A perspective of the engineering applications of carbon-based selenium-containing materials

Recent progress in the organoselenium-catalyzed difunctionalization of alkenes

Selenium-based catalysts have recently been utilized to facilitate a variety of new organic transformations, owing to their intrinsic advantages, including low cost, low toxicity, stability in both air and water, and strong compatibility with diverse functional groups. The difunctionalization of alkenes-the process of incorporating two functional groups onto a carbon-carbon double bond-has garnered particular interest within the chemical community owing to its significant applications in organic synthesis. Recently, organoselenium-catalyzed difunctionalization of alkenes has emerged as an ideal and powerful route to obtain high-value vicinal difunctionalized molecules. This review emphasizes recent advancements in this rapidly evolving field, focusing on the scope, limitations, and mechanisms of various reactions.

Self-Produced O2 CNs-Based Nanocarriers of DNA Hydrophobization Strategy Triggers Photodynamic and Mitochondrial-Derived Ferroptosis for Hepatocellular Carcinoma Combined Treatment

Hypoxia can aggravate tumor occurrence, development, invasion, and metastasis, and greatly inhibit the photodynamic therapy (PDT) effect. Herein, carbon nitride (CNs)-based DNA and photosensitizer co-delivery systems (BPSCNs) with oxygen-producing functions are developed to address this problem. Selenide glucose (Seglu) is used as the dopant to prepare red/NIR-active CNs (SegluCNs). The tumor-targeting unit Bio-PEG2000 is utilized to construct BPSCNs nanoparticles through esterification reactions. Furthermore, DNA hydrophobization is realized via mixing P53 gene with a positively charged mitochondrial-targeted near-infrared (NIR) emitting photosensitizer (MTTPY), which is encapsulated in non-cationic BPSCNs for synergistic delivery. Ester bonds in BPSCNs@MTTPY-P53 complexes can be disrupted by lipase in the liver to facilitate P53 release, upregulated P53 expression, and promoted HIF-1α degradation in mitochondria. In addition, the oxygen produced by the complexes improved the hypoxic microenvironment of hepatocellular carcinoma (HCC), synergistically downregulated HIF-1α expression in mitochondria, promoted mitochondrial-derived ferroptosis and enhanced the PDT effect of the MTTPY unit. Both in vivo and in vitro experiments indicated that the transfected P53-DNA, produced O2 and ROS by these complexes synergistically led to mitochondrial-derived ferroptosis in hepatoma cells through the HIF-1α/SLC7A11 pathway, and completely avoiding PDT resistance caused by hypoxia, exerting a significant therapeutic role in HCC treatment.

Visible-Light-Promoted Selenylation/Cyclization of o-Alkynyl Benzylazides/o-Propargyl Arylazides: Synthesis of Seleno-Substituted Isoquinolines and Quinolines

A simple and efficient visible-light-promoted selenylation/cyclization of o-alkynyl benzylazides/o-propargyl arylazides have been realized for the practical synthesis of seleno-substituted isoquinolines and quinolines. This strategy provides the synthesis of valuable seleno-substituted isoquinoline and quinoline derivatives via the construction of one C(sp2)-Se bond and one C-N bond within one process.

Environmental surveillance in Jinan city of East China (2014-2022) reveals improved air quality but remained health risks attributable to PM2.5-bound metal contaminants

PM2.5-bound metal contaminants are associated with multiple chronic diseases in human. At global level, the contamination status has not been well controlled yet. Here we report findings from a long-term air pollution surveillance in Jinan city of Shandong, China. During 2014-2022, the dynamics and trends of PM2.5-bound heavy metal contaminants were monitored in an industrial area and a downtown area. The surveillance targets included: antimony (Sb), aluminum (Al), arsenic (As), beryllium (Be), cadmium (Cd), chromium (Cr), mercury (Hg), lead (Pb), manganese (Mn), nickel (Ni), selenium (Se). The human exposure and health risks were calculated and we found that the health risks of most contaminants showed peak values in autumn and winter. But Al, Mn, Hg and Be were found to result in highest health risk in spring or summer in the downtown area. In the industrial area we identified 100% alarming health index >1 (ranged from 1.12 to 3.35) in autumn and winter. In winter the total non-carcinogenic HI was all above 1 (peak value 2.21). Mn and As together posed >85% non-carcinogenic risk. As and Cd were ranked as major drivers of carcinogenic risks (5.84 × 10-6 and 2.78 × 10-6). Pd and Cd both showed non-negligible environmental levels but risk assessment model for their air-exposure associated non-carcinogenic risks are not yet available. This study updates air pollution data and status for air pollution status in China. This study provides valuable 9 year long-term reference to experimental and field studies in the related fields.

Iron-Promoted Catalytic Activity of Selenium Endowing the Aerobic Oxidative Cracking Reaction of Alkenes

Oxidative cracking of alkenes is a significant process in industry. In this work, it was found that catalyzed by Se/Fe via hybrid mechanisms, the carbon-carbon double bond in alkenes can break to produce carbonyls under mild conditions. Since O2 can be used as a partial oxidant, the employed H2O2 amount can be reduced (90 mol % vs 250 mol %) to avoid the peroxide residues, making the process even safer for operation.

Methyl jasmonate and selenium synergistically mitigative cadmium toxicity in hot pepper (Capsicum annuum L.) plants by improving antioxidase activities and reducing Cd accumulation

Methyl jasmonate (MeJA) or selenium (Se)-mediated response to cadmium (Cd) stress in plant has been widely reported, but the combined effects both on plant growth in response to Cd stress and the underlying mechanisms remain obscure. Here, we showed the combined effects of MeJA (2.5 μM) and Se (7 μM) on hot pepper growth under Cd stress (CdCl2, 5 μM). The results showed Cd suppressed the accumulation of total chlorophyll and carotenoid and reduced the photosynthesis, while it increased the content of endogenous signaling molecules, e.g. nitric oxide (NO) and hydrogen peroxide (H2O2), as well as Cd content in leaves. The combined application of MeJA and Se significantly decreased the malondialdehyde (MDA) accumulation and improved the activities of antioxidant enzymes (AOEs, e.g. SOD and CAT) and defense-related enzymes (DREs, POD and PAL). Additionally, the synergistic application of MeJA and Se also obviously improved photosynthesis in hot pepper plants under Cd stress compared with those treated with MeJA or Se respectively or not. Moreover, the treatment of MeJA associated with Se also effectively reduced the Cd accumulation in hot pepper leaves under Cd stress compared with the plants treated with MeJA or Se separately, which implied a potentially synergistic role of MeJA and Se in alleviating Cd toxicity in hot pepper plants. This study provides a theoretical reference for the further analysis of the molecular mechanism of MeJA and Se in jointly mediating the response to heavy metals in plants.

Conversion of 5-hydroxymethylfurfural to furan-2,5-dicarboxylic acid by a simple and metal-free catalytic system

A simple and metal-free catalytic system composed of NaOtBu/DMF and an O2 balloon efficiently converted 5-hydroxymethylfurfural (5-HMF) to furan-2,5-dicarboxylic acid with an 80.85% yield. 5-HMF analogues and various types of alcohols were also transformed to their corresponding acids in satisfactory to excellent yield by this catalytic system.

A review on adsorption characteristics and influencing mechanism of heavy metals in farmland soil

The accumulation of heavy metals in soil and crops is considered to be a severe environmental problem due to its various harmful effects on animals and plants. Soil adsorption is an essential characteristic of mud, which is the fundamental reason for soil to have a specific self-purification capacity and environmental capacity for heavy metals. The adsorption of heavy metals by soil reduces the uptake of these pollutants by crops, thereby limiting food contamination. Therefore, the adsorption of heavy metals in crop soils was taken as the primary research object. Based on the entire reading of the literature, the previous research results were compared and discussed from the four aspects of heterogeneity, physical and chemical properties, competitive adsorption, and external factors. The influencing mechanism of heavy metal adsorption characteristics in soil was reviewed. Finally, suggestions and prospects for future research on heavy metal adsorption were put forward.

Silver-catalyzed direct selanylation of indoles: synthesis and mechanistic insights

Herein we describe the Ag(i)-catalyzed direct selanylation of indoles with diorganoyl diselenides. The reaction gave 3-selanylindoles with high regioselectivity and also allowed direct access to 2-selanylindoles when the C3 position of the indole ring was blocked via a process similar to Plancher rearrangement. Experimental analyses and density functional theory calculations were carried out in order to picture the reaction mechanism. Among the pathways considered (via concerted metalation-deprotonation, Ag(iii), radical, and electrophilic aromatic substitution), our findings support a classic electrophilic aromatic substitution via Lewis adducts between Ag(i) and diorganoyl diselenides. The results also afforded new insights into the interactions between Ag(i) and diorganoyl diselenides.

Organoselenium functionalized SBA-15 as a new catalyst for the cyanide-free conversion of oximes to nitriles

BACKGROUND

Here we report a new selenium-based heterogeneous catalyst, which was prepared from the immobilization of diphenyl diselenide on amine-functionalized Santa Barbara Amorphous-15 (SBA-15). The catalyst characterization study has been confirmed by different analysis methods including Fourier transform infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA), energy-dispersive X-ray spectroscopy (EDX), X-ray diffraction patterns (XRD), field-emission scanning electron microscopy (FE-SEM), and Brunauer-Emmett-Teller (BET) surface area analysis.

RESULTS

The newly designed catalyst was successfully applied in the green dehydration reaction of oximes to corresponding nitriles in the presence of hydrogen peroxide/air. To demonstrate the role of the catalyst in this study, the model reaction was also carried out in the absence of the catalyst and a trace yield of the relevant product was achieved.

CONCLUSION

In this way, a series of nitrile derivatives were obtained with 72-96% yields, also, the catalyst could be separated easily and recycled for four consecutive runs with no obvious drop in catalytic activity.

Chemical Structure, Hypoglycemic Activity, and Mechanism of Action of Selenium Polysaccharides

Selenium polysaccharides (Se-polysaccharides) are one of important forms of organic Se, in which selenium (Se) and polysaccharides are joined by covalent bonds. In the present review, recent progress in chemical structure and hypoglycemic activity of Se-polysaccharides is summarized. In particular, the mechanism underlying hypoglycemic capacity of Se-polysaccharides is discussed, and the relationship between hypoglycemic activity and chemical structure is analyzed. Besides, strategies for further research into chemical structure and hypoglycemic activity of Se-polysaccharides are proposed. Hypoglycemic activity of Se-polysaccharides is closely related to their inhibitory effect on α-amylase and α-glucosidase, influence on insulin signal pathway especially IRS-PI3K-Akt signaling pathway, and protection capacity against oxidative stress.

Stereoselective Reduction of Alkynes: Synthesis of 4-Organoselenyl Quinolines

This study describes the reaction of 2-amino arylalkynyl ketones with organoselenolates to form (Z)-vinyl selenides, which lead to 4-organoselenyl quinolines via an intramolecular condensation. Using the optimized reaction conditions, the generality of this cyclization was studied with various arylalkynyl ketones and diorganyl diselenides. The study of the reaction mechanisms led to the isolation and identification of a vinyl selenide, which was the key intermediate for this cyclization. To expand the structural diversity and to demonstrate the applicability of the 4-organoselenyl quinolines prepared, we studied their application as substrates in the cleavage of the carbon-selenium bond using n-butyllithium followed by the capture of the lithium intermediate by electrophiles and Suzuki and Sonogashira cross-coupling reactions.

Synthesis of β-Arylseleno Sulfoximines: A Metal-Free Three-Component Reaction Mediated by Tetrabutylammonium Tribromide

A tetrabutylammonium tribromide-mediated three-component reaction of alkenes, diselenides, and sulfoximines has been established herein, providing direct and metal-free access to diverse β-arylseleno sulfoximine derivatives. This regioselective sulfoximido-selenization protocol proceeds efficiently under mild and ambient conditions with generally good yields. This strategy is featured by step and atom economy, practicability, a broad substrate scope, and gram-scale synthesis.

Organobase-catalyzed 1,1-diborylation of terminal alkynes under metal-free conditions

An organobase-catalyzed 1,1-diborylation of terminal alkynes from propargylic derivatives with bis(2,4-dimethylpentane-2,4-glycolato)diboron (B₂oct₂) is first reported, regioselectively providing 1,1-diborylalkene products with high efficiency. The catalytic pathway is well postulated on the basis of DFT calculations.

An organobase-catalyzed 1,1-diborylation of terminal alkynes from propargylic derivatives with B₂oct₂ is first reported, providing 1,1-diborylalkene products with high efficiency. The catalytic pathway is well postulated on the basis of DFT calculations.

Peroxide activation by selenium-doped graphite

Selenium-doped graphitic material has shown GPx-like activity and carried out epoxidation of various aromatic and aliphatic alkenes using H2O2, a green oxidant.

PhSe(O)OH/Al(NO3)3-Catalyzed selectivity controllable oxidation of sulphide owing to the synergistic effect of Se, Al3+ and nitrate

Catalyzed by PhSe(O)OH/Al(NO3)3, selective oxidation of sulphides to produce sulfoxides or sulphones could be achieved under mild conditions. The synergistic effect of Se, Al3+ and nitrate is the key factor for the reaction.

Highly crystalline K-intercalated Se/C: An easily accessible mesoporous material catalyzing the epoxidation of β-ionone

Highly crystalline K-intercalated Se/C was fabricated by calcining the commercially available methylselenized glucose with KBr being followed by the subsequent water washing. The corrosion of water to KBr led to...

Progresses in synthetic technology development for the production of L-lactide

L-Lactide is an intermediate for the industrial production of polylactic acid (PLA). The chemical and optical purities of lactide determine the quality of the prepared PLA. It is of great challenge to synthesize L-lactide efficiently with high chemical and optical purities under the conditions applicable for industrial production. With the national plastic reduction order issued, developing biodegradable materials such as PLA has gradually become a hot topic, and the production of upstream lactide is the key technique for the whole industrial chain. This mini-review aims to summarize typical works on the related synthetic technology development in recent years.

Catalytic Antioxidant Activity of Bis-Aniline-Derived Diselenides as GPx Mimics

Herein, we describe a simple and efficient route to access aniline-derived diselenides and evaluate their antioxidant/GPx-mimetic properties. The diselenides were obtained in good yields via ipso-substitution/reduction from the readily available 2-nitroaromatic halides (Cl, Br, I). These diselenides present GPx-mimetic properties, showing better antioxidant activity than the standard GPx-mimetic compounds, ebselen and diphenyl diselenide. DFT analysis demonstrated that the electronic properties of the substituents determine the charge delocalization and the partial charge on selenium, which correlate with the catalytic performances. The amino group concurs in the stabilization of the selenolate intermediate through a hydrogen bond with the selenium.

Preparation and catalytic behavior of antioxidant cassava starch with selenium active sites and hydrophobic microenvironments

The preparation of antioxidant starch with the activity of glutathione peroxidase (GPx) for scavenging free radicals can not only enrich the types of modified starch but also alternate native GPx to overcome its drawbacks.

Catalytic epoxidation of β-ionone with molecular oxygen using selenium-doped silica materials

Se-doped silica could catalyze the β-ionone epoxidation reaction. Interestingly, by doping with fluorine in the catalyst, the reaction selectivity was significantly enhanced. The metal-free process is suitable for pharmaceutical synthesis.

Me3SI-promoted chemoselective deacetylation: a general and mild protocol

A catalytic and practical approach for the selective removal of acetyl groups using various substrates bearing orthogonal moieties has been demonstrated under ambient conditions.