Chemical Science最新文献

Poly(ethylene oxide) (PEO)-based solid-state polymer electrolyte (SPE) is a promising candidate for the next generation of safer lithium-metal batteries. However, the serious side reaction between PEO and lithium metal and the uneven deposition of lithium ions lead to the growth of lithium dendrites and the rapid decline of battery cycle life. Building a LiF-rich solid electrolyte interface (SEI) layer is considered to be an effective means to solve the above problems. Here, porous organic polymers (POPs) with aromatic structures and non-aromatic structures were synthesized and introduced into the PEO-based SPE as fillers to explore the effect of aromatic structures on LiF-rich SEI formation. The results show that the POPs containing aromatic groups could catalyze the decomposition of LiTFSI to form a stable LiF-rich SEI layer and inhibit the growth of lithium dendrites. The discharge capacity of the LFP/Li battery is 103 mA h g^-1 after 500 cycles at 1C (100 °C). It provides a promising way to improve the stability of the solid electrolyte matrix and SEI layer.

Two-dimensional conductive metal-organic frameworks (2D c-MOFs) with high electrical conductivity and tunable structures hold significant promise for applications in metal-ion batteries. However, the construction of 3D interpenetrated c-MOFs for applications in metal-ion batteries is rarely reported. Herein, a 3D four-fold interpenetrated c-MOF (Cu-DBC) constructed by conjugated and contorted dibenzo[g,p]chrysene-2,3,6,7,10,11,14,15-octaol (DBC) ligands is explored as an advanced cathode material for sodium-ion batteries (SIBs) for the first time. Notably, the expanded conjugated and four-fold interpenetrating structure endows Cu-DBC with transmission channels for electrons and sufficient spacing for sodium ion diffusion. As expected, the Cu-DBC cathode showcases higher specific capacity (120.6 mA h g^-1, 0.05 A g^-1) and robust cycling stability (18.1% capacity fade after 4000 cycles, 2 A g^-1). Impressively, the Cu-DBC cathode also exhibits good electrochemical properties at extreme temperatures (-20 °C and 50 °C). A series of in/ex situ characterizations and systematic theoretical calculations further reveal the sodium-ion storage mechanism of Cu-DBC, highlighting a three-electron redox process on the redox-active [CuO₄] units. This work provides valuable insights for exploring and enriching the applications of 3D interpenetrated c-MOFs in metal-ion batteries.

Traditional photosensitive polyimide (PSPI) materials require a high curing temperature and exhibit low transparency, limiting their applications in thermally sensitive optical devices. To overcome this challenge, soluble photosensitive polyimide resins were synthesized based on the structural design of a bio-based magnolol monomer. It is noteworthy that the PI photoresist, developed by using the as-prepared polyimides and non-toxic solvents (2-acetoxy-1-methoxypropane, PGEMA) and other additives, demonstrated an impressive low-temperature curing performance (180 °C). Furthermore, the solvent residue in the cured film prepared using PGEMA as solvent was markedly decreased compared to that prepared using N-methyl pyrrolidone (NMP). In addition, the C-PI-3 films cured by photoinitiated thiol-ene radical reactions exhibited high transparency with an average visible light transmittance of 87.8%, as well as excellent thermal stability, dielectric and breakdown properties, and photo-patterning capabilities. This partially bio-based and innocuous solvent-based PSPI with low-temperature curability and high transparency properties could be a pioneering example to resolve the challenges of energy efficiency and environmental sustainability and is expected to be used in the field of color filters.

Metal oxides are promising catalysts for small molecule hydrogen chemistries, mediated by interfacial proton-coupled electron transfer (PCET) processes. Engineering the mechanism of PCET has been shown to control the selectivity of reduced products, providing an additional route for improving reductive catalysis with metal oxides. In this work, we present kinetic resolution of the rate determining proton-transfer step of PCET to a titanium-doped POV, TiV₅O₆(OCH₃)₁₃ with 9,10-dihydrophenazine by monitoring the loss of the cationic radical intermediate using stopped-flow analysis. For this reductant, a 5-fold enhanced rate (k _PT = 1.2 × 10⁴ M^-1 s^-1) is accredited to a halved activation barrier in comparison to the homometallic analogue, [V₆O₇(OCH₃)₁₂]^1-. By switching to hydrazobenzene as a reductant, a substrate where the electron transfer component of the PCET is thermodynamically unfavorable (ΔG _ET = +11 kcal mol^-1), the mechanism is found to be altered to a concerted PCET mechanism. Despite the similar mechanisms and driving forces for TiV₅O₆(OCH₃)₁₃ and [V₆O₇(OCH₃)₁₂]^1-, the rate of PCET is accellerated by 3-orders of magnitude (k _PCET = 0.3 M^-1 s^-1) by the presence of the Ti(iv) ion. Possible origins of the accelleration are considered, including the possibility of strong electronic coupling interactions between TiV₅O₆(OCH₃)₁₃ with hydrazobenzene. Overall, these results offer insight into the governing factors that control the mechanism of PCET in metal oxide systems.

Controlling symmetrical or asymmetrical growth has allowed a series of novel nanomaterials with prominent physicochemical properties to be produced. However, precise and continuous size growth based on a preserved template has long been a challenging pursuit, yet little has been achieved in terms of manipulation at the atomic level. Here, a correlated silver cluster series has been established, enabling atomically precise manipulation of symmetrical and asymmetrical surface structure expansions of metal nanoclusters. Specifically, the C ₃-axisymmetric Ag₂₉(BDTA)₁₂(PPh₃)₄ nanocluster underwent symmetrical and asymmetrical surface structure expansions via an acid-mediated synthetic procedure, giving rise to C ₃-axisymmetric Ag₃₂(BDTA)₁₂(PPh₃)₁₀ and C ₁-axisymmetric Ag₃₃(BDTA)₁₂(PPh₃)₁₁, respectively. In addition, structural transformations, including structural degradation from Ag₃₂ to Ag₂₉ and asymmetrical structural expansion from Ag₃₂ to Ag₃₃, were rationalized theoretically. More importantly, the asymmetrically structured Ag₃₃ nanoclusters followed a chiral crystallization mode, and their crystals displayed high optical activity, derived from CD and CPL characterization. This work not only provides an important model for unlocking the symmetrical/asymmetrical size growth mechanism at the atomic level but also pioneers a promising approach to activate the optical activity of cluster-based nanomaterials.

Despite the evident demand and promising potential of disulfide-functionalized amino acids and peptides in linker chemistry and peptide drug discovery, those disulfurated specifically at the α-position constitute a unique yet rather highly underexplored chemical space. In this study, we have developed a method for preparing SS-linked amino acid/peptide derivatives through a base-catalyzed disulfuration reaction of azlactones, followed by the ring-opening functionalization. The disulfuration reaction proceeds under mild conditions, yielding disulfurated azlactones in excellent yields across a variety of N-dithiophthalimides and diverse azlactones derived from various amino acids and peptides. Leveraging the ready availability of N-dithiophthalimides from several bilateral disulfurating reagents, this method allows for the modular integration of functional molecules and azlactones into SS-linkage in two-step operations. Furthermore, due to the transformability of the azlactone moiety through ring-opening with various nucleophiles, our method provides a wide variety of functional molecule-tagged amino acids and oligopeptides bearing SS-linkages in a modular and time-efficient manner, serving as a valuable tool for linker chemistry and peptide chemistry.

Doping strategies have been recognized as effective approaches for developing cost-effective and durable catalysts with enhanced reactivity and selectivity in the electrochemical synthesis of value-added compounds directly from CO₂. However, the reaction mechanism and the specific roles of heteroatom doping, such as N doping, in advancing the CO₂ reduction reaction are still controversial due to the lack of precise control of catalyst surface microenvironments. In this study, we investigated the effects of N doping on the performances for electrochemically converting CO₂ to CO over Ni@NCNT/graphene hybrid structured catalysts (Ni@NCNT/Gr). Ni nanoparticles (Ni NPs) were encapsulated in N-doped carbon nanotubes (NCNTs) which were in situ generated from g-C₃N₄ during the annealing process due to the thermal catalysis of the existing Ni NPs. Our results show that the optimized pyrrolic N doping level, coupled with stable NCNT/Gr hybrid structures, high electrochemically active surface area, rich active sites, and reduced Ni NP size, synergistically contribute to the distinguished electrocatalytic performances. The as-prepared Ni@NCNT/Gr-R catalyst demonstrated a high CO faradaic efficiency (>90%) with negligible differences in CO FE across a wide potential range (-0.71--0.91 V vs. RHE) in an H-cell while maintaining magnificent stability with negligible current density loss for 24 hours at -0.71 V (vs. RHE). Our findings provide evidence and insight into the optimization of pyrrolic N doping levels together with reducing NP size within the stable NCNT/Gr hybrid substrate for designing efficient CO₂ reduction catalysts.

Silicon (Si) is considered a promising anode material for next-generation lithium-ion batteries due to its high theoretical specific capacity and earth-abundancy. However, challenges such as significant volume expansion, unstable solid electrolyte interphase (SEI) formation in incompatible electrolytes, and slow lithium-ion transport lead to its poor cycling and rate performance. In this work, it is demonstrated that superior cyclability and rate capability of Si anodes can be achieved using ethyl fluoroacetate (EFA) and fluoroethylene carbonate (FEC) solvents with low binding energy with Li⁺ but with sufficiently high relative dielectric constants. By weakening the interaction between Li⁺ and the solvent, the energy barrier for the Li⁺ desolvation process is lowered, while ensuring the conductivity and diffusion of Li⁺. As a result, the silicon-carbon anode with the optimized electrolyte exhibits excellent cycling and rate performance, and can work reversibly with a high capacity of 1709.1 mAh g^-1 that proceeds for over 250 cycles and retains 85.2% of its capacity at 0.2C. Furthermore, the Si/C‖LiFePO₄ (LFP) full cell shows an extended service life of more than 500 cycles. This work offers valuable insights into the design of weakly solvating electrolytes for high-performance Si-based batteries.

Correction for ‘Radical ligand transfer: mechanism and reactivity governed by three-component thermodynamics’ by Zuzanna Wojdyla et al., Chem. Sci., 2024, 15, 8459–8471, https://doi.org/10.1039/D4SC01507J.

We report a series of dibenzyl isophthalates (DBIs) as novel hosts for room-temperature phosphorescence (RTP) host-guest systems, achieving RTP quantum yields (QY) of up to 77% or lifetimes of up to 21.0 s with the guest coronene-d ₁₂. Furthermore, a 4,4'-Br substituted DBI was used to form host-guest RTP systems with 15 different aromatic guest molecules, to tune the phosphorescence emission color from blue to red and to demonstrate the versatility of the host. Mechanistic insights were gained through a host-guest-matrix system which shows RTP by trace combinations of a 4,4'-Br DBI host (0.10 wt%) and a pyrene-d ₁₀ guest (0.01 wt%) in an otherwise non-RTP-emissive aromatic matrix. This work establishes DBIs as readily available and versatile, tunable hosts for RTP host-guest systems, posing an alternative to polymeric hosts.