The treatment of MWCNTs with the water-soluble cobalt octacarboxyphthalocyanine derivative theraphthal under ultrasonic conditions led to the dispersion and unfolding of MWCNTs, producing onion-like carbon nanostructures and graphene sheets. This differs from the conventional concepts of classic π–π stacking interactions and/or σ-bonding between macrocycles and carbon nanotubes, as well as differing from the classic high-temperature formation of carbon nano-onions.