Latest ArticlesTo overcome the shortcomings of single component carrier supported platinum (Pt)-based catalysts, herein, we demonstrate the fabrication of alumina combined mesoporous carbon to prepare a series of alumina-carbon composites and their corresponding Pt-based catalysts. The alumina-carbon composites Al@PhFC are synthesized by using phloroglucinol-formaldehyde resin as carbon source and aluminum acetylacetone as the aluminum source. Further, the effect of alumina content on the properties of the composites is investigated. The composites and catalysts are characterized by using XRD, XPS, N2 sorption, and TEM. The Pt/Al@PhFC-1.8 composite with appropriate amounts of alumina, pore diameter, and moderate Pt nanoparticle size, resulted in 99.5% of conversion efficiency and 77.4% of optical selectivity in the asymmetric hydrogenation of ethyl 2-oxo-4-phenylbutanoate (EOPB). Interestingly, this composite can be used more than 20 times without a significant decrease in its performance.
Direct C(sp3)-H functionalization of N-unprotected aliphatic amines represents one of the most efficient and straightforward strategies for amine synthesis. Despite some recent progress in this field, the NH2-directed γ-C(sp3)-H arylation of primary aliphatic amines except α-amino esters remained an unmet challenge. In this report, we established a simple and efficient method for site-selective C(sp3)-H arylation of primary aliphatic amines by aryl iodides. In the presence of only 5 mol% Pd(OAc)2, a wide range of aliphatic amines including O-benzyl and O-silyl amino alcohols were arylated at γ-or δ-positions by aryl iodides containing a broad scope of functional groups. The synthetic application of this method had also been demonstrated by large-scale synthesis, the synthesis of a fingolimod analogue, and the conjugation with natural D-menthol and fluorescent 1, 8-naphthalimide.
The copper-catalyzed directed dearomatization of indoles with the assistance of directing groups has been developed for the synthesis of 2, 3-diazido indolines with good yields and excellent diastereoselectivities in aqueous solution. The resultant 2, 3-diazides can be smoothly converted to other functional groups, including vicinal diamines, triazoles and benzotriazoles, in a single step.
The three-component reaction of triphenylphosphine, dimethyl hex-2-en-4-ynedioate and arylidene N, N'-dimethylbarbituric acids in dry methylene dichloride at room temperature afforded trans-1, 3-disubstituted 7, 9-diazaspiro[4.5]dec-1-enes in good yields and with high diastereoselectivity. However, the similar three-component reaction with arylidene Meldrum acids resulted in a mixtures of cis/trans-1, 2-disubstituted 7, 9-dioxaspiro[4.5]dec-1-enes. Additionally, the three-component reaction of triphenylphosphine, dimethyl but-2-ynedioate and arylidene Meldrum acids gave polysubstituted 5-(triphenyl-λ5-phosphanylidene)cyclopenta-1, 3-dienes. A plausible reaction mechanism was proposed for the formation of various products with different regioselectivity and diastereoselectivity.
The limited knowledge on low-coordinate zero-valent transition-metal species has intrigued great synthetic efforts in developing ligand sets for their stabilization. While the combined ligand set of N-heterocyclic carbene (NHC) with vinylsilanes was the only known ligand system amenable to the stabilization of three-coordinate formal zero-valent cobalt, iron, and manganese complexes, the exploration on other ligands has proved that the ligand set of NHCs with styrene is equally effective in stabilizing three-coordinate formal zero-valent metal complexes in the form of (NHC)M(η2-CH2CHPh)2 (NHC=IPr, IMes; M=Co, Fe, Mn). These styrene complexes can be prepared by the one-pot reactions of MCl2 with styrene, NHC and KC8, and have been characterized by various spectroscopic methods. Preliminary reactivity study indicated that the interaction of[(IMes)Fe(η2-CH2CHPh)2] with DippN3 produces the iron(Ⅳ) bisimido complex[(IMes)Fe(NDipp)2] and styrene, which hints at the utility of these zero-valent metal styene complexes as synthons of the mono-coordinate species (NHC)M(0).
MXenes have emerged as versatile 2D materials that are already gaining paramount attention in the areas of energy, catalyst, electromagnetic shielding, and sensors. The unique surface chemistry, graphene-like morphology, high hydrophilicity, metal-like conductivity with redox capability identifies MXenes, as an ideal material for surface-related applications. This short review summarizes the most recent reports that discuss the potential application of MXenes and their hybrids as a transducer material for advanced sensors. Based on the nature of transducing signals, the discussion is categorized into three sections, which include electrochemical (bio) sensors, gas sensors, and finally, electro-chemiluminescence & fluorescent sensors. The review provides a concise summary of all the analytical merits obtained subsequent to the use of MXenes, followed by endeavors that have been made to accentuate the future perspective of MXenes in sensor devices.
MXenes, the new family of two-dimensional (2D) transition metal carbides/nitrides, can serve as the substrate materials for the catalysts due to the large specific surface area, tunable electronic structures and thermal stability. The first 2D layered MXene, Ti3C2, was successfully obtained by selective etching of the A element from the MAX phases using hydrofluoric acid (HF) at room temperature in 2011. In this review, we summarize the preparation, structure of MXenes and discuss the recent progress in potential application of MXenes in catalysis, mainly in CO oxidation and oxygen reduction reaction (ORR), from the views of both experimental and theoretical investigations. The outlook of the major challenges and future directions on research of MXenes is also included.
Transition metal carbide, carbonitride and nitride MXenes, as the emerging two-dimensional (2D) nanomaterials, have aroused burgeoning research interest in a broad range of applications ranging from energy conversion to biomedicines attributing to their distinctive planar nanostructure, physiochemical properties and biological effects. They are featured with fascinating electronic, optical, magnetic, mechanical and thermal properties, which exert significant roles in biomedical applications of 2D MXenes. In this review, we briefly summarize the recent research progress of 2D MXenes and highlight their intrinsic chemistry in theranostic nanomedicines, focusing on the synthetic chemistry for MXenes construction, surface chemistry for surface engineering, physiochemical property for theranostic application and biological chemistry for biosafety evaluation. Furthermore, based on the current achievements on MXenes, their potential research direction, critical challenges and future development in biomedicine are also discussed. It is highly expected that 2D MXene-based nanosystems would have a broad application prospect in theranostic biomedicine provided the current facing critical issues and challenges are adequately solved.
The development of two-dimensional hybrid nanomaterial derived from MXenes as high performance electrode material is the key component for the advanced energy storage and conversion systems. In the past decades, MXene derived nanomaterials have attracted greatly interest in scientific activity and potential applications because of their unique synergistic properties such as high thermal stability, excellent electrical conductivity, large surface area, easy to handle and outstanding electro and photo chemical properties. This review is focused on the synthesis of hybrid nanomaterials from MXene (Ti3C2Tx) for renewable energy conversion and storage application including hydrogen evolution reaction, supercapacitor, lithium-ion batteries and photocatalysis. Finally, we also summarized the prospect and opportunities of novel two-dimensional hybrid nanomaterials derived MXene (Ti3C2Tx) for futuristic sustainable energy technology
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