Exciplex-like emission from a closely-spaced, orthogonally-sited anthracenyl-boron dipyrromethene (Bodipy) molecular dyad

Abstract

A molecular dyad, ANTBD, has been prepared that incorporates a boron dipyrromethene (Bodipy) group functionalized at the meso position with an anthracenyl unit. Emission from the dyad contains contributions from both localized fluorescence from the Bodipy unit and exciplex-like emission associated with an intramolecular charge-transfer state. The peak position, intensity and lifetime of this exciplex emission are solvent dependent and the shift in the emission maximum shows a linear relationship to the solvent polarity function (Δf). The calculated dipole moment for the exciplex is 22.5 ± 2.2 D. The radiative rate constant (kRAD) for exciplex emission decreases progressively with increasing solvent polarity. In this latter case, kRAD shows an obvious dependence on the energy gap between the exciplex state and the first-excited singlet state resident on the Bodipy unit. The emission characteristics for ANTBD dissolved in perfluorooctane are used to characterize the refractive index and dielectric constant of the solvent. © 2010 The Royal Society of Chemistry and Owner Societies.