1. Raman Spectroscopy for Characterizing Gold Nanoparticles on Polyaniline (PANI) Thin Films Yi-Hsiu Chen, Cai-Wei Lin, Chun-Guey Wu, and Bor-Chen Chang Department of Chemistry National Central University Chung-Li 32001, TAIWAN

2. Acknowledgements Cai-Wei LinYi-Hsiu Chen (M.S. 2006) Prof. Chun-Guey Wu StudentsIn Collaboration with Financial Supports: National Science Council, TAIWAN National Central University

3. Pernigraniline Base (PNB) Violet Emeraldine Base (EB) Blue reductionoxidation reduction oxidation acid base Protonated Emeraldine Salt (ES) Green Leucoemeraldine Base (LEB) Pale Yellow Polyaniline (PANI) Structures MacDiarmid and Epstein, Synth. Met. 29, E409 (1989)

4. Gold (Au) Nanoparticles Green Oxidations of primary alcohols. Catalysts: Au/TiO 2 or Au-Pd/TiO 2. [G. J. Hutchings and co- workers, Nature 437, 1132 (2005) and Science 311, 362 (2006).] Green Oxidations of primary alcohols. Catalysts: Au/TiO 2 or Au-Pd/TiO 2. [G. J. Hutchings and co- workers, Nature 437, 1132 (2005) and Science 311, 362 (2006).] We tried the oxidation of benzyl alcohol with Au/PANI as the catalyst. We tried the oxidation of benzyl alcohol with Au/PANI as the catalyst. O2O2 O2O2 Benzyl AlcoholBenzaldehydeBenzoic Acid

5. Use HPLC to Monitor the Oxidation HPLC Chromatogram Benzyl Alcohol Benzaldehyde Benzoic Acid Internal Standard ： 1,3,5-benzenetricarboxylic acid

6. Catalysis Study Au-CHCl 3 /PANI has a better catalytic activity than Au-H 2 O/PANI. Au-CHCl 3 /PANI has a better catalytic activity than Au-H 2 O/PANI. The temperature-dependency experiments (273K to 353K) show a smaller activation energy of Au-CHCl 3 /PANI (ca. 6 kJ mol -1 ) than that of Au-H 2 O/PANI (ca. 23 kJ mol -1 ). The temperature-dependency experiments (273K to 353K) show a smaller activation energy of Au-CHCl 3 /PANI (ca. 6 kJ mol -1 ) than that of Au-H 2 O/PANI (ca. 23 kJ mol -1 ).

7. Scanning Electron Microscopy (SEM) Images Diameter (nm) 249 ± 50 nm 31.4 ± 5.0 nm Diameter (nm) Au-H 2 O/PANI Au-CHCl 3 /PANI Au nanoparticles prepared in an aqueous solution. Au nanoparticles prepared in a chloroform solution.

8. Questions? The size distributions in SEM images are INCONSISTENT with the catalytic activities. The size distributions in SEM images are INCONSISTENT with the catalytic activities. SEM shows only the Au nanoparticles on surface and these particles may not be the real catalytic centers. SEM shows only the Au nanoparticles on surface and these particles may not be the real catalytic centers. Small angle X-Ray diffraction (XRD) study shows the particle sizes of the embedded Au nanoparticles are roughly the same for differently preparation methods. Small angle X-Ray diffraction (XRD) study shows the particle sizes of the embedded Au nanoparticles are roughly the same for differently preparation methods. Why? Spectroscopy? Why? Spectroscopy?

9. 1513 1622 1621 1511 1620 1581 1515 1582 Raman Spectra for Au-H 2 O/PANI Benzoid ring C ＝ C stretch. Quinoid ring C ＝ C stretch. C ＝ N stretch. EB PNB LEB 544 541 542 1344 1243 1269 1208 1189 1542 1270 1196 1186 1542 1444 599 1473 1335 598 1445 1339 801 596 802 1240 (a) PANI (b) Au-H 2 O/PANI before reaction (c) Au-H 2 O/PANI after reaction

10. 16201587 1342 1208 1621 1516 1341 1245 1190 1583 1445 1511 1339 1269 1186 596 542 1620 1581 1240 1542 Benzoid ring C ＝ C stretch. Quinoid ring C ＝ C stretch. C ＝ N stretch. EB PNB LEB 801 798 (a) PANI (b) Au-CHCl 3 /PANI before reaction (c) Au-CHCl 3 /PANI after reaction Raman Spectra for Au-CHCl 3 /PANI

11. After reaction Before reaction Raman shift (cm -1 ) PANI Au-H 2 O/PANI Au-CHCl 3 /PANI The bonding between Au nanoparticles and PANI is stronger in Au-CHCl 3 /PANI than in Au-H 2 O/PANI.

12. Summary Gold nanoparticles prepared by different solvents exhibit distinctively different catalytic activities. Gold nanoparticles prepared by different solvents exhibit distinctively different catalytic activities. Raman spectroscopy reveals the bonding differences between different gold nanoparticles. Raman spectroscopy reveals the bonding differences between different gold nanoparticles. Anisotropy Raman spectroscopy? A probe of morphology? Anisotropy Raman spectroscopy? A probe of morphology?