Electroreductively Induced Radicals for Organic Synthesis.

Organic electrochemistry has attracted tremendous interest within the novel sustainable methodologies that have not only reduced the undesired byproducts, but also utilized cleaner and renewable energy sources. Particularly, oxidative electrochemistry has gained major attention. On the contrary, reductive electrolysis remains an underexplored research direction. In this context, we discuss advances in transition-metal-free cathodically generated radicals for selective organic transformations since 2016. We highlight the electroreductive reaction of alkyl radicals, aryl radicals, acyl radicals, silyl radicals, fluorosulfonyl radicals and trifluoromethoxyl radicals.

New fluorescent probes based on supramolecular diastereomers for the detection of 2-nitrophenol.

A couple of new fluorescent probes, based on diethoxycarbonyl glycoluril, were synthesized and characterized by (1)H NMR, X-ray crystal structure. The probes were found to be relatively highly fluorescence with quantum yields of 0.20 and 0.18, respectively, at room temperature in THF solution. Both of the proposed probes were tested using different phenolic compounds, showing very high selectivity and sensitivity for 2-nitrophenol by forming a 1:1 complex in THF-MeOH (9:1, v/v). Additionally, the sensors could be used for the qualitative analysis of 2-nitrophenol in real water samples.

Diethyl 2-tert-butyl-4,11-dioxo-2,3-di-hydro-cis-1H,5H,10H-2,3a,4a,10a,11a-penta-azabenzo[f]indeno[2,1,7-ija]azulene-11b,11c-dicarboxyl-ate.

In the title mol-ecule, C(24)H(31)N(5)O(6), the two ethyl fragments are each disordered over two conformations [occupancy ratios 0.58 (13)/0.42 (13) and 0.56 (12)/0.44 (12)]. The crystal packing exhibits inter-molecular non-classical C-H⋯O hydrogen bonds and π-π inter-actions between benzene rings [centroid-centroid distances = 3.836 (5) Å].

[Hydrogen bis-(1,2,4-triazole)] 1,2,4-triazolium bis-(3-carb-oxy-4-hy-droxy-benzene-sulfonate) 1,2,4-triazole disolvate.

The title compound, C(2)H(4)N(3) (+)·[H(C(2)H(3)N(3))(2)](+)·2C(7)H(5)O(6)S(-)·2C(2)H(3)N(3), consists of two types of 1,2,4-triazole monocation, one protonated at the 2-site lying across a twofold axis and the other protonated at the 4-site with the H atom disordered over a center of symmetry, a 5-sulfosalicylate anion and a neutral 1,2,4-triazole mol-ecule. The component ions are linked into a three-dimensional network by a combination of N-H⋯O, N-H⋯N, O-H⋯O, O-H⋯N, C-H⋯O and C-H⋯N hydrogen bonds. In addition, benzene-benzene π-π inter-actions of 3.942 (2) Š[inter-planar spacing = 3.390 (2) Å] and C-O⋯π (3.331 Å) inter-actions are observed.

Template-free synthesis of BiVO4 nanostructures: II. Relationship between various microstructures for monoclinic BiVO4 and their photocatalytic activity for the degradation of rhodamine B under visible light.

The shape-controlled synthesis of nanostructured materials has opened up new possibilities to improve their physical and chemical properties. In this work, new types of monoclinic structured BiVO4 with complex morphologies, namely flowerlike, disclike, tubelike and platelike shapes, have been synthesized in a binary green solvent (water and ethanol) through controlling reaction conditions such as solvent, pH value, concentration of precursors and reaction temperature. The morphology of BiVO4 can transform from three-dimensional (3D) flowerlike superstructures and hexagonal-prismatic nanotubes to two-dimensional (2D) platelike and disclike structures. UV-vis absorption spectra show that all of the prepared nano- and microstructures can respond to visible light and the optical properties of BiVO4 samples are relevant to their structures. More importantly, the photocatalytic activities of various BiVO4 samples are strongly dependent on their morphology for the degradation of rhodamine B (RhB) under visible-light irradiation. The 2D (disclike and platelike) BiVO4 demonstrates better photocatalytic activity than 3D and bulk BiVO4. Among the nano- and microstructures, the nanoplate BiVO4 exhibit the highest photocatalytic activity for degradation of organic pollutants. Additionally, it is found that the different microstructure of BiVO4 leads to the different degradation route for organic compounds of RhB. The reasons for the differences in the photocatalytic behavior for these BiVO4 nanostructures are further discussed. The relationship between the microstructure and the photocatalytic activity for BiVO4 may give clues for the preparation of photocatalysts with high activity based on material morphology design. Moreover, the prepared 2D BiVO4 can be a good photocatalyst used in environmental pollution control.

Template-free synthesis of BiVO4 nanostructures: I. Nanotubes with hexagonal cross sections by oriented attachment and their photocatalytic property for water splitting under visible light.

Monoclinic structured BiVO(4) nanotubes have been selectively prepared by a template-free and surfactant-free solvothermal process in an ethanol-H(2)O mixed solvent. Interestingly, the nanotubes obtained at V(ethanol):V(water) = 3:1 have hexagonal cross sections with long lengths of approx. 1.2 microm, side lengths of approx. 200 nm and wall thicknesses of approx. 30 nm. A possible oriented attachment growth mechanism has been proposed based on the results of time-dependent experiments. Nanoplates were firstly formed by aggregation of primary nanocrystallites and then self-assembly converted to hexagonal-prismatic nanotubes via the corresponding oriented attachment mechanism. During this process, the presence of ethanol and the volume ratio of ethanol and water play important roles in the formation of the nanotubes with hexagonal cross sections. UV-vis spectroscopy was further employed to estimate the bandgap energy of the novel structure, which is larger (2.53 eV) than that for the bulk BiVO(4). The valence band edge position for the as-synthesized material was estimated to be 2.8 eV, which is positive enough for water oxidation. The photocatalytic activity for O(2) evolution from water splitting over the samples under visible light (lambda>420 nm) irradiation was investigated by using AgNO(3) as a sacrificial reagent. Experiment results indicate that the as-synthesized nanotubes exhibit higher photocatalytic activities for O(2) evolution than that of bulk BiVO(4), which is attributed to the special tubular structure morphology.

Adsorption of water-soluble dyes onto modified resin.

Adsorption behavior of five kinds of water-soluble dyes onto functionalized resin NKY has been dynamically and thermodynamically investigated. The results showed that the adsorption rates of dye K-GN, K-2BP, KN-R, AAB and 2G are all controlled by liquid film diffusion and particle diffusion. Equilibrium adsorption data can be well described by three-parameter equation. The first layer adsorption is the physical enhanced by chemical effect but multilayer adsorption is typically physical adsorption. Standard free energy change DeltaG(0) and standard entropy change DeltaS(0) indicate the adsorption of the dyes onto NKY can occur spontaneously.