We describe the spectroscopic characterization of a supramolecular trisporphyrin complex that is heterogeneously self-assembled onto mesoporous Al₂O₃ films and can be used as efficient light harvesting complex. The parameters for an efficient complexation process, such as dye loading, are evaluated and discussed. In addition, the heterosupramolecular complex is tested on TiO₂ nanoparticles and the charge transfer process elucidated.