Photochemistry of chromophore-functionalized gold nanoparticles*
K. George Thomas,** Binil Itty Ipe, and P. K. Sudeep
Photochemistry Research Unit, Regional Research Laboratory
(CSIR), Trivandrum-695019, India
Abstract: It is generally believed that metal nanoparticles
strongly quench the singlet-excited states of chromophores when attached
to nanoparticle surfaces, through an energy-transfer mechanism, which
limits their application in optoelectronic devices and photonic materials.
Recent studies of fluorophore-linked metal nanoparticles reveal that
there is a dramatic suppression in the quenching of the singlet-excited
state of these molecules and they possess unusual photophysical properties.
A summary of our work on the photophysical and excited-state properties
of chromophore-functionalized gold nanoparticles is presented in this
article. Pyrene-capped gold nanoparticles showed normal fluorescence
in nonpolar solvents and an intermolecular excimer formation at higher
loadings. The quenching of the emission, observed in pyrene-labeled
gold nanoparticles in polar solvents, is attributed to the formation
of pyrene radical cation through a photoinduced electron-transfer process.
We have also functionalized gold nanoparticles using a thiol derivative
of fullerene. The quenching of fluorescence and decreased yields of
triplet-excited state, observed in these systems, are attributed to
an energy-transfer process.
* Special Topic Issue on the Theme
of Nanostructured Advanced Materials
**Corresponding
author
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