Programmable supramolecular chirality in non-equilibrium systems affording a multistate chiroptical switch.

The dynamic regulation of supramolecular chirality in non-equilibrium systems can provide valuable insights into molecular self-assembly in living systems. Herein, we demonstrate the use of chemical fuels for regulating self-assembly pathway, which thereby controls the supramolecular chirality of assembly in non-equilibrium systems. Depending on the nature of different fuel acids, the system shows pathway-dependent non-equilibrium self-assembly, resulting in either dynamic self-assembly with transient supramolecular chirality or kinetically trapped self-assembly with inverse supramolecular chirality. More importantly, successive conducting of chemical-fueled process and thermal annealing process allows for the sequential programmability of the supramolecular chirality between four different chiral hydrogels, affording a new example of a multistate supramolecular chiroptical switch that can be recycled multiple times. The current finding sheds new light on the design of future supramolecular chiral materials, offering access to alternative self-assembly pathways and kinetically controlled non-equilibrium states.

A Full-Device Autonomous Self-Healing Stretchable Soft Battery from Self-Bonded Eutectogels.

Next-generation energy storage devices should be soft, stretchable, and self-healable. Previously reported self-healable batteries mostly possess limited stretchability and rely on healable electrodes or electrolytes rather than achieving full-device self-healability. Herein, an all-component self-bonding strategy is reported to obtain an all-eutectogel soft battery (AESB) that simultaneously achieves full-cell autonomous self-healability and omnidirectional intrinsic stretchability (>1000% areal strain) over a broad temperature range (-20~60 °C). Without requiring any external stimulus, the five-layered soft battery can efficiently recover both its mechanical and electrochemical performance at full-cell level. The developed AESB can be easily configured into various 3D architectures with highly interfacial compatible eutectogel electrodes, electrolyte, and substrate, presenting an excellent opportunity for the development of embodied energy technologies. The present work provides a general and user-friendly soft electronic material platform for fabricating a variety of intrinsic self-healing stretchable multi-layered electronics, which are promising beyond the field of energy storage, such as displays, sensors, circuits, and soft robots.

Supramolecular Gel-Derived Highly Efficient Bifunctional Catalysts for Omnidirectionally Stretchable Zn-Air Batteries with Extreme Environmental Adaptability.

Most existing stretchable batteries can generally only be stretched uniaxially and suffer from poor mechanical and electrochemical robustness to withstand extreme mechanical and environmental challenges. A highly efficient bifunctional electrocatalyst is herein developed via the unique self-templated conversion of a guanosine-based supramolecular hydrogel and presents a fully integrated design strategy to successfully fabricate an omnidirectionally stretchable and extremely environment-adaptable Zn-air battery (ZAB) through the synergistic engineering of active materials and device architecture. The electrocatalyst demonstrates a very low reversible overpotential of only 0.68 V for oxygen reduction/evolution reactions (ORR/OER). This ZAB exhibits superior omnidirectional stretchability with a full-cell areal strain of >1000% and excellent durability, withstanding more than 10 000 stretching cycles. Promisingly, without any additional pre-treatment, the ZAB exhibits outstanding ultra-low temperature tolerance (down to -60 °C) and superior waterproofness, withstanding continuous water rinsing (>5 h) and immersion (>3 h). The present work offers a promising strategy for the design of omnidirectionally stretchable and high-performance energy storage devices for future on-skin wearable applications.

Low-molecular-weight supramolecular adhesives based on non-covalent self-assembly of a small molecular gelator.

Currently developed adhesives are overwhelmingly polymeric in nature. Herein, we highlight for the first time the potential of supramolecular eutectogels assembled from small molecules as robust low-molecular-weight (LMW) supramolecular adhesives in air, water and organic solvents, and under low temperatures. These supramolecular eutectogels were produced from commercial alkyl trimethyl ammonium bromide (CnTAB) in emerging deep eutectic solvents (DESs), which demonstrated rapid (∼2 min), robust, and tunable adhesion to both hydrophilic and hydrophobic surfaces at room temperature in air. Moreover, high adhesion performance was maintained even in liquid nitrogen (-196 °C), underwater, and in organic solvents. A study of the structure-property relationship of these adhesives and molecular dynamics (MD) simulations further clarified the assembly and adhesion mechanism of the C12TAB molecules in DESs. Compared with traditional polymer adhesives and several existing examples of LMW supramolecular adhesives with solvent-free dry network structures, the spontaneous self-assembly of LMW gelators in versatile DESs provides a new strategy for the facile construction of high-strength supramolecular adhesives with gel network structures for a diverse range of harsh environments.

Programmable Transient Supramolecular Chiral G-quadruplex Hydrogels by a Chemically Fueled Non-equilibrium Self-Assembly Strategy.

The temporal and spatial control of natural systems has aroused great interest for the creation of synthetic mimics. By using boronic ester based dynamic covalent chemistry and coupling it with an internal pH feedback system, we have developed a new chemically fueled reaction network for non-equilibrium supramolecular chiral G-quadruplex hydrogels with programmable lifetimes from minutes, to hours, to days, as well as high transparency and conductivity, excellent injectability, and rapid self-healing properties. The system can be controlled by the kinetically controlled in situ formation and dissociation of dynamic boronic ester bonds between the cis-diol of guanosine (G) and 5-fluorobenzoxaborole (B) in the presence of chemical fuels (KOH and 1,3-propanesultone), thereby leading to a precipitate-solution-gel-precipitate cycle under non-equilibrium conditions. A combined experimental-computational approach showed the underlying mechanism of the non-equilibrium self-assembly involves aggregation and disaggregation of right-handed helical G-quadruplex superstructures. The proposed dynamic boronic ester-based non-equilibrium self-assembly strategy offers a new option to design next-generation adaptive and interactive smart materials.

Super-stretchable and extreme temperature-tolerant supramolecular-polymer double-network eutectogels with ultrafast in situ adhesion and flexible electrochromic behaviour.

The current tough and stretchable gels with various integrated functions are mainly based on polymer hydrogels. By introducing a non-covalent supramolecular self-assembled network into a covalently cross-linked polymer network in the presence of eco-friendly and cost-effective deep eutectic solvents (DESs), we developed a new small molecule-based supramolecular-polymer double-network (SP-DN) eutectogel platform. This exciting material exhibits high stretchability and toughness (>18 000% areal strain), spontaneous self-healing ability, ultrafast (∼5 s) in situ underwater and low-temperature (-80 °C) adhesion, and unusual boiling water-resistance, as well as strong base-, strong acid- (even aqua regia), ultra-low-temperature- (liquid nitrogen, -196 °C), and high-temperature- (200 °C) resistance. All these outstanding properties strongly recommend the SP-DN eutectogels as a quasi-solid electrolyte for soft electrochromic devices, which exhibited exceptional flexibility and consistent electrochromic behaviours in harsh mechanical or temperature environments. The experimental and simulation results uncovered the assembly mechanism of the SP-DN eutectogels. Unlike polymer hydrogels, the obtained SP-DN eutectogels showed high molecular design freedom and structural versatility. The findings of this work offer a promising strategy for developing the next generation of mechanically robust and functionally integrated soft materials with high environmental adaptability.

Self-healing mechanism and bioelectrochemical interface properties of core-shell guanosine-borate hydrogels.

The self-healing mechanism and bioelectrochemical interface properties of supramolecular gels have been rarely explored. In this context, we propose a constitutive "fibril-reorganization" model to reveal the self-healing mechanism of a series of core-shell structured guanosine-borate (GB) hydrogels and emphasize that interfibrillar interactions at the supramolecular polymer scale (G-quadruplex nanowires) drive the self-healing process of GB hydrogels. Structure-electrochemical sensing performance studies reveal that GB hydrogel nanofibers with relatively strong biomolecular affinity such as -SH modified GB hydrogel (GB-SH) show a high sensitivity of response and low limit of detection for tumour marker alpha-fetoprotein sensing (AFP; 0.076 pg mL-1). Guanosine/ferroceneboronic acid (GB-Fc) hydrogel nanofibers with superior conductivity and redox activity display the widest linear detection range for AFP (0.0005-100 ng mL-1). Structure-property correlations of GB hydrogels provide useful insight for the future design of advanced self-healing materials and electrochemical biosensors.

NiO nanoparticles decorated hexagonal Nickel-based metal-organic framework: Self-template synthesis and its application in electrochemical energy storage.

A one-pot solvothermal strategy and subsequent calcination were proposed for fabricating a composite of NiO nanoparticles on hexagonal Ni-based metal-organic framework (Ni-MOF) (Ni-MOF@NiO). The prepared NiO nanoparticles on the hexagonal Ni-MOF not only improves the electrical conductivity and increases redox active sites, but also prevents the agglomeration of NiO nanoparticles. In particular, highly dispersed and small-sized NiO nanoparticles on the hexagonal Ni-MOF facilitates the migration of electrolyte ions, and the pseudocapacitive performance is evaluated through electrochemical measurements. At 0.5 A g-1, the Ni-MOF@NiO composite shows a specific capacitance of up to 1192.7 F g-1 and a high capacity retention (93.23% over 5000 cycles) in 3 M KOH. Moreover, the Ni-MOF@NiO nanoparticles and activated carbon are assembled into aqueous devices with a maximum energy density of 62.2 Wh kg-1. These results indicate the potential of Ni-MOF@NiO composite as an electrode material for application in supercapacitors. Additionally, the method of synthesizing Ni-MOF@NiO in this study can be used to synthesize other MOF@metal oxide materials for electrochemical energy storage and other related applications.

Rhodium-catalyzed multiple C-H activation/highly meta-selective C-H amination between amidines and alkynes.

A tandem process of multiple C-H activation and intermolecular highly meta-selective C-H amination between amidines and alkynes has been developed. Mechanistic studies demonstrate that the reaction is proposed to proceed through two different Rh(i)-Rh(iii) catalytic cycles, wherein Rhodium-complex I and Rhodacycle intermediate II were isolated for the first time.

Supramolecular G4 Eutectogels of Guanosine with Solvent-Induced Chiral Inversion and Excellent Electrochromic Activity.

Supramolecular eutectogels, an emerging class of materials that have just developed very recently, offer a new opportunity for generating functional supramolecular gel materials in biocompatible anhydrous or low-water media. As the first example of supramolecular G4 eutectogels, complexes of natural guanosine and H3 BO3 exhibited excellent gelation capacity in choline chloride/alcohol deep eutectic solvents. The as-prepared supramolecular eutectogels displayed unexpected solvent-induced chiral inversion and significantly high ionic conductivity (up to 7.78 mS cm-1 ), as well as outstanding thixotropic/injectable properties, high thermal stability and excellent electrochromic activity. These features make these versatile supramolecular G4 eutectogels promising candidates for developing next-generation flexible electronics with low environmental impact.

High electrochemical performance carbon nanofibers with hierarchical structure derived from metal-organic framework with natural eggshell membranes.

Carbon nanofibers with hierarchical structure were synthesized by combining Co-containing zeolitic imidazolate frameworks (ZIF-67) with natural eggshell membranes (ESMs). Benefiting from the hierarchical structure and element modification of Co/N, the obtained nanofibers exhibited excellent oxygen reduction reaction (ORR) performance. The reusing of ESMs trash made this strategy meaningful for environment.

Mechanism-Property Correlation in Coordination Polymer Crystals toward Design of a Superior Sorbent.

A methodology was developed to design superior sorbents of oxoanions. To integrate the high efficiency of chemisorption, selectivity, and recyclability into one sorbent, understanding the nature of oxoanions-sorbent interactions and the structural evolution of the sorbents is essential. Three cationic Ag(I) coordination polymers (CPs) are synthesized for dichromate (Cr2O72-) removal, and three distinct oxoanion-exchange mechanisms are identified, namely, the replacement, breath, and reconstruction processes, depending on the degree of framework distortion induced by the dichromate-CP interactions. The single crystal to single crystal transformation during the oxoanion exchange has been investigated by using single-crystal X-ray diffraction and energy-dispersive X-ray microanalysis. The replacement process, due to a weak chemisorption, shows excellent recyclability at the cost of reduction of efficiency and selectivity of adsorption. The reconstruction process may achieve a high efficiency and selectivity, but it loses recyclability. Due to the formation of a Ag-O(dichromate) bond and the breathing effect of the framework, the sorbent with the breath mechanism shows both superior efficiency and high recyclability in dichromate removal. The study of perrhenate (ReO4-) removal using the same CPs demonstrates that one CP performing the reconstruction process during dichromate removal turns to the breath process in removal of perrhenate anions. These results of mechanism-property correlation provide an insight into improvement of the methodology to fabricate a superior CP sorbent for oxoanion removal.

PBA@POM Hybrids as Efficient Electrocatalysts for the Oxygen Evolution Reaction.

To realize the effective conversion of renewable energy through water decomposition, efficient electrocatalysts for the oxygen evolution reaction (OER) are essential. In this article, PBA@POM was successfully prepared with a Prussian blue analogue (PBA) as the initial structure. A facile hydrothermal process is reported for obtaining PBA@POM by etching the cubic PBA with a strong Brønsted acid, H3 PMo12 O40 (HPMo). The hollow cube structure not only exposes more active sites but also promotes electron transport, which results in excellent electrocatalytic activity for the OER. Compared with the PBA, which initially simply adhered to POM, the optimum PBA@POM hybrids display remarkably enhanced OER catalytic activity, with an almost constant overpotential of 440 mV at a current density of 10 mA cm-2 and a small Tafel slope (23.45 mV dec-1 ). The facilely prepared PBA@POM with good electrochemical activity and stability promises great potential for the OER.

A multifunctional self-healing G-PyB/KCl hydrogel: smart conductive, rapid room-temperature phase-selective gelation, and ultrasensitive detection of alpha-fetoprotein.

A multifunctional G-PyB/KCl hydrogel showed outstanding self-healability, high conductivity, and rapid room-temperature phase-selective gelation capacity, and was developed as an electrochemical aptamer sensing platform for the ultrasensitive detection of alpha-fetoprotein.

Dual-Functionalized Mixed Keggin- and Lindqvist-Type Cu24-Based POM@MOF for Visible-Light-Driven H2 and O2 Evolution.

The development of logical visible-light-driven heterogeneous photosystems for water splitting is a subject of new research. As the first example of a noble-metal-free photocatalyst for both H2 and O2 production, a high-nuclear {CuI24(µ3-Cl)8(µ4-Cl)6}-based polyoxometalate (POM)@metal-organic framework (MOF) (ZZULI-1) is rationally designed to serve as a robust dual-functionalized photocatalyst. ZZULI-1 exhibits highly efficient photocatalytic H2 evolution (6614 µmol g-1 h-1) and O2 evolution (1032 µmol g-1 calculated for the first 6 min). The {CuI24(µ3-Cl)8(µ4-Cl)6} clusters and mixed POMs not only work as the active units for H2 and O2 production, respectively, but also improve the effective electron transfer between the photosensitizer and ZZULI-1. The highly stable dual-functionalized ZZULI-1 affords new penetrations into the development of cost-effective high-nuclear cluster-based POM@MOFs for efficient solar-to-fuel generation.

Palladium-Catalyzed C-N Bond Cleavage of 2 H-Azirines for the Synthesis of Functionalized α-Amido Ketones.

A Pd-catalyzed ring-opening reaction of 2 H-azirines with carboxylic acids was developed. This reaction undergoes nucleophilic addition between 2,3-diaryl-2 H-azirines and carboxylic acids followed by C-N single-bond cleavage and a subsequent thermal rearrangement. This method enables the rapid construction of valuable α-amido ketone derivatives with high atomic efficiency and superb functional group tolerance.

A water-stable EuIII-based MOF as a dual-emission luminescent sensor for discriminative detection of nitroaromatic pollutants.

A water-stable EuIII-based metal-organic framework (MOF) with dual-emission luminescence behavior, namely {[Eu4(INO)5(µ3-OH)2Cl4(H2O)]·(NO3)·(H2O)5}n (Eu-MOF; HINO = isonicotinic acid N-oxide), was successfully constructed by the solvothermal reaction of Eu3+ ions with the organic ligand HINO. The cationic 3D framework contains microporous channels with accessible Lewis-base sites and NO3- ions as balanced anions, which all contribute to the selective detection of multifarious analytes. This MOF shows ratiometric detection of acetone, Cr2O72- ions, and nitroaromatic compounds (NACs). In particular, it shows great recognition of four NACs in water, representing the first LnIII-MOF which can display distinguishing fluorescence phenomena on NACs rather than relying on the quenching effect. Furthermore, this is also the first example of a MOF-sensor for detecting these explosives discriminatively by ratiometric methods. Additionally, the mechanisms for luminescent responses towards different analytes have been discussed in detail.

The ARF7 and ARF19 Transcription Factors Positively Regulate PHOSPHATE STARVATION RESPONSE1 in Arabidopsis Roots.

PHOSPHATE STARVATION RESPONSE1 (PHR1) is a key regulatory component of the response to phosphate (Pi) starvation. However, the regulation of PHR1 in this response remains poorly understood. Here, we report that PHR1 is a target of the transcription factors AUXIN RESPONSE FACTOR7 (ARF7) and ARF19 and is positively regulated by auxin signaling in Arabidopsis (Arabidopsis thaliana) roots. PHR1 expression was induced by exogenous auxin and suppressed by auxin transport inhibitors in Arabidopsis roots. In the PHR1 promoter, three auxin-response elements, which are bound directly by ARF7 and ARF19, were shown to be essential for PHR1 expression. The arf7, arf19, and arf7 arf19 mutants showed down-regulated expression of PHR1 and downstream Pi starvation-induced genes in roots; they also exhibited defective Pi uptake in roots and overaccumulation of anthocyanin in shoots. The induction of lateral root formation in response to low Pi and to exogenous auxin was decreased in the phr1 mutant, whereas the expression of LATERAL ORGAN BOUNDARIES-DOMAIN16 (LBD16) and LBD29 was not changed significantly. PHR1 acted independently of LBD16 and LBD29 in the regulation of lateral root formation in response to low Pi. Under low-Pi conditions, lateral root impairment in the arf7 arf19 mutant was partially rescued by constitutive expression of PHR1, demonstrating that reduced PHR1 expression contributed to the arf7 arf19 phenotype. In addition to PHR1, other genes encoding MYB-CC members also were targets of ARF7 and ARF19. Our work thus reveals a mechanism coordinating auxin signaling and the PHR1 regulon in Arabidopsis responses to Pi deficiency.

Co/Fe-bimetallic organic framework-derived carbon-incorporated cobalt-ferric mixed metal phosphide as a highly efficient photocatalyst under visible light.

A new bimetallic Co/Fe-MOF was synthesized and phosphatized to produce a visible-light-active Co/Fe binary metal phosphide embedded in a mesoporous carbon matrix (denoted by CoP/Fe2P@mC). The results of X-ray diffraction and photoelectron spectroscopy, scanning electron microscopy, and transmission electron microscopy reveal the formation of CoP and Fe2P nanoparticles together with the Co and Fe metallic state. Combining the high electron-hole separation rate of Fe2P@mC, fast electron transfer of CoP@mC, and the strong adsorption of mesoporous carbon, the as-prepared CoP/Fe2P@mC catalyst exhibits substantially enhanced photocatalytic activity toward rhodamine B (RhB) degradation under visible light irradiation. Visible light harvesting efficiency is enhanced by the suitable bandgap structure of the CoP/Fe2P@mC photocatalyst. Moreover, the possible photocatalytic mechanism of CoP/Fe2P@mC toward RhB degradation was proposed on the basis of radical trapping and electron spin resonance results. This finding illustrates a potential utilization of bimetallic MOF-derived metal phosphide as a photocatalyst to remove dye pollutants in the environment.