Photophysics of 3,5-diphenoxy substituted BODIPY dyes in solution

Abstract

We have prepared two fluorescent dyes derived from 8-(4-tolyl)-4,4-difluoro-4-bora-3a,4a-diaza-s-indacene with phenoxy and (o-bromo)phenoxy substituents at the 3,5-positions by a novel nucleophilic substitution reaction of the corresponding 3,5-dichloroBODIPY analogue. UV-vis absorption, steady-state and time-resolved fluorimetry have been used to investigate their solvent-dependent photophysical properties. The two BODIPY derivatives show narrow absorption and emission bands and display small Stokes shifts. The substituents at the 3,5-positions (phenoxy in 1 and o-bromophenoxy in 2) have a minor effect on the fluorescence quantum yields (0.16–0.40 for 1, 0.17–0.44 for 2) and lifetimes (1.09–2.51 ns for 1, 1.11–2.78 ns for 2). For both compounds, the fluorescence rate constant equals (1.5 ± 0.1) × 10⁸ s⁻¹.