Fulgides as switches for intramolecular energy transfer

In a molecular unit which is a donor-fulgimide-acceptor triade, the possibility of an intramolecular energy transfer from donor to acceptor depends upon the isomer configuration of the photochromic fulgimide. It is shown that a switching on and off of this intramolecular energy transfer is possible by photoinduced shifting of the fulgimide levels between a trap and an antitrap function.