Controlling Lanthanide Exchange in Triple‐Stranded Helicates: A Way to Optimize Molecular Light‐Upconversion

The kinetic lability of hexadentate gallium‐based tripods is sufficient to ensure thermodynamic self‐assembly of luminescent heterodimetallic [GaLn( L3 )₃]⁶⁺ helicates on the hour time scale, where Ln is a trivalent 4f‐block cation. The inertness is, however, large enough for preserving the triple‐helical structure when [GaLn( L3 )₃]⁶⁺ is exposed to lanthanide exchange. The connection of a second gallium‐based tripod further slows down the exchange processes to such an extent that spectroscopically active [CrErCr( L4 )₃]⁹⁺ can be diluted into closed‐shell [GaYGa( L4 )₃]⁹⁺ matrices without metal scrambling. This feature is exploited for pushing molecular‐based energy‐transfer upconversion (ETU) at room temperature.     

Rapid Guest Exchange and Ultra‐Low Surface Tension Solvents Optimize Metal–Organic Framework Activation

Exploratory research into the critical steps in metal–organic framework (MOF) activation involving solvent exchange and solvent evacuation are reported. It is discovered that solvent exchange kinetics are extremely fast, and minutes rather days are appropriate for solvent exchange in many MOFs. It is also demonstrated that choice of a very low surface tension solvent is critical in successfully activating challenging MOFs. MOFs that have failed to be activated previously can achieve predicted surface areas provided that lower surface tension solvents, such as n‐hexane and perfluoropentane, are applied. The insights herein aid in the efficient activation of MOFs in both laboratory and industrial settings and provide best practices for avoiding structural collapse.     

Thioamide‐Directed Cobalt(III)‐Catalyzed Selective Amidation of C(sp3)−H Bonds

A mild, oxidant‐free, and selective Cp*Co^III‐catalyzed amidation of thioamides with robust dioxazolone amidating agents via C(sp³)−H bond activation to generate the desired amidated products is reported. The method is efficient and allows for the C−H amidation of a wide range of functionalized thioamides with aryl‐, heteroaryl‐, and alkyl‐substituted dioxazolones under the Cp*Co^III‐catalyzed conditions. The observed regioselectivity towards primary C(sp³)−H activation is supported by computational studies and the cyclometalation is proposed to proceed by means of an external carboxylate‐assisted concerted metalation/deprotonation mechanism. The reported method is a rare example of the use of a directing group other than the commonly used pyridine and quinolone classes for Cp*Co^III‐catalyzed C(sp³)−H functionalization and the first to exploit thioamides.     

A Lewis Base Catalysis Approach for the Photoredox Activation of Boronic Acids and Esters

We report herein the use of a dual catalytic system comprising a Lewis base catalyst such as quinuclidin‐3‐ol or 4‐dimethylaminopyridine and a photoredox catalyst to generate carbon radicals from either boronic acids or esters. This system enabled a wide range of alkyl boronic esters and aryl or alkyl boronic acids to react with electron‐deficient olefins via radical addition to efficiently form C−C coupled products in a redox‐neutral fashion. The Lewis base catalyst was shown to form a redox‐active complex with either the boronic esters or the trimeric form of the boronic acids (boroxines) in solution.     

Hydrogen Peroxide Insular Dodecameric and Pentameric Clusters in Peroxosolvate Structures

Peroxosolvates of 2‐aminonicotinic acid ( I ) and lidocaine N ‐oxide ( II ) including the largest insular hydrogen peroxide clusters were isolated and their crystal structures were determined by single‐crystal X‐ray diffraction. An unprecedented dodecameric hydrogen peroxide insular cluster was found in I . An unusual cross‐like pentameric cluster was observed in the structure of II . The topology of the (H₂O₂)₁₂ assembly was never observed for small‐molecule clusters. In I and II new double and triple cross‐orientational disorders of H₂O₂ were found. Cluster II is the first example of a peroxosolvate crystal structure containing H₂O₂ molecules with a homoleptic hydrogen peroxide environment. In II , a hydrogen bond between an H₂O₂ molecule and a peptide group ‐CONH⋅⋅⋅O₂H₂ was observed for the first time.     

Borane‐Stabilized Isomeric Dimers of the Phosphaethynolate Anion

The reactions of the phosphaethynolate anion ([PCO]⁻) with a range of boranes were explored. BPh₃ and [PCO]⁻ form a dimeric anion featuring P−B bonds and is prone to dissociation at room temperature. The more Lewis acidic borane B(C₆F₅)₃ yields a less symmetric dimer of [PCO]⁻ with P−B and P−O bonds. Less sterically demanding HB(C₆F₅)₂ and H₂B(C₆F₅) boranes form a third isomer with [PCO]⁻ featuring both boranes bound to the same phosphorus atom. Despite the unexpected thermodynamic preference for P‐coordination, computational data illustrate that electronic and steric features impact the binding modes of the resulting dianionic dimers.     

A Three‐Dimensionally π‐Conjugated Diradical Molecular Cage

π‐Conjugated molecular cages are very challenging targets in structural organic chemistry, supramolecular chemistry, and materials science. The synthesis and physical characterizations are reported of the first three‐dimensionally π‐conjugated diradical molecular cage PTM‐C, in which two polychlorotriphenylmethyl (PTM) radicals are linked by three bis(3,6‐carbazolyl) bridges. This cage compound was synthesized mainly by intermolecular Yamamoto coupling followed by deprotonation and oxidation. It is stable and its structure was confirmed by X‐ray crystallographic analysis. The two carbon‐centered PTM radicals are weakly coupled through electronic interactions with the carbazole spacers, as revealed by optical, electronic, and magnetic measurements as well as theoretical calculations.     

A Simple Prelithiation Strategy To Build a High‐Rate and Long‐Life Lithium‐Ion Battery with Improved Low‐Temperature Performance

Lithium‐ion batteries (LIBs) are being used to power the commercial electric vehicles (EVs). However, the charge/discharge rate and life of current LIBs still cannot satisfy the further development of EVs. Furthermore, the poor low‐temperature performance of LIBs limits their application in cold climates and high altitude areas. Herein, a simple prelithiation method is developed to fabricate a new LIB. In this strategy, a Li₃V₂(PO₄)₃ cathode and a pristine hard carbon anode are used to form a primary cell, and the initial Li⁺ extraction from Li₃V₂(PO₄)₃ is used to prelithiate the hard carbon. Then, the self‐formed Li₂V₂(PO₄)₃ cathode and prelithiated hard carbon anode are used to form a 4 V LIB. The LIB exhibits a maximum energy density of 208.3 Wh kg⁻¹, a maximum power density of 8291 W kg⁻¹ and a long life of 2000 cycles. When operated at −40 °C, the LIB can keep 67 % capacity of room temperature, which is much better than conventional LIBs.