COLL 280 |
| Chander Radhakrishnan1, Manoj V. Warrier1, Fung K. Lo1, Miguel Garcia-Garibay2, and Harold Monbouquette1. (1) Department of Chemical Engineering, University of California, Los Angeles, 5531 Boelter Hall, University of California, Los Angeles, Los Angeles, CA 90095, (2) Department of Chemistry and Biochemistry, University of California Los Angeles, 405 Hilgard Avenue, Los Angeles, CA 90095-1569 |
| Semiconductor nanoparticles or quantum dots (q-dots) have drawn a lot of attention in the recent past due to their improved electronic properties over their bulk counterparts owing to quantum confinement effects. In the quantum confinement regime, the electron-hole redox potentials have been efficiently varied by changing the q-dot size, making them “size tunable photo catalysts”.Here we report a novel method to chemically modify the surface functionality of a photoreactive self-assembled monolayer (SAM) using cadmium selenide (CdSe) and cadmium sulfide (CdS) q-dot photocatalysts. To our best knowledge there are currently no reports of q-dots driving photocatalytic reactions on monolayer surfaces. Highly monodisperse CdS and CdSe q-dots (amino or carboxy thiol capped) of different sizes were synthesized in an aqueous medium. Aryl azide functionalized SAMs were assembled on atomically smooth gold from synthesized disulfide precursors. Surface photolysis of the azide monolayer was carried out in the presence of q-dots using a 1000-Watt Hanovia medium pressure mercury lamp. The reduction of the aryl azide to the corresponding aryl amine was confirmed using Ft-IR, contact angle measurements and matrix assisted laser desorption/ionization and time of flight mass spectrometry (MALDI-TOF). The significant reduction in the azide peak (Ft-IR spectra) after photocatalysis is shown below (fig. 1). The experimental methods and the characterization results will be discussed in detail at the meeting. |
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Nanoscience and Nanotechnology
6:00 PM-8:00 PM, Monday, March 29, 2004 Disneyland -- North Exhibit Hall, Poster
Division of Colloid and Surface Chemistry |
