Mesogenic BODIPYs: An investigation of the correlation between liquid crystalline behaviour and fluorescence intensity

Benstead, Michael; Mehl, Georg; Beeby, Andrew; Rosser, Geraldine A.; Mehl, Georg H.; Boyle, Ross W.

Abstract

A series of mesogenic molecules based on the 4,4¢-di?uoro-3a,4a-diaza-s-indacene (BODIPY) ?uorophore have been synthesised and characterised. Each compound consists of one mesogenic unit, based on a cyanobiphenyl core, and one ?uorophore, of varying alkyl substitution. The compounds were prepared by microwave-assisted palladium-catalyzed couplings (Suzuki and Sonogashira) due to slow reaction rates under conventional heating conditions. The effect of increasing the molecular length was also investigated by incorporating an ethynyl unit between the mesogen and the ?uorophore. The molecules self-assemble into monotropic nematic phases which were identi?ed by optical polarising microscopy (OPM) and differential scanning calorimetry (DSC). The compounds were found to display varying degrees of ?uorescence quantum yield dependant on the number of alkyl substituents attached to the ?uorophore. A relationship was observed between the nematic phase stability and ?uorescence intensity of the compounds with increasing alkyl substitution causing an increase in ?uorescence intensity due to restriction of the 8-phenyl ring rotation while simultaneously disrupting nematic phase formation, causing a reduction in nematic range. Temperature-dependant ?uorescence measurements were also acquired along with ?uorescence measurements of four of the synthesised BODIPYs dissolved in a commercial nematic liquid crystal (BL024) and incorporated into a twisted nematic cell.

Citation

Benstead, M., Beeby, A., Rosser, G. A., Mehl, G. H., & Boyle, R. W. (2011). Mesogenic BODIPYs: An investigation of the correlation between liquid crystalline behaviour and fluorescence intensity. Photochemical & photobiological sciences : an international journal, 10(6), 992-999. https://doi.org/10.1039/c0pp00388c

• Journal Article Type: Article
• Acceptance Date: Feb 7, 2011
• Online Publication Date: Mar 7, 2011
• Publication Date: Jun 1, 2011
• Journal: PHOTOCHEMICAL & PHOTOBIOLOGICAL SCIENCES
• Print ISSN: 1474-905X
• Electronic ISSN: 1474-9092
• Publisher: Royal Society of Chemistry
• Peer Reviewed: Peer Reviewed
• Volume: 10
• Issue: 6
• Pages: 992-999
• DOI: https://doi.org/10.1039/c0pp00388c
• Keywords: Physical and Theoretical Chemistry
• Public URL: https://hull-repository.worktribe.com/output/424103
• Publisher URL: http://pubs.rsc.org/en/Content/ArticleLanding/2011/PP/c0pp00388c#!divAbstract