of freedom to be considered. This is due to the activation of the rotation of the malonitrile moiety in the excited state, which may be regarded as a consequence of consecutive isomerizations of the =C(CN)2 double bond. Coherently with what was already observed for 4a and CC, the inclusion of a donor group in 4d only slightly modifies the topology of the PES (Figure ). In particular we can observe that the isomerization of the ethynyl double bond is possible through a conical intersection which can be reached on both the nπ* and the ππ* state. However, the path going through the latter state appears more favorable and should result in a faster process and higher efficiency.