Recent Advances in the Synthesis of Aromatic Azo Compounds.

Aromatic azo compounds have -N=N- double bonds as well as a larger π electron conjugation system, which endows aromatic azo compounds with wide applications in the fields of functional materials. The properties of aromatic azo compounds are closely related to the substituents on their aromatic rings. However, traditional synthesis methods, such as the coupling of diazo salts, have a significant limitation with respect to the structural design of aromatic azo compounds. Therefore, many scientists have devoted their efforts to developing new synthetic methods. Moreover, recent advances in the synthesis of aromatic azo compounds have led to improvements in the design and preparation of light-response materials at the molecular level. This review summarizes the important synthetic progress of aromatic azo compounds in recent years, with an emphasis on the pioneering contribution of functional nanomaterials to the field.

Urchin-like hollow SiO2@γ-MnO2 microparticles for the rapid degradation of organic dyes.

In this paper, using hollow silica microspheres as carriers, we developed a facile one-pot method for the preparation of hollow SiO2@MnO2 composite microparticles. Under a certain proportion of hollow silica microspheres and manganese salt, a novel kind of hollow urchin-like SiO2@γ-MnO2 microparticles was obtained. The structure and morphology of the composite microparticles were characterized by XRD, SEM and TEM. On this basis, using rhodamine B and methyl orange as model molecules, the oxidative degradation ability of the hollow SiO2@γ-MnO2 microparticles for organic dyes in water was investigated through UV-vis analysis technology. The urchin-like SiO2@γ-MnO2 microparticles showed excellent performance for the rapid oxidative degradation of organic dyes under acidic conditions. This study indicated that γ-MnO2 loaded on hollow materials can be used as an efficient tool for treating organic dye wastewater, and shows broad application prospects for solving environmental problems in the related industry.

Enhanced Catalytic Activity of Magnetic Bimetallic Ag-Au Nanoparticles Mediated by Surface Plasmon Resonance.

We firstly discover the enhanced catalytic activity of magnetic noble metal nanoparticles mediated by surface plasmon resonance. Under light irradiation with certain wavelength, the catalytic performance of magnetic noble metal nanoparticles shows changes with different degrees and directions that are associated with the surface plasmon resonance (SPR) of the noble metal. Moreover, the coupling of silver and gold allows the catalytic performance of magnetic bimetallic Ag-Au nanoparticles to show more positive response to surface plasmon resonance. The magnetic bimetallic Ag-Au nanoparticles show excellent catalytic performance toward the reduction reaction of aromatic nitro group, and corresponding rate constant of the catalytic reduction reaction increases about three times with light irradiation.

Copper(II)-Mediated Ring Opening/Alkynylation of Tertiary Cyclopropanols by Using Nonmodified Terminal Alkynes.

The copper(II)-mediated ring opening/alkynylation of cyclopropanol by employing inexpensive and commercially available terminal alkyne is developed. The reactions proceeded efficiently to afford synthetically useful alk-4-yn-1-ones in moderate to good yields with good functional group tolerance. Control experiments showed that the reaction presumably proceeds via the formation of intermediates of copper homoenolate and/or alkynylcopper species.

pH-Mediated Synthesis and Mechanistic Study of Homogeneous Magnetic Ag@Fe3O4 Nanoparticles.

In this paper, we report a novel kind of pH-mediated homogeneous magnetic Ag@Fe3O4 nanoparticles prepared by facile one-pot synthesis. The nanostructure and surface element composition along with magnetism of the as-synthesized hybrid nanoparticles can be easily adjusted by pH value in synthetic process. Furthermore, XRD and XPS detections indicated that the two components in the nanoparticles are both independent and certain synergistic. Compared with magnetic silver nanoparticles prepared by traditional multi-step methods, the homogeneous Ag@Fe3O4 nanoparticles showed excellent monodispersity and stability. Moreover, corresponding formation mechanism of the homogeneous hybrid magnetic nanoparticles was demonstrated in detail. Catalytic application of the homogeneous hybrid nanoparticles prepared under different pH values also verified rationality of the formation mechanism from side. This research provides a general strategy for constructing and large-scale preparing homogeneous magnetic hybrid metal nanoparticles.

Synthesis of carboxylated silicon phthalocyanine photosensitive microspheres with controllable etching.

Using a new kind of alkenyl silicon phthalocyanine, styrene (St) and methacrylic acid as monomers and potassium persulfate as an initiator, carboxylated silicon phthalocyanine photosensitive microspheres were synthesized by in-situ emulsion copolymerization. The structure and morphology of the microspheres were characterized by Fourier transform infrared spectroscopy (FT-IR)and scanning electron microscopy. Fluorescence spectrometer was used to characterize the optical property of the microspheres. The experimental results show that silicon phthalocyanine molecules with flexible unsaturated side chains have good compatibility with styrene. With the presence of carboxyl groups, the as-prepared photosensitive microspheres show high monodispersity and stability. On the basis of this, 9,10-diphenylanthracene (DPA) as singlet oxygen indicator was used to evaluate the photosensitivity of the microspheres. In addition, we report a novel phenomenon that the microspheres can be controllable etched by light irradiation with the presence of DPA in a specific solvent.

Selective Reduction of Nitro Group in Aryl Halides Catalyzed by Silver Nanoparticles Modified with ß-CD.

In this paper, we first report the selective reduction of nitro group in aryl halides catalyzed by silver nanoparticles modified with ß-CD. Taking advantage of hydrophobic lumen and donor-acceptor behavior of ß-CD, the halogenated alkyl groups on the aromatic ring can be enveloped in the inner cavity that thereby inhibits the reduction of the halogen. For validating the mechanism proposed by us, different silver nanoparticles were applied in parallel experiments. In our experiments, UV-vis spectra and NMR spectra were used to characterize the selectivity. This strategy represents an outstanding improvement on the synthesis of halogenated aromatic amines in comparison with the traditional route, and greatly expands the application of silver nanoparticles in catalytic field.

Gold Nanoparticles Prepared by ß-CD and Dispersion Behavior in Oil/Water Mixed System.

In this paper, we report a green and controllable synthetic method of gold nanoparticles (AuNPs) by directly ß-CD reduction under mild conditions. Analysis of UV-vis spectra, along with TEM was applied to study the effects of experimental parameters on morphologies of the gold nanoparticles. The corresponding formation mechanism of the nanoparticles was evaluated by redox potential. In particular, compared with the traditional method of sodium citrate or ascorbic reduction, this method can facilely realize multi-dimensional regulation. On this basis, we further studied the dispersion behavior of the as-prepared gold nanoparticles in oil/water mixed system that would provide a possible strategy for optical sensor.

Green Synthesis of Silver Nanoparticles Decorated by Fe3O4/GO with Enhanced Catalytic Activity.

We report a simple and green approach to synthesize stable water-dispersible silver nanoparticles decorated by magnetic Fe3O4 and graphene oxide (GO). These results of UV-Vis spectra, along with TEM and SEM indicated that the water-dispersible silver nanoparticles had cluster flat structure and retained the optical properties of the original silver particle. Combining the advantages of Fe3O4 and GO, the composite nanoparticles showed enhanced catalytic activity with good recycling utilization rate by magnetic separation.

Metal-Crown Ether-Porphyrin Decorated Gold Nanoparticles as High Sensitive Raman Ion Probe.

A kind of gold nanoparticles modified with metal crown ether porphyrin (GNPs-CP) was synthesized and characterized. The surface of the resulting gold particles was partially covered by metal crown ether porphyrin molecules through strong covalent Au-S bond. Based on the coupling effect of metal porphyrin and crown ether, the resulting composite gold nanoparticles can serve as a kind of ion probe. Raman and UV-Vis spectra were utilized to evaluate the ion recognition of the system, both of which changed dramatically when meeting metal ion corresponding to ligand of crown ether. Compared with UV-Vis spectra, Raman spectra of the composites are more sensitive and the limit of detection (LOD) can reach 1 × 10-8 g/mL. The study provides a candidate with higher sensitivity to replace current UV-Vis spectrum based evaluation tool for ion recognition.

A Facile Green Synthesis of Silver Nanoparticles Based on Poly-L-Lysine.

In this paper, we report a novel synthesis method for silver nanoparticles with facilely controllable morphology under mild conditions. The particles were synthesized by reducing silver nitrate in the presence of water soluble polymer of poly-L-Lysine (PLL) which was used as reducing agent and stabilizer. Experimental results revealed that size variation and overall formation mechanism of the resulting silver particles were mostly determined by the conformation of PLL which was in turn controlled by pH of solution and temperature. Due to biological activity and response ability of PLL to outer stimuli, the method provides a facile and controllable method for producing silver particles with different morphologies. We believe that the synthesis method will contribute to applications of the PLL and silver particles in biomaterials.

2-Methyl-3-nitro-benzonitrile.

The asymmetric unit of the title compound, C(8)H(6)N(2)O(2), contains two independent mol-ecules, the aromatic rings of which are oriented at a dihedral angle of 1.68 (3)°. Intra-molecular C-H⋯O hydrogen bonds result in the formation of two non-planar six-membered rings, which adopt envelope and twisted conformations. In the crystal structure, inter-molecular C-H⋯O hydrogen bonds link the mol-ecules. There are π-π contacts between the benzene rings [centroid-centroid distances = 3.752 (3) and 3.874 (3) Å].