Search

Developing luminescent radicals with tunable emission is a challenging task due to the limitation of alternative skeletons. Herein, a series of carbene‐triphenylamine hybrids were prepared by the direct C2‐arylation of N‐heterocyclic carbenes with 4‐bromo‐N,N‐bis(4‐methoxyphenyl)aniline. These hybrids showed multiple redox‐active properties and could be converted to carbon‐centered luminescent radicals with blue‐to‐cyan emissions (λmax: 436–486 nm) or nitrogen‐centered luminescent radicals with orange emissions (λmax: 590–623 nm) through chemical reduction or oxidation, respectively. The radical species were characterized by electron paramagnetic resonance spectroscopy, ultraviolet‐visible spectroscopy, and single‐crystal X‐ray diffractometry analysis. Notably, the corresponding nitrogen‐centered radicals exhibited good stability in atmospheric air, and their thermal decomposition temperatures were determined to be above 200 °C. In addition, spectral and theoretical calculations indicate that all radicals exhibit anti‐Kasha emissions. [ABSTRACT FROM AUTHOR]

Fixing nitrogen (N2) by electrosynthesis method has become a promising way to ammonia (NH3) production, nevertheless, developing electrocatalysts combining long‐term stable and low‐cost feathers are still a great challenge to date. Using comprehensive first‐principles calculations, we herein investigate the potential of a new class of two‐dimensional (2D) transition metal tri‐borides (TMB3s) as nitrogen reduction reaction (NRR) electrocatalysts, and explore the effect of magnetic orders on the NRR. Our results show that the TMB3s can sufficiently activate N2 and convert it to NH3. Particularly, TiB3 is identified as a high‐efficiency catalyst for NRR because of its low limiting potential (−0.24 V) and good suppression of the competitive hydrogen evolution reaction (HER). For the first time, we present that these TMB3s with various magnetic states exhibit different performances in the adsorption of N2 and NRR intermediates, and minor effect on activation of N2. Besides, VB3, CrB3, MnB3, and FeB3 monolayers possess the superior capacity to suppress surface oxidation via the self‐activating process, which reduces *O/*OH into *H2O under NRR electrochemical conditions, thus favoring the N2 electroreduction. This work paves the way for finding high‐performance NRR catalysts for transition metal borides and pioneering the research of magnetic states effects in NRR. [ABSTRACT FROM AUTHOR]

Chiral pseudo[1]rotaxanes and [1]rotaxanes constructed from macrocyclic arenes still remain a big challenge mainly owing to the lack of such chiral macrocycles. In this work, a new system of chiral pseudo[1]rotaxanes formed by self‐inclusion of helic[6]arene containing amide linked with the terminal tertiary amines was first discovered. Based on an atom‐economic stopping strategy, a pair of chiral [1]rotaxanes were conveniently obtained in almost quantitative yields by blocking the pseudo[1]rotaxanes with monobenzyl bromide of tetraphenylethene. The structures of pseudo[1]rotaxanes and [1]rotaxanes were characterized by 2D NMR spectra in solution, combined with DFT calculations. The photophysical properties further revealed the efficient chirality transfer of helic[6]arene to the tetraphenylethene moiety, compared to their unthreaded chiral isomers. The discovery of the chiral pseudo[1]rotaxanes allows for a wide and available synthesis of chiral [1]rotaxanes, and also opening a new avenue to the design of chiral supramolecular materials. [ABSTRACT FROM AUTHOR]

Thanks to the potential of aggregation‐induced emission (AIE) phenomena, improved stabilities, and the good selectivity and sensitivity of the chemical responses exhibited by the products, coordination‐driven self‐assembly with tetraphenylethylene (TPE) units has recently received much attention and has been widely investigated for application in chemical sensors, cell imaging agents, light‐harvesting systems, and others. Several reviews have emerged on the topics of AIE chemistry and aggregation‐induced emission luminogen (AIEgen)‐based supramolecular assembles, however, there is still a distinct lack of full overviews of emission enhancement from the viewpoint of metal‐coordination effects. Thus, this minireview offers recent advances that have been made in the design and application of TPE‐based metallacycles, metallacages, metal‐organic frameworks (MOFs) and coordination polymers (CPs). [ABSTRACT FROM AUTHOR]

The metal‐controlled self‐assembly of organometallic molecular cylinders from a series of imidazo[1,5‐a]pyridine‐based tris‐NHC ligands is described in this report. The imidazo[1,5‐a]pyridinium salts H3‐L(PF6)3 (L=4 a–4 c) were treated with 1.5 equivalents of Ag2O to yield the trinuclear AgI hexacarbene cages [Ag3(L)2](PF6)3 (L=4 a–4 c), in which three AgI are sandwiched between the two tricarbene ligands. The silver(I) complexes [Ag3(L)2](PF6)3 underwent a facile transmetalation reaction in the presence of 3 equivalents of [AuCl(tht)] (tht=tetrahydrothiophene) to furnish the trinuclear AuI cylinder‐like cages [Au3(L)2](PF6)3 (L=4 a–4 c) without destruction of the metallosupramolecular structure. The new hexacarbene assemblies feature a large cavity that can easily accommodate a molecule of dimethyl sulfoxide as molecular guest. This is the first study of a unique "host–guest" system containing an organometallic cylinder‐like cage derived exclusively from poly‐NHC ligands. Well done imidazopyridine! A set of novel organometallic molecular cylinders comprising imidazo[1,5‐a]pyridine‐based tris‐NHC ligands is described. The incorporation of imidazo[1,5‐a]pyridine scaffolds into the poly‐NHC ligands enhances the cavity size of the new trinuclear metallacages prepared by a silver‐ and gold‐mediated self‐assembly strategy. The metallacages have potential in molecular recognition (see figure). [ABSTRACT FROM AUTHOR]

The internal cavity size of a metallosupramolecular assembly can be tuned by thoughtful design of the ligand. This work reports the introduction of imidazo[1,5‐a]pyridine scaffolds in place of the conventional imidazol‐2‐ylidene moieties, which resulted in new molecular containers bearing significantly enlarged cavities. The new hexacarbene metal assemblies can easily accommodate a dimethylsulfoxide molecule as a molecular guest. This is the first study of a unique "host–guest" system featuring an organometallic cylinder‐like cage exclusively derived from poly‐NHC ligands. More information can be found in the Full Paper by Y.‐F. Han et al. on page 5472. [ABSTRACT FROM AUTHOR]