Functionalized gold nanoparticles as phosphorescent nanomaterials and sensors

Ipe, Binil Itty ; Yoosaf, Karuvath ; Thomas, Kakkudiyil George (2006) Functionalized gold nanoparticles as phosphorescent nanomaterials and sensors Journal of the American Chemical Society, 128 (6). pp. 1907-1913. ISSN 0002-7863

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Ligand-capped gold nanoparticles were synthesized by capping monothiol derivatives of 2,2'-dipyridyl onto the surface of Au nanoparticles (Au-BT). The average size of the metal core is around 4 nm, with a shell of ~340 bipyridine ligands around the Au nanoparticle. The high local concentration of the chelating ligands (~5 M) around the Au nanoparticle makes these particles excellent ion sponges, and their complexation with EuIII/TbIII ions yields phosphorescent nanomaterials. Absorption spectral studies confirm a 1:3 complexation between EuIII/TbIII ions and bipyridines, functionalized on the surface of Au nanoparticles. The red-emitting Au-BT:EuIII complex exhibits a long lifetime of 0.36 ms with six line-like emission peaks, whereas the green-emitting Au-BT:TbIII complex exhibits a lifetime of 0.7 ms with four line-like emission peaks. These phosphorescent nanomaterials, designed by linking BT:EuIII complexes to Au nanoparticles, were further utilized as sensors for metal cations. A dramatic decrease in the luminescence was observed upon addition of alkaline earth metal ions (Ca2+, Mg2+) and transition metal ions (Cu2+, Zn2+, Ni2+), resulting from an isomorphous substitution of EuIII ions, whereas the luminescence intensity was not influenced by the addition of Na+ and K+ ions. Direct interaction of bipyridine-capped Au nanoparticles with Cu2+ ions brings the nanohybrid systems closer, leading to the formation of three-dimensional superstructures. Strong interparticle plasmon interactions were observed in these closely spaced Au nanoparticles.

Item Type:Article
Source:Copyright of this article belongs to American Chemical Society.
ID Code:51390
Deposited On:28 Jul 2011 11:46
Last Modified:28 Jul 2011 11:46

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