUTHOR]

Quantum mechanical and molecular dynamics simulations have been carried out on a series of anthracene‐o‐carborane derivatives (ANT‐H, ANT‐Ph, ANT‐Me and ANT‐TMS) with rare red‐light emission in the solid state. The simulation of the heating process of the crystals and further comparison of the molecular structures and excited‐state properties before and after heating help us to disclose the thermochromic behavior, that is, the red‐shift emission is caused by elongation of the C1−C2 bond in the carborane moiety after heating. Thus, we believe that the molecular structure in the crystal is severely affected by heating. Transformation of the molecular conformation appears in the ANT‐H crystal with increasing temperature. More specifically, the anthracene moiety moves from nearly parallel to the C1−C2 bond to nearly perpendicular, causing the short‐wavelength emission to disappear after heating. As for the aggregation‐induced emission phenomenon, the structures and photophysical properties were investigated comparatively in both the isolated and crystal states; the results suggested that the energy dissipation in crystal surroundings was greatly reduced through hindering structure relaxation from the excited to the ground state. We expect that discussion of the thermochromic behavior will provide a new analysis perspective for the molecular design of o‐carborane derivatives. [ABSTRACT FROM AUTHOR]

The production of hydrogen via electrochemical water splitting combined with fuel cells is a promising way to realize sustainable energy systems. Herein, we report a simple one-step, scalable glucose-blowing method to synthesize substrate-free porous molybdenum carbide nanoparticles coated with an N-doped porous carbon shell, termed Gb-Mo2C@PC. This catalyst exhibited a good hydrogen evolution reaction (HER) performance with overpotentials of 169 and 188 mV at a current density of 10 mA cm−2 and long-term stability in basic and acid electrolyte, respectively. The HER activity can be ascribed to the fact that the high surface area of its carbon shell can effectively prevent the aggregation of the Mo2C nanoparticles, and their uniform distribution favourably exposes abundant active sites. Moreover, the porous carbon shell coating can accelerate the charge transfer during the process of hydrogen generation and protect the Mo2C nanoparticles from corrosion. Furthermore, this strategy may provide a versatile route for the scaled-up production of cost-effective materials for electrochemical applications. [ABSTRACT FROM AUTHOR]