Discotic liquid-crystalline materials based on porphycenes: A mesogenic metalloporphycene–tetracyanoquinodimethane (TCNQ) adduct

Stępień, M.; Donnio, B.; Sessler, J. L.
Chem. Eur. J. 2007, 13, 6853–6863 | view at publisher's site

A number of substituted zinc(II) porphycenes and porphyrins have been synthesized as potentially mesogenic materials. One of the resulting porphycenes, bearing eight decyloxy chains, exhibits two mesophases, a transient lamellar phase (Lam) and a highly ordered lamello-columnar phase (LCol), with remarkably different structural characteristics. The same zinc(II) porphycene also forms an electron donor-acceptor (EDA) complex with tetracyanoquinodimethane (TCNQ), generating a hexagonal columnar mesophase (Colh) that is thermally stable up to ca. 200 °C. The EDA interaction between porphycene and TCNQ has been probed using electronic and vibrational spectroscopy. A mixture of zinc(II) porphyrins, isomeric with the above porphycene complex, forms a rectangular columnar mesophase (Colr).