An octacationic diazaperopyrenium (DAPP(2+))-based homo[2]catenane (DAPPHC(8+)), wherein no fewer than eight positive charges are associated within a mechanically interlocked molecule, has been produced in 30% yield under ambient conditions as a result of favorable homophilic interactions, reflecting a delicate balance between strong pi-pi interactions and the destabilizing penalty arising from Coulombic repulsions between DAPP(2+) units. This DAPPHC(8+) catenane is composed of two identical mechanically interlocked tetracationic cyclophanes, namely DAPPBox(4+), each of which contains one DAPP(2+) unit and one extended viologen (ExBIPY(2+) unit, linked together by two p-xylylene bridges. The solid-state structure of the homo[2]catenane demonstrates how homophilic interactions play an important role in the formation of DAPPHC(8+), in which the mean ring planes of the two DAPPBox(4+) cyclophanes are oriented at about 60 with respect to each other, with a centroid-to-centroid separation of 3.7 angstrom between the mean planes of the outer ExBIPY(2+) and inner DAPP(2+) units, and 3.6 angstrom between the mean planes of the two inner DAPP(2+) units. We show that irradiation of the DAPPHC(8+) catenane at 330 nm in acetonitrile solution results in simultaneous energy and electron transfer. The latter occurs from the inner DAPP(2+) dimer to the outer ExBIPY(2+) unit, leading to the generation of a temporary charge-separated state within a rigid and robust homo[2]catenane. Compared to DAPPBox(4+), both forward- and back-electron transfer in DAPPHC(8+) occur with faster rates, owing to the closer proximity between the electron donor and acceptor in the homo[2]catenane than in the separated cyclophane.