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Toward Smaller Aqueous-Phase Plasmonic Gold Nanoparticles: High-Stability Thiolate-Protected ~ 4.5 Nm Cores

preprint
submitted on 10.07.2019, 23:17 and posted on 11.07.2019, 13:48 by M. Mozammel Hoque, Kathryn M. Mayer, Arturo Ponce, Marcos M. Alvarez, Robert L. Whetten

Most applications of aqueous plasmonic gold nanoparticles benefit from control of the core size and shape, control of the nature of the ligand shell, and a simple and widely applicable preparation method. Surface functionalization of such nanoparticles is readily achievable but is restricted to water-soluble ligands. Here we have obtained highly monodisperse and stable smaller aqueous gold nanoparticles (core diameter ~ 4.5-nm), prepared from citrate-tannate precursors via ligand exchange with each of three distinct thiolates: 11-mercaptoundecanoic acid, a-R-lipoic acid, and para-mercaptobenzoic acid. These are characterized by UV-Vis spectroscopy for plasmonic properties; FTIR spectroscopy for ligand exchange confirmation; X-ray diffractometry for structural analysis; and high-resolution transmission electron microscopy for structure and size determination. Chemical reduction induces a blueshift, maximally +0.02-eV, in the localized surface-plasmon resonances band; this is interpreted as an electronic (-) charging of the MPC gold core, corresponding to a -0.5-V change in electrochemical potential.

Funding

5G12RR013646-12

72489-RT-REP

AX-1857

History

Email Address of Submitting Author

mohammad.hoque64@gmail.com

Institution

The University of Texas at San Antonio

Country

United States

ORCID For Submitting Author

0000-0003-2667-2668

Declaration of Conflict of Interest

no competing financial interests

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