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Abstract:
Introduction of the dialkylaminophenyl group in position 7 of
3
‑
hydroxychromone changes the orientation of the excited-state dipole moment and
leads to superior solvatochromic properties (>170 nm emission shift in aprotic media).
The excited-state intramolecular proton-transfer (ESIPT) reaction of 7-aryl-3-hydrox-
ychromones is almost completely inhibited in most solvents. Methylation of the 3-OH
abolishes ESIPT completely and also leads to improved photostability. The probes exhibit
a
∼
100-fold increase in fluorescence intensity and large Stokes shifts upon binding to
membranes, reflecting differences in membrane phase and charge by a >40 nm spread in the emission band position.