硼酸酯合成.pdf

FULL PAPER
Synthesis and Characterization of Monodisperse Oligofluorenes
Jungho Jo,+[b] Chunyan Chi,+[a] Sigurd Hˆger,[c] Gerhard Wegner,*[a] and Do Y. Yoon*[b]
Abstract: An efficient synthesis of 9,9- tion) and the application of the much nium salts. Variation of the UV/Vis ab-
bis(2-ethylhexyl)fluorene oligomers up higher reactivity of aryl boronic esters sorption and photoluminescence char-
to the heptamer is reported, with repet- over aryl bromides in the Pd-catalyzed acteristics with chain length is report-
itive Suzuki and Yamamoto coupling cross-coupling reaction with aryl diazo- ed. Moreover, glass transition and
reactions employed in the synthesis. liquid-crystal characteristics of the
The key steps for preparation of the es- oligomers are described and compared
Keywords: fluorene ¥ glasses ¥ liq-
sential intermediates include Pd-cata- with those of the polymer.
uid crystals ¥ oligomerization ¥ pho-
lyzed transformation of aryl bromides
toluminescence
to aryl boronic esters (Miyaura reac-
Introduction Polyfluorenes are readily prepared by Ni0-mediated cou-