title: Organic fluorescent thermometers based on borylated arylisoquinoline dyes.
abstract: Borylated arylisoquinolines with redshifted internal charge-transfer (ICT) emission were prepared and characterized. Upon heating, significant fluorescence quenching was observed, which forms the basis for a molecular thermometer. In the investigated temperature range (283-323 K) an average sensitivity of -1.2 to -1.8% K(-1) was found for the variations in fluorescence quantum yield and lifetime. In the physiological temperature window (298-318 K) the average sensitivity even reaches values of up to -2.4% K(-1). The thermometer function is interpreted as the interplay between excited ICT states of different geometry. In addition, the formation of an intramolecular Lewis pair can be followed by (11)B NMR spectroscopy. This provides a handle to monitor temperature-dependent ground-state geometry changes of the dyes. The role of steric hindrance is addressed by the inclusion of a derivative that lacks the Lewis pair formation.
authors.affiliation: CIQSO-Center for Research in Sustainable Chemistry and Department of Chemical Engineering, Physical Chemistry and Organic Chemistry, University of Huelva, Campus El Carmen s/n, 21071 Huelva (Spain).
authors.forename: Vânia F
authors.initials: VF
authors.lastname: Pais
authors.forename: José M
authors.initials: JM
authors.lastname: Lassaletta
authors.forename: Rosario
authors.initials: R
authors.lastname: Fernández
authors.forename: Hamdy S
authors.initials: HS
authors.lastname: El-Sheshtawy
authors.forename: Abel
authors.initials: A
authors.lastname: Ros
authors.forename: Uwe
authors.initials: U
authors.lastname: Pischel
keywords: Lewis pairs; boron; charge transfer; fluorescence; molecular devices