In the present Communication, a completely "green" synthetic method for producing silver nanoparticles is introduced. The process is simple, environmentally benign, and quite efficient. By gentle heating of an aqueous starch solution containing silver nitrate and glucose, we produce relatively monodisperse, starched silver nanoparticles. beta-d-Glucose serves as the green reducing agent, while starch serves as the stabilization agent.
Understanding the fundamental principles for the design of CO(2)-philic materials is of growing importance due to the potential for enabling "green" chemistry and technologies in liquid and supercritical CO(2) as alternative solvent systems. Recently, there have been numerous efforts to develop hydrocarbon-based CO(2)-philes containing carbonyl groups, which are known to interact through a Lewis acid-Lewis base (LA-LB) interaction with CO(2) molecules, thereby providing the necessary solvation energy for dissolution. In this work, we investigate the role of a weaker, but cooperative, C-H...O hydrogen bond as an additional stabilizing interaction in the solvation of polycarbonyl moieties with hydrogen atoms attached directly to the carbonyl carbon or to the alpha-carbon atom. Ab initio calculations are performed on simple intermolecular complexes of CO(2) with compounds capable of acting as Lewis bases. Systems studied in different interaction configurations include formaldehyde, acetaldehyde, acetic acid, and methyl acetate, as model carbonyl compounds, and dimethyl sulfoxide as a model system for the sulfonyl group. Interaction energies, vibrational frequencies, charge transfer, and other molecular properties are calculated. Results indicate that C-H...O hydrogen bonds may be an important stabilizing interaction that merits consideration in the design of future CO(2)-philes.
Integration of ''green chemistry'' principles into nanotechnology is one of the key issues in nanoscience research today. In this work, we report an environmentally benign method for the preparation of Au, Ag, and Au-Ag nanoparticles in water, using glucose as the reducing agent and starch as the protecting agent. The alloy nanoparticles prepared in this way appears to be homogeneous and their sizes are well within the quantum size domain (,10 nm), where they are more amenable to size-dependent changes in electronic properties.
Acetylation of carbohydrates is proposed as a method for the synthesis of inexpensive CO2-philes that can easily be modified for a wide variety of green chemistry applications in liquid and supercritical CO2. The deliquescence of peracetylated sugars in contact with CO2 is reported in this communication as well as the unparalleled solubility of these compounds in supercritical CO2.
We present a straightforward, economically viable, and "green" approach for the synthesis and stabilization of relatively monodisperse Au nanocrystals with an average diameter of 8.2 nm (standard deviation, SD=2.3 nm) by using nontoxic and renewable biochemical of beta-D-glucose and by simply adjusting the pH environment in aqueous medium. The beta-D-glucose acts both as reducing agent and capping agent for the synthesis and stabilization of Au nanocrystals in the system. The UV/Vis spectroscopy, Fourier transform infrared (FT-IR) spectroscopy, transmission electron microscopy (TEM), electron diffraction (ED), and X-ray diffraction (XRD) techniques were employed to systematically characterize Au nanocrystals synthesized. Additionally, it is shown that these beta-D-glucose-stabilized Au nanocrystals function as effective catalyst for the reduction of 4-nitrophenol in the presence of NaBH4 (otherwise unfeasible if only the strong reducing agent NaBH4 is employed), which was reflected by the UV/Vis spectra of the catalytic reaction kinetics.
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