Editors choice — 2021
Elucidation of the pre-nucleation phase directing metal-organic framework formation
The molecular pathway that governs metal-organic framework formation is challenging to grasp. Filez et al. establish a multi-scale characterization approach combined with theory to link the somewhat different worlds of “molecular” metal-organic ligand assembly and MOF “particle” crystallization.Lead-free B-site bimetallic perovskite photocatalyst for efficient benzylic C–H bond activation
Shi et al. propose a crystal structure design strategy to tune the electronic band structure and photogenerated carrier properties of lead-free halide perovskites. Furthermore, they reveal that the regulation of local structural symmetry could modulate the surface charge distribution and improve the adsorption and activation of C–H bond.Light-induced performance increase of carbon-based perovskite solar module for 20-year stability
Improving stability is one of the most important objectives in the practical application of perovskite photovoltaics. Kobayashi et al. work toward this goal by developing encapsulated mesoporous-carbon perovskite solar mini-modules that retain more than 92% of their initial performance after 3,000 h of damp-heat aging at 85°C/85% relative humidity, while maintaining 90% of the initial value (T90) for 3,260 h, equivalent to 20-year stability in outdoor use.Composition-dependent structure and properties of 5- and 15-element high-entropy alloy nanoparticles
Morris et al. report the variation in the structure and electronic properties of high-entropy alloy nanoparticles when the number of elements is varied between 5 and 15. These findings provide insight into how the structure of high-entropy alloys can be tuned for use in applications such as catalysis.Selective phase transformation of layered double hydroxides into mixed metal oxides for catalytic CO oxidation
Synthesis of phase-pure materials is important for studying structure-property relationship. Jang et al. selectively prepared pure copper-based spinels and delafossites exploiting phase transformation of layered double hydroxides in different atmospheric conditions. The spinels exhibit higher CO oxidation activities and improved CO adsorption active sites than those of delafossites.Ultra-high-performance heat spreader based on a graphite architecture with three-dimensional thermal routing
In this paper by Xu et al., the anisotropic heat conduction of graphite is overcome by assembling graphite blocks into a double-decker structure, which provides effectively isotropic heat dissipation comparable to isotropic materials with thermal conductivity as high as 900 W/m·K. This is more than twice the value of the typically used copper.High-phase purity two-dimensional perovskites with 17.3% efficiency enabled by interface engineering of hole transport layer
Sidhik et al. report a high-efficiency 2D hybrid perovskite solar cell with an open circuit voltage of 1.22 V by using Li-doped nickel oxide as the hole transport layer with a phase-pure vertically oriented thin film.Comparative study of fluorinated triarylalanes and their borane counterparts
The current spotlight on main-group chemistry has led to the development of a variety of Lewis acids, typically boron compounds. Kaehler et al. highlight the synthesis, properties, and reactivity of fluorinated triarylaluminium Lewis acids in direct comparison to their boron counterparts.Lessons learned from FeSb2O4 on stereoactive lone pairs as a design principle for anion insertion
Despite several decades of research, fundamental design principles for anion insertion in crystalline lattices remain poorly explored. Zaheer et al. provide a fundamental design principle based on electronic structure considerations that allows use of anions (fluoride ions) instead of cations for electrochemical energy storage.Combined hydrogen production and electricity storage using a vanadium-manganese redox dual-flow battery
The redox dual-flow battery system offers the opportunity to combine electricity storage and renewable hydrogen production. Reynard and Girault present a vanadium-manganese redox dual-flow system that is flexible, efficient, and safe and that provides a competitive alternative for large-scale energy storage, especially for service stations for both fast charging of electric vehicles and hydrogen refueling of fuel cell vehicles.A self-degradable hydrogel sensor for a nerve agent tabun surrogate through a self-propagating cascade
Lee et al. describe a self-degradable hydrogel that is used as both an optical and physical-change sensor for a nerve agent tabun surrogate. Upon detection, the hydrogel will degrade through a self-propagating cascade. Furthermore, the hydrogel acts as a barrier in an hourglass, as is confirmed using nanocrystals.Sustainable afterglow materials from lignin inspired by wood phosphorescence
Inspired by the afterglow room-temperature phosphorescence (RTP) of natural wood, Yuan et al. prepare sustainable afterglow RTP materials by confining lignin within a 3D molecular matrix, which paves a route for sustainable RTP materials.Atomically dispersed S-Fe-N4 for fast kinetics sodium-sulfur batteries via a dual function mechanism
Zhang et al. report that atomically dispersed Fe-N4 sites can modify sulfur’s electronic structure and enhance the activity of sulfur. They can boost the performance toward Na-S batteries by a dual function mechanism, accelerating Na+ ion diffusion and enhancing the kinetic conversion of polysulfides by weakening their S-S bonds.Twist-driven wide freedom of indirect interlayer exciton emission in MoS2/WS2 heterobilayers
Interlayer excitons (ILEs) involving an electron and a hole situated in separate adjacent layers are pronounced in type-II TMD-based heterobilayers. Tebyetekerwa et al. report a high twist-angle-dependent energy shift of the ILE emission peak in MoS2/WS2 heterobilayers for different samples investigated with a twist angle range of 0° to 60°.Reversible molecular motional switch based on circular photoactive protein oligomers exhibits unexpected photo-induced contraction
Lee et al. report molecular switches, ring-shaped circular oligomer PYPs (coPYPs), designed and generated to exploit the structural and photochromic properties of photoactive yellow protein (PYP). X-ray scattering and structural analysis of coPYP-4 show that the photoproduct of coPYPs undergoes contraction of the ring.Self-powered flexible artificial synapse for near-infrared light detection
To mimic the human visual system, Chen et al. adopt organic materials to sense and memorize light, including infrared light. The simple device can operate without voltage, and the strategy may provide sustainable energy solutions for artificial intelligence applications.Non-fullerene acceptor photostability and its impact on organic solar cell lifetime
Clarke et al. find that ITIC and ITIC-M can twist upon illumination in inert conditions, leading to eventual bond breakage and poor device stability. In contrast, O-IDTBR and EH-IDTBR devices show excellent stability. These findings provide insights that could aid with the design of more photostable acceptors.Topologically non-trivial metal-organic assemblies inhibit β2-microglobulin amyloidogenesis
Prakasam et al. report that topologically non-trivial metal-organic species inhibit the in vitro fibrillogenesis of the paradigmatic amyloidogen β2-microglobulin and the effects of the D76N mutant expression in a Caenorhabditis elegans disease model. Acting as small-molecule chaperones, the metal-templated assemblies suppress the formation of soluble protofibrillar oligomers by engaging labile supramolecular interactions that interfere with protein-protein pairing.Topology and ground state control in open-shell donor-acceptor conjugated polymers
Donor-acceptor (DA) conjugated polymers (CPs) with narrow bandgaps and open-shell (diradical) character demonstrate emergent phenomena that emanate from their collective electronic properties and diminished electron pairing. Mayer et al. report DA CPs that enable a strategy to control the ground state spin multiplicity and connect structural, physicochemical, electronic, spin, and magnetic properties.Scalable bacterial production of moldable and recyclable biomineralized cellulose with tunable mechanical properties
Scalable and biological production of nacre-like high-performance materials remains challenging. Yu et al. produce a self-assembling 3D moldable material with a layered microstructure. The material shows high toughness values, making it suitable for use in protective garments and plastics substitution.Synthesis, structure, and C–H bond activation reaction of an iron(IV) terminal imido complex bearing trifluoromethyl groups
Iron imido complexes are implicated as key intermediates in many iron-catalyzed reactions such as C–H bond amination and dinitrogen reduction. Liu et al. report an Fe(IV) terminal imido complex bearing CF3 groups [(IPr)Fe(NC(CF3)2Ph)], which has an S = 1 ground spin-state, long Fe-N(imido) bonds, and highly bent Fe-N(imido)-C angles and can readily undergo intramolecular C–H bond activation reactions. These structure and reactivity features are different from its analog [(IPr)Fe(NC(CH3)2Ph)].Enhancement of ion diffusion by targeted phonon excitation
Gordiz et al. computationally show that, by exciting the top contributing phonons to the ion hop, diffusivity increases without raising the bulk temperature. This observation suggests that diffusion,or more generally any transition, can be enhanced by exciting only the contributing phonons to that transition to elevated temperatures, instead of heating up the entire material.Synthesis strategies and biomedical applications for doped inorganic semiconductor nanocrystals
Doped semiconductor nanostructured materials with tunable properties are promising nanomedicine candidates to improve early diagnostics and therapies in medical research. Peng et al. provide an up-to-date review of doped semiconductor nanostructured materials, covering synthetic strategies and biomedical applications.Mixed electron-ion-water transfer in macromolecular radicals for metal-free aqueous batteries
Polymer-based, metal-free aqueous batteries represent a challenging “green” electrochemical energy storage technology. Ma et al. quantify the effects of polymer-water interactions on the kinetics and real-time mass and charge transfer of TEMPO-substituted non-conjugated polymers in metal-free aqueous electrolyte, showing a design strategy for polymer-based metal-free aqueous batteries.Efficient molecular encoding in multifunctional self-immolative urethanes
Dense and cost-effective means for storing information for future use is needed as society continues to produce data exponentially. Abiotic polymers (plastics) are an exceptional platform for information storage because of their accessibility and limitless structural modifications. However, efficient, high-throughput means for “writing” on them and “reading” them are still needed. Herein, Dahlhauser et al. report the high-throughput synthesis (writing) and sequencing (reading) of urethanes.
