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

Billa, Muralidhar Reddy; 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

Stephen M. Kelly

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.


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.

Journal Article Type Article
Acceptance Date Mar 31, 2011
Online Publication Date Jul 12, 2011
Publication Date 2011-07
Journal Liquid Crystals
Print ISSN 0267-8292
Electronic ISSN 1366-5855
Publisher Taylor and Francis
Peer Reviewed Peer Reviewed
Volume 38
Issue 7
Pages 813-829
Keywords Spiro-fluorenes; Nematics; Organic semiconductors,
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