On the formation of protected gold nanoparticles from AuCl by the reduction using aromatic amines 4 −
Received: 23 July 2004 Accepted: 04 January 2005 DOI:
10.1007/s11051-005-0315-0 Cite this article as: Subramaniam, C., Tom, R.T. & Pradeep, T. J Nanopart Res (2005) 7: 209. doi:10.1007/s11051-005-0315-0 Abstract
Amines are used extensively as reductants and subsequent capping agents in the synthesis of metal nanoparticles, especially gold, due to its affinity to nitrogen. Taking 2-methyl aniline as an example, we show that metal reduction is followed by polymerization of the amine, while part of it covers the nanoparticle surface another fraction deposits in the solution. It is found that the oxidative polymerization of the amine goes in step with the formation of gold nanoparticles. The gold nanoparticles thus formed have a mean diameter of 20 nm. The polymerized amine encapsulates the gold nanoparticle forming a robust shell of about 5 nm thickness, making the gold core inert towards mineralizing agents such as chloroform, bromoform, sodium cyanide, benzylchloride, etc. which react with the naked gold nanoparticles. The deposited polymer is largely protonated, taking up protons from the medium during its formation. Similar results have been observed in the case of aniline also. The materials have been fully characterized by spectroscopy and microscopy.
Keywords gold nanoparticles poly(2-methyl aniline) core–shell nanomaterials oxidative polymerization MALDI-MS
This revised version was published online in August 2005 with a corrected issue number.
References Andrade, E.M., Moline, F.V., Florit, M.I., Posadas, D. 1996 IR response of poly(o-toluidine): Spectral modifications upon redox state change Electroanal. Chem. 419 15 21 CrossRef Aslam, M., Fu, L., Su, M., Vijayamohanan, K., Dravid, V.P. 2004 Novel one-step synthesis of amine-stabilized aqueous colloidal gold nanoparticles J. Mater. Chem. 14 1795 1797 CrossRef Brust, M., Walker, M., Bethell, D., Schiffrin, DJ., Whyman, R. 1994 Synthesis of thiol-derivatised gold nanoparticle in a two-phase liquid–liquid system J. Chem. Soc. Chem. Commun. 7 801 802 CrossRef Colombian, P., Gruger, A., Novak, A., Regis, A. 1994 Infrared and Raman study of polyaniline Part I. Hydrogen bonding and electronic mobility in emeraldine salts. J. Mol. Struct. 317 261 266 CrossRef Eswaranand, V., Pradeep, T. 2002 Zirconia protected silver clusters through functionalised monolayers J. Mater. Chem. 12 2421 2425 CrossRef Graf, C., Blaaderen, A. 2002 Metallodielectric colloidal core–shell particles for photonic applications Langmuir 18 524 534 CrossRef Hostetler, M.J., Wingate, JE., Zhong, CJ., Harris, JE., Vachet, RW., Clark, MR., Londono, JD., Green, SJ., Stokes, JJ., Wignall, GD., Glish, GL., Porter, MD., Evans, ND., Murray, R.W. 1998 Alkanethiolate gold cluster molecules with core diameters from 1.5 to 5.2 nm: Core and monolayer properties as a function of core size Langmuir 14 17 30 CrossRef Kumar, A., Mandal, S., Selvakannan, PR., Pasricha, R., Mandale, AB., Sastry, M. 2003 Investigation into the interaction between surface-bound alkylamines and gold nanoparticles Langmuir 19 6277 6282 CrossRef Leff, D.V., Brandt, L., Heath, J.R. 1996 Synthesis and characterization of hydrophobic, organically-soluble gold nanocrystals functionalized with primary amines Langmuir 12 4723 4730 CrossRef Liu, G., Freund, M.S. 1997 New approach for the controlled cross-linking of polyaniline: Synthesis and characterization Macromolecules 30 5660 5665 CrossRef Mitra, S., Nair, B., Pradeep, T., Goyal, PS., Mukhopadhyay, R. 2002 Alkyl chain dynamics in monolayer protected clusters (MPCs): A quasielastic neutron scattering investigation J. Phys. Chem. B 106 3960 3967 CrossRef Mukhopadhyay, R., Mitra, S., Tsukushi, I., Ikeda, S., Pradeep, T. 2003 Evolution of dynamical motions in monolayer protected metal clusters Chem. Phys. 292 223 227 CrossRef
Nair A.S., Pradeep T., I. Maclaren. (2004a). An investigation of the structure of stearate monolayer on Au@ZrO
2 and Ag@ZrO 2 core–shell nanoparticles. J. Mater. Chem. DOI: 10.1039/b313850j
Nair A.S., Suryanarayanan V., Tom RT., Pradeep T. (2004b). Porosity of core shell nanoparticles. J. Mater. Chem. In press
Nair, A.S., Tom, RT., Suryanarayanan, V., Pradeep, T. 2003 ZrO 2 bubbles from core shell nanoparticles J. Mater. Chem. 13 297 300 CrossRef Nair, A.S., Pradeep, T. 2003 Halocarbon mineralization and catalytic destruction by metal nanoparticles Curr. Sci. 84 1560 1564 Nakao, H., Shiigi, H., Yamamoto, Y., Tokonami, S., Nagaoka, T., Sugiyama, S., Ohtani, T. 2003 Highly ordered assemblies of Au nanoparticles organized on DNA Nano Lett. 10 1391 1394 CrossRef Patel, H., Das, SK., Sundararajan, T., Nair, AS., George, B., Pradeep, T. 2003 Thermal conductivities of naked and monolayer protected metal nanoparticle based nanofluids: Manifestation of anomalous enhancement and chemical effects Appl. Phys. Lett. 83 2931 2933 CrossRef
Pillalamarri S.K., Blum FD., M.F. Bertino. (2004). Surface-initiated polyaniline-coated gold nanoparticles. Abstracts of Papers, 228th ACS National Meeting, Philadelphia, PA, United States, August 22–26. 2004
Pradeep, T., Mitra, S., Nair, AS., Mukhopadhyay, R. 2004 Dynamics of alkyl chains in monolayer protected Au and Ag clusters and silver thiolates: A comprehensive QENS investigation J. Phys. Chem. B 108 7012 7020 CrossRef Sandhyarani, N., Pradeep, T. 2003 Towards understanding structure and phase transitions of self-assembled monolayers on two- and three-dimensional surfaces: An overview of current efforts Int. Rev. Phys. Chem. 22 221 262 CrossRef Selvakannan, P.R., Mandal, S., Phadtare, S., Pasricha, R., Sastry, M. 2003 Capping of gold nanoparticles by the amino acid lysine renders them water-dispersible Langmuir 19 3545 3549 CrossRef Thomas, K.G., Kamat, P.V. 2000 Making gold nanoparticles glow: Enhanced emission from a surface-bound fluoroprobe J. Am. Chem. Soc. 122 2655 2656 CrossRef Thomas, K.G., Zajicek, J., Kamat, P.V. 2002 Surface binding properties of tetraoctylammonium bromide-capped gold nanoparticles Langmuir 18 3722 3727 CrossRef Tom, R.T., Nair, AS., Singh, N., Aslam, M., Nagendra, CL., Philip, R., Vijayamohanan, K., Pradeep, T. 2003 Freely dispersible Au@TiO 2, Au@ZrO 2, Ag@TiO 2 and AgZrO 2 core-shell nano particles: One step synthesis, characterization, spectroscopy and optical limiting properties Langmuir 19 3439 3445 CrossRef Wang, R., Yang, J., Zheng, Z., Carducci, MD., Jiao, J., Seraphin, S. 2001 Dendron-controlled nucleation and growth of gold nanoparticles Angew. Chem. 40 549 551 CrossRef