Chemical Transformation Networks using Ultra-small Particles

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Nanoparticles in 1 nm dimension consisting of tens to thousands of atoms exhibit materials properties sensitively dependent on the number of constituent atoms, in contrast to those over a few nm which are regarded essentially as the bulk. This project investigates two or three dimensional networks of these ultra-small nanoparticles inducing detection, conduction, decomposition, transformation, storage of electrons, atoms, molecules and ions.The research is divided into 1.synthesis of ultra-small particles of high functionalities, 2.linking them into networks, and 3.evaluating their device characteristics. The special attention was focused on producing the smallest particles of practically useful II-VI semiconducting compounds, succeeding in finding atomically precise and perfectly monosized 1 nm particles of (CdSe)_n. The number of constituent atoms is less than a hundred and is small enough that the particle behaves like a molecule to be linked or assembled under atomic scale and prec … More ision. They exhibit functional devices realized by and based on the properties arising from special atomic arrangements not achieved by bulk crystalline structures, leading to a new approach in nanometer science and technology.Ultra-small particles of (CdSe)_n were synthesized with n= 13,34,48,60.... Such small particles exhibit their stabilities extremely sensitive to the number of constituent atoms, n, so as to be selectively grown only at these n's.Networks with these particles were produced not only by simple array formation but also by their liking with organic polymers to form two and three dimensional arrangements.These 1nm particles are further functionalized by surface modification with such as trioctylphosphine (TOP) to yield extremely high luminescence efficiency comparable to rhodamines of commercial organic dyes.These functionalities are realized by our atomically precise synthesis and characterization made possible because of their molecular nature, proven as a desirable approach in the nanoscience and technology. Less