搜索结果：Chemistry (Weinheim an der Bergstrasse, Germany)

Attempts to design transmembrane channels with selective transport properties using advanced chemistry and computational tools have had limited success. Previously, we characterized 15-mer α-peptide-oligourea chimeric foldamers that form anion channels with high Cl- selectivity. Here, we report the design and synthesis of four 13-mer α-peptide-oligourea chimeric foldamers (HPU-EK, HPU-QQ, HPU-AA, and HPU-RH) as part of our attempts to generate new foldamers with distinct hydrophobic and hydrophilic surfaces in their helices. They consist of an 8-mer peptide with varied sequences at the N-terminal of a shorter oligourea segment (5-mer). They self-assemble into supramolecular channels. A 6.5 Å cryo-EM structure of HPU-AA revealed nanofibers with distinct dimensions and diverse modes of molecular assembly. Functional assays of the four chimeras demonstrated varying anion transport activities across lipid bilayer membranes. Enhanced ion transport activity was achieved by selective mutations within the foldamer sequences. HPU-AA, which has extended hydrophobic and narrower hydrophilic surfaces, showed the highest ion transport activity among the four foldamers. It exhibits distinct anion selectivity (I->SCN->NO3 - = Cl->Br->OAc->F-), with ∼3-fold higher conductance value for I- than Cl-. These studies help us understand the self-assembly of these chimeric foldamers and offer opportunities for designing novel channels for various biomedical applications.

We report a systematic investigation of β-ketonitrile-modified Prodan-type solvatochromic fluorophores as an alternative to conventional π-extension. A series of donor-π-acceptor dyes incorporating a β-ketonitrile acceptor and a unified piperidyl donor and compared with the corresponding acetyl analogues. The β-ketonitrile substitution produced pronounced bathochromic shifts in both absorption and emission, together with substantial enhancement of fluorescence quantum yields (Φfl) in nonpolar solvents, effectively overcoming the low-Φfl limitation of Prodan. These improvements are attributed to reduced intersystem crossing arising from destabilization of the n-π* triplet manifold. The dyes also exhibit markedly increased molar absorption coefficients at 405 nm, facilitating efficient excitation at 405 nm. In polar media, polarity-dependent formation of TICT states or promotion of internal conversion modulates the emission response, with the π-extended dye FπAc-CN displaying exceptionally strong positive temperature sensitivity from -10 to 75°C, functioning as a ratiometric fluorescent thermometer. In membrane-mimetic lipid bilayers, the naphthalene and fluorene derivatives (NAc-CN, FRAc-CN) showed significantly larger phase-dependent λfl shifts than Prodan or Laurdan, exhibiting enhanced sensitivity to membrane-mimetic polarity environments. These results establish β-ketonitrile substitution as a powerful design principle that achieves large-Stokes-shift emission, enhanced brightness, temperature responsiveness, and phase-dependent fluorescence response in model membranes.

Microporous organic networks (MONs) have attracted considerable attention because of their high porosity, modifiable structure and excellent stability. However, their rigid structure makes it difficult to form membranes, leading to limited separation applications. MONs' powder suffers from issues of dusting and severe aggregation, leading to difficulties in separation and recycling. Herein, MONs' powder was converted into flexible and reusable membranes via phase inversion. The membranes were applied to enrich and extract domoic acid (DA, an algal toxin) from complex matrices. The adsorption performance and mechanism of three MONs membranes with different amino content were investigated and compared. The results indicate that the adsorption energy of the membranes for DA is positively correlated with the number of amino groups. Under optimized conditions, by combining syringe filter-based membrane micro-solid-phase extraction (SF-M-µSPE), with high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS), the developed method showed a low detection limit (0.5 pg mL-1), a wide linear range (1.5∼1000.0 pg mL-1, R ≥ 0.9999) and good repeatability (RSD ≤ 3.8%, n = 6). The membranes were successfully used to extract DA from seafood. There was trace DA (9.4 pg mL-1) found in oyster samples. This work demonstrates the great potential of MONs membranes in sample pretreatment.

Molecularly imprinted polymers have broad applications in chemistry and biology. Nanomaterials differ substantially from analogous materials on the macroscopic scale. In this work, ligand-stabilized gold nanoparticles and two micelles with different surfactant structures are used as nanoplatforms for molecular imprinting. Each platform due to its unique structure strongly impacts the imprinting, to the point that the best template molecule on one platform could become the worst on another. Ligand-stabilized gold nanoparticles can be engineered to contain unsatisfied or 'frustrated' hydrophobic and hydrogen-bonding interactions within the monolayer, causing molecular imprinting on these particles to strongly favor templates that satisfy these interactions and to penalize those that do not, dramatically improving binding affinity and selectivity as a result. In contrast, with freely moving surfactants that rapidly optimize their interactions with the templates, micelles give more predictable results during imprinting, governed by the hydrogen-bonding abilities and hydrophobicity of the surfactant molecules. These results indicate that the unique features of each nanoplatform can be exploited to improve molecular imprinting on the nanoscale and facilitate the preparation of advanced nanomaterials with tailored molecular recognition properties.

Although metal alcoholates have certain applications in the research of oxygen evolution reaction (OER) catalysts, they still have problems of low stability and activity, which restrict their development. To address these issues, this work regulates the ratio of iron-based metal alcoholate ligands by the hydrothermal method and constructs nanoflower-like nanostructures with crystalline and amorphous coupling through etching, thereby improving the catalytic activity. Among them, Fe-gly-1.5 demonstrates exceptional catalytic performance under high current density, evidenced by a 243 mV overpotential (100 mA cm-2) and 200 h stability (250 mA cm-2). Moreover, the two-electrode alkaline water electrolyzer assembled with Fe-gly-1.5 and Pt/C catalysts shows sustainable stability in the overall water splitting process. Electrochemical studies using probe molecules such as TMAOH and methanol demonstrate that the mixed‑ligand system exhibits unique advantages in catalytic reactions. Further investigations through in situ Raman and Fourier transform infrared (FTIR) spectroscopy, combined with differential electrochemical mass spectrometry (DEMS), reveal that the active phase of Fe-gly-1.5 is δ/β-FeOOH formed via reconstruction during the OER process, and confirm that its reaction pathway follows the lattice oxygen-mediated mechanism (LOM).

Metal-based anticancer agents occupy a distinctive niche in cancer therapy owing to their exceptional coordination versatility, redox activity, and tunable photochemical properties, which enable simultaneous engagement of multiple cellular pathways. Despite the clinical success of platinum-based chemotherapy, metal-based monotherapy is frequently hindered by resistance development, dose-limiting toxicity, and incomplete tumor control. Combination therapy has therefore emerged as an indispensable approach in clinical oncology, offering synergistic enhancement of antitumor efficacy, mitigation of resistance, and expansion of therapeutic windows. In this review, we summarize recent advances in metal-based anticancer combinations from three mechanistic perspectives. First, we categorize combinations of metal-based agents with mechanistically distinct chemotherapeutics based on their ability to reinforce DNA damage, promote apoptotic execution, disrupt redox homeostasis, and exploit metabolic vulnerabilities. Second, we discuss the immunomodulatory functions of metallodrugs, emphasizing their capacity to induce immunogenic cell death and reprogram tumor microenvironment, thereby establishing a rational basis for combinations with immune checkpoint blockade. Third, we explore emerging multimodal strategies in which metal-based systems function as energy-responsive agents, enabling photodynamic, photothermal, or sonodynamic therapy and rational integration with other modalities. Collectively, these insights provide a robust mechanistic foundation to guide the rational design of next-generation metal-based combination therapies for improved cancer treatment.

Converting CO2 into cyclic carbonates through cycloaddition with epoxides is an attractive route for carbon utilization, but efficient and recyclable heterogeneous catalysts that operate under mild conditions remain desirable. Herein, five BisTris-modified decavanadate-based coordination polymers were prepared under mild acidic conditions. Compound 1 is assembled from [V10O28]6- anions, Na+ cations, and BisTris ligands, whereas isostructural compounds 2-5 incorporate Co2+, Ni2+, Cu2+, or Zn2+ centers as BisTris-chelated complex cations. Single-crystal analyses reveal that these transition-metal-BisTris units are integrated with decavanadate-sodium chains through hydrogen-bonding, electrostatic, and, in minor disordered components, Na-O coordination interactions, creating multiple accessible activation sites. In the cycloaddition of CO2 with epichlorohydrin, all catalysts afford >99% selectivity under 1 atm CO2 at 60°C, with the Zn-containing compound 5 giving the highest yield of 98.2%. Compounds 2-5 outperform the metal-free analogue 1, and control experiments with isolated BisTris-Co and decavanadate components confirm a cooperative contribution from vanadium Lewis acid sites, transition-metal centers, and BisTris hydroxyl groups. The best catalyst retains high activity over five cycles and shows broad epoxide tolerance, highlighting a modular strategy for constructing POM-based catalysts for mild CO2 fixation.

Chlorinated (hetero)arenes are key structural motifs existed in various bioactive molecules, and serve as versatile building blocks in modern organic synthesis. Classical chlorination methods generally suffer from harsh reaction conditions, corrosive chlorinated reagents, and poor functional group tolerance. In recent years, photocatalysis and electrocatalysis have emerged as powerful and sustainable platforms for the sustainable synthesis of chlorinated (hetero)arenes under mild conditions, which significantly expand the diversity of chlorination reactions. This review summarizes the latest and representative advances in photo- and electrochemical chlorination of functionalized (hetero)arenes over the past decade, with particular emphasis on mechanistic understanding, catalyst and reagent design, and synthetic applications involving C(sp2)-H functionalization and ipso-chlorination of C(sp2)-X (X = C, N, S, and etc.) bonds. Elegant applications in late-stage functionalization of complex molecules and the upcycling of waste plastics are also highlighted in this review.

Metal oxide nanomaterials are among the most compelling electrode materials for supercapacitors. In contrast to carbon-based electrodes that store charge via electric double-layer mechanisms, pseudocapacitive materials operate through rapid, reversible surface or near-surface redox reactions, enabling higher densities. This review examines the non-aqueous solvothermal synthesis of nine major transition metal oxide nanomaterials (Fe3O4, Co3O4, NiO, RuO2, V2O5, CuO, WO3, Nb2O5, and MnO2). Solvothermal synthesis is a powerful and indispensable strategy for tailoring the intrinsic physicochemical properties of these nanomaterials, that is, phase composition, crystallinity, morphology, and particle size, that directly govern their pseudocapacitive performance. We focus on a critical gap in literature: the limited reporting and understanding of key solvothermal parameters, particularly solvent identity and reactor fill ratio. These variables dictate autogenous pressure and determine whether the synthesis occurs under subcritical or supercritical conditions. Therefore, we propose a conceptual framework linking solvent choice and fill ratio to autogenous pressure, phase evolution, defect chemistry, morphology, and pseudocapacitive behavior. Because systematic studies remain scarce, existing evidence is critically evaluated to identify trends and knowledge gaps. The findings suggest that optimizing pristine metal oxide nanostructures through controlled solvothermal synthesis, rather than relying on conductive-carbon compositing, is essential for achieving meaningful improvements in next-generation supercapacitors.

Copper and zinc homeostasis is tightly regulated in mammalian cells, and their dysregulation is implicated in various pathological conditions including cancer. Herein, we have designed rhenium (I) complexes with Cu2+ and Zn2+ chelating properties, exhibiting significant antiproliferative activities against various tumor cell lines. Mechanistic studies have found that mitochondria-targeted complex Re2 induces a substantial increase in the intracellular Cu/Zn levels, especially in the mitochondrial compartment, disrupting the homeostasis of copper and zinc ions in cells and mitochondria, thereby triggering cuproptosis, GSDMD-mediated pyroptosis, and p16/p21-dependent cellular senescence signaling pathway simultaneously. Moreover, co-incubation with copper/zinc ions can further enhance the antitumor activity of Re2 significantly. In the 4T1 murine breast cancer model, Re2 demonstrated potent tumor suppression efficacy with excellent in vivo biocompatibility. This work suggests that intervening in copper and zinc homeostasis is an effective means of regulating multiple programmed cell death, providing new strategies for the rational design of the next-generation metal-based antitumor agents.

A multifunctional smart film was fabricated via dynamic Schiff base cross-linking between quaternary ammonium chitosan (HACC) and dialdehyde cellulose (DAC), enabling the integrated encapsulation, controlled release, and visual indication of curcumin within a single matrix without external sensors. Structural analyses (FTIR, XPS) confirmed the formation of the pH-responsive dynamic network. Curcumin incorporation significantly enhanced the film's performance, increasing tensile strength (TS) by ∼60%, improving barrier properties, and providing potent antioxidant activity (DPPH scavenging efficiency approaching 90%). The swelling behavior and release kinetics of the films were highly pH-dependent. Rapid burst release dominated by nonFickian diffusion was observed under acidic conditions (pH 4.0), whereas slow, sustained Fickian diffusion-controlled release occurred in neutral and alkaline environments (pH 7.0 and 9.0). Owing to the intrinsic chromophoric properties of curcumin, the films displayed distinct and reversible pH-dependent color changes, transitioning from bright yellow in acidic media to reddish-brown in alkaline conditions, enabling intuitive visual monitoring of environmental changes. This work demonstrates an effective strategy for designing bio-based innovative packaging materials that integrate sensing, protection, and controlled release functions within a unified, dynamically responsive polysaccharide network.

The development of non-noble metal catalysts with high activity and stability for the electrocatalytic hydrogen evolution reaction (HER) remains highly important. This study addresses the challenge of simultaneously achieving high activity and durability by proposing a hard-soft template synergistic strategy to construct mesoporous carbon-coated carbon nanotube heterostructures. Using 3-aminophenol as the carbon and nitrogen source and phosphomolybdic acid as the metal precursor, Mo─N modified mesoporous carbon layers were in situ grown on carbon nanotube surfaces, yielding CNT@Mo3O8/NC composites. The optimized catalyst, CNT@Mo3O8/NC-0.1-2Mo, exhibited favorable HER activity in both acidic and alkaline electrolytes, requiring overpotentials of 143 and 169 mV at 10 mA cm-2, with Tafel slopes of 100.2 and 92.1 mV dec-1, respectively. It demonstrated excellent stability, with less than 5% degradation after 1000 CV cycles and 15-20 h of chronoamperometry. The enhanced performance is attributed to Mo─N─C active sites, improved mass transfer via the mesoporous structure, suppressed agglomeration through strong metal-support interactions, and enhanced electron transport via the CNT conductive network. This work provides a feasible approach for transition metal/carbon-based composite electrocatalysts.

Superparamagnetic iron oxide nanoparticles (SPIONs) are widely employed as platforms for ligand-mediated targeting in multimodal imaging and targeted therapeutic applications owing to their intrinsic magnetic properties and versatility for surface and core modification. In addition to magnetic resonance imaging contrast, SPIONs can be labeled with radioisotopes incorporated into the crystalline structure or functionalized with chemically bound dyes or chelating agents, enabling complementary imaging modalities such as fluorescence imaging and positron emission tomography. However, chemical functionalization of nanoparticles with targeting ligands can induce alterations not only in their physicochemical properties but also in their interactions with biological systems. These nano-biointeractions are critical determinants of biological performance and must be carefully evaluated. In this study, we investigate the impact of ligand functionalization on SPION-cancer cell interactions to elucidate key parameters relevant to the successful clinical translation of nanomedicine-based targeted imaging agents.

Antimony(V) azadipyrromethene complexes featuring a tetradentate N2O2-type ligand were synthesized to investigate the impact of axial ligands on their photophysical properties. Reaction of the azadipyrromethene ligand with SbCl5 afforded the benchtop-stable dichloro complex aza-LSbCl2 in high yield. Axial ligand substitution enabled the conversion of aza-LSbCl2 to its dihydroxy, chloromethoxy, and dimethoxy derivatives aza-LSb(OH)2, aza-LSbCl(OMe), and aza-LSb(OMe)2, respectively. Photophysical studies revealed a ligand-dependent fluorescence turn-on effect; while the dichloro complex aza-LSbCl2 and the chloromethoxy complex aza-LSbCl(OMe) are nearly nonemissive, the aza-LSb(OH)2 and aza-LSb(OMe)2 exhibit near-infrared (NIR) emission with photoluminescence quantum yields (PLQYs) of 8 and 6%, respectively. Time-dependent density functional theory (TD-DFT) calculations indicate that the fluorescence quenching in the dichloro and chloromethoxy complexes stems from a dissociative excited state characterized by Sb─Cl bond elongation, whereas oxygen-based ligands provide a structurally stable singlet excited state (S1) manifold. These findings demonstrate that post-complexation axial-ligand engineering at the antimony center is an effective strategy for modulating the optical properties of antimony(V) azadipyrromethene complexes, highlighting a distinctive feature not accessible in conventional coordinatively saturated aza-BODIPY systems.

Self-assembled molecular cages and capsules attracted considerable attention, owing to their unique structures and ability to function as nano-reactors and catalysts. In recent years, porous liquids have emerged into an intriguing class of functional materials. Herein, we prepared a series of per-ethylene-glycol (EG)-functionalized resorcin[4]arene hosts, bearing side chains with three, four, or five EG units (compounds 1d, 1e, and 1f, respectively). We studied their melting points, solubility, self-assembly, and encapsulation abilities. Interestingly, 1e and 1f were found to be viscous liquids at RT and compound 1d melts at 104°C-105°C, while alkyl-substituted resorcin[4]arenes (1a and 1c) melt at ∼300°C. We found in contrast to expectations, that the number of EG groups on the side chains affects the self-assembly, the stability of the formed aggregates, and the encapsulation power of those systems in organic solvents. System 1d behaved, in CDCl3, much like alkyl-substituted resorcin[4]arenes, forming self-assembled hexameric capsules of comparable stability and size capable of encapsulating even tetra-hexyl ammonium salts. Compounds 1e and 1f, however, form, in CDCl3, hexameric capsules, which are more dynamic than the capsules of 1c or even 1d that encapsulate smaller ammonium salts and appear to be promising candidates for the preparation of liquid capsules and capsular liquids.

Five heteroleptic iridium(III) complexes bearing cyclometalated 2,4-diphenylpyridinato ligands and a 4,4'-dimethyl-2,2'-bipyridine ancillary ligand were synthesized. Modulation of substituents at the 4'-position of the cyclometalated phenyl ring provided systematic variation in oxidation potentials, emission wavelengths, and luminescence quantum yields, used herein to interrogate the relationship between electronic structure and electrochemiluminescence (ECL) response. With tri-n-propylamine as co-reactant, the relative ECL intensities of the complexes depended strongly on the excitation pathway, for which distinct optima in co-reactant concentration were also identified. The complexes bearing more electron-withdrawing substituents exhibited the greatest ECL intensities via the reductive excitation (direct) pathway, but rendered the oxidative excitation (indirect) pathway energetically inaccessible. Under cathodic potentials with benzoyl peroxide as co-reactant, the unsubstituted complex exhibited the highest ECL intensities within the series, exceeding those of [Ru(bpy)3]2+ under selected conditions. These findings highlight that ECL performance is governed by luminescence efficiency, the excitation pathway and energetic alignment with the co-reactant system, and that even subtle changes in luminophore properties can have multiple, sometimes competing, effects on ECL intensity.

The preparation of novel chiral λ3-iodane reagents bearing transferable halogen-, oxygen- or carbon-based ligands is described. Among these hypervalent iodine(III)-based compounds are (i) the first chiral bis(cyano-λ3-iodane), whose bis(benziodazolone) structure is derived from an enantiopure cyclohexyldiamine-based bis(amidoiodoarene), and (ii) the two first chiral benziodoxolones bearing a carbon-based ligand (i.e., cyano and trifluoromethyl groups) together with a lactate moiety ortho-positioned to the iodine(III) atom. The proposed iodine-containing heterocyclic structures of these new λ3-iodanes are supported by x-ray diffraction analyses and DFT calculations. Their capacity to transfer their ligand(s) in an asymmetric fashion to different substrates (i.e., β-ketoesters, naphthols, and oxindoles) was also examined.

The ability of polymer and metallic materials to deform without breaking is one of their most useful properties, however, this behavior was only recently discovered in crystalline molecular materials. Attempts to categorize molecular crystals as either mechanically plastic or elastic have relied on basic qualitative observations. In this study, we employ X-ray quantum crystallography (QCr) to distinguish these distinct mechanical behaviors through a comparative quantitative analysis of three pairs of isostructural organic crystals that demonstrate both plastic and elastic bending. QCr analysis identified subtle yet consistent differences in lattice cohesive energies (LCE) of 1-4 kJ mol- 1, with higher dispersion energy components and potential energy densities at the bond critical points of intermolecular interactions in elastic relative to plastic crystals. While the intermolecular force constants (k) of elastic crystals are systematically higher, kelastic > kplastic, the trend in the corresponding pairwise compressibilities ( τ ), τ elastic > τ plastic, is counterintuitive. Contrary to some intuitive considerations, our analysis of slip planes and rugosity does not effectively differentiate between elasticity and plasticity; instead, the QCr-derived atomic displacement parameters implicate more pronounced lattice vibrations and higher entropy and thus, shallower intermolecular potential wells, in plastically bending crystals.

In ultrahigh-nickel layered cathode materials, regulating the morphology and arrangement of primary particles is a strategy that effectively to mitigate particle microcrack formation and enhance structural stability during electrochemical cycling. Nevertheless, current investigations on Ta-doped cathodes have primarily focused on the relationships between primary particle morphology, size distribution, and electrochemical performance. The fundamental mechanisms by which Ta doping influences primary-particle evolution, lattice microstrain, stress redistribution during electrochemical cycling, mechanical strength, and structural stability remain poorly understood. In this work, a Ta doping strategy was employed to engineer the microstructure of LiNi0.90Co0.05Mn0.05O2 cathodes, resulting in refined and radially aligned primary particles. The results reveal that LiNi0.90Co0.05Mn0.05O2 containing 0.5 mol% Ta exhibits refined radially aligned primary particles, reduced lattice microstrain, possessed more homogeneous stress distribution, and diminished strain fluctuations during cycling, which collectively contribute to enhanced mechanical strength and improved cycling stability. This work establishes the correlations among microstructural characteristics, chemo-mechanical behavior, and electrochemical performance laying the foundation for the rational design of high-stability Ni-rich layered cathodes.