ZnO nanoparticles have been synthesized by using biodegradable natural biopolymer viz. Gum Tragacanth. This single step approach is very cost effective and reproducible. The reaction time and concentration of precursor zinc acetate play a major role in the nature and growth of ZnO nanoparticles. ZnO nanoparticles were characterized by X-ray diffraction, SEM, FTIR, EDAX, UVvisible spectroscopy and TEM. ZnO nanoparticles with 20-30 nm in diameter and hexagonal morphology were found; dispersed uniformly. Raman spectrum shows the mode E 2 high at 437 cm ¡1 that is related to the vibration of wurtzite Zn-O bond in crystal structure of ZnO. The space between adjacent lattice fringes is » sharp 2.42 A . UV-visible absorption spectrum shows the sharp absorption band at 308 nm assigned to the intrinsic transition from valance band to conduction band. The ZnO nanoparticles display superior catalytic activity of conversion of aldehyde to acid as compared to bulk-ZnO material, because of high surface area of ZnO nanoparticles. A trace amount of ZnO nanoparticles catalyst required for organic conversion. The ZnO nanoparticles as catalyst are highly stable, recyclable and efficient in its activity.

A Polyindole-ZnO nanocomposite particle was synthesized by using a chemical oxidative polymerization method. Synthesized nanocomposite was characterized by UV-Visible, FTIR, SEM, XRD, EDAX and electrical conductivity measurements. The band at $3400 cm À1 and 735 cm À1 in FTIR spectra confirmed the polyindole formation. XRD spectral studies exhibits major diffraction in between 30-40 (2h) indicates the partial crystalline nature of the polyindole-ZnO nanocomposite. SEM image reveals agglomerated granular particulate nature with ZnO embedded in the polyindole matrix. The application of Polyindole-ZnO nanocomposite as a polymer-supported catalyst was studied for the synthesis of one pot multicomponent Biginelli condensation.

No abstract

Quantum dots also known as quasi zero dimensional system are nanostructures with a wide range of engineering applications. This manuscript reviews various synthesis routes of Quantum Dots. Of the various methods, chemical synthesis, chemical vapour deposition-gas phase synthesis, laser ablation, molecular beam epitaxial, lithographic methods have been discussed and overviewed. The latter half of the paper discusses some properties and applications of quantum dots. Their interesting and unique optical properties, some Quantum Dots also exhibit semi conducting properties results in potential applications in electronics, biology and energy applications.

No abstract