123rd General Meeting of the KCS

Type Poster Presentation
Area Material Chemistry
Room No. Exhibition Hall 2
Time 4월 19일 (금요일) 11:00~12:30
Code MAT.P-408
Subject Size-Dependent Nonthermalized Energy Transfer in Dye-Conjugated Gold Nanoclusters
Authors SangMyeong Han, Kyunglim Pyo1, Dongil Lee1,*
department of chemistry, Yonsei University, Korea
1Department of Chemistry, Yonsei University, Korea
Abstract Energy transfer is one of the most important properties that enables the luminescence-based techniques to be used in large areas. Above all, nonthermalized energy transfer is a unique property that occurs in donor’s long-lived upper excited stated. This is usually shown at specific molecules like carotenoids. Recently, nanoclusters have suggested as alternative of quantum dots in energy transfer region because of their stability, low toxicity, etc. In this work, we observed nonthermalized energy transfer in dye-conjugated gold nanoclusters. 6-aminofluorescein(AF) was conjugated to various size of glutathione(SG) protected gold nanoclusters by using dicyclohexylcarbodiimide(DCC). As nanoclusters are not soluble in organic solvent, least amount of water was mixed to main solvent, acetone. The activity of DCC is inhibited by water, but this means that the binding number of AF can be controlled. Comparing nanoclusters of different sizes with the same AF conjugation numbers, Au18-AF shows much brighter emission while Au102-AF shows similar emission with SG-AF even it has much intense absorption near 490nm. This phenomenon cannot be explained by FRET theory including spectral overlap concept. To finding the origin of size-dependent emission, transient absorption measurement was proceeded. It confirms that nonthermalized energy transfer occurs only in small-sized nanoclusters, which is the same trend as PL results. It is well known that small-sized nanoclusters have slower relaxation rate compared with large nanoparticles. Based on principle of nonthermalized energy transfer, slower intracore relaxation may induce highly efficient energy transfer. This result shows the potential that nanoclusters can be a valuable platform for luminescence system.
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