Latest ArticlesTo discover novel fluorophores of solution and solid dual-state emission (DSE) materials, unique V-shape furo[2, 3-b]furans have been designed and synthesized by a one-pot method for the first time and their photoluminescent properties have been explored in benzene, THF, DMF and DMSO, as well as in the solid state. As the best example, 2, 5-bis(4-(9H-carbazol-9-yl)phenyl)-6a-amino-3a, 6a-dihydrofuro[2, 3-b] furan-3, 3a, 4-tricarbonitrile (3g) exhibited solution and solid DSE properties in THF, benzene, and in the solid state with quantum yields of 55%, 92%, and 45%, respectively.
The cheap and easily available sodium dithionite and thiourea dioxide have been used as the source of sulfonyl group in the synthesis of sulfones and sulfonamides recently. Compared with other methods for the sulfonylation reactions, the strategies using sodium dithionite or thiourea dioxide provide an alternative and complementary route to diverse sulfonyl compounds. During the reaction process, sulfur dioxide anion radical is the key intermediate, which is usually generated from a single electron transfer under suitable conditions. The advantages using sodium dithionite or thiourea dioxide in the sulfonylation reactions include mild conditions and broad substrate scope with excellent functional group compatibility. Further applications by using sodium dithionite and thiourea dioxide in organic transformations will be anticipated.
Since graphene-based materials have shown great potential in many fields, it is important to explore ultrafast and high-efficient methods to synthesize reduced graphene oxide (rGO) using inexpensive reducing agents under mild conditions. Here, we reported a novel method for the ultrafast chemical reduction of graphene oxide (GO) at room temperature using sodium borohydride (NaBH4), sodium molybdate (Na2MoO4) and hydrochloric acid (HCl). The reduction was carried out within 2 min. A series of characterization results revealed that the obtained reduced graphene oxide has higher reduction degree than that synthesized by NaBH4 alone at high temperature. Moreover, rGO electrode based on the present reducing method exhibited a superior specific capacitance of 139.8 F/g at a current density of 1 A/g, indicating that it can be used as electrode materials for supercapacitors.
A Rh(Ⅰ)-catalyzed highly regio- and enantioselective allylic alkylation of Meldrum acid with racemic allylic substrates bearing alkyl groups has been developed. The applying of chiral bisoxazopinephosphine ligand is essential for the high yields and selectivities. This method provides a rapid access to various chiral β-alkyl-λ, δ-unsaturated carboxylic acids and their derivatives.
S-Monofluoromethyl phosphorothioates represent an important class of organofluorine compounds and are reported here for the first time. A series of S-monofluoromethyl phosphorothioates are conveniently synthesized from different PV-H compounds and PhSO2SCH2F under mild conditions. The method is compatible with common functional groups and provides potential opportunities to synthesize new bioactive molecules for medicinal chemistry.
Transition metal phosphide (TMP) based electrocatalysts possessing special crystal and electronic structures attract broad attention in the field of electrocatalysis. Immense effort is made to optimize TMP catalysts aiming to satisfy the electrochemical catalysis performance. In this work, an environmentally friendly in situ green phosphating strategy and spatial limiting effect of the RuCo precursor is employed to fabricate the ruthenium nanoclusters anchored on cobalt phosphide hollow microspheres (Ru NCs/Co2P HMs). The obtained Ru NCs/Co2P HMs electrocatalysts exhibit high hydrogen evolution reaction (HER) activity at wide pH ranges, which require an overpotential of 77 mV to achieve the current density of 10 mA/cm2 in 0.5 mol/L H2SO4 and 118 mV in 1.0 mol/L KOH. Besides, the multifunctional Ru NCs/Co2P HMs exhibit good oxygen evolution reaction (OER) activity with an overpotential of 197 mV to reach the current density of 10 mA/cm2 in 0.5 mol/L H2SO4, which is below that of the commercial RuO2 electrocatalyst (248 mV). A two-electrode electrolyzer is assembled as well, in acid electrolyte, it achieves a current density of 10 mA/cm2 at a voltage of 1.53 V, which is superior to that of the benchmark of precious metal-based electrolyzer (1.58 V).
Reported herein is the first example of heterogeneous palladium catalyzed C(sp3)-H bonds arylation by a transient-ligand-directed strategy. Using supported palladium (metallic state) nanopariticles as catalyst, a wide range of aryl iodides undergo the coupling with various o-methylbenzaldehyde derivatives to assemble a library of highly selective and functionalized o-benzylbenzaldehydes. The stability of the catalyst was easily recovered four runs without significant loss of activity. The XPS analysis of the catalyst before and after reaction indicated that the reaction might be carried out by a catalytic cycle starting with Pd0.
Multi-bond network (MBN) hydrogels contain hierarchical dynamic bonds with different bond association energy as energy dissipation units, enabling super-tough mechanical properties. In this work, we copolymerize a protonated 2-ureido-4[1H]-pyrimidone (UPy)-contained monomer with acrylic acid in HCl solution. After removing excess HCl, UPy motifs are deprotonated and from dimers, thus generating an UPy-contained MBN hydrogel. The obtained MBN hydrogels (75 wt% water content) exhibit super-tough mechanical properties (0.39 MPa to 2.51 MPa tensile strength), with tremendous amount of energy (1.68 MJ/m3 to 11.1 MJ/m3) dissipated by the dissociation of UPy dimers. The introduction of ionic bonds can further improve the mechanical properties. Moreover, owing to their dynamic nature, both UPy dimers and ionic bonds can re-associate after being dissociated, resulting in excellent self-recovery ability (around 90% recovery efficiency within only 1 h). The excellent self-recovery ability mainly originates from the re-association of UPy dimers based on the high dimerization constant of UPy motifs.
An intramolecular dehydrogenative homo- and hetero-coupling of phenols has been successfully developed for quick preparation of enantiopure axial diphenols under mild Cu(Ⅱ)-mediated conditions, using ((4S, 5S)-2,2-dimethyl-1,3-dioxolane-4,5-diyl)dimethanol as the chiral auxiliary. The commercially available (R)-α-methylbenzylamine was identified as the best amine ligand for Cu(Ⅱ) in the reactions. A variety of homo/hetero bis-dihydroxylbenzoate substrates were examined, affording the corresponding axially chiral diphenols with satisfactory to excellent diastereomeric ratios, and a representative scalable preparation was also attempted. A formal synthesis of natural product (+)-deoxyschizandrin has been achieved in this work using one axially chiral diphenol as the synthetic intermediate.
A palladium-catalyzed [4 + 1] cycloaddition of prop-2-yn-1-ones with double isocyanides is developed herein. The transformation worked well to produce a series of 2-amino-4-cyanofurans with high efficiency and a broad reaction scope. Based on mechanism studies, it is believed that the palladium-catalyzed [4 + 1] imidoylative cycloaddition of prop-2-yn-1-ones was concerted. Treated with aryl amine and H2O, the [4 + 1] cycloaddition of prop-2-yn-1-ones with double isocyanides provided 2-amino-4-amidylpyrroles efficiently.