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GREENER SYNTHESIS OF NANOMETALS AND NANOCOMPOSITES AND THEIR APPLICATION IN ORGANIC SYNTHESES
Citation:
VARMA, R. S., M. N. NADAGOUDA, AND D. KUMAR. GREENER SYNTHESIS OF NANOMETALS AND NANOCOMPOSITES AND THEIR APPLICATION IN ORGANIC SYNTHESES. Presented at 39Th Central Regional American Chemical Society Meeting, Covington, KY, May 20 - 23, 2007.
Impact/Purpose:
To inform the public.
Description:
A brief account of a greener preparation of nanoparticles which reduces or eliminates the use and generation of hazardous substances is described. The use of vitamins B1 and B2, which can function both as reducing and capping agents, provides a simple, one-pot, greener method to synthesize bulk quantities of nanospheres, nanorods, nanowires, and nanoballs of aligned nanobelts and nanoplates of the metals in water without the need for large amounts of insoluble templates. Alternatively, microwave (MW) approach enables the bulk and shape-controlled synthesis of gold (Au) nanostructures with various shapes (such as prisms, cubes and hexagons) that occurs via MW-assisted spontaneous reduction of noble metal salts using an aqueous solution of -D-glucose, sucrose, and maltose; the strategy can be extended to the generation of nanospheres of silver (Ag), palladium (Pd), and platinum (Pt). The noble nanocrystals undergo catalytic oxidation with monomers such as pyrrole to generate noble nanocomposites which have potential functions in catalysis, biosensors, energy storage systems, and nanodevices. MW heating accomplishes the cross-linking reaction of poly (vinyl alcohol) (PVA) with single-wall carbon nanotubes (SWNT); multi-wall carbon nanotubes (MWNT); Buckminsterfullerene (C-60); metallic systems such as Pt, Cu, and In; and bimetallic systems, namely Pt-In, Ag-Pt, Pt-Fe, Cu-Pd, Pt-Pd and Pd-Fe. A newer form of carbon-doped porous titania that can be useful for visible-light induced photodegradation of pollutants has also been prepared using a benign natural polymer, dextrose. This general and eco-friendly protocol utilizes dextrose to create spongy porous structures of other transition metal oxides as well, such as ZrO2, Al2O3, and SiO2. A nanosized MgO-catalyzed three-component condensation reaction that proceeds in water-polyethylene glycol (PEG) to afford 2-amino-2-chromenes at room temperature will be described.