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Issue 23, 2010
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Excited-state dynamics and dye–dye interactions in dye-coated gold nanoparticles with varying alkyl spacer lengths

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Abstract

Gold nanoparticles (ca. 3 nm in diameter) coated with bis(diarylamino)biphenyl-based thiols with two different alkyl spacers (propyl and dodecyl) between the chromophore and the surface-anchoring thiol group have been prepared and characterized with a variety of techniques. The excited-state dynamics of the dyes in close proximity to the nanoparticle surface were studied using the time-correlated single-photon counting technique and near-IR fs transient absorption spectroscopy. The excited states of the dyes in the hybrid metal/organic systems exhibit an ultrafast (<5 ps) deactivation as evidenced by the fs transient absorption measurements. The length of the alkyl spacer between the dye and the thiol group has a profound effect on the ultrafast dynamics of the photoexcited systems. An ultrafast formation (ca. 0.5 ps) of a cation-like species has been recorded for the system incorporating the propyl spacer but not for the dodecyl-linker system. The formation of the cation-like species has been shown to be less efficient in a mixed-ligand system in which the bis(diarylamino)biphenyl-based thiol was diluted on the surface with dodecanethiol. Additionally, the ultrafast formation (ca. 1 ps) of a cation-like species with a similar spectroscopic signature has been observed in the solid state of the dye. A combination of the ultrafast dynamics and 1H NMR spectroscopic data has been used to discuss the observed behavior in terms of dyedye interactions in the nanoparticle systems. Due to the surface curvature of the nanoparticle, the propyl spacer imposes a closer dyedye distance than the dodecyl spacer, thus facilitating dyedye interactions that lead to the formation of a charge-transfer species involving two or more dye molecules.

Graphical abstract: Excited-state dynamics and dye–dye interactions in dye-coated gold nanoparticles with varying alkyl spacer lengths

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Supplementary files

Article information


Submitted
22 Dec 2009
Accepted
25 Mar 2010
First published
20 Apr 2010

Phys. Chem. Chem. Phys., 2010,12, 6267-6277
Article type
Paper

Excited-state dynamics and dyedye interactions in dye-coated gold nanoparticles with varying alkyl spacer lengths

M. Malicki, J. M. Hales, M. Rumi, S. Barlow, L. McClary, S. R. Marder and J. W. Perry, Phys. Chem. Chem. Phys., 2010, 12, 6267
DOI: 10.1039/B926938J

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