A series of brominated mono-methano[60]fullerene malonate derivatives (two diads and one triad) are investigated for intramolecular and external heavy-atom effects on their fluorescence. Significant internal and external heavy-atom effects are observed in the three cases. It is shown that the internal effect doubles when going from the diads to the triad. In bromobenzene and in iodobenzene, the external effect is predominant, and diads and triad behave identically.