Search

Trifluoromethyl cationic carbyne (CF3C+:) possessing dual carbene‐carbocation behavior emulated as trifluoromethyl metal‐carbynoid (CF3C+=M) has not been explored yet, and its reaction characteristics are unknown. Herein, a novel α‐diazotrifluoroethyl sulfonium salt was prepared and used in Rh‐catalyzed three‐component [2+1+2] cycloadditions for the first time with commercially available N‐fused heteroarenes and nitriles, yielding a series of imidazo[1,5‐a] N‐heterocycles that are of interest in medicinal chemistry, in which the insertion of trifluoromethyl Rh‐carbynoid (CF3C+=Rh) into C=N bonds of N‐fused heteroarenes was involved. This strategy demonstrates synthetic applications in late‐stage modification of pharmaceuticals, construction of CD3‐containing N‐heterocycles, gram‐scale experiments, and synthesis of phosphodiesterase 10A inhibitor analog. These highly valuable and modifiable imidazo[1,5‐a] N‐heterocycles exhibit good antitumor activity in vitro, thus demonstrating their potential applications in medicinal chemistry. [ABSTRACT FROM AUTHOR]

Precisely introducing topological defects is an important strategy in nanographene crystal engineering because defects can tune π‐electronic structures and control molecular assemblies. The synergistic control of the synthesis and assembly of nanographenes by embedding the topological defects to afford two‐dimensional (2D) crystals on surfaces is still a great challenge. By in‐situ embedding ladder bipyrazinylene (LBPy) into acene, the narrowest nanographene with zigzag edges, we have achieved the precise preparation of 2D nonbenzenoid heteroacene crystals on Au(111). Through intramolecular electrocyclization of o‐diisocyanides and Au adatom‐directed [2+2] cycloaddition, the nonbenzenoid heteroacene products are produced with high chemoselectivity, and lead to the molecular 2D assembly via LBPy‐derived interlocking hydrogen bonds. Using bond‐resolved scanning tunneling microscopy, we determined the atomic structures of the nonbenzenoid heteroacene product and diverse organometallic intermediates. The tunneling spectroscopy measurements revealed the electronic structure of the nonbenzenoid heteroacene, which is supported by density functional theory (DFT) calculations. The observed distinct organometallic intermediates during progression annealing combined with DFT calculations demonstrated that LBPy formation proceeds via electrocyclization of o‐diisocyanides, trapping of heteroarynes by Au adatoms, and stepwise elimination of Au adatoms. [ABSTRACT FROM AUTHOR]

Satoh–Miura reaction is an important method for extending π‐systems by forging multi‐substituted benzene rings via double aryl C−H activation and annulation with alkynes. However, the development of highly enantioselective Satoh–Miura reaction remains rather challenging. Herein, we report an asymmetric Satoh–Miura reaction between 1‐aryl benzo[h]isoquinolines and internal alkynes enabled by a SCpRh‐catalyst. Judiciously choosing the counteranion of the Rh‐catalyst is crucial for the desired reactivity over the competitive formation of azoniahelicenes. Detailed mechanistic studies support the proposal of counteranion‐directed switching of reaction pathways in Rh‐catalyzed asymmetric C−H activation. [ABSTRACT FROM AUTHOR]

Despite the advances in the area of catalytic alkene hydrosilylation, the enantioselective hydrosilylation of alkenes bearing a heteroatom substituent is scarce. Here we report a rhodium‐catalyzed hydrosilylation of β,β‐disubstituted enamides to directly afford valuable α‐aminosilanes in a highly regio‐, diastereo‐, and enantioselective manner. Stereodivergent synthesis could be achieved by regulating substrate geometry and ligand configuration to generate all the possible stereoisomers in high enantio‐purity. [ABSTRACT FROM AUTHOR]

Materials showing synergy of magnetic and dielectric transitions are promising candidates for future molecular devices. The challenge is how to realize synergy between spin and dielectric transitions with responses to external stimuli. Herein, we design a 2D spin crossover (SCO) complex, [FeII(dpa)][(pzTp)FeIII(CN)3]2 (1) (dpa=1,2‐bis(4‐pyridyl)ethyne and pzTp=tetrakis(pyrazolyl)borate). The local structural changes about the FeII ion were propagated to the whole crystal through the rigid bridging ligands (dpa), leading to elastic interactions to realize the abrupt SCO and rotational movements of polar apical pyrazolyl rings in the [(pzTp)FeIII(CN)3]− units. Dielectric measurements confirmed a substantial dielectric change (Δϵ′=2.3) upon the spin transition. This work provides a rational strategy to couple the spin transition and rotation of polar components, which is crucial for the synergetic switch of magnetism and dielectricity. [ABSTRACT FROM AUTHOR]

A series of solid supramolecules based on acrylamide–phenylpyridium copolymers with various substituent groups (P−R: R=−CN, −CO2Et, −Me, −CF3) and cucurbit[7]uril (CB[7]) are constructed to exhibit tunable second‐level (from 0.9 s to 2.2 s) room‐temperature phosphorescence (RTP) in the amorphous state. Compared with other solid supramolecules P−R/CB[7] (R=−CN, −CO2Et, −Me), P−CF3/CB[7] displays the longest lifetime (2.2 s), which is probably attributed to the fluorophilic interaction of cucurbiturils leading to a uncommon host–guest interaction between 4‐phenylpyridium with −CF3 and CB[7]. Furthermore, the RTP solid supramolecular assembly (donors) can further react with organic dyes Eosin Y or SR101 (acceptors) to form ternary supramolecular systems featuring ultralong phosphorescence energy transfer (PpET) and visible delayed fluorescence (yellow for EY at 568 nm and red for SR101 at 620 nm). Significantly, the ultralong multicolor PpET supramolecular assembly can be further applied in fields of anti‐counterfeiting and information encryption and painting. [ABSTRACT FROM AUTHOR]

An enhancement strategy is realized for ultralong bright room‐temperature phosphorescence (RTP), involving polymerization between phosphor monomers and acrylamide and host–guest complexation interaction between phosphors and cucurbit[6,7,8]urils (CB[6,7,8]). The non‐phosphorescent monomers exhibit 2.46 s ultralong lifetime after copolymerizing with acrylamide. The improvement is due to the rich hydrogen bond and carbonyl within the polymers which promote intersystem crossing, suppress nonradiative relaxation and shield quenchers effectively. By tuning the ratio of chromophores, a series of phosphorescent copolymers with different lifetimes and quantum yields are prepared. The complexation of macrocyclic hosts CB[6,7,8] promote the RTP of polymers by blocking aggregation‐caused quenching, and offsetting the losses of aforementioned interaction provided by polymer. Multiple lifetime‐encoding for digit and character encryption are achieved by utilizing the difference of their lifetimes. [ABSTRACT FROM AUTHOR]

It is promising and challenging to manipulate the electronic structures and functions of materials utilizing both metal‐to‐metal charge transfer (MMCT) and spin‐crossover (SCO) to tune the valence and spin states of metal ions. Herein, a metallocyanate building block is used to link with a FeII‐triazole moiety and generates a mixed‐valence complex {[(Tp4‐Me)FeIII(CN)3]9[FeII4(trz‐ph)6]}⋅[Ph3PMe]2⋅[(Tp4‐Me)FeIII(CN)3] (1; trz‐ph=4‐phenyl‐4H‐1,2,4‐triazole). Moreover, MMCT occurs between FeIII and one of the FeII sites after heat treatment, resulting in the generation of a new phase, {[(Tp4‐Me)FeII(CN)3][(Tp4‐Me)FeIII(CN)3]8 [FeIIIFeII3(trz‐ph)6]}⋅ [Ph3PMe]2⋅[(Tp4‐Me)FeIII(CN)3] (1 a). Structural and magnetic studies reveal that MMCT can tune the two‐step SCO behavior of 1 into one‐step SCO behavior of 1 a. Our work demonstrates that the integration of MMCT and SCO can provide a new alternative for manipulating functional spin‐transition materials with accessible multi‐electronic states. [ABSTRACT FROM AUTHOR]

Chiral propargyl amines are valuable synthetic intermediates for the preparation of biologically active compounds and functionalized amines. Catalytic methods to access propargyl amines containing vicinal stereocenters with high diastereoselectivity are particularly rare. We report an unprecedented strategy for the synthesis of enantioenriched propargyl amines with two stereogenic centres. An iridium complex, ligated by a phosphoramidite ligand, catalyzes the hydroalkynylation of β,β‐disubstituted enamides to afford propargyl amides in a highly regio‐, diastereo‐, and enantioselective fashion. Stereodivergent synthesis of all four possible stereoisomers was achieved using this strategy. [ABSTRACT FROM AUTHOR]

Extra‐large‐pore zeolites for processing large molecules have long been sought after by both the academia and industry. However, the synthesis of these materials, particularly extra‐large‐pore pure silica zeolites, remains a big challenge. Herein we report the synthesis of a new extra‐large‐pore silica zeolite, designated NUD‐6, by using an easily synthesized aromatic organic cation as structure‐directing agent. NUD‐6 possesses an intersecting 16×8×8‐membered ring pore channel system constructed by four‐connected (Q4) and unusual three‐connected (Q3) silicon species. The organic cations in NUD‐6 can be removed in nitric acid to yield a porous material with high surface area and pore volume. The synthesis of NUD‐6 presents a feasible means to prepare extra‐large pore silica zeolites by using assembled aromatic organic cations as structure‐directing agents. [ABSTRACT FROM AUTHOR]

Developing red thermally activated delayed fluorescence (TADF) emitters, attainable for both high‐efficient red organic light‐emitting diodes (OLEDs) and non‐doped deep red/near‐infrared (NIR) OLEDs, is challenging. Now, two red emitters, BPPZ‐PXZ and mDPBPZ‐PXZ, with twisted donor–acceptor structures were designed and synthesized to study molecular design strategies of high‐efficiency red TADF emitters. BPPZ‐PXZ employs the strictest molecular restrictions to suppress energy loss and realizes red emission with a photoluminescence quantum yield (ΦPL) of 100±0.8 % and external quantum efficiency (EQE) of 25.2 % in a doped OLED. Its non‐doped OLED has an EQE of 2.5 % owing to unavoidable intermolecular π–π interactions. mDPBPZ‐PXZ releases two pyridine substituents from its fused acceptor moiety. Although mDPBPZ‐PXZ realizes a lower EQE of 21.7 % in the doped OLED, its non‐doped device shows a superior EQE of 5.2 % with a deep red/NIR emission at peak of 680 nm. [ABSTRACT FROM AUTHOR]

Room‐temperature thermoelectric materials are the key to miniaturizing refrigeration equipment and have great scientific and social implications, yet their application is hindered by their extreme scarcity. BiTe exhibiting strong spin‐orbit coupling peaks ZT at 600 K. Herein, we discover the synergy effect of Sb doping in BiTe that eliminates the detrimental band inversion and leads to an overlap of conduction band (CB) and valence band that significantly increases the S from 33 to 124 μV K−1. In addition, this effect enhances the μ from 58 to 92 cm2 V−1 s−1 owing to the sharp increase in the CB slope along the Γ‐A in the first Brillouin zone. Furthermore, Sb doping increases the anharmonicity, shortens the phonon lifetime and lowers κlat. Finally, Se/Sb codoping further optimizes the ZT to 0.6 at 300 K, suggesting that Bi0.6Sb0.4Te1−ySey is a potential room‐temperature TE material. [ABSTRACT FROM AUTHOR]

Sind gründlich studiert worden, allerdings verlief die Entwicklung von roten/nahinfraroten TADF-Emittern viel langsamer als die von grünen und blauen Emittern (TADF: thermisch aktivierte verzögerte Fluoreszenz). Sind gründlich studiert worden, allerdings verlief die Entwicklung von roten/nahinfraroten TADF-Emittern viel langsamer als die von grünen und blauen Emittern (TADF: thermisch aktivierte verzögerte Fluoreszenz). Zhang et al. präsentieren in ihrem Forschungsartikel auf S. 14808 zwei neuartige rote TADF-Emitter. [Extracted from the article]

Direct asymmetric functionalization of the inert α C−H bonds of N‐unprotected propargylic amines is a big challenge in organic chemistry, due to the low acidity (pKa≈42.6) of the α C−H bonds and interruption of the nucleophilic NH2 group. By using a chiral pyridoxal as carbonyl catalyst, we have successfully realized direct asymmetric α‐C−H addition of N‐unprotected propargylic amines to trifluoromethyl ketones, producing a broad range of chiral alkynyl β‐aminoalcohols in 54–84 % yields with excellent stereoselectivities (up to 20 : 1 dr and 99 % ee). The α C−H bonds of propargylic amines are greatly activated by the pyridoxal catalyst via the formation of an imine intermediate, resulting in the increase of acidity by up to 1022 times (from pKa 42.6 to pKa 20.1), which become acidic enough to be deprotonated under mild conditions for the asymmetric addition. This work presented an impressive example for asymmetric functionalization of inert C−H bonds enabled by an organocatalyst. [ABSTRACT FROM AUTHOR]

A direct and catalyst-free method for the intramolecular aminoboration of unfunctionalized olefins is reported. In the presence of BCl3 (1 equiv) as the sole boron source, intramolecular aminoboration of sulfonamide derivatives of 4-penten-1-amines, 5-hexen-1-amines, and 2-allylanilines proceeded readily without the use of any catalyst. The boronic acids obtained after hydrolysis could be converted into the corresponding pinacol borates in a straightforward manner by treatment with pinacol under anhydrous conditions. [ABSTRACT FROM AUTHOR]

Owing to the strong nucleophilicity of the NH2 group, free‐NH2 glycinates react with MBH acetates to usually deliver N‐allylated products even in the absence of catalysts. Without protection of the NH2 group, chiral pyridoxal catalysts bearing an amide side chain at the C3 position of the naphthyl ring switched the chemoselectivity of the glycinates from intrinsic N‐allylation to α‐C allylation. The reaction formed chiral multisubstituted glutamic acid esters as SN2′–SN2′ products in good yields with excellent stereoselectivity (up to 86 % yield, >20 : 1 dr, 97 % ee). As compared to pyridoxal catalysts bearing an amide side arm at the C2 position, the pyridoxals in this study have a bigger catalytic cavity to enable effective activation of larger electrophiles, such as MBH acetates and related intermediates. The reaction is proposed to proceed via a cooperative bifunctional catalysis pathway, which accounts for the high level of diastereo‐ and enantiocontrol of the pyridoxal catalysts. [ABSTRACT FROM AUTHOR]

Uncontrolled growth of Zn dendrites and side reactions are the major restrictions for the commercialization of Zn metal anodes. Herein, we develop a TiOx/Zn/N‐doped carbon inverse opal (denoted as TZNC IO) host to regulate the Zn deposition. Amorphous TiOx and Zn/N‐doped carbon can serve as the zincophilic nucleation sites to prevent the parasitic reactions. More importantly, the highly ordered IO host homogenizes the local current density and electric field to stabilize Zn deposition. Furthermore, the three‐dimensional open networks could regulate Zn ion flux to enable stable cycling performance at large current densities. Owing to the abundant zincophilic sites and the open structure, granular Zn deposits could be realized. As expected, the TZNC IO host guarantees the steady Zn plating/stripping with a long‐term stability over 450 h at the current density of 1 mA cm−2. As a proof‐of‐concept demonstration, a TZNC@Zn||V2O5 full cell shows long lifespan over 2000 cycles at 5.0 A g−1. [ABSTRACT FROM AUTHOR]

Aufopferungsvoll: Kommerzielle Katalysatoren, wie sie in Biomassekraftwerken eingesetzt werden, werden durch das alkalireiche Verbrennungsgas desaktiviert (siehe Diagramm, schwarze Linie). Ein alkaliresistenter Hollandit ‐ Katalysator wird beschrieben, bei dem eines der beiden aktiven Zentren Alkalimetallionen bindet und so das zweite, katalytisch aktive Zentrum für die Reduktion von NO durch NH3 freihält. [ABSTRACT FROM AUTHOR]

Unterschiede in der Bindung der Neuraminidase ‐ Inhibitoren Zanamivir und Oseltamivir (OS) werden in einem Assay genutzt, um Influenza ‐ Unterarten zu identifizieren, die resistent gegen OS, aber noch empfindlich gegen Zanamivir sind (siehe Schema). Der Assay setzt ein Zanamivir ‐ Biotin ‐ Konjugat ein, um die OS ‐ Empfindlichkeit von Influenzaviren und über 200 klinischen Isolaten zu ermitteln. [ABSTRACT FROM AUTHOR]

The production of photo‐switchable molecular nanomagnets with substantial coercivity, which is indispensable for information storage and process applications, is challenging. Introducing photo‐responsive spin‐crossover units provides a feasible means of controlling the magnetic anisotropy, interactions, and overall nanomagnet properties. Herein, we report a cyanide‐bridged chain 1⋅12H2O ({[(PzTp)FeIII(CN)3]2FeII(Pmat)2}n⋅12 H2O) generated by linking the FeII‐based spin‐crossover unit with the [(PzTp)Fe(CN)3]− (PzTp: tetrakis(pyrazolyl)borate) building block in the presence of asymmetric ditopic ligand Pmat ((4‐pyridine‐4‐yl)methyleneamino‐1,2,4‐triazole). Structural characterization revealed that the introduction of this asymmetric ligand led to a distorted coordination environment of FeII ions, which were equatorially coordinated by four cyanide N atoms, and apically coordinated by one pyridine N atom and one triazole N atom. Upon 808‐nm light irradiation, 1⋅12H2O underwent photoinduced spin‐crossover and exhibited single‐chain magnet behavior with a coercive field of up to 1.3 T. This represents a 3d‐based photoinduced single‐chain magnet exhibiting pronounced hysteresis. [ABSTRACT FROM AUTHOR]

Understanding the effects of intermolecular interactions on metal‐to‐metal charge transfer (MMCT) is crucial to develop molecular devices by grafting MMCT‐based molecular arrays. Herein, we report a series of solvent‐free {Fe2Co2} compounds sharing the same cationic tetranuclear {[Fe(PzTp)(CN)3]2[Co(dpq)2]2}2+ (PzTp−=tetrakis(pyrazolyl)borate, dpq=dipyrido[3,2‐d:2′,3′‐f]quinoxaline) square units but having anions with different size, including BF4−, PF6−, OTf−, and [Fe(PzTp)(CN)3]−. Intermolecular π⋅⋅⋅π interactions between dpq ligands, which coordinate to cobalt ions in the {[Fe(PzTp)(CN)3]2[Co(dpq)2]2}2+ units, can be modulated by introducing different counterions, regulating the distortion of the CoN6 octahedron and ligand field around the cobalt ions. This change results in different MMCT behavior. Computational analyzes reveal the substantial role of the intermolecular interactions tuned by the presence of different counteranions on the MMCT behavior. [ABSTRACT FROM AUTHOR]

Reported herein are two new polymorphic Co-MOFs (CTGU-5 and -6) that can be selectively crystallized into the pure 2D or 3D net using an anionic or neutral surfactant, respectively. Each polymorph contains a H2O molecule, but differs dramatically in its bonding to the framework, which in turn affects the crystal structure and electrocatalytic performance for hydrogen evolution reaction (HER). Both experimental and computational studies find that 2D CTGU-5 which has coordinates water and more open access to the cobalt site has higher electrocatalytic activity than CTGU-6 with the lattice water. The integration with co-catalysts, such as acetylene black (AB) leads to a composite material, AB&CTGU-5 (1:4) with very efficient HER catalytic properties among reported MOFs. It exhibits superior HER properties including a very positive onset potential of 18 mV, low Tafel slope of 45 mV dec−1, higher exchange current density of 8.6×10−4 A cm−2, and long-term stability. [ABSTRACT FROM AUTHOR]

Blockade of the protein-protein interaction between the transmembrane protein programmed cell death protein 1 (PD-1) and its ligand PD-L1 has emerged as a promising immunotherapy for treating cancers. Using the technology of mirror-image phage display, we developed the first hydrolysis-resistant D-peptide antagonists to target the PD-1/PD-L1 pathway. The optimized compound DPPA-1 could bind PD-L1 at an affinity of 0.51 μ M in vitro. A blockade assay at the cellular level and tumor-bearing mice experiments indicated that DPPA-1 could also effectively disrupt the PD-1/PD-L1 interaction in vivo. Thus D-peptide antagonists may provide novel low-molecular-weight drug candidates for cancer immunotherapy. [ABSTRACT FROM AUTHOR]

Cobalt‐MOFs, …… deren Phase durch anionische und neutrale Tenside vorgegeben wird, sind unterschiedlich affin gegenüber eingelagerten Wassermolekülen. Diesen Umstand nutzen D.‐S. Li, C. Sun, X. Bu und Mitarbeiter in ihrer Zuschrift auf S. 13181 für die leistungsstarke elektrokatalytische Wasserstoffentwicklung (HER). Im Bildhintergrund symbolisieren eine Meereswelle und der Drei‐Schluchten‐Damm das Potenzial von Wasser als “grüne” Energiequelle. Fortschritte bei der Wasserspaltung ergänzen die Nutzung dieser Energieformen. [ABSTRACT FROM AUTHOR]