Experimental and theoretical studies on oligomer formation of N-confused porphyrin-zinc(II) complexes.

Dimer formation of the N-confused porphyrin zinc(II), cadmium(II), and mercury(II) complexes was investigated experimentally as well as theoretically. The stable dimers were formed through coordination of the peripheral nitrogen atoms owing to flexible rotation of the confused pyrrole rings. The Z dimers were significantly more stable than the E dimers likely due to pi-pi interaction between the two confused pyrrole rings. The possible formation of higher oligomers such as trimers was suggested in the case of meso-unsubstituted derivatives.