title: Gold nanoparticles assembled with dithiocarbamate-anchored molecular wires.
abstract: A protocol for the bottom-up self-assembly of nanogaps is developed through molecular linking of gold nanoparticles (AuNPs). Two π-conjugated oligo(phenylene ethynylene) molecules (OPE) with dithiocarbamate anchoring groups are used as ligands for the AuNPs. OPE-4S with a dithiocarbamate in each end of the molecule and a reference molecule OPE-2S with only a single dithiocarbamate end group. The linking mechanism of OPE-4S is investigated by using a combination of TEM, UV-Vis absorption and surface enhanced Raman spectroscopy (SERS) as well as studying the effect of varying the OPE-4S to AuNP concentration ratio. UV-Vis absorption confirms the formation of AuNP aggregates by the appearance of an extended plasmon band (EPB) for which the red shift and intensity depend on the OPE-4S:AuNP ratio. SERS confirms the presence of OPE-4S and shows a gradual increase of the signal intensity with increasing OPE-4S:AuNP ratios up to a ratio of about 4000, after which the SERS intensity does not increase significantly. For OPE-2S, no linking is observed below full coverage of the AuNPs indicating that the observed aggregate formation at high OPE-2S:AuNP ratios, above full AuNP coverage, is most likely of a physical nature (van der Waals forces or π-π interactions).
authors.affiliation: Nano-Science Center &Department of Chemistry, University of Copenhagen, Universitetsparken 5, 2100 Copenhagen, Denmark.|Sino-Danish Centre for Education and Research (SDC), Niels Jensens Vej 2, 8000 Aarhus C, Denmark.
authors.forename: Nini E A
authors.initials: NE
authors.lastname: Reeler
authors.affiliation: Nano-Science Center &Department of Chemistry, University of Copenhagen, Universitetsparken 5, 2100 Copenhagen, Denmark.
authors.forename: Knud A
authors.initials: KA
authors.lastname: Lerstrup
authors.affiliation: MacDiarmid Institute for Advanced Materials and Nanotechnology, School of Chemical and Physical Sciences, Victoria University of Wellington, PO Box 600, Wellington 6140, New Zealand.
authors.forename: Walter
authors.initials: W
authors.lastname: Somerville
authors.affiliation: Nano-Science Center &Department of Chemistry, University of Copenhagen, Universitetsparken 5, 2100 Copenhagen, Denmark.
authors.forename: Jozsef
authors.initials: J
authors.lastname: Speder
authors.affiliation: Nano-Science Center &Department of Chemistry, University of Copenhagen, Universitetsparken 5, 2100 Copenhagen, Denmark.
authors.forename: Søren V
authors.initials: SV
authors.lastname: Petersen
authors.affiliation: Nano-Science Center &Department of Chemistry, University of Copenhagen, Universitetsparken 5, 2100 Copenhagen, Denmark.
authors.forename: Bo W
authors.initials: BW
authors.lastname: Laursen
authors.affiliation: Nano-Science Center &Department of Chemistry, University of Copenhagen, Universitetsparken 5, 2100 Copenhagen, Denmark.
authors.forename: Matthias
authors.initials: M
authors.lastname: Arenz
authors.affiliation: National Center for Nanoscience and Technology, Beijing 100190, P. R. China.
authors.forename: Xiaohui
authors.initials: X
authors.lastname: Qiu
authors.affiliation: Nano-Science Center &Department of Chemistry, University of Copenhagen, Universitetsparken 5, 2100 Copenhagen, Denmark.
authors.forename: Tom
authors.initials: T
authors.lastname: Vosch
authors.affiliation: Nano-Science Center &Department of Chemistry, University of Copenhagen, Universitetsparken 5, 2100 Copenhagen, Denmark.
authors.forename: Kasper
authors.initials: K
authors.lastname: Nørgaard