An electrochemical sensor based on porous heterojunction hollow NiCo-LDH/Ti3C2Tx MXenes composites for the detection of quercetin in natural plants.

Cubic hollow-structured NiCo-LDH was synthesized using a solvothermal method. Subsequently, clay-like Ti3C2Tx MXenes were electrostatically self-assembled with NiCo layered double hydroxides (NiCo-LDH) to form composites featuring three-dimensional porous heterostructures. The composites were characterized using SEM, TEM, XRD, XPS, and FT-IR spectroscopy. Ti3C2Tx MXenes exhibit excellent electrical conductivity and hydrophilicity, providing abundant binding sites for NiCo-LDH, thereby promoting an increase in ion diffusion channels. The formation of three-dimensional porous heterostructural composites enhances charge transport, significantly improving sensor sensitivity and response speed. Consequently, the sensor demonstrates excellent electrochemical detection capability for quercetin (Qu), with a detection range of 0.1-20 µM and a detection limit of 23 nM. Additionally, it has been applied to the detection of Qu in natural plants such as onion, golden cypress, and chrysanthemum. The recovery ranged from 97.6 to 102.28%.

A novel electrochemical sensor for detection of luteolin in food based on 3D networked electrically interconnected SiO2@GO/MXene composite.

Luteolin (Lu), a compound with various biochemical and pharmacological activities beneficial to human health, has attracted researchers' attention. This study proposes an efficient and scalable method using ultrasound to intercalate graphene oxide (GO)-coated silica spheres (SiO2) into MXenes, resulting in a 3D conductive interconnected structural composite material. Characterization of the composite material was conducted using SEM, TEM, XRD, XPS, and Raman spectroscopy. MXenes exhibit excellent electrical conductivity, and the SiO2@GO surface with abundant hydroxyl and silanol groups provides high-binding active sites that facilitate Lu molecule enrichment. The formation of the 3D conductive interconnected structural composites enhances charge transport, significantly improving sensor sensitivity. Consequently, the sensor demonstrates excellent detection capabilities (detection range 0.03-7000 nM, detection limit 12 pM). Furthermore, the sensor can be applied to quantitative determination of Lu in real samples, including chrysanthemums, Jiaduobao, honeysuckle, purple perilla, and peanut shells, achieving recoveries between 98.2 and 104.7%.

An Efficient Metal-Free Oxidative Esterification and Amination of Benzyl C-H Bond.

An esterification and amination of benzylic C-H bonds was developed by using 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) under metal- and iodide-free conditions. Both carboxylic acids and amines could be used as ideal coupling partners for the oxidative coupling reactions with various diarylmethanes. A close to equal amount of coupling reagents was enough to afford the product in good to high yields.

Copper-Catalyzed Redox Coupling of Nitroarenes with Sodium Sulfinates.

A simple copper-catalyzed redox coupling of sodium sulfinates and nitroarenes is described. In this process, abundant and stable nitroarenes serve as both the nitrogen sources and oxidants, and sodium sulfinates act as both reactants and reductants. A variety of aromatic sulfonamides were obtained in moderate to good yields with broad substrate scope. No external additive is employed for this kind of transformation.

Iron-catalyzed tetrasubstituted alkene formation from alkynes and sodium sulfinates.

An iron-catalyzed sulfenylation and arylation of alkynes with aryl sulfinic acid sodium salts is described. Various aromatic sodium sulfinates acted both as aryl and sulfenylation reagents, affording tetrasubstituted alkenes in one pot with good yields.

Palladium-catalyzed direct arylation of indoles with cyclohexanones.

A novel palladium catalyzed approach to 3-arylindoles was developed from indoles and cyclohexanones. Various cyclohexanones acted as aryl sources via an alkylation and dehydrogenation sequence using molecular oxygen as the hydrogen acceptor. This method showed good regioselectivity and afforded 3-arylindoles as the sole products.

Iron-catalyzed one-pot 2,3-diarylquinazolinone formation from 2-nitrobenzamides and alcohols.

A novel approach for the synthesis of 2,3-diarylquinazolinones using iron as catalyst is described. Various 2-nitro-N-arylbenzamides reacted with benzylic alcohols to selectively give the corresponding products in the absence of external oxidant or reductant.

Palladium-catalyzed desulfitative hydroarylation of alkynes with sodium sulfinates.

A palladium-catalyzed desulfitative hydroarylation of alkynes with aryl sulfinic acid sodium salts is described. The reaction showed good regio- and stereoselectivity, and afforded the hydroarylation products in good yields. Various functional groups were well tolerated under the optimized reaction conditions.

Palladium-catalyzed one-pot diarylamine formation from nitroarenes and cyclohexanones.

The first palladium-catalyzed diarylamine formation from nitroarenes and cyclohexanone derivatives using borrowed hydrogen is described. Various diarylamines were selectively obtained in good to excellent yields. The reaction tolerated a wide range of functionalities. The nitro reduction, cyclohexanone dehydrogenation, and imine formation and reduction were realized in a cascade without an external reducing reagent and oxidant.

Palladium-catalyzed desulfitative C-H arylation of azoles with sodium sulfinates.

A palladium-catalyzed desulfitative C-H arylation of azoles with sodium sulfinates using Cu(OAc)(2)·H(2)O as oxidant has been discovered. The reaction proceeded well for a range of different substrates under oxidative conditions. A series of aryl-substituted azoles have been synthesized in moderate to good yields.