Synthesis of two-photon absorbing unsymmetrical branched chromophores through direct tris(bromomethylation) of fluorene

Research output: Contribution to journalArticlepeer-review

98 Scopus citations

Abstract

Branched fluorene-based chromophores bearing electron-donating diphenylamino or electron-withdrawing nitro groups were synthesized as well as their linear analogues. An efficient synthetic method was developed via a novel 2,4,7-tris(bromomethyl)-9,9-diethylfluorene intermediate. The bromomethyl groups in this key intermediate were converted to either phosphonate or carboxaldehyde moieties, facilitating preparation of a high functionality branched structure. It was found that the reactivity at position 4 is attenuated in the bromomethyl and phosphorylated derivates, facilitating the selective and systematic functionalization of the fluorenyl system. All compounds were stable up to ca. 350 °C, except for a sterically crowded branched derivative. The linear optical properties of the compounds were investigated by UV-visible, steady-state fluorescence, and excitation anisotropy spectroscopic measurements. Fluorescence quantum yields were greater than or equal to 0.84 for symmetric linear and unsymmetric branched derivatives. Very high two-photon absorption (2PA) cross-sections were achieved (5765 GM at 520 nm and 4194 GM at 570 nm), as determined with use of picosecond and femtosecond laser excitation sources, respectively.

Original languageEnglish (US)
Pages (from-to)5126-5132
Number of pages7
JournalJournal of Organic Chemistry
Volume70
Issue number13
DOIs
StatePublished - Jun 24 2005
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Organic Chemistry

Fingerprint

Dive into the research topics of 'Synthesis of two-photon absorbing unsymmetrical branched chromophores through direct tris(bromomethylation) of fluorene'. Together they form a unique fingerprint.

Cite this