Two series of BODIPYs (4,4′-difluoro-3a,4a-diaza-s-indacene) bearing mesogenic substituents have been synthesised and their fluorescent and self-assembly behaviour has been observed and characterised. In order to induce a strong preference for liquid crystallinity, two mesogenic units have been attached to each fluorophore. The compounds were prepared by microwave-assisted Suzuki couplings in moderate yields. Two different, but related, mesogens were employed but only one series was found to exhibit the formation of liquid crystal mesophases. Monotropic nematic phases, observed by differential scanning calorimetry (DSC) and optical polarising microscopy (OPM), were adopted over varying temperature ranges depending on the degree of alkyl substitution on the fluorophore. Increasing alkyl substitution caused a gradual increase in fluorescence quantum yield due to rotational restriction of the BODIPY 8-phenyl ring, however, this also disrupted the formation of the nematic phase causing a reduction in the temperature range over which the mesophase was exhibited. The large, branched structure of the compounds prepared caused them to have a high viscosity in both the nematic and isotropic liquid phase. Due to the high viscosity, the Schlieren texture of the nematic phase could only be observed after several hours annealing.

Applications of BODIPY fluorophores as components of light active materials are reviewed.

ADVERTISEMENT RETURN TO ISSUEPREVNoteNEXTStructural Analysis of Linear PEEK via MALDI-TOF Mass SpectrometryJonathan M. Behrendt†, Michael Benstead†‡, Adam Chaplin‡, Brian Wilson‡, and Michael L. Turner*†View Author Information† School of Chemistry, University of Manchester, Oxford Road, Manchester M13 9PL, U.K.‡ Victrex Technology Centre, Hillhouse International, Thorton-Cleveleys, Lancashire FY5 4QD, U.K.E-mail [email protected]; Tel 0161 275 4625.Cite this: Macromolecules 2011, 44, 22, 9054–9056Publication Date (Web):October 21, 2011Publication History Received11 July 2011Revised29 September 2011Published online21 October 2011Published inissue 22 November 2011https://pubs.acs.org/doi/10.1021/ma201580dhttps://doi.org/10.1021/ma201580dbrief-reportACS PublicationsCopyright © 2011 American Chemical SocietyRequest reuse permissionsArticle Views1177Altmetric-Citations5LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InRedditEmail Other access optionsGet e-AlertscloseSupporting Info (1)»Supporting Information Supporting Information SUBJECTS:Mass spectrometry,Oligomers,Polymer solutions,Polymers,Solvents Get e-Alerts

A series of mesogenic molecules based on the 4,4'-difluoro-3a, 4a-diaza-s-indacene (BODIPY) fluorophore have been synthesised and characterised. Each compound consists of one mesogenic unit, based on a cyanobiphenyl core, and one fluorophore, 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 fluorophore. The molecules self-assemble into monotropic nematic phases which were identified by optical polarising microscopy (OPM) and differential scanning calorimetry (DSC). The compounds were found to display varying degrees of fluorescence quantum yield dependant on the number of alkyl substituents attached to the fluorophore. A relationship was observed between the nematic phase stability and fluorescence intensity of the compounds with increasing alkyl substitution causing an increase in fluorescence intensity due to restriction of the 8-phenyl ring rotation while simultaneously disrupting nematic phase formation, causing a reduction in nematic range. Temperature-dependant fluorescence measurements were also acquired along with fluorescence measurements of four of the synthesised BODIPYs dissolved in a commercial nematic liquid crystal (BL024) and incorporated into a twisted nematic cell.