Red fluorescent monobenzo-BODIPY dyes: Solvent effects on spectra and efficient fluorescence quenching by quinones and phenols

• Monobenzo-BODIPY dyes emit bright red fluorescence (wavelength >605 nm).
• Monobenzo-BODIPY dyes show high fluorescence quantum yields (Φf ≥ 0.60).
• Monobenzo-BODIPY dyes have long fluorescence lifetimes (τf ∼ 5 ns).
• The fluorescence properties are not remarkably affected by solvent polarity.
• Quinones quench their fluorescence with large rate constants (1010 L mol−1 s−1).

The fluorescence properties of five monobenzo-BODIPY compounds were measured in nonpolar and polar solvents by UV–vis absorption, steady-state fluorescence and time-correlated single-photon counting methods. These monobenzo-BODIPY dyes emit bright red fluorescence (wavelength >605 nm) with high fluorescence quantum yields (Φf ≥ 0.60) which are slightly affected by solvent polarity. The fluorescence lifetimes of these BODIPY compounds are also long (τf ∼ 5 ns) and not affected remarkably by solvent polarity. These fluorescence properties make them good fluorescent markers/probes in the red visible region. Quinones can efficiently quench the fluorescence of monobenzo-BODIPYs with the dynamic quenching rate constants in the order of 1010 L mol−1 s−1, suggesting that the BODIPY compounds can act as good electron donors for photoinduced electron transfer in artificial photosynthesis and organic solar cells.

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