Title

Synthesis Of Two-Photon Absorbing Unsymmetrical Branched Chromophores Through Direct Tris(Bromomethylation) Of Fluorene

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. © 2005 American Chemical Society.

Publication Date

6-24-2005

Publication Title

Journal of Organic Chemistry

Volume

70

Issue

13

Number of Pages

5126-5132

Document Type

Article

Personal Identifier

scopus

DOI Link

https://doi.org/10.1021/jo0503512

Socpus ID

20844441793 (Scopus)

Source API URL

https://api.elsevier.com/content/abstract/scopus_id/20844441793

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