Communications Chemistry最新文献

Photochemical sensing demands systems that adjust their optical properties without altering chromophore structure. Here, we report CPCQ, a thermally activated delayed fluorescence (TADF)-active macrocycle, as a responsive platform for optical sensing. CPCQ shows a photoluminescence quantum yield (PLQY) of 78%, a delayed lifetime of 243 ns, and an efficient reverse intersystem crossing rate of 2.68 × 10⁷ s⁻¹. Unlike conventional fluorescent and TADF emitters, CPCQ with cyclic array of four TADF active donor-acceptors enables reversible state switching of its emission mechanism. Electron-deficient guests form exciplexes with reducing fluorescence and shifting emission. In contrast, electron-rich guests enhance delayed fluorescence (248 ns) via the heavy atom effect. Oxygen quenches charge-transfer emission and restores blue-shifted locally excited (LE) emission. Strikingly, hydrogen flips the effect, triples LE emission (k_r = 2.07 × 10⁸s^-1, PLQY = 93%), and hints at superradiance from cooperative behavior of donor-acceptor units. These adaptive responses establish CPCQ as a highly sensitive and selective molecular tool for next-generation sensing and optoelectronic applications.

The development of high-performance organic photothermal conversion agents (PTCAs) with strong near-infrared (NIR) absorption, high photothermal conversion efficiency (PCE), and excellent biocompatibility remains a critical challenge in photothermal therapy (PTT). In this study, we designed and synthesized a series of novel donor-acceptor-donor (D-A-D) small molecules based on a benzo[1,2-b:4,3-b']dithiophene-4,5-dione (BDTD-4,5-dione) core as a strong electron-accepting unit, symmetrically functionalized with triphenylamine (TPA) derivatives as tunable electron donors. By focusing on the strong electron-donating N,N-dimethylaniline (NPA) unit-contrasted with a methoxy-substituted analog-we achieved effective modulation of the HOMO energy, bandgap, and supramolecular aggregation, underscoring the advantage of enhanced donor strength for photothermal applications. Spectroscopic and electrochemical analyses revealed that electron-rich substituents significantly redshifted the intramolecular charge transfer (ICT) absorption into the NIR region (650-900 nm) and enhanced molar extinction coefficients. Among the derivatives, the dimethylamino-functionalized compound (BDQ-NPA) exhibited the most redshifted absorption, a narrow bandgap (2.0 eV), and an outstanding PCE of 35.05% under 808 nm laser irradiation. Theoretical calculations confirmed strong D-A interactions and efficient charge separation in the excited state. BDQ-NPA self-assembled into stable nanoparticles with excellent photostability and biocompatibility, facilitating efficient cellular uptake and NIR-triggered photothermal ablation of cancer cells in vitro. In vivo studies demonstrated significant tumor growth inhibition in a murine model following a single dose of BDQ-NPA and 808 nm irradiation, with no observable systemic toxicity. This work establishes BDTD-4,5-dione as a promising acceptor core for NIR-absorbing organic PTCAs and highlights the efficacy of substituent engineering in optimizing photothermal performance for cancer theranostics.

Large polycyclic aromatic hydrocarbon (PAH) imides are promising candidates for optoelectronic applications in view of their narrow optical gaps and/or excited state charge transfer character. Diels-Alder (D-A) reactions of PAHs at bay regions can enable simultaneous extension of the aromatic structure and introduction of the imide moieties, but the actual use of this strategy has been limited. Herein, we demonstrate the D-A cycloaddition of dibenzo[hi,st]ovalene, one of the largest PAHs functioning as bisdiene, with maleimides to afford circumpyrene tetracarboxydiimides. Notably, efforts to optimize the yield of di-adduct revealed that the fully aromatized mono-adduct is inert toward further D-A reaction, and density functional theory (DFT) calculations instead indicated a partially dehydrogenated mono-adduct as the key intermediate enabling the second cycloaddition. The resulting product represents a rare example of PAH diimide featuring an acceptor-donor-acceptor type structure. Detailed spectroscopic and theoretical studies, including transient absorption and two-dimensional electronic spectroscopy, revealed the emergence of a bright intramolecular charge transfer state that could be directly excited to demonstrate distinct photophysical dynamics. These findings provide deep mechanistic insights into the D-A reactivity of large PAHs and underscores the potential of such PAH imides for advanced optoelectronic and photonic applications.

Accurate characterization of multi-state protein conformations is crucial for understanding their functional mechanisms and advancing targeted therapies. Extracting coevolutionary constraints from homologous sequences helps reveal protein structure and function, which can be automatically captured by MSA Transformer leveraging attention mechanisms. Making use of the multi-conformational coevolutionary signals captured by MSA Transformer, we introduce in this study EvoSplit to disentangle coevolutionary signals associated with distinct conformations to guide protein structure predictions. EvoSplit outperforms AF-Cluster on 85 fold-switching proteins and successfully models the conformations of proteins beyond AlphaFold2's training set. We then identify 54 candidates with potential conformational diversity for cancer-related human proteins. Notably, for five GTPases, EvoSplit consistently predicts two conformations, one of which has not been previously reported. As an important example, the protein-protein interaction analysis provides new insights into novel HRAS function-associated conformations. Furthermore, the validity of these newly identified conformations is examined by evolutionary analysis and extensive molecular dynamics simulations.

Triboelectric nanogenerators (TENGs) offer a potential power source for compact electronics and self-powered portable devices, with increasing interest in integrating metal-organic frameworks (MOFs) due to their tunable physical and chemical properties. However, the direct incorporation of MOF powders in TENG is hindered by their weak and unstable attachment to the underlying conductive substrates. Herein, we show that electrochemical MOF deposition offers a facile approach to deposit hydrophilic HKUST-1 films on a copper electrode, yielding a robust tribopositive layer after a growth time of 2 h. When this surface was impacted against a tribonegative layer such as Kapton under contact-separation mode, the optimal output of the TENG device reached the highest voltage output of  ~99 V with a power density of 771.8 ± 0.3 mW m^-2. The device exhibits extended stability, with a negligible voltage decay under ambient environment and exposed to relative humidity from 10% to 70%. This study demonstrates a feasible strategy to generate mechanically resilient MOF-based TENGs with reproducible output for real-world environmental conditions.

The Ferrier rearrangement is a cornerstone transformation in carbohydrate chemistry, typically requiring strongly acidic or oxidative conditions. Here we report a continuous-flow electrochemical Ferrier rearrangement operating in an undivided microreactor equipped with inexpensive graphite electrodes mitigating batch process limitations, such as insufficient mass transfer and charge utilization. The process proceeds efficiently with minimal supporting electrolyte and charge input, converting a wide range of acyloxy- and alkoxyglycals with diverse oxygen-, sulfur-, nitrogen-, and carbon-based nucleophiles to 2,3-unsaturated glycosides in up to 94% yield and excellent diastereoselectivity. The short interelectrode distance enables completion under 20 seconds residence time, affording gram-scale productivity (10 mmol·h^-1) and high faradaic efficiency. Mechanistic and electrochemical data support a radical-chain pathway initiated by anodic oxidation of glycal. This operationally simple and scalable protocol advances electrochemical glycosylation toward sustainable, industry-relevant synthesis.

In recent years, there has been no shortage of research achievements in light-responsive materials based on azobenzene photoswitches. Of growing interest is the ability to reversibly tune the competing "dark" thermal cis-trans back-isomerization through protonation effects. The hydroxy-substituted azobenzenes are well-known for their complex pH-dependent behavior, including azo-hydrazone tautomerism. Presently, experimental studies rationalize only qualitatively the marked acceleration in thermal switching upon acquiring the hydrazone tautomer, while the results of theoretical treatments have experienced a persistent cusp problem in calculated potential energy surfaces. Here, using density functional theory, spin-flip, and multireference wavefunction quantum chemical methods, we provide for the first time a comprehensive explanation of thermal switching in the hydrazone tautomer. We show that, through concerted torsion of two dihedral angles, the hydrazone tautomer unexpectedly acquires a maximally puckered transition state, enabling rapid rotation of the entire system. This study demonstrates the exploitative advantages of protonation for tuning thermal isomerization in azobenzene photoswitches.

This study presents a Co catalyst with coexisting single-atoms and nanoparticles on N-doped carbon (Co₁+Co_n/N-C). Synthesized via a sacrificial MgO-template method, it achieves 100% vanillin conversion and >99% selectivity to 2-methoxy-4-methylphenol at 160°C using formic acid, outperforming single-component catalysts. Kinetic studies reveal a water-mediated dual hydrogen transfer pathway, lowering the apparent activation energy to 61.7 kJ/mol. Isotopic studies suggest a water-mediated mechanism, wherein water molecules facilitate proton transfer and hydrogen spillover through a hydrogen-bonding network. This process synergizes with formic acid dehydrogenation to enable a dual hydrogen transfer pathway, involving protonation of the aldehyde group and hydride (H⁻) attack. The catalyst maintains 95% conversion over ten cycles, demonstrating high stability for biomass upgrading.

Continuous flow chemistry has transformed the synthesis of pharmaceuticals and specialty chemicals by advancing sustainability, efficiency, and process control. Despite these advantages, the management of solids remains a major challenge, often leading to clogging, inefficient mixing, and limitations in scalability. This review discusses recent strategies developed to overcome these obstacles, including the use of continuous stirred-tank reactors, packed-bed reactors with immobilized reagents, reaction design modifications, Pickering emulsions, colloidal nanoparticle suspensions, and specialised equipment such as agitated tubular reactors, spinning disk reactors, and sonicated systems. By critically assessing these developments, we chart the trajectory toward more resilient and robust flow-based manufacturing, consolidating continuous flow chemistry as a cornerstone of modern chemical manufacturing.

The nuclear spin-lattice relaxation rate 1/T₁ depends on the correlation time τ_c of the molecule bearing the nuclear spin, and can therefore probe changes of τ_c upon binding of a rapidly moving small ligand to a more slowly moving larger protein. In practice however, the dependence is such that only a small difference in relaxation rate is obtained at high field. Here we present a scheme in which nuclear spins are first hyperpolarized using DNP, and then allowed to relax at low magnetic field in presence of a target protein, which generates a large T₁ contrast. The sample is subsequently transferred into a conventional nuclear magnetic resonance probe (NMR), where the effect of the low-field relaxation is read out using high-field liquid-state NMR. Using only 14 μM of a ¹³C-labeled reporter ligand, we observe protein binding reliably for protein concentrations as low as 2 μM in a single scan. The scheme is expanded to a label-free ligand via a competitive binding experiment in which the label-free ligand displaces the ¹³C-labeled reporter ligand.