Hexafluorophosphate-Triggered Hydrogen Isotope Exchange (HIE) in Fluorinated Environments: A Platform for the Deuteration of Aromatic Compounds via Strong Bond Activation
There is a perpetual need for efficient and mild methods to integrate deuterium atoms into carbon frameworks through late-stage modifications. We have developed a simple and highly effective synthetic route for hydrogen isotope exchange (HIE) in aromatic compounds under ambient conditions. This method utilizes catalytic amounts of hexafluorophosphate (PF6-) in deuterated 1,1,1,3,3,3-hexafluoroisopropanol (HFIP-d1) and D2O. Phenols, anilines, anisoles, and heterocyclic compounds were converted with high yields and excellent deuterium incorporations, which allows for the synthesis of a wide range of deuterated aromatic compounds. Spectroscopic and theoretical studies show that an interactive H-bonding network triggered by HFIP-d1 activates the typically inert P-F bond in PF6- for D2O addition. The thus in-situ formed DPO2F2 triggers then HIE, offering a new way to deuterated building blocks, drugs, and natural-product derivatives with high deuterium incorporation via the activation of strong bonds.
Applicable Descriptors under Weak Metal-Oxygen d-p Interaction for the Oxygen Evolution Reaction
The oxygen evolution reaction (OER) plays a crucial role in water electrolysis and renewable energy conversion processes. Descriptors are utilized to elucidate the structure-performance relationships of OER catalytic materials, yet each descriptor exhibits specificity to particular systems. Currently, there is a lack of effective descriptors to describe the relationship between electronic structure and OER performance in ionic systems. This study reveals for the first time that widely used OER descriptors, the d-band center and charge transfer energy, are limited in their effectiveness for oxide systems dominated by ionic bonds, in which ionic interactions significantly enhance or suppress the catalytic activity. Furthermore, composite descriptors tailored for ionic systems are proposed, with findings extended to complex multi-component and high-entropy oxides. The results indicate that the metal d-band unoccupied states parameter and the active states parameter can serve as effective OER descriptors for ionic catalytic materials. This work addresses the gap in OER descriptors for ionic systems, offering a new theoretical foundation and guidance for the development of efficient OER catalytic materials.
Stabilization Strategies of Buried Interface for Efficient SAM-based Inverted Perovskite Solar Cells
In recent years, self-assembled monolayers (SAMs) anchored on metal oxides (MO) have greatly boosted the performance of inverted (p-i-n) perovskite solar cells (PVSCs) by serving as hole-selective contacts due to their distinct advantages in transparency, hole-selectivity, passivation, cost-effectiveness, and processing efficiency. While the intrinsic monolayer nature of SAMs provides unique advantages, it also makes them highly sensitive to external pressure, posing a significant challenge for long-term device stability. At present, the stability issue of SAM-based PVSCs is gradually attracting attention. In this review, we discuss the fundamental stability issues arising from the structural characteristics, operating mechanisms, and roles of SAMs, and highlight representative works on improving their stability. We identify the buried interface stability concerns in three key aspects: 1) SAM/MO interface, 2) SAM inner layer, and 3) SAM/perovskite interface, corresponding to the anchoring group, linker group, and terminal group in the SAMs, respectively. Finally, we have proposed potential strategies for achieving excellent stability in SAM-based buried interfaces, particularly for large-scale and flexible applications. We believe this review will deepen understanding of the relationship between SAM structure and their device performance, thereby facilitating the design of novel SAMs and advancing their eventual commercialization in high-efficiency and stable inverted PVSCs.
Enantioselective Synthesis of Axially Chiral Tetrasubstituted Alkenes by Copper-Catalyzed C(sp2)-H Functionalization of Arenes with Vinyl Cations
Axially chiral tetrasubstituted alkenes are of increasing value and interest in chemistry-related areas. However, their catalytic asymmetric synthesis remains elusive, due to the high steric repulsion and relatively low conformational stability. Herein, we disclose the straightforward construction of atropisomeric tetrasubstituted alkenes via an effective enantiocontrol of vinyl cations. This copper-catalyzed enantioselective C(sp2)-H functionalization of sterically hindered (hetero)arenes with vinyl cations enables the efficient and atom-economical preparation of axially chiral acyclic tetrasubstituted styrenes and pyrrolyl ethylenes with high atroposelectivities. Importantly, this reaction represents the first example for the assembly of axially chiral alkenes through vinyl cation approach. Computational mechanistic studies reveal the reaction mechanism, origin of regioselectivity, Z/E selectivity and enantioselectivity. The synthetic utility has been demonstrated by diverse product derivatizations, chiral organocatalyst synthesis, as well as further applications in asymmetric catalysis.
Azopyridine Polymers in Organic Phase Change Materials for High Energy Density Photothermal Storage and Controlled Release
Azo-compounds molecules and phase change materials offer potential applications for sustainable energy systems through the storage and controllable release photochemical and phase change energy. Developing novel and highly efficient Azo-based solar thermal fuels (STFs) for photothermal energy storage and synergistic cooperation with organic phase change materials present significant challenges. Herein, three types of (ortho-, meta-, and para-) azopyridine polymers hinged with flexible alkyl chain are synthesized, in which meta-azopyridine polymer exhibits striking photothermal storage capacity of 430 J/g, providing a feasibility solution for developing high energy density Azo-based STFs. Furthermore, a stable two-phase hybrid system was innovatively constructed by combining the meta-azopyridine polymer with organic phase change materials leveraging hydrogen bonds and van der Waals interactions to collectively harness phase change energy and photothermal energy. The organic phase change material not only supplies additional phase change latent heat but also serves as a solvent, offering abundant free volume for the photo-induced isomerization of the azopyridine chromophores, which successfully circumvents the low charging efficiency in the condensed state and reliance on solvent-assisted charging in traditional Azo-based STFs. This study demonstrates the energy distribution and utilization for household consumers and the photothermal-assisted insulation strategy, achieving more extensive potential implementation for STFs.
Enhanced Stability and Properties of Benzene-1,3,5-tricarboxamide Supramolecular Copolymers through Engineered Coupled Equilibria
Improving the stability of multi-component and functional assemblies such as supramolecular copolymers without impeding their dynamicity is key for their implementation as innovative materials. Up to now, this has been achieved by a trial-and-error approach, requiring the time-consuming characterization of a series of supramolecular coassemblies. We report herein that this is possible to significantly enhance the stability of supramolecular copolymers by a minimal change in the chemical nature of one of the interacting monomers. This is achieved by replacing an ester function by an ether function in the structure of a chiral benzene-1,3,5-tricarboxamide (BTA) monomer, used as "sergeant", coassembled with achiral monomers, the "soldiers". Pseudo-phase diagrams, constructed by probing the nature of the coassemblies with multifarious analytical techniques, confirm that the greater stability of the resulting copolymers is mainly due to the minimization of competing species. This leads to better rheological and catalytic properties of the corresponding supramolecular copolymers. Favouring coassembly over undesired assembly pathways must be considered as a blueprint for the development of better-performing supramolecular multi-component systems.
Mechanics-Photophysics Correlation in Tough, Stretchable and Long-Lived Room Temperature Phosphorescence Ionogels Deciphered by Dynamic Mechanical Analysis
The development of tough, stretchable and long-lived room temperature phosphorescence (RTP) materials holds great significance for manufacturing and processing photoluminescent materials, but limited techniques are available to profile their mechanics-photophysics correlation. Here we report glassy ionogels, and their mechanical properties and photophysical properties are fused by dynamic mechanical analysis (DMA), functioning like a human brain that perceives a material instantaneously by linking sensory perception and cognition. Depending on two special temperatures presented in DMA curves, Tloss (the peak of loss modulus (E")) and Tg (glass transition temperature), the ionogels can vary from being either tough with persistent phosphorescence, extensible with effective phosphorescence or resilience with inefficient phosphorescence. Leveraging this method, we achieve stretchable and long-lived RTP ionogels with tensile yield strength of 53 MPa, tensile strain of 497%, Young's modulus of 782 MPa, toughness of 111.2 MJ/m3, and lifetime of 113.05 ms. Our work provides a simple yet powerful method to reveal the mechanics-photophysics correlation of RTP ionogels, to predict their performance without laborious synthesis and characterization, opening new avenues for applications of RTP materials, including applications in harsh conditions (257 K or 347 K), shape memory and shape reconstruction.
One-Step Maleimide-Based Dual Functionalization of Protein N-Termini
Maleimide derivatives are privileged reagents for chemically modifying proteins through the Michael addition reaction with cysteine due to their selectivity, operational simplicity, and commercial availability. However, since accessible free cysteine is rarely found in natural proteins, it is highly desirable to find alternative targets to enable direct bioconjugation of proteins with maleimides. In this study, we have developed an operationally simple and straightforward method for the N-terminal modification of proteins without the need for mutagenesis via a copper(II)-mediated [3+2] cycloaddition reaction with maleimides and 2-pyridinecarboxaldehyde (2-PCA) derivatives under non-denaturing conditions at pH 6 and 37 °C in aqueous media. Our method utilizes commercially available maleimides to attach diverse functionalities to various N-terminal amino acids. We demonstrate the preparation of a ternary protein complex cross-linked at the N-termini and dually modified trastuzumab equipped with monomethyl auristatin E (MMAE), a cytotoxic agent, and a Cy5 fluorophore (MMAE-Cy5-trastuzumab). MMAE-Cy5-trastuzumab retained human epidermal growth factor receptor 2 (HER2) recognition activity and exerted cytotoxicity against HER2-positive cells. Furthermore, MMAE-Cy5-trastuzumab allowed successful visualization of HER2-positive cancer cells in mouse tumors. This straightforward method will expand the accessibility of protein conjugates with well-defined structures in a wide range of research fields.
Organic Crystal with Anti-Stokes Photoluminescent Excitation and Thermally Activated Delayed Fluorescence Features
Thermal activation process utilizes environmental thermal energy to help supplement energy for the nonspontaneous energy-consuming upconversion physical transitions with positive free energy change (ΔG > 0). Reverse intersystem crossing (rISC) and hot band absorption are two kinds of thermal activation transitions. Thermally activated delayed fluorescence (TADF) materials with rISC have significantly propelled advancements in organic semiconductors. Hot band absorption, enables anti-Stokes photoluminescence, offering a promising route for efficient photon upconversion. In this work, we constructed a crystal consisting of a donor-acceptor type TADF molecule, DPQ-DPAC, demonstrating dual thermal activation properties of hot band absorption with a notable 0.1 eV anti-Stokes shift emission and proficient TADF performance. Only in the crystal TADF efficiency facilitates and the photoluminescence quantum yield elevates to an impressive 90.8%. Combining the extended absorption spectrum, these enhancements collectively realize anti-Stokes photoluminescence in crystal. Experimental and theoretical results on the DPQ-DPAC crystal indicate optimizations in its conformational and vibrational modes, resulting in enhancements to its properties. This finding provides insight into crafting organic materials with thermally activated functionalities and contributes to fully exploiting the potential of organic materials, further advancing versatile materials applications.
Enhancing Low-Concentration Electroreduction of NO to NH3 via Potential-Controlled Active Site-Intermediate Interactions
Electronic defect states in catalysts are recognized as effective active sites for enhancing the low-concentration electroreduction of NO to NH3 (NORR). Their structures dynamically evolve with applied potentials, allowing the active sites to adjust interactions with intermediates, thereby improving electrocatalytic performance. However, the dynamic changes in these interactions under applied potentials remain poorly understood, hindering the design of diverse electrocatalytic systems. Herein, we developed a strategy that unitizes potential to control the interactions between active sites and intermediates over VO-TiO2-x to enhance NORR performance. Combining constant inner potential (CIP) DFT calculations with in situ (spectro)electrochemical measurements, we investigated how the electrode potential influences these interactions in NORR. The results demonstrate that applying external potentials promote the formation of Ti3+ active sites and alter its spatial symmetry of degenerate orbitals to facilitate the generation of key intermediates for NO-to-NH3 conversion. Therefore, the VO-TiO2-x catalyst exhibited superior NORR performance with Faradaic efficiency of 76.4% and NH3 yield rate of 632.9 μg h-1 mgcat.-1 under 1.0 vol% NO atmosphere, which is competitive with reported works under higher NO concentration (above 10 vol%). Remarkably, the NORR process achieved a record-breaking NH3 yield of 2292.7 μg h-1 mgcat.-1 in a membrane electrode assembly (MEA) electrolyzer.
Selective Nonenzymatic Formation of Biologically Common RNA Hairpins
The prebiotic formation of RNA building blocks is well-supported experimentally, yet the emergence of sequence- and structure-specific RNA oligomers is generally attributed to biological selection via Darwinian evolution rather than prebiotic chemical selectivity. In this study, we investigated the partitioning of randomized RNA overhangs into ligated products via these two competing pathways using deep sequencing. Comprehensive sequence-reactivity profiles revealed that loop-closing ligation preferentially yields hairpin structures with loop sequences UNNG, CNNG, and GNNA (where N represents A, C, G, or U) under both loose and stringent competing conditions. In contrast, splinted ligation products favor CG-rich overhangs. Notably, the overhang sequences that preferentially partition to loop-closing ligation significantly overlap with the most common biological tetraloops, whereas the overhangs favoring splinted ligation exhibit an inverse correlation with biological tetraloops. These sequence rules enable the high-efficiency assembly of functional ribozymes from short RNAs free from template inhibition. Our findings suggest that the RNA tetraloop structures that are common in biology may have been predisposed and prevalent in the prebiotic pool of RNAs, prior to the advent of Darwinian evolution. We suggest that the one-step prebiotic chemical process of loop-closing ligation could have favored the emergence of the first RNA functions.
Earth: An Oxidative Planet with Limited Atom Resources and Rich Chemistry
Humanity faces an unprecedented survival challenge: climate change, driven by the depletion of natural resources, excessive waste generation, and deforestation. Six out of nine planetary boundaries have been exceeded, signaling that Earth is far from a safe operating space for humanity. In this Viewpoint Article we explore three critical "atomic-molecular" challenges: Earth's limited atomic resources, its oxidative nature, and very rich chemistry. Addressing these requires a transformation in how we produce and consume, emphasizing sustainable practices aligned with the United Nations' 17 goals. The advancement of science and technology has extended human life expectancy and improved quality of life. However, to ensure a sustainable future, we must move towards less oxidative chemical processes, incorporate CH-CO redox chemistry into the circular economy, and transition from a linear, fossil fuel-dependent economy to a circular bioeconomy. Reforestation and the recovery of degraded lands are essential, alongside the shift towards green and sustainable chemistry. Earth's dynamic chemistry is governed by the principles of thermodynamics and kinetics, but science alone is insufficient. Achieving global sustainability requires coordinated economic, political, and social decisions that recognize Earth's limited resources and oxidative nature. Together, these efforts will position humanity to meet the challenges of climate change and secure a sustainable future.
A C156 Molecular Nanocarbon: Planar/Rippled Nanosheets Hybridization
A novel hybrid nanocarbon consisting of one rippled and two planar nanosheets has been synthesized and characterized. Two meso pairs of [5]helicenes are formed along the long molecular axis of the hybrid to connect rippled and planar subunits, leading to a stable conformation. It is shown that the hybrid possesses the individual electronic properties of the rippled and planar subunits. Compared to the rippled subunit, such hybrid has a better geometric match to C60 and complexes with C60 in a 1:1 stoichiometry, with the association constant on the order of 105 M-1. The hybrid displays unusual anti-Kasha fluorescence emission. The transient absorption spectroscopy revealed that the singlet fission (SF) from higher level singlet excited states (Sn) is operative in the film of the hybrid.
Palladium-Catalyzed, Regio-/Stereo- and Enantiospecific Anti-Carboxylation of Unactivated Internal Allenes
We report herein a directing group-controlled, palladium-catalyzed, regio-, stereo-, and enantiospecific anti-carboxylation of unactivated, internal allenes enabled via the synergistic interplay of a rationally designed bidentate directing group, palladium catalyst, and a multifunctional acetate ligand. The corresponding trans allyl ester was obtained in excellent yields with exclusive δ-regioselectivity and anti-carboxypalladation stereocontrol. The acetate ligand of the palladium catalyst controls the regio-, stereo- and enantioselectivity in the desired transformation. The potential of this concept has been demonstrated by the development of the chiral version of this transformation by using axial-to-central chirality transfer with good yields and enantioselectivities. Detailed investigations, including kinetic studies, order studies, and DFT studies, were performed to validate the ligand-assisted nucleopalladation process and the rationale behind the observed racemization of chiral allenes. The studies also indicated that the anti-carboxypalladation step was the rate-limiting as well as the stereo- and enantiodetermining step.
Polymeric Iodine Transport Layer Enabled High Areal Capacity Dual Plating Zinc-Iodine Battery
Iodine cathode in aqueous battery has drawn great attention due to its high energy density and high safety. However, iodine has extremely low conductivity of 1×10-7 S cm-1, which usually results in low specific capacity. In this work, a PVA-hydrogel layer was designed to enhance the areal capacity of zinc-iodine cell. The areal capacity of PVA-hydrogel layer modified CNT cathode showed twice as higher capacity than that of pure CNT film in a dual-plating cell, The significant enhancement of the capacity was attributed to the fast iodine transport in the PVA-hydrogel layer. Besides, the strong interaction between PVA chain and polyiodide anions prevented the shuttle effect. The PVA modified CNT cathode could stably operate for over 3000 hours with remarkably higher capacity and cycle life. We analyzed the uniquely fast transport behavior of polyiodides in PVA hydrogel by in-situ Raman spectroscopy, in-situ optical micrography, as well as DFT calculations. It was found that the strong binding force together with lower dissociation energy of iodine on PVA chain is the dominate reason for reduced shuttle effect and fast polyiodide transport. As a result, the assembled PVA-I2 pouch cells showed excellent performance in both dual-plating cells and conventional-type cells.
Nickel-Catalyzed Difluoroalkylation of β,γ-Unsaturated α-Amino Nitrile Derived Lithium Reagents
Organolithium reagents, known for their low cost, ready availability, and high reactivity, allow fast cross-coupling under ambient conditions. However, their direct cross-coupling with fluoroalkyl electrophiles remains a formidable challenge due to the easy formation of thermo-unstable fluoroalkyl lithium species during the reaction, which are prone to decomposition via rapid α/β-fluoride elimination. Here, we exploit heteroatom-stabilized allylic anions to harness the exceptional reactivity of organolithium reagents, enabling the compatibility of difluoroalkyl halides and facilitating versatile and precise fluorine functionality introduction under mild conditions. In this process, a nickel-catalyzed difluoroalkylation of β,γ-unsaturated α-amino nitrile derived lithium reagents (N-stabilized allyl lithium reagents) with various difluoroalkyl bromides has been developed, opening a new avenue to access fluorinated compounds through catalytic cross-coupling of organolithium reagents with fluoroalkyl electrophiles. This approach allows for the efficient and precise construction of secondary C(sp3)-CF2R bonds, previously challenging in transition-metal-catalyzed fluoroalkylation reactions due to β-hydride elimination. The rapid fluorine-editing of drugs demonstrates the synthetic versatility and utility of this protocol, showing the perspective in modern drug discovery.
Screened d-p Orbital Hybridization in Turing Structure of Confined Nickel for Sulfion Oxidation Accelerated Hydrogen Production
The sulfion oxidation reaction (SOR) could offer an energy-efficient and tech-economically favorable alternative to the oxygen evolution reaction (OER) for H2 production. Transition metal (TM) based catalysts have been considered promising candidates for SOR but suffer from limited activity due to the excessive bond strength from TM-S2- d-p orbit coupling. Herein, we propose a feasible strategy of screening direct d-p orbit hybridization between TM and S2- by constructing the Turing structure composed of lamellar stacking carbon-confined nickel nanosheets. The optimized p-p orbit coupling between electron-injected carbon and S2- enables exceptional catalytic activity and stability for sulfion degradation and energy-efficient yet value-added H2 production. Specifically, it achieves a current density of 500 mA cm-2 at an ultralow potential of 0.67 V vs. RHE for alkaline SOR. Theoretical calculations indicate that the electron transfer from Ni imparts metallicity and a higher p-band center to carbon shells, thereby contributing to optimized p-p orbit hybridization and a thermodynamically favorable stepwise sulfion degradation. Practically, a two-electrode flow cell achieves an industrial current density of 1 Acm-2 at an unprecedented low voltage of 0.91 V while maintaining stability for over 300 hours, and exhibits high productivities of 3.83 and 0.32 kgh-1m-2 for sulfur and H2, respectively.
Synthesis and Characterizations of Dibenzo-Fused Perioctacene
Dibenzoperioctacene (DBPO) with extended zigzag edges was synthesized and unambiguously characterized by a combination of nuclear magnetic resonance (NMR), mass spectrometry, and single-crystal X-ray diffraction analysis. Variable-temperature (VT) NMR analysis indicated the closed-shell character of DBPO, yet an electron paramagnetic resonance (EPR) signal was observed at room temperature suggesting its potential open-shell diradicaloid nature. The bond lengths in the single-crystal structure of DBPO aligned more closely with those of open-shell teranthene than closed-shell bisanthene. Spin-unrestricted density functional theory (DFT) calculations using various methods supported that ground state of DBPO might be on the borderline between closed- and open-shell singlet states, with a large singlet-triplet energy gap (ΔEST), consistent with the VT-NMR and EPR results. UV-vis-near infrared (NIR) absorption spectrum showed the longest-wavelength peak at 905 nm, marking the NIR optical properties of DBPO. DBPO exhibited a tendency to react with atmospheric oxygen, which additionally hinted at its possible open-shell character. Furthermore, the oxidized species of non-fluorescent DBPO exhibited strong emission at 820 and 915 nm, which opens its potential for oxygen detection via a "turn-on" NIR fluorescence response.
Hubbard Gap Closure-Induced Dual-Redox Li-Storage Mechanism as the Origin of Anomalously High Capacity and Fast Ion Diffusivity in MOFs-Like Polyoxometalates
MOFs-like polyoxometalate (POMs) electrodes have already emerged as promising candidates for lithium-ion batteries (LIBs), yet the origins of the underlying redox mechanism in such materials remain a matter of uncertainty. Of critical challenges are the anomalously high storage capacities beyond their theoretical values and the fast ion diffusivity that cannot be satisfactorily comprehended in the theory of crystal lattice. Herein, for the first time we decode t2g electron occupation-regulated dual-redox Li-storage mechanism as the true origin of extra capacity in POMs electrodes. Enhanced V-t2g orbital occupation by Li coordination significantly triggers the Hubbard gap closure and reversible Li deposition/dissolution at surface region. Conjugated V-O-Li configuration at interlayers endow Li+ ion pathways along pore walls as the dominant contribution to the low migration barrier and fast diffusivity. As a result, remarkable cycle stability (~100 % capacity retention after 2000 cycles at 1 A g-1), extremely high specific capacity (1200 mAh g-1 at 100 mA g-1) and excellent rate performance (404 mAh g-1 at 8 A g-1) were achieved, providing new understandings on the underlying mechanism of POMs electrodes and pivotal guidance for dual-storage materials.
Stereoselective Synthesis of 1,n-Dicarbonyl Compounds Through Palladium-Catalyzed Ring Opening/Isomerization of Densely Substituted Cyclopropanols
We report a highly diastereoselective protocol for the synthesis of 1,4- and 1,5-dicarbonyl compounds from densely substituted cyclopropanols. The methodology involves a palladium-catalyzed ring opening reaction followed by a "metal-walk" and oxidation of a remote hydroxyl group. The methodology represents a new application of cyclopropanols as initiation sites for chain walking remote functionalization. Importantly, this approach provides a straightforward access to highly valuable succinaldehyde derivatives bearing vicinal quaternary and tertiary stereocenters as single diastereomers.
Neuromorphic Nanofluidic Sense Digitalization
Nanofluidic memristors have recently been reshaped into artificial synapses capable of mimicking many fundamental neurosynaptic patterns, while sense digitalization has been increasingly explored to link the neuromorphic devices with external equipment. By inspiration of dopaminergic nerve, here a nanofluidic nerve with sense digitalization is devised by engineering a dopamine (DA)-specific nanofluidic synapse as mediated by PC-12 cells to manage the robotic arm. Different from previous neuromorphic perception of DA via redox reaction, the aptamer-based perception here is based on biological DA recognition by its receptor as indicated by the ionic signals. Various neurosynaptic patterns are emulated with DA-dependent plasticity, based on which the digital representation of DA perception is used to control the robotic arm.