Title: Solvent and pH dependent fluorescent properties of a dimethylaminostyryl borondipyrromethene dye in solution
Authors: Baruah, Mukulesh
Qin, WW
Flors, C
Hofkens, Johan
Vallee, RAL
Beljonne, D
Van der Auweraer, Mark
De Borggraeve, Wim
Boens, Noël # ×
Issue Date: May-2006
Publisher: American Chemical Society
Series Title: Journal of Physical Chemistry A vol:110 issue:18 pages:5998-6009
Abstract: Steady-state and time-resolved fluorescence techniques have been used to study the photophysical properties of the fluorescent BODIPY-derived dye 3-{2-[4-(dimethylamino) phenyl] ethenyl}-4,4-difluoro-8-( 4- methoxyphenyl)1,5,7-trimethyl-3a, 4a-diaza-4-bora-s-indacene. This compound has been synthesized via a microwave-assisted condensation of p-N,N-dimethylaminobenzaldehyde with the appropriate 1,3,5,7-tetramethyl substituted borondipyrromethene unit. The fluorescence properties of the dye are strongly solvent dependent: increasing the solvent polarity leads to lower fluorescence quantum yields and lifetimes, and the wavelength of maximum fluorescence emission shifts to the red. The Catalan solvent scales are found to be the most suitable for describing the solvatochromic shifts of the fluorescence emission. These are dominated by polarity/polarizability effects, as confirmed by quantum-chemical calculations performed in the dielectric continuum approximation. Fluorescence decay profiles of the dye can be described by a single-exponential fit in most solvents investigated, while two decay times are found in alcohols. The dye undergoes a reversible protonation-deprotonation reaction in the acidic pH range with a pKa of 2.25 in acetonitrile solution. Fluorimetric titrations as a function of pH produce fluorescence emission enhancements at lower pH. The fluorescence excitation spectra show a hypsochromic shift from 600 nm for the neutral amine to 553 nm for the ammonium form, so that ratiometric measurements can be used to determine pK(a).
ISSN: 1089-5639
Publication status: published
KU Leuven publication type: IT
Appears in Collections:Molecular Design and Synthesis
Molecular Imaging and Photonics
× corresponding author
# (joint) last author

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