The synthesis and photophysical evaluation of new chlorin derivatives are described. The Diels–Alder reaction between protoporphyrin IX dimethyl ester and substituted maleimides furnishes endo-adducts that completely prevent the self-aggregation of the chlorins. Fluorescence, resonant light scattering (RLS) and 1H NMR experiments, as well as X-ray crystallographic have demonstrated that the configurational arrangement of the ...