Supramolecular orientation of conjugated porphyrin oligomers in stretched polymers

Conjugated porphyrin oligomers show strong optical dichroism when oriented in a stretched polymer matrix. It is shown that the zinc porphyrin polymer (∼10 repeat units) aligns, as expected, with its backbone in the stretch direction, whereas the dimer orients with its molecular plane perpendicular to the stretch. This anomalous behavior is explained as being due to the formation of supramolecular stacks that orient as single units.