A composite material, {Fe(L)(TPPE)0.5⋅3 CH3OH}n, has been constructed by integrating the spin‐crossover (SCO) subunit ...FeII{diethyl(E,E)‐2,2′‐1,2‐phenyl‐bis(iminomethylidyne)bis(3‐oxobutanoate)‐(2‐)‐N,N′,O3,O3′} and the highly luminescent connector 1,1,2,2‐tetrakis(4‐(pyridin‐4‐yl)phenyl)‐ethene. Its structure contains four staggered 4×4 layers and intercalated methanol. The packing is dominated by considerable H‐bonds either between adjacent layers and between layers and guests. A crystal‐structure transformation was detected upon removal of the guest molecules. The SCO transition of the solvated crystals is centered at ca. 215 K with a non‐symmetrical hysteresis of 25 K wide, and the desolvated Fe(L)(TPPE)0.5n exhibits gradual SCO without hysteresis. Intriguingly, the intensity of the fluorescence at 460 nm for the latter is maximized at the SCO transition. The energy transfer between luminescent and SCO entities is achievable as confirmed by theoretical calculations.
A square‐grid layered FeII coordination polymer based on a luminophore connector TPPE was studied. This framework not only features a solvent‐dependent structure and spin crossover (SCO) behavior, but also exhibits a switch between spin transition and fluorescence for the guest‐free species. Theoretical calculation reveals an energy‐transfer mechanism.
Azadipyrromethenes were first described over 70 years ago as blue pigments, but now are rapidly emerging as a compound class with highly desirable near infrared photophysical properties. Since the ...turn of the century several routes to azadipyrromethenes have been developed and numerous post-synthesis derivatizations have allowed for their exploitation in both biological and material sciences. The relative ease of access to specifically designed derivatives is now allowing their use in multiple technological formats from real-time fluorescence imaging, to solar energy materials, to optoelectronic devices and many more. In this review we have highlighted the synthetic component of this story as it is the ability to generate the designer azadipyrromethene that opens the door to exciting applications.
The journey of azadipyrromethenes from accidental dye chemistry to a compound class with widely applicable near infrared photophysical properties is documented.
Metal-organic frameworks (MOFs) that respond to external stimuli such as guest molecules, temperature, or redox conditions are highly desirable. Herein, we coupled redox-switchable properties with ...breathing behavior induced by guest molecules in a single framework. Guided by topology, two flexible isomeric MOFs, compounds 1 and 2, with a formula of In(Me
NH
)(TTFTB), were constructed via a combination of In(COO)
metal nodes and tetratopic tetrathiafulvalene-based linkers (TTFTB). The two compounds show different breathing behaviors upon the introduction of N
. Single-crystal X-ray diffraction, accompanied by molecular simulations, reveals that the breathing mechanism of 1 involves the bending of metal-ligand bonds and the sliding of interpenetrated frameworks, while 2 undergoes simple distortion of linkers. Reversible oxidation and reduction of TTF moieties changes the linker flexibility, which in turn switches the breathing behavior of 2. The redox-switchable breathing behavior can potentially be applied to the design of stimuli-responsive MOFs.
Developing high-efficiency electrocatalysts for both oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) is vital for the production of hydrogen on a large scale by electrocatalytic ...splitting of water. Herein, Fe-doped Ni(OH)
nanosheets directly grown on commercial Ni foam (FeNiOH/NF) were fabricated through a facile hydrothermal method in (NH
)
S
O
aqueous solution containing iron salts. The integrated architecture with hierarchical pores is beneficial for exposing sufficient catalytically active sites and providing evaluated structural and electrical properties. In particular, the Fe-induced partial-charge-transfer greatly modifies the electronic structure of Ni(OH)
, which evidently promotes the electrocatalytic activity of the as-fabricated FeNiOH/NF for OER and HER. Thus, as an electrocatalyst for OER, FeNiOH/NF exhibits excellent activity with overpotentials of 271 and 318 mV to deliver current densities of 20 and 100 mA cm
, respectively, with a small Tafel slope of 72 mV dec
in 1.0 M KOH, demonstrating the very high level of novelty and sufficient improvement over the current state-of-the-art IrO
electrocatalyst. Most importantly, there is an increase in overpotential by only 23 mV during continuous reaction for over 20 h at an applied potential of 1.62 V to deliver current density of 500 mA cm
. The as-fabricated electrocatalyst also enables high HER activity with robust stability. Finally, an overall water splitting current density of 10 mA cm
can be obtained at a cell voltage of 1.67 V in a two-electrode alkaline electrolyzer using FeNiOH/NF as both anode and cathode, along with impressive operation stability. This development with significant over the state-of-the-art IrO
electrocatalyst can be widely extended to large-scale fabrication of versatile electrocatalysts for efficient water splitting technology.
Developing highly efficient and cost‐effective electrocatalysts to boost the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) is vital for the sustainable energy systems. The ...nitrogen and phosphorus codoped vesica‐like carbons with hierarchical nanoporous structure are synthesized through an efficient self‐polymerization strategy with the template of g‐C3N4 monolith. Featuring sufficient heteroatom‐doping, well‐developed porous hierarchy, and high electrochemical surface area, the fabricated carbon materials exhibit considerable activity and robust stability in both electrocatalyzing ORR and OER, in competition with the precious metal electrocatalysts, which are thus capable of using as air cathode catalysts for rechargeable Zn‐air batteries, affording large discharge current density and impressive operation stability.
Get on top of your electrocat: Hierarchically porous heteroatoms‐doped vesica‐like carbons were synthesized through a polymerization‐carbonization approach using g‐C3N4 as template, exhibiting considerable performance towards ORR and OER.
Herein, we report a cobalt‐catalyzed hydroarylation of maleimides followed by an annulation sequence for the synthesis of polycyclic azaheterocycles in one pot. The reaction proceeds under ...redox‐neutral conditions and is compatible with various functional groups. Notably, the as‐prepared product exhibits potential photophysical properties.
A major challenge is the development of multifunctional metal–organic frameworks (MOFs), wherein magnetic and electronic functionality can be controlled simultaneously. Herein, we rationally ...construct two 3D MOFs by introducing the redox active ligand tetra(4‐pyridyl)tetrathiafulvalene (TTF(py)4) and spin‐crossover FeII centers. The materials exhibit redox activity, in addition to thermally and photo‐induced spin crossover (SCO). A crystal‐to‐crystal transformation induced by I2 doping has also been observed and the resulting intercalated structure determined. The conductivity could be significantly enhanced (up to 3 orders of magnitude) by modulating the electronic state of the framework via oxidative doping; SCO behavior was also modified and the photo‐magnetic behavior was switched off. This work provides a new strategy to tune the spin state and conductivity of framework materials through guest‐induced redox‐state switching.
A 3D FeII metal–organic framework (MOF) based on the tetrathiafulvalene tetrapyridyl ligand and its I2‐doped analogue were prepared. The TTF moieties provide redox activity, and I2 doping improves the conductive properties. Doping or light irradiation significantly alters the magnetic properties, indicating the material has electronically and photo‐switchable spin‐crossover properties.
Bread wheat expanded its habitat from a core area of the Fertile Crescent to global environments within ~10,000 years. The genetic mechanisms of this remarkable evolutionary success are not well ...understood. By whole-genome sequencing of populations from 25 subspecies within the genera Triticum and Aegilops, we identified composite introgression from wild populations contributing to a substantial portion (4-32%) of the bread wheat genome, which increased the genetic diversity of bread wheat and allowed its divergent adaptation. Meanwhile, convergent adaptation to human selection showed 2- to 16-fold enrichment relative to random expectation-a certain set of genes were repeatedly selected in Triticum species despite their drastic differences in ploidy levels and growing zones, indicating the important role of evolutionary constraints in shaping the adaptive landscape of bread wheat. These results showed the genetic necessities of wheat as a global crop and provided new perspectives on transferring adaptive success across species for crop improvement.
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