Synthesis, characterization, and optical properties of new two-photon-absorbing fluorene derivatives

Kevin D. Belfield, Alma R. Morales, Bong Soo Kang, Joel M. Hales, David J. Hagan, Eric W. Van Stryland, Victor M. Chapela, Judith Percino

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The synthesis of a series of four new compounds containing fluorenyl chromophores is presented, along with the results of spectroscopic and photochemical studies aimed at understanding the two-photon absorption properties and energetics of their electronically excited states. The molecular structures of the compounds were systematically varied to allow comparison of molecules possessing high and low molecular symmetry, short and long alkyl chains, and a fluorenyl conjugated π-system. Solvent-dependent absorption and emission were investigated along with π-conjugation length. Preliminary measurements of two-photon absorption (2PA) using a two-photon fluorescence method indicate that these chromophores exhibit high two-photon absorptivity. A symmetrical molecule (3), possessing a relatively large π-conjugated system, flanked on either side by electron-withdrawing groups (benzothiazole), exhibited a peak 2PA cross section (δ) of 6000 × 10-50 cm 4 s photon-1 molecule-1 at 600 nm. Excitation anisotropy studies revealed the position of the S0 → S 1 and S0 → S2 electronic transitions. Consistent with quantum mechanical selection rules, the two-photon allowed transition (S0 → S2) was dominant.

Original languageEnglish (US)
Pages (from-to)4634-4641
Number of pages8
JournalChemistry of Materials
Issue number23
StatePublished - Nov 16 2004
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • General Chemistry
  • General Chemical Engineering
  • Materials Chemistry


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