The absorption and fluorescence emission properties of 1a, pyrene and anthracene dyads 1b and 1c, respectively, are presented in Figure and summarized in Table . It should be noted that the observed photoluminescence emission is concentration dependent: bathochromic shift of up to 15 nm was observed both for reference BODIPY and for the studied donor acceptor dyads when increasing the dye concentration (Figure ); similar behaviour was previously observed for J-aggregates forming BODIPYs. The absorption spectra show transitions associated with the two subunits, indicating weak coupling of the chromophores in the ground state. Upon changing the solvent polarity, the shape and maxima of the absorption undergo little change (Figure ), but the emission properties are greatly affected. Figure shows the emission spectra of pyrene dyad 1b in different solvents. In THF the local exciton (LE) peak appears at 516 nm, and is accompanied by broad band centred at 634 nm. This second signal can also be seen in the emission spectrum in EtOH, further red-shifted to 672 nm. These bands are not seen in the emission spectra of 1b in toluene or hexane, indicating that the energy of the corresponding excited state strongly depends on the solvent polarity. The appearance of these broader signals is accompanied by a remarkable drop in emission intensity and quantum yield to 0.002 in THF and 0.015 in EtOH.