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Liquid crystalline organic semiconductors: nematic spiro[cyclopentyl-1,9']fluorenes

Billa, Muralidhar Reddy; Kelly, Stephen; Kassireddy, Krishna; Haro, Marta; Al-Kalifah, Manea S.; Kelly, Stephen M.; Kitney, Stuart P.; O'Neill, Mary


Muralidhar Reddy Billa

Krishna Kassireddy

Marta Haro

Manea S. Al-Kalifah

Stuart P. Kitney

Mary O'Neill


A number of nematic spiro[cyclopentyl-1,9′]fluorene reactive mesogens with polymerisable oxetane or non-conjugated diene end-groups have been successfully synthesised. The melting and clearing points of these new spiro[cyclopentyl-1,9′]fluorenes are much higher than those of the corresponding 9,9-diethyl- or 9,9-dipropyl-substituted fluorenes, which are present in many light-emitting polymers currently used in polymer light-emitting diodes. The significant difference in transition temperature may be attributed to the lower intermolecular separation induced by the more rigid and less bulky cyclopentyl group, confirmed by molecular modelling. The presence of either these short but flexible aliphatic chains, or a rigid alicyclic group of similar size and shape, results in only small differences in the photoluminescence spectra and efficiency of these model liquid crystalline organic semiconductors, and in their improved thermal stability.

Journal Article Type Article
Publication Date 2011-07
Journal Liquid Crystals
Print ISSN 0267-8292
Electronic ISSN 1366-5855
Publisher Taylor & Francis
Peer Reviewed Peer Reviewed
Volume 38
Issue 7
Pages 813-829
APA6 Citation Billa, M. R., Kassireddy, K., Haro, M., Al-Kalifah, M. S., Kelly, S. M., Kitney, S. P., & O'Neill, M. (2011). Liquid crystalline organic semiconductors: nematic spiro[cyclopentyl-1,9']fluorenes. Liquid crystals, 38(7), 813-829.
Keywords Spiro-fluorenes; Nematics; Organic semiconductors,
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