Abstract The synthesis and energy-transfer properties of a series of oligo (p-phenylene ethynylene)–BODIPY (OPEB) cassettes are reported. A series of oligo (p-phenylene ethynylene) s (OPEs) with different conjugated chain lengths as energy donor subunit in the energy-transfer system were capped at both ends with BODIPY chromophores as energy- acceptor subunits. The effect of the conjugated chain of OPEs on energy transfer in the ...