A novel nickel(II) naringenin-oxime complex was designed, synthesized and characterized. Therein, the nickel(II) naringenin oxime complex as an efficient catalyst was used in Mizoroki–Heck coupling reactions of aryl halides containing electron-rich and electron-deficient substituents with styrene, methyl acrylate and divinylbenzene (DVB), respectively. The reaction proceeded efficiently under alkaline conditions in the presence of 0.30 mol% of the Ni(II) naringenin oxime complexand N2H4·H2O as the reductant in EtOH at 80 °C, and 32 alkene products were afforded in moderate to excellent yields, containing four new olefins. The new catalytic system not only provided an inexpensive and efficient process with greener conditions, but also broadened the reaction scope.

A novel nickel(II) naringenin-oxime complex was designed, synthesized and characterized. Therein, the nickel(II) naringenin oxime complex as an efficient catalyst was used in Mizoroki–Heck coupling reactions of aryl halides containing electron-rich and electron-deficient substituents with styrene, methyl acrylate and divinylbenzene (DVB), respectively. The reaction proceeded efficiently under alkaline conditions in the presence of 0.30 mol% of the Ni(II) naringenin oxime complexand N2H4·H2O as the reductant in EtOH at 80 °C, and 32 alkene products were afforded in moderate to excellent yields, containing four new olefins. The new catalytic system not only provided an inexpensive and efficient process with greener conditions, but also broadened the reaction scope.

A novel synthetic protocol for the construction of eight-membered heterocycles by intramolecular palladium-catalyzed ortho C–H activation/C–C cyclization was proposed. With protosappanin A as the lead compound, 25 derivatives of 8-azaprotosappanin A were prepared in good yields by this protocol. Besides, a plausible reaction mechanism of the intramolecular cyclization was proposed. This strategy could be widely used in the synthesis of some natural products and drugs with large heterocycles due to the fast reaction rate and the mild conditions. In vitro antimicrobial activities of the synthesized compounds were assessed against the strains of Gram-positive bacteria and linezolid and ciprofloxacin were selected as the standard drugs. Some of the synthesized compounds were found to have excellent antibacterial activities.

A series of N,O-bidentate ligands were synthesized using the Vilsmeier–Haack reaction and oximation. 2,5-Dihydroxyterephthalaldehyde dioxime (L8) as an efficient N,O-symmetrical bidentate ligand was prepared from hydroquinone. It was studied as a high activity ligand for palladium-catalyzed Suzuki–Miyaura cross-coupling reactions of aryl chlorides with arylboronic acids under mild conditions. The coupling reactions were performed in the presence of PdCl2 as the catalyst, L8 as the ligand, Na2CO3 as the base, PEG-400 as the PTC and in ethanol/water (1 : 1) as an environmentally benign solvent at 85 °C. Plentiful biaryls were obtained by the optimized reaction with good yields at a low palladium loading of 0.20 mol%.

A series of N,O-bidentate ligands were synthesized using the Vilsmeier–Haack reaction and oximation. 2,5-Dihydroxyterephthalaldehyde dioxime (L8) as an efficient N,O-symmetrical bidentate ligand was prepared from hydroquinone. It was studied as a high activity ligand for palladium-catalyzed Suzuki–Miyaura cross-coupling reactions of aryl chlorides with arylboronic acids under mild conditions. The coupling reactions were performed in the presence of PdCl2 as the catalyst, L8 as the ligand, Na2CO3 as the base, PEG-400 as the PTC and in ethanol/water (1 : 1) as an environmentally benign solvent at 85 °C. Plentiful biaryls were obtained by the optimized reaction with good yields at a low palladium loading of 0.20 mol%.

•Ten new compounds with Indolo[2,3-a]carbazole as backbone was designed and synthesized by Symmetric/Asymmetric modification.•The symmetric substituted indolo[2,3-a]carbazole derivatives (6a-e) are more suitable for application in blue emitters for OLEDs.•The introduction of a more electronegative group is good to improve the energy gaps.•Compounds 6d and 6e are the most potential for application in hole-transport and host materials.A series of new symmetric/asymmetric aryl-substituted indolo[2,3-a]carbazole derivatives were designed and synthesized. The thermal stability, photophysical properties and electrochemical properties of these compounds were characterized by thermal analysis, UV absorption spectra, photoluminescence (PL) spectrometer, quantum calculation texting and cyclic voltammetric (CV) measurements. Compared with these compounds, symmetric substituted indolo[2,3-a] carbazole derivatives (6a-e) exhibit good properties as Luminescent materials. The compounds (6a-e) showed high thermal stability with thermal decomposition temperatures at 5% weight loss in a range of 312–370 °C. In the solution and the solid states, these compounds exhibited stable blue light emission. The optical band gaps of compounds 6a-e in CH2Cl2 solution were in a range of 3.09–3.32 eV. The wide energy gaps are helpful to electronic transfers and transports. The introduction of a more electronegative –F or -CF3 group at the meta or para-position of the phenyl rings in the compounds 6d and 6e were good for improving the energy gaps. Compared with other compounds, compounds 6d and 6e are more potential for application in blue OLEDs.

AbstractA protocol for the Cu(TFA)2-catalyzed (TFA=trifluoroacetic acid) picolinamido-directed C8−H cyanation of naphthalene derivatives with benzoyl cyanide as the cyano source has been developed. A series of 8-cyano-1-(picolinamido)naphthalene derivatives were efficiently obtained in moderate to good yields by using this method. We prepared a total of 22 products, 10 of which have not previously been reported. Benzoyl cyanide was originally employed for the C(sp2)−H cyanation of arenes. The picolinamide moiety served a critical role as the directing group in this cyanation reaction of naphthalenes.

•ZnO nanoparticles supported on reduced graphene oxide were prepared.•ZnO/RGO as catalyst was applied to the Claisen-Schmidt condensation.•A new catalytic system was developed under microwave conditions.•ZnO/RGO could be recycled without obvious losses of catalytic activity.ZnO nanoparticles supported on reduced graphene oxide (ZnO/RGO) were prepared by the hydrothermal method and characterized by TEM, XPS, XRD, and Raman spectroscopy. As a green catalyst, ZnO/RGO was applied to the Claisen-Schmidt condensation reaction of aryl aldehydes and aryl ketones under microwave irradiation. Therein, chalcone products could be efficiently synthesized and easily separated from the heterogeneous catalysis system. The catalyst could be recycled four times without significant loss of catalytic activity.Download high-res image (169KB)Download full-size image

•A series of novel indolo[3,2-b]indole derivatives were designed and synthesized.•All compounds exhibited high thermal stability (Td = 302–362 °C).•These new compounds exhibited good blue fluorescent properties both in dilute solutions and solid films.•All the target compounds showed the potential to be used as blue fluorescent materials.A series of novel indolo[3,2-b]indole derivatives as blue-light-emitting materials were designed and synthesized by Pd (Ⅱ) catalyzed Suzuki coupling reaction in good yields. The thermal, photophysical, electrochemical properties of the derivatives were investigated and compared by introducing different terminal aromatic units into the target compounds. The results indicated that these new compounds exhibited high thermal stabilities, good solubility, stably blue fluorescent properties and good electronic transmission abilities. All the target compounds showed the potential to be used as blue fluorescent materials.

A sustainable and efficient catalyst for converting carbohydrates to a renewable platform chemical 5-hydroxymethylfurfural (HMF) is the goal in the study of biomass recycling. Reduced graphene oxide-supported tungsten trioxide (WO3/RGO) as an acidic catalyst was synthesized through a one-step hydrothermal method, characterized via TEM, XPS, XRD and Raman spectroscopy and applied to the conversion of fructose to HMF. The WO3/RGO catalyst showed a highly efficient catalytic activity, and the yield of HMF could reach up to 84.2% with complete conversion of fructose. The catalyst could be reused five times with a slight decrease in activity. Further study indicated that WO3/RGO could also catalyze the conversion of cellulose, glucose and sucrose to HMF.

A total synthesis method for protosappanin A, which is a complex natural product with many biological activities, was developed with 6 linear steps. Dibenzo[b,d]oxepinones as the key intermediates of the synthetic route were prepared by a palladium-catalyzed ortho C–H activation/C–C cyclization under microwave irradiation. 25 derivatives of protosappanin A were obtained.

A mild, practical and efficient palladium-catalyzed decarboxylative ortho-aroylation of N-acetyl-1,2,3,4-tetrahydroquinolines with α-oxoarylacetic acids via C–H bond activation is described. This protocol provides efficient access to a series of C8-aroyl terahydroquinolines.

As an outstanding mesh catalyst support, reduced graphene oxide (RGO) has attracted enormous attention in recent years. Cu nanoparticles-RGO (Cu NPs@RGO) as a green catalyst was prepared through a green reduction method by ascorbic acid in N-methyl-2-pyrrolidone. The structure of prepared Cu NPs@RGO was characterized. The catalytic activity of Cu NPs@RGO was estimated. A green and efficient method for synthesizing symmetrical biaryl compounds was developed by Cu NPs@RGO-catalyzed Ullmann homocoupling of aryl halides or arylboronic acids in ionic liquids under microwave (MW) irradiation. The catalytic system could be recycled five times with slight loss of activity. Through this method, nine kinds of biaryls were prepared by homocoupling reaction of the corresponding aryl iodides, aryl bromides, aryl chlorides and aryl boronic acids in moderate to good yields.

A series of five β-diketone erbium complexes with various azacyclo-auxiliary ligands, namely, Er(Hbta)3(H2O)2 (1), Er(Hbta)3(bpy) (2), Er(Hbta)3(phen) (3), Er(Hbta)3(dpq) (4) and Er(Hbta)3(dppz) (5) (Hbta = benzoyltrifluoroacetone, bpy = 2,2′-bipyridine, phen = 1,10-phenanthroline, dpq = pyrazino[2,3-f][1,10]phenanthroline, dppz = dipyrido[3,2-a:2′,3′-c]phenazine) have been isolated and characterized by X-ray crystallographic analysis. Near-infrared luminescence analysis reveals that all complexes 1–5 exhibit strong NIR luminescence of Er(III) ions around 1535 nm with the highest lifetime of 4.532 μs, quantum yield of 3.24 × 10−4 and broadband emission around 1.5 μm for complex 5, in which the azacyclo-auxiliary ligand absorbs and transfers the energy leading to complete quenching of the ligand-associated visible emission. The energy transfer processes among benzoyltrifluoroacetone, the Er(III) ion and the auxiliary ligands in complexes 1–5 have been investigated.

A series of three luminescent single molecule magnets of β-diketone mononuclear dysprosium complexes, namely, Dy(tfa)3(H2O)2·Me2CO (1), Dy(tfa)3(bpy) (2) and Dy(tfa)3(phen) (3) (tfa = trifluoroacetylacetonate, bpy = 2,2′-bipyridine, phen = 1,10-phenanthroline, C3H6O = Me2CO) have been isolated. Single-crystal X-ray analysis shows all the central Dy(III) ions are eight-coordinated adopting the coordination geometries of the distorted dodecahedron, bicapped trigonal prism and square antiprism for complexes 1–3, respectively. Magnetic analyses exhibit slow magnetic relaxation with the barrier heights (Ueff/kB) of 41 K, 33 K and 55 K for complexes 1–3, respectively. Photo-luminescent analysis reveal that complexes 1–3 exhibit the typical yellow luminescence of Dy(III) ions. The correlation between the structure and physical properties has been investigated.

A series of novel butterfly-shaped aryl-substituted indolo[2,3-a]carbazole derivatives have been synthesized by Suzuki–Miyaura coupling reaction as fluorescent materials. Their properties were studied by the combination of experimental and theoretical methods. These new compounds exhibited blue light emission both in dilute solutions and solid films. The compounds also exhibited good thermal stabilities with decomposition temperatures in the range of 316–396 °C. And via density functional theory (DFT) calculations, they are proved to have good electronic transmission ability.

A total synthesis method for protosappanin A, which is a complex natural product with many biological activities, was developed with 6 linear steps. Dibenzo[b,d]oxepinones as the key intermediates of the synthetic route were prepared by a palladium-catalyzed ortho C–H activation/C–C cyclization under microwave irradiation. 25 derivatives of protosappanin A were obtained.

A novel synthetic protocol for the construction of eight-membered heterocycles by intramolecular palladium-catalyzed ortho C–H activation/C–C cyclization was proposed. With protosappanin A as the lead compound, 25 derivatives of 8-azaprotosappanin A were prepared in good yields by this protocol. Besides, a plausible reaction mechanism of the intramolecular cyclization was proposed. This strategy could be widely used in the synthesis of some natural products and drugs with large heterocycles due to the fast reaction rate and the mild conditions. In vitro antimicrobial activities of the synthesized compounds were assessed against the strains of Gram-positive bacteria and linezolid and ciprofloxacin were selected as the standard drugs. Some of the synthesized compounds were found to have excellent antibacterial activities.