Novel preparation of β,β′-connected porphyrin dimersElectronic supplementary information (ESI) available: experimental procedures employed in Scheme 1, ORTEP drawing of 3 and a ball and stick model of 3 showing hydrogen bonding. See http://www.rsc.org/suppdata/cc/b1/b108819j

Porphyrin dimers were prepared from β,β′-dipyrrole derivatives via the double pyrrolylmethylation followed by double [2+2] MacDonald porphyrin synthesis.