Chemistry - An Asian Journal最新文献

Herein, we report the first total synthesis of the conjugation-ready tetrasaccharide repeating units of Pseudomonas aeruginosa (Lányi) O11. The all-6-deoxy-sugars containing tetrasaccharides were synthesized using an efficient convergent methodology employing a (2 + 2) glycosylation strategy. A key to this approach is utilizing a common disaccharide donor, which streamlines the assembly of both the tetrasaccharides by minimizing protecting group manipulations and enhancing overall efficiency. The disaccharide donor was synthesized through a highly chemoselective activation of a meticulously designed reactive thioglycoside donor, allowing for precise control over stereochemistry and regioselectivity during the glycosylation.

One of the most important sources of chemical hydrogen, Ammonia-Borane (AB), contributes greatly to the advancement of the Hydrogen Economy. The real challenge lies in addressing its sluggish kinetics and thermodynamics in terms of its dehydrogenation or the formation of molecular H₂ employing catalysis. Although it has been a decade-long enigma, the quest for an appropriate catalyst that can enable the utilization of AB in a more pragmatic way, such as its mass commercialization in society, is still ongoing. In this regard, there have been many contributions in terms of molecular catalysis towards AB dehydrogenation, encompassing both metal and metal-free compounds as efficient catalysts. Herein, we have focused on some of the transition metal-based complexes as homogeneous catalysts for AB dehydrogenation that have been known for paving the way for synthesizing, modeling, and investigating better complexes of this kind, showing improved functionality and efficacy towards the release of molecular H₂ from AB.

We report a reversible dehydrogenation–hydrogenation of cyclohexanol–cyclohexanone pair over Ru supported on Hierarchical Zeolite (Ru/HZ4A) under neat conditions. The catalyst Ru/HZ4A demonstrated high activity for both dehydrogenation of cyclohexanol to cyclohexanone (at 160°C) and hydrogenation of cyclohexanone back to cyclohexanol (60°C) with appreciably high selectivity and conversion. Moreover, the catalyst Ru/HZ4A displayed high durability under bulk and recyclability experiments, achieving hydrogen productivity as high as 156 L_H2/g_Ru (STY 89 mmol_H2/g_Ru/h). The developed protocol was also applied to 5-membered and 8-membered cycloalkanol–cycloalkanone pairs with excellent selectivity for a one-pot reversible dehydrogenation–hydrogenation cycle. These findings underscore the potential of the developed catalytic system for a reversible hydrogen storage system.

With increasing water scarcity, capacitive deionization (CDI) has emerged as a promising desalination technology due to its cost-effectiveness and environmental friendliness. However, electrode materials significantly influence the CDI performance. To address the poor cycling stability of manganese-based Prussian blue analogs (MnHCF), this study synthesized biomass-derived porous carbon (FSB850) from the bark of Firmiana simplex (commonly known as Chinese parasol tree, synonymous with Firmiana platanifolia) via KOH activation for use as an anode, paired with MnHCF as a cathode. Electrochemical and desalination tests revealed a synergistic effect between the two materials, achieving a high salt adsorption capacity (SAC) of 25.80 mg·g⁻¹ in 500 mg·L⁻¹ NaCl solution and 83.72% cycling stability over 100 cycles. The results demonstrate the potential of biomass-derived carbon for enhancing CDI performance and provide insights into sustainable electrode design. Moreover, we observed that the asymmetric device demonstrated superior SAC under a constant current of 0.053 mA compared to that at a constant voltage of 1.4 V, indicating a potential pathway toward achieving lower energy consumption in capacitive deionization operations.

Hybridization chain reaction (HCR), as an enzyme-free and isothermal molecular signal amplification technique, has been used to construct powerful biosensing platform for multiple kinds of targets. However, biosensors based on conventional HCR (cHCR) suffered slow kinetics and insufficient sensitivity from the low efficiency of free hairpins linear cross hybridization in surrounding solution. To achieve super-fast and ultrasensitive monitoring target molecules, non-classical HCRs (ncHCRs) have been gradually developed by combining cHCR with other signal amplified tools, designing the new probes polymerization modes and changing hairpins spatial distribution. In this review, we categorized ncHCRs into three types, including cascaded linear HCRs, nonlinear HCRs and localized HCRs. Working principles and applications of ncHCR is detailed discussed to show its advantages such as excellent sensitivity, stable signal output, and ideal reaction time in vitro & vivo. Finally, we also give a perspective about the current challenges and future development of ncHCRs.

Herein, we report an ion-tolerant supramolecular hydrogel formed from a pyrene-conjugated amino acid in an electrolytic (saline) aqueous medium with a minimum gelator concentration of 1.8 mM. The hydrogel exhibits thermoreversible and thixotropic behavior, undergoing reversible gel–sol transitions in response to thermal and mechanical stimuli. Spectroscopic and microscopic studies reveal that cooperative π–π stacking of pyrene units and directional hydrogen-bonding interactions from the amino acid backbone drive the self-assembly process. UV–visible and fluorescence analyses confirm the formation of J-type aggregates, while AFM demonstrates a concentration-dependent transition from spherical aggregates to an interconnected fibrous network. Circular dichroism spectroscopy indicates efficient transfer of supramolecular chirality, leading to left-handed helical assemblies that are disrupted at elevated temperatures. X-ray diffraction reveals an ordered lamellar packing with a characteristic π–π stacking distance of ∼0.38 nm. Rheological investigations confirm the viscoelastic and thixotropic nature of the hydrogel. Importantly, the hydrogel exhibits good biocompatibility and effective antibacterial and antifungal activity, highlighting its potential as an injectable, ion-resilient soft material for antimicrobial applications, localized drug delivery, and tissue engineering under physiological saline conditions.

A holey porous carbon nitride system has been prepared from melamine and cyanuric acid. It is further attached to Nickel phytic acid complex. Detailed morphological and elemental features have been further correlated with the ongoing photophysical properties. Later, the excited state dynamics has been clarified by femtosecond transient absorption spectroscopy. Results suggest a highly efficient photoinduced charge separation process between the two counterparts of the composite system. The overall charge separation process has been further supported by electrochemical impedance spectroscopy and transient photocurrent studies. Finally, the composite system has been utilized for photocatalytic H₂ production from water. The H₂ production efficiency has reached up to 11 mmol/g under full Xe light irradiation and it remains active even under near-infrared light irradiation. The calculated apparent QYs for the H₂ productions are ∼7% and 4.2% at 400 and 850 nm, respectively.

Electrocatalysis is an efficient method for reducing greenhouse gas emissions and producing high-value chemicals. Metal-organic materials are currently popular materials to improve the catalytic performance of the electrocatalytic CO₂ reduction reaction (CO₂RR), but due to their inherent conductivity and poor internal active sites, direct application is challenging. Halogens have potential advantages in regulating the activity of carbon dioxide reduction reactions, but they have not yet been directly applied in the practical use of Cd-based electrocatalysts. In this paper, Cd-1,3,5-benzenetricarboxylic acid (Cd-BTC) was prepared by the solvothermal method, and halogen atoms were introduced into Cd-BTC materials to obtain halogen-containing X-Cd-BTC (X = F, Cl, Br, and I) catalysts. Their electrocatalytic CO₂RR activity changed significantly with the electronegativity of halogen. Among them, the CO faradaic efficiency (FE_CO) of the best Cl-Cd-BTC catalyst was as high as 97.2% at the potential of −1.3 V versus reversible hydrogen electrode (vs. RHE), and the FE_CO remained above 93% after 25,200 s stability test. It showed that the introduction of halogen Cl⁻ will lead to strong electronic interaction between Cl⁻ and Cd²⁺, which will accelerate the reaction kinetics, thus significantly improving the electrocatalytic efficiency of Cd-BTC. This catalyst is expected to efficient electrochemical CO₂ to CO.

In this study, we investigated the chain-length dependence of circular dichroism (CD) and circularly polarized luminescence (CPL) properties of trans-bis(2-iminomethylpyrrolato)platinum(II) complexes (1a–d) featuring polymethylene-chain bridges that vaulted across the platinum center. These complexes are almost non-emissive in solution or in PMMA films; however, when dispersed in β-estradiol as a host matrix, their emission quantum yields increase markedly, enabling direct comparison of their CPL characteristics and correlation with molecular structure. Systematic variation of the vaulted chain length revealed that the anisotropy factors (g values) of both CD and CPL (g_abs and g_em) vary as a function of the chain length. DFT-optimized geometries indicated that complexes with shorter vaulted chains exhibit greater bending and torsional distortion between the two 2-iminomethylpyrrolate ligand planes. These structural distortions modulate the angle θ_e,m between the electric and magnetic transition dipole moments (µ_e and µ_m), thereby governing the observed g-value changes. This study demonstrates that precise control of the vaulted chain length enables molecular-level tuning of structural distortion and chiroptical responses in platinum(II) complexes, providing a new design strategy for highly efficient and structurally tunable CPL materials.

Galvanic replacement is a powerful strategy for incorporating heterometal atoms into preformed metallic nanostructures. However, the resulting architectures are highly sensitive to the reaction environment, which influences the relative stability and solubility of the redox species involved. Previous studies on Cu–Ag nanocatalysts synthesized via galvanic replacement have reported diverse product selectivities, underscoring the need for a systematic investigation of the process. In this work, we performed galvanic replacement of Cu nanowires with Ag ions in various solvents and evaluated the resulting nanostructures and their performance in CO₂ electroreduction. The choice of solvent significantly affected the dispersity of the nanocomposites, the size of Ag nanocrystals, and the structure and chemical state of oxidized Cu species. Among these factors, the size of the Ag nanocrystals emerged as the dominant parameter influencing CO₂ electrolysis selectivity, despite notable variations in the Cu species oxidized in different solvents. The results suggest that methane production sites are formed during electrolysis via the reconstruction of Cu nanoparticles on the surface of large Ag crystal facets. This highlights the critical role of copper structural reconstruction during CO₂ electroreduction, particularly when the initial Cu species are readily deformable due to their nanoscale dimension.