Intramolecular Directional Förster Resonance Energy Transfer at the Single-Molecule Level in a Dendritic System

Mircea Cotlet, Roel Gronheid, Satoshi Habuchi, Alina Stefan, Arianna Barbafina, Klaus Müllen, Johan Hofkens*, Frans C. De Schryver

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

106 Scopus citations

Abstract

We report on the directional Förster resonance energy transfer (FRET) process taking place in single molecules of a first (T1P4) and a second (T2P8) generation of a perylenemonoimide (P)-terrylenediimide (T)-based dendrimer in which the chromophores are separated by rigid polyphenylene arms. At low excitation powers, single-molecule detection and spectroscopy of T1P4 and T2P8 dendrimers point to a highly efficient directional FRET from P donors to the central T acceptor, optical excitation at 488 nm resulting in exclusively acceptor emission in the beginning of the detected fluorescence intensity. Donor emission is seen only upon the bleaching of the acceptor. High-resolution time-resolved single-molecule fluorescence data measured with a microchannel plate photomultiplier reveal, for T2P8, a broad range of FRET rates as a result of a broad range of distances and orientations experienced by the donor-acceptor dendrimers when immobilized in a polymer matrix. Single-molecule data from T2P8 on 488 nm excitation are indicative for the presence, after terrylenediimide bleaching, of a P-P excited dimer characterized by a broad emission spectrum peaking around 600 nm and by fluctuating fluorescence decay times. At high excitation powers, single T1P4 and T2P8 molecules display simultaneous emission from both donor and acceptor chromophores. The effect, called "exciton blockade", occurs due to the presence of multiple excitations in a single molecule.

Original languageEnglish (US)
Pages (from-to)13609-13617
Number of pages9
JournalJournal of the American Chemical Society
Volume125
Issue number44
DOIs
StatePublished - Nov 5 2003
Externally publishedYes

ASJC Scopus subject areas

  • Chemistry(all)

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