Advances in the chemical synthesis of C-pyranosides/furanosides are summarized, covering the literature from 2000 to 2016. The majority of the methods take advantage of the construction of the glycosidic C-C bond. These C-glycosylation methods are categorized herein in terms of the glycosyl donor precursors, which are commonly used in O-glycoside synthesis and are easily accessible to nonspecialists. They include glycosyl halides, glycals, sugar acetates, sugar lactols, sugar lactones, 1,2-anhydro sugars, thioglycosides/sulfoxides/sulfones, selenoglycosides/telluroglycosides, methyl glycosides, and glycosyl imidates/phosphates. Mechanistically, C-glycosylation reactions can involve glycosyl electrophilic/cationic species, anionic species, radical species, or transition-metal complexes, which are discussed as subcategories under each type of sugar precursor. Moreover, intramolecular rearrangements, such as the Claisen rearrangement, Ramberg-Bäcklund rearrangement, and 1,2-Wittig rearrangement, which usually involve concerted pathways, constitute another category of C-glycosylations. An alternative to the C-glycosylations is the formation of pyranoside/furanoside rings after construction of the predetermined glycosidic C-C bonds, which might involve cyclization of acyclic precursors or D-A cycloadditions. Throughout, the stereoselectivity in the formation of the resultant C-glycosidic linkages is highlighted.

Nickel is an important ferromagnetic material. Anisotropic magnetic nanoparticles are expected to exhibit interesting magnetic properties.[1] Nickel one-dimensional (1D) nanostructures have thus attracted much attention recently because of their potential applications in magnetic sensors and memory devices.[2] Different Ni 1D nanostructures have been successfully synthesized by various methods. [3±5] Currently, the fabrication of Ni nanowires mainly depends on a template technique that involves electrochemical deposition or metal± organic chemical vapor deposition (CVD) of metals into the nanopores of template materials, such as anodic alumina (AAO) film [3] and carbon nanotubes.[6] However, little work on the preparation of Ni 1D nanostructures in aqueous solution has been reported to date. [7] Such a solution-phase approach may provide a more promising technique for preparing 1D nanostructures than conventional methods in terms of cost and potential for large-scale production.[8] Here we report a complex-surfactant-assisted hydrothermal reduction method to synthesize single-crystal Ni nanobelts with high yield. Ni nanobelts were generated by reducing a Ni II -tartrate complex in alkaline solution and in the presence of a suitable surfactant at relatively low temperature (110 C). These nanobelts had typical widths of 500±1000 nm, a thickness of onlỹ 15 nm, and lengths of up to 50 lm. This new type of nanostructure of a ferromagnetic metal should be explored in physical property studies and for interesting applications as a new kind of nanoblock.Practically, the present approach to the synthesis of Ni nanobelts is similar to the process for electroless Ni plating. [9] In our study, sodium tartrate (Na 2 C 4 H 4 O 6 ) was used as the complexing reagent to form a complex, Ni(C 4 H 2 O 6 ) 2± . The formation of Ni II complex sharply decreased the free Ni 2+ concentration in the solution, which resulted in a relatively slow rate of generation of Ni atoms. A slow reaction rate was favorable for separating the growth step from the nucleation step. For this reason, we selected a high concentration of both tartrate and alkali. Nevertheless, we found that adjusting the concentrations of tartrate and NaOH was not sufficient for the formation of 1D nanostructures. In this case, only spongelike Ni particles were produced. In the solution-phase synthesis of nanocrystals, kinetically controlling the nucleation and growth rate could conceivably modulate the size and shape of the final products.[10] Some recent work has suggested that the shape of the nanocrystals can be effectively modulated by adding chemical capping reagents to the synthetic systems. It is believed that the selective interaction of the capping molecules on a facet of the first-formed nanoparticles is the key to anisotropic growth of nanoparticles. [4,11] In this work, in order to achieve the desired Ni nanobelts, the anion surfactant sodium dodecyl benzenesulfonate (SDBS) was introduced to the synthesis system. We found that SDBS had a remarkable effect o...

This paper describes a simple complex-surfactant-assisted hydrothermal reduction approach to the facile synthesis of metal copper nanowires with average diameters of ∼85 nm and lengths of several tens of micrometers. These copper nanowires were formed through the reduction of the CuII−glycerol complexes (Cu(C3H6O3)) by phosphite (HPO3 2-) in the presence of surfactant sodium dodecyl benzenesulfonate (SDBS) at 120 °C. High-resolution transmission electron microscopy (HRTEM) and selected-area electron diffraction (SAED) indicate that the resulted nanowires had preferred [11̄0] growth direction. The formation mechanism for Cu nanowires had been properly proposed. Some influencing factors on the morphologies of the final products had also been discussed.

Ultralong Bi2S3 nanoribbons have been synthesized by a solvothermal process, using a mixture of aqueous NaOH solution and glycerol as the solvent. These nanoribbons (see Figure) are 50–300 nm wide, 20–80 nm thick, and up to several millimeters long, and the initial formation of the precursor polycrystalline NaBiS2 phase is crucial to their formation. The nucleation and growth process was interpreted as a solid–solution–solid transformation.

This article describes a surfactant-assisted approach to the size-controlled synthesis of uniform nanorods of trigonal tellurium (t-Te). These nanorods were grown from a colloidal dispersion of amorphous Te (a-Te) and t-Te nanoparticles at room temperature, which was first formed through the reduction of (NH4)2TeS4 by Na2SO3 in aqueous solution at 80 degrees C. Nuclei formed in the reduction process had a strong tendency to grow along the [001] direction due to the inherently anisotropic structure of t-Te. The formation of Te nanorods could be ascribed to the confined growth through the surfactant adsorbing on the surfaces of the growing Te particles. By employing various surfactants in the synthesis system, Te nanorods with well-controlled diameters and lengths could be reproducibly produced by this method. Both the diameters and lengths of nanorods decreased with the increase of the alkyl length and the polarity of the surfactants. Te nanorods could also be obtained in mixed surfactants, where the different surfactants were used to selectively control the growth rates of different crystal planes. We also observed that the as-synthesized nanorods with uniform size could be self-assembled into large-area smecticlike arrays.