Synthesis and characterization of monodisperse oligofluorenes.
An efficient synthesis of 9,9-bis(2-ethylhexyl)fluorene oligomers up to the heptamer is reported, with repetitive Suzuki and Yamamoto coupling reactions employed in the synthesis. The key steps for preparation of the essential intermediates include Pd-catalyzed transformation of aryl bromides to aryl boronic esters (Miyaura reaction) and the application of the much higher reactivity of aryl boronic esters over aryl bromides in the Pd-catalyzed cross-coupling reaction with aryl diazonium salts. Variation of the UV/Vis absorption and photoluminescence characteristics with chain length is reported. Moreover, glass transition and liquid-crystal characteristics of the oligomers are described and compared with those of the polymer.
Jo
Jungho
J
School of Chemistry, Seoul National University, San 56-1, Sillim-dong, Seoul, 151-747, Korea.
Chi
Chunyan
C
Höger
Sigurd
S
Wegner
Gerhard
G
Yoon
Do Y
DY
D003432:Cross-Linking Reagents / Q000737:chemistry; D005449:Fluorenes / Q000138:chemical synthesis / Q000737:chemistry; D015394:Molecular Structure; D011108:Polymers / Q000138:chemical synthesis / Q000737:chemistry; D013237:Stereoisomerism; D013696:Temperature
D003432:Cross-Linking Reagents; D005449:Fluorenes; D011108:Polymers