Issue 44, 2016

Covalently linked multimers of gold nanoclusters Au102(p-MBA)44 and Au∼250(p-MBA)n

Abstract

We present the synthesis, separation, and characterization of covalently-bound multimers of para-mercaptobenzoic acid (p-MBA) protected gold nanoclusters. The multimers were synthesized by performing a ligand-exchange reaction of a pre-characterized Au102(p-MBA)44 nanocluster with biphenyl-4,4′-dithiol (BPDT). The reaction products were separated using gel electrophoresis yielding several distinct bands. The bands were analyzed by transmission electron microscopy (TEM) revealing monomer, dimer, and trimer fractions of the nanocluster. TEM analysis of dimers in combination with molecular dynamics simulations suggest that the nanoclusters are covalently bound via a disulfide bridge between BPDT molecules. The linking chemistry is not specific to Au102(p-MBA)44. The same approach yields multimers also for a larger monodisperse p-MBA-protected cluster of approximately 250 gold atoms, Au∼250(p-MBA)n. While the Au102(p-MBA)44 is not plasmonic, the Au∼250(p-MBA)n nanocluster supports localized surface plasmon resonance (LSPR) at 530 nm. Multimers of the Au∼250(p-MBA)n exhibit additional transitions in their UV-vis spectrum at 630 nm and 810 nm, indicating the presence of hybridized LSPR modes. Well-defined structures and relatively small sizes make these systems excellent candidates for connecting ab initio theoretical studies and experimental quantum plasmonics. Moreover, our work opens new possibilities in the controlled synthesis of advanced monodisperse nanocluster superstructures.

Graphical abstract: Covalently linked multimers of gold nanoclusters Au102(p-MBA)44 and Au∼250(p-MBA)n

Supplementary files

Article information

Article type
Paper
Submitted
02 Jul 2016
Accepted
01 Sep 2016
First published
21 Sep 2016

Nanoscale, 2016,8, 18665-18674

Covalently linked multimers of gold nanoclusters Au102(p-MBA)44 and Au∼250(p-MBA)n

T. Lahtinen, E. Hulkko, K. Sokołowska, T. Tero, V. Saarnio, J. Lindgren, M. Pettersson, H. Häkkinen and L. Lehtovaara, Nanoscale, 2016, 8, 18665 DOI: 10.1039/C6NR05267C

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