Phthalimides are electron deficient aromatics. They often serve as acceptors in donor acceptor conjugates for photo induced electron transfer. Surprisingly, the photo-physics of this important chromophore has not been studied in detail yet. Here, in a collaborative effort involving groups from Cologne (Axel Griesbeck) and Düsseldorf (Peter Gilch and Oliver Weingart), the response of the phthalimide chromophore on photo-excitation was scrutinized by time resolved spectroscopy and quantum chemistry. Based on the results, the large Stokes shift of phthalimides and their solvent dependent fluorescence decay can be explained. Read more in 10.1039/C8CP07795A.