Chemistry - An Asian Journal最新文献

Multifunctional electrochromic systems with divergent functions are highly sought after but rare and challenging to develop. Here, we report the synthesis and multi-functional electrochromic behaviour (multi-colour modulation, visible-to-near IR absorption switching, and electrofluorochromism) of electron-deficient indenofluorene-based systems. The compounds (IF₁-IF₅) have been obtained via Knoevenagel condensation of indenofluorenone (IF_K) with various nucleophiles (malononitrile, benzylcyanide, dimethyl malonate, methyl cyanoacetate, benzothiazole-2-acetonitrile). IF₁-IF₅ possess strong colours and absorb in the visible region (λ_max=295-388 nm). These compounds are electroactive and exhibit two reversible reduction waves (-0.35--0.88 V and -0.65--1.30 V vs Ag/AgCl), generating radical anion and dianion systems. For the electrochromic studies, upon applying the one-electron reduction potential (-0.35 V vs Ag/AgCl), the absorption maximum of IF₁ redshift from 382 nm to 1240 nm (IF₁ ^-⋅), which subsequently blueshifts to 466 & 745 nm (IF₁ ^2-⋅) upon increasing to two-electron reduction potential (-0.65 V vs Ag/AgCl). The color of the solution was switched from green to dark blue and further to light orange. The electrochromic behaviour is highly reversible and cycling. In addition, unlike the non-fluorescent (IF₁ and IF₁ ^-⋅), the two-electron reduced system (IF₁ ^2-⋅) is red-emissive (λ_em=630 nm) due to the combination of radicals leading to the formation of antiaromatic quinoidal π-conjugated system (IF₁ ^2-).

Triple negative breast cancers (TNBCs) lacking estrogen receptor (ER), progesterone receptor (PR) and human epidermal growth factor receptor 2 (HER2) on their cell surfaces are highly aggressive, difficult-to-treat and often relapse. Herein, we report on the self-assembled lipid nanoparticles (LNPs) of two new pegylated lipopeptides for killing TNBCs (MDA-MB-231). The pegylated lipopeptides were synthesized by conjugating an n-hexadecyl hydrophobic tail to one end of a (PEG)27 unit the other distal end of which was covalently grafted with two previously reported tumor targeting RGDK- and CGKRK- peptides. The SEM images of the self-assembled LNPs formed upon dissolution of the pegylated lipopeptides in aqueous medium revealed formation of spherical aggregates. The degree of cellular uptake for the self-assembled LNPs formed by the pegylated CGKRK-lipopeptide were found to be significantly higher than that for the self-assembled LNPs formed by the pegylated RGDK-lipopeptide in MCF-7, MDA-MB-231, HEK-293 and HFF cells.  Notably, about 60% TNBCs (MDA-MB-231 cells) were killed upon treatment with commercially available potent JAK2 inhibitor (WP 1066) loaded LNPs of the pegylated RGDK-lipopeptide. Contrastingly, the same treatment killed only about 20% non-cancerous HEK-293 cells. The self-assembled pegylated LNPs described herein open the door for undertaking preclinical studies in animal models for TNBCs.

Human production and living processes emit excessive VOCs into the atmosphere, posing significant threats to both human health and the environment. The photothermal catalytic oxidation process is an organic combination of photocatalysis and thermocatalysis. Utilizing photothermal catalytic degradation of VOCs can achieve better catalytic activity at lower temperatures, resulting in more rapid and thorough degradation of these compounds. Photothermal catalysis has been increasingly applied in the treatment of atmospheric VOCs due to its many advantages. A brief introduction on the three modes of photothermal catalysis is presented. Depending on the main driving force of the reactions, they can be categorized into thermal-assisted photocatalysis (TAPC), photo-assisted thermal catalysis (PATC) and photo-driven thermal catalysis (PDTC). The commonly used catalyst design methods and reactor types for photothermal catalysis are also briefly introduced. This paper then focuses on recent developments in specific applications for photothermal catalytic oxidation of different types of VOCs and their corresponding principles. Finally, the problems and challenges facing VOC degradation through this method are summarized, along with prospects for future research.

The development of ammonium nitrate (AN)/ammonia borane (AB) as a green propellant is crucial for their applicability in different engines. This study investigates the release patterns of small products, particularly nitrogen-containing molecules, during the initial pyrolysis of AN/AB at low and high pressures using ReaxFF MD simulations. Compared with pure AN, the addition of AB gives the hybrid system enhanced reactivity, leading to faster decomposition and higher energy release. The results show that the consumption of AN in the S₁₃ system (AB with a mass ratio of 12.6 %) is accelerated at 1.47 MPa. NO₂ and NO are produced through HNO₃ and NO₃. At 6.89 MPa, AN exhibits the fastest decomposition rate in the S₁₅ system. The high pressure enhances more reactions of NO with free radicals such as NH and accelerates the release of N₂. As the percentage content of AB increases to 15.3 %, more H₂O while more NO₂ is generated. The effect of AB on the generation of radicals such as H₂ and H, is analyzed. AB not only promotes the initial pyrolysis of AN but also accelerates the conversion of intermediates.

Layered double hydroxides (LDHs) have been regarded as excellent catalysts for a variety of photocatalytic applications including the hydrogen production, carbon dioxide reduction, and nitrogen fixation, et al. The elucidation of the photocatalytic mechanism of LDH-based photocatalysts under light irradiation, especially at the ultraviolet (UV) and deep ultraviolet (DUV) region, at the molecular level has remained elusive. In this study, the photo-induced electronic structure of ZnAl-LDH materials was investigated, and a comprehensive understanding of its underlying mechanism, both in the UV and DUV region, was gained using density functional theory (DFT) calculations. The UV and DUV regions exhibit distinct excitation characteristics, revealing the complex interactions between electrons and holes within the system. The DUV region significantly promotes electron transfer, indicating the potential application of LDH materials as a DUV catalysis material. This study elucidates the electron transfer kinetics in LDHs upon UV and DUV irradiation, thereby offering new perspective for the development of photocatalytic materials under different light region.

We have explored NHSi-supported copper(I) complexes as active and highly efficient catalysts for A³ (aldehyde-alkyne-amine) and KA² (ketone-alkyne-amine) three-component coupling reactions to synthesize propargyl amines in excellent yields with high TOF under solvent-and additive-free conditions.

The antitumor activity of various gold compounds is a promising field of investigation, attracting researchers seeking potential clinical candidates. To advance this research, they explore the complex mechanisms of action of these compounds. Since the discovery of the strong inhibition of thioredoxin reductase by auranofin, the primary mechanism explored has been the inhibition of this enzyme. This inhibition disrupts the redox balance in cells, promoting oxidative stress and triggering cell death. In this review, we analyzed studies from the past decade that measured cellular ROS increase and examined the coordination structures of gold compounds. We also correlate ROS increase with the inhibition of redox-regulating enzymes, thioredoxin reductase, and glutathione reductase, to elucidate the relationship between these cellular effects and chemical structures. Our data compilation reveals that different structures exhibit varying efficacy: some significantly increase ROS production and inhibit thioredoxin reductase or glutathione reductase, while others elevate ROS levels without affecting these target enzymes, suggesting alternative mechanisms of action. This review consolidates critical evidence, enhancing our understanding of the mechanisms by which these gold complexes act and providing valuable insights for developing new therapeutic strategies against tumor cells.

A series of N,O donor-based mono- and binuclear four-coordinated boron complexes were synthesized. Depending on the substitution and spacer, these complexes exhibit intense blue, green and yellow emission in solution states. Notably, the fluorescence quantum yields (Φ_F) and fluorescence decay (lifetime, τ) of mononuclear boron complexes (2 a-2 e) were higher than the binuclear boron complexes (2 f-2 k). The lowest lifetime and quantum yield in binuclear boron complexes were due to intramolecular rotation induced non radiative processes. The disulphide spacer-based boron complexes 2 i-2 k showed aggregation-caused quenching in the THF/H₂O mixture whereas no other complexes were ACQ responsive. These complexes show large Stokes shift, one of them i. e. 2 e has the highest Stokes shift of 130 nm. Further, the electrochemical study suggests the presence of two redox incidences. Theoretical studies show close corroboration between the TD-DFT computed and experimentally measured absorption maxima as well as DFT (GIAO) calculated and experimentally measured ¹¹B NMR values. This complements the appropriate selection of the theoretical methods to shed light on the electronic transitions in the mono- and binuclear BF₂ complexes.

In article number e202400584, Hongzhi Liu and co-workers describe the creation of a new hybrid dendrimer network using octa(aminophenyl) silsesquioxane (OAPS) and glycidyl methacrylate (GMA) for environmental cleanup. The material shows high thermal stability and impressive adsorption abilities for iodine (3.4 g/g from vapors) and dyes such as Rhodamine B and Congo red. This indicates potential for use in pollution control.

A convenient and highly sensitive biosensor is constructed for the selective detection of neurotransmitters (5-hydroxytryptamine, 5-HT) using rationally designed anionic conjugated polyelectrolyte PFPS. The polyelectrolyte displayed a fluorescence turn-off response on successive addition of 5-HT with clear visual color fading under 365nm UV light, resulting in the onsite visual detection with a limit of detection in part per million. More details can be found in article number e202400544 by Parameswar Krishnan Iyer and co-workers.