Relaxation dynamics and structural characterization of organic nanoparticles with enhanced emission

Chetan Jagdish Bhongale, Chih Wei Chang, Chi Shen Lee, Eric Wei Guang Diau, Chain Shu Hsu

Research output: Contribution to journalArticle

155 Citations (Scopus)

Abstract

With a reprecipitation method, we prepared fluorescent organic nanoparticles of 1,4-di[(E)-2-phenyl-1-propenyl]-benzene (PPB) that feature weak emission in solution but exhibit blue-shifted absorption and strong emission as aggregates. Picosecond fluorescent transients of these PPB nanoparticles showed biexponential decay, described with a consecutive kinetic model involving two emissive states. X-ray diffraction patterns of PPB nanocrystals indicate long-range packing structures of two types, one the same as in a single crystal and the other not yet determined. PPB molecules in a crystal show an arrangement of a herringbone type with three benzene rings in a PPB unit being nearly planar and two methyl groups of the unit pointing along the same direction, in contrast to the twisted structure of an isolated PPB molecule. Fluorescence transients of PPB on a femtosecond scale indicate an efficient channel for isomerization that is activated for free PPB in solution but inhibited in PPB forming nanoparticles, demonstrating the significance of molecular geometry and twisting motions that affect the relaxation dynamics in the excited state. The versatile techniques combined in this work provide strong evidence to improve our understanding of optical properties in organic nanoparticles dependent on size.

Original languageEnglish
Pages (from-to)13472-13482
Number of pages11
JournalJournal of Physical Chemistry B
Volume109
Issue number28
DOIs
Publication statusPublished - 2005 Jul 21

Fingerprint

Nanoparticles
nanoparticles
Benzene
benzene
Molecules
twisting
Isomerization
Excited states
Nanocrystals
Diffraction patterns
isomerization
molecules
nanocrystals
diffraction patterns
Optical properties
Fluorescence
Single crystals
optical properties
X ray diffraction
fluorescence

All Science Journal Classification (ASJC) codes

  • Physical and Theoretical Chemistry
  • Surfaces, Coatings and Films
  • Materials Chemistry

Cite this

Bhongale, Chetan Jagdish ; Chang, Chih Wei ; Lee, Chi Shen ; Diau, Eric Wei Guang ; Hsu, Chain Shu. / Relaxation dynamics and structural characterization of organic nanoparticles with enhanced emission. In: Journal of Physical Chemistry B. 2005 ; Vol. 109, No. 28. pp. 13472-13482.
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Relaxation dynamics and structural characterization of organic nanoparticles with enhanced emission. / Bhongale, Chetan Jagdish; Chang, Chih Wei; Lee, Chi Shen; Diau, Eric Wei Guang; Hsu, Chain Shu.

In: Journal of Physical Chemistry B, Vol. 109, No. 28, 21.07.2005, p. 13472-13482.

Research output: Contribution to journalArticle

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