Modulation of energy/electron transfer in gold nanoclusters by single walled carbon nanotubes and further consequences

• Single walled carbon nanotubes (SWCNTs) can quench fluorescence of gold nanoclusters (AuNCs).
• The quenching of fluorescence depends on their microenvironment.
• Resonance energy transfer and/or excited state electron transfer results into fluorescence quenching.
• Proximity of the donor and the acceptor induces metallic character into the SWCNTs by the AuNCs.

Semiconductor or metallic character in single-walled carbon nanotubes (SWCNTs) is developed because of their chirality and diameter. Depending upon the extent of these characters in a particular sample of SWCNT, various electronic and mechanical applications are formulated. In this work we used protein protected red emitting gold nanoclusters (AuNCs) to enhance the metallic character in SWCNTs through electron transfer induced by photonic excitation. The AuNCs have been synthesized following a known protocol that generates Au+ protected Au0 clusters. Normal and carboxylic acid functionalized SWCNTs were obtained commercially for usage in the experiments. The non-functionalized SWCNTs facilitate intersystem electron transfer while the functionalized ones defer the phenomenon, which, in turn, affects the metallic character in the nanotubes. Steady state and time resolved fluorescence spectroscopy prove the dynamics and electrochemistry supports the intersystem electron transfer process.

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