Chemistry - An Asian Journal最新文献

Injectable hydrogels are a sub-type of hydrogels which can be delivered into the host in a minimally invasive manner. They can act as carriers to encapsulate and deliver cells, drugs or active biomolecules across several disease conditions. Polymers, either synthetic or natural, or even a combination of the two, can be used to create injectable hydrogels. Clinically approved injectable hydrogels are being used as dressings for burn wounds, bone and cartilage reconstruction. Injectable hydrogels have recently gained tremendous attention for their delivery into the liver in pre-clinical models. However, their efficacy in clinical studies remains yet to be established. In this article, we describe principles for the design of these injectable hydrogels, delivery strategies and their potential applications in facilitating liver regeneration and ameliorating injury. We also discuss the several constraints related to translation of these hydrogels into clinical settings for liver diseases and deliberate some potential solutions to combat these challenges.

Nickel-rich cobalt-free LiNi0.9Mn0.05Al0.05O2 (NMA955) is considered a promising cathode material to address the scarcity and soaring cost of cobalt. Particle size and elemental composition significantly impact the electrochemical performance of NMA955 cathodes. However, differences in precipitation rates among metal ions coveys a challenge in obtaining cathode materials with the desired particle size and composition via hydroxide co-precipitation synthesis. Utilizing complexing agents like ammonia offers an effective strategy to tackle these issues. Here, we investigate the optimal ammonia concentration to achieve moderate particle size and precise material composition. Although ammonia only forms complex coordination with transition metals, its concentration also affects the final product's precipitation and composition, including aluminum. This study shows that ammonia serves a dual function in NMA synthesis via hydroxide co-precipitation, i.e., regulating particle size and adjusting elemental composition. It was found that an ammonia concentration of 1.2 M achieved optimal particle size and composition, resulting in superior electrochemical performance. NMA955 synthesized in 1.2 M ammonia demonstrated a high specific capacity of 188.12 mAh g-1 at 0.1C, retained 71.16% of its capacity after 200 cycles at 0.2C, and delivered 110.30 mAh g-1 at 5C. These results suggest tuning ammonia concentration is crucial for producing high-performance cathode materials.

In this study, we focus on the designability and controllability of the interaction interface between secondary structures, and discover an important interface interaction between helical secondary structures by non-covalent synthesis along the helical axis. The formation of discrete heterochiral dimers consisting of left-handed helix and right-handed helix not only helps to discover nonclassical supramolecular chirality phenomena, but also enables controllable protein assembly. Highly ordered nanostructures were thus constructed using p-stacking dimerization of helical foldamers to control tetrameric avidin proteins. The designable and modifiable primitives of artificial folded molecules enable the modification of secondary structure interfaces through non-covalent interactions, leading to the generation of unique structures and functions. These findings are of fundamental importance to the understanding of the precise assembly process of helical foldamers and can provide insights to facilitate the rational design of abiotic protein-like tertiary structures and further functionalization.

Controlling the redox states of single-walled carbon nanotubes (SWNTs) is important for the optimization of their real performances in various fields. By means of in situ photoluminescence (PL) spectroelectrochemical measurements, we report a successful modulation for the redox parameters (redox potentials and electrochemical band gap) of (6,5) and (7,5)SWNTs with a simple change in conjugated polymers (CPs) non-covalently wrapped on the nanotubes. The large shift in the band gap (187 meV for (6,5)SWNTs and 101 meV for (7,5)SWNTs) was connected to the prominent difference in the interactions between the CPs and SWNTs as suggested by molecular dynamics (MD) simulations, while a striking difference in the 𝜋-electrons states of CP/SWNTs enabled the tuning of SWNTs' electronic states. Asymmetrical modulation for the reduction potential (LUMO) and oxidation potential (HOMO) of the SWNTs was observed as well. Our results can be promising for a simple but precise control of the electric states of SWNTs.

Unlike traditional multi-step synthetic approaches, we developed a single-step synthesis of versatile π-conjugated building blocks bearing post-functionalizable C-H and C-Br bonds. Direct C-H arylation of 3-bromothiophene with various iodo(hetero)aryls was successfully carried out with good regio- and chemo-selectivity. Under optimized reaction conditions, 20 new compounds were facilely prepared in yields up to 91%. One of the obtained compounds was demonstrated to further extend its conjugation length using a succinct synthetic plan to create two symmetrical oligo(hetero)aryls (MLC01 and MLC02) that were fabricated as effective hole-transporting materials (HTM) for perovskite solar cells (PSC). PSC devices utilizing MLC01 as hole-transport layer displayed promising power conversion efficiencies of up to 17.01%.

Conventional zeolites are limited in their ability to catalyze macromolecular reactions due to micropore constraints, resulting in sluggish reactant and product diffusion and subsequently pore clogging and catalyst deactivation. Consequently, the pore and textural refinement of zeolites to meet industrial demands has become a research hotspot. Herein, we review the amino acid-assisted methods in zeolite synthesis and scrutinize the principle and influential factors governing amino acid involvement in zeolite synthesis. Additionally, we analyze the advantages and challenges associated with the amino acid-assisted method. Certain amino acids can interact with zeolite precursors or crystal surface, thus altering the crystal growth rate and enabling precise control over the crystal size and shape. On the other hand, amino acids can serve as structure-directing agents to orchestrate the generation of mesoporous pores. These capabilities enable the production of zeolites with well-defined pores, particle sizes and/or crystal shapes that satisfy catalytic requirements. Moreover, the unique properties of amino acids allow their complete elimination from the solid product through a simple aqueous washing process, facilitating their recovery for subsequent usage. As result, the amino acid-assisted synthesis methods offer a convenient, green route to zeolites with modulated textual properties for high-performance catalysis.

Sn(IV) complex of N-Confused Porphyrin (Sn(IV)-NCP) has been prepared and characterized by several spectroscopic techniques to verify its structure and purity. Sn(IV)-NCP shows a red shift in both the Soret and Q bands compared to the free base NCTPP. The last Q band appears in the NIR region. Based on these characteristics, we investigated the antiproliferative properties and antimicrobial photodynamic therapy (a-PDT) efficiency of Sn(IV)-NCP against the bacteria Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus). Further, we investigated the photodynamic activity of Sn (IV)-NCP against Michigan cancer foundation-7 (MCF-7) cancer cells, to assess its potential as an effective therapeutic agent. Treated MCF-7 cells with the compound show cytotoxic effects as compared to the untreated ones. At a higher concentration (128 µg/ml), Sn(IV)-NCP exhibited 90% inhibition, while at a lower concentration (32 µg/ml), it showed 70% inhibition in MCF-7 cells. The IC50 value for this compound against MCF-7 cells was found 16.67 µg/ml. At 32 µg/ml, Sn(IV)-NCP showed only around 4% cell inhibition, indicating minimal cytotoxic effects on human embryonic kidney cells (HEK293).

Herein we report chemoselective transfer hydrogenation (TH) of aldehydes in aqueous medium using a series of homobimetallic Ru(II) catalysts. Two homobimetallic complexes (Ru1 and Ru3) and one monometallic complex (Ru2) have been employed in the catalytic reduction of aldehydes. Bimetallic complex [(p-cymene)2(RuCl)2L3] (Ru3) is obtained from the reaction of Schiff base ligand 2,2'-((1E,1'E)-((3,3',5,5'-tetraisopropyl-[1,1'-biphenyl]-4,4'diyl)bis(azaneylylidene))bis(methaneylylidene))bis(4-bromophenol) (H2L3) and characterized by various spectroscopic and analytical techniques. The use of formic acid/formate buffer as the hydride source and a catalyst loading of 0.01 mol% of Ru1 or Ru3 resulted in the conversion of various aldehydes to the corresponding alcohols in good to excellent yield. This method is very efficient for selective reduction of aldehydes in the presence of other reducible functional groups. A loading of 0.0001 mol% of Ru1 catalyst is sufficient to achieve a turnover frequency (TOF) of 5.5× 105 h-1. Furthermore, the catalyst can been recycled and reused for six consecutives cycles without sacrificing the efficiency. A comparison of results obtained between bimetallic and monometallic complexes offers valuable insights into the distinct reactivity patterns of the bimetallic complexes, presumably originating from a cooperative effect. We have explored the mechanistic pathway using DFT methods.

Chemically active colloids that release/consume ions are an important class of active matter, and exhibit interesting collective behaviors such as phase separation, swarming, and waves. Key to these behaviors is the pair-wise interactions mediated by the concentration gradient of self-generated ions. This interaction is often simplified as a pair-wise force decaying at 1/r2, where r is the interparticle distance. Here, we show that this simplification fails for isotropic and immotile active colloids with net ion production, such as Ag colloids in H2O2. Specifically, the production of ions on the surface of the Ag colloids increases the local ion concentration, c, and attenuates the pair-wise interaction force that scales with ∇c/c. As a result, the attractive force between an Ag colloid and its neighbor (active or passive) decays at 1/r or 1/r2 for small or large r, respectively. In a population, the attraction of a colloid by a growing cluster also scales with ∇c/c, so that medium-sized clusters grow fastest, and that the cluster coarsening slows with time. These results, supported by finite element and Brownian dynamic simulations, highlight the important role of self-generated ions in shaping the collective behavior of chemically active colloids.

beta-(Trifluoromethyl)styrenes are potentially useful building blocks for the synthesis of organofluorine compounds because their electron-deficient C=C double bonds can undergo diverse transformations. One of the most practical methods for preparing b-(trifluoromethyl)styrenes is the decarboxylative trifluoromethylation of readily available cinnamic acid derivatives using the Langlois reagent as a less expensive trifluoromethyl source. We revisited the electrochemical decarboxylative trifluoromethylation of cinnamic acid derivatives to identify modified conditions that reduce the loading of the Langlois reagent without additional additives. The reaction mechanism was computationally investigated to gain insight into the dependence of the product yields on the aryl terminal groups. The synthetic utility of the obtained b-(trifluoromethyl)styrenes was demonstrated by their transformation into 4-aryl-3-(trifluoromethyl)pyrrolidines.