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Related Concept Videos

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Synthesis of pH Dependent Pyrazole, Imidazole, and Isoindolone Dipyrrinone Fluorophores using a Claisen-Schmidt Condensation Approach
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Efficient two-photon absorbing acceptor-pi-acceptor polymethine dyes.

Lazaro A Padilha1, Scott Webster, Olga V Przhonska

  • 1CREOL, The College of Optics and Photonics, University of Central Florida, Orlando, Florida 32826, USA. padilha@creol.ucf.edu

The Journal of Physical Chemistry. A
|May 22, 2010
PubMed
Summary
This summary is machine-generated.

We studied anionic polymethine dyes, finding that longer conjugation enhances two-photon absorption (2PA) properties. These dyes exhibit strong 2PA cross-sections and good photochemical stability, making them promising for optical applications.

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Area of Science:

  • Materials Science
  • Optics
  • Photochemistry

Background:

  • Acceptor-pi-acceptor symmetrical anionic polymethine dyes are investigated for their optical properties.
  • The influence of conjugation length on linear and nonlinear optical characteristics is crucial for dye design.

Purpose of the Study:

  • To experimentally and theoretically investigate the linear and nonlinear optical properties of polymethine dyes.
  • To correlate changes in conjugation length with two-photon absorption (2PA) cross-sections and fluorescence quantum yields.

Main Methods:

  • Synthesis and characterization of a series of anionic polymethine dyes with varying conjugation lengths.
  • Measurement of 2PA cross-sections (delta(2PA)) and spectra using nonlinear spectroscopy.
  • Quantum-chemical calculations and excitation anisotropy measurements to confirm spectral assignments.
  • Determination of fluorescence quantum yields and excited-state absorption spectra.

Main Results:

  • 2PA cross-sections significantly increase with extended pi-conjugation length, reaching up to 17,000 GM.
  • Two distinct 2PA bands were observed, with the first falling within the telecommunications window.
  • High fluorescence quantum yields (up to 0.90) and good photochemical stability were found for shorter dyes.
  • Excited-state absorption spectra showed intense bands across the visible region, red-shifting with increased conjugation.

Conclusions:

  • Increasing conjugation length is an effective strategy to enhance 2PA properties in these anionic polymethine dyes.
  • The dyes demonstrate potential for applications in nonlinear optics and photonics due to their strong 2PA and fluorescence.
  • The observed optical properties are well-supported by theoretical calculations, providing a basis for further molecular engineering.