Columnar Discotic Mesophases from Novel Non-symmetrically Substituted (Octylsulfanyl) Porphyrazines

Abstract

Synthesis and mesomorphism of novel non-symmmetric mono β-aryl (octylsulfanyl)porphyrazines and their Ni(II) complexes were reported. A recently disclosed asymmetrization procedure led to mono β-bromo substituted porphyrazines, which provided access to aryl substituted derivatives through Suzuki cross-coupling. UV-Vis spectroscopy showed a bathochromic shift for bromine and aryl substituted nickel complexes. Optical Microscopy and DSC showed that Br derivatives 3a–3b and H-heptakis Ni(II) complex 2b display two columnar mesophases (Col_h and Col_r) stable even at RT and a wide ΔT (100°C). Introduction of the aryl substituent on the macrocycle caused the appearance of only the Col_h mesophase and lower ΔT.

Keywords:

• columnar discotic mesophase
• non-symmetric porphyrazines
• Suzuki cross-coupling

Acknowledgments

Dedicated to late Professor Augusto Sirigu

This work has been supported by the Italian Ministero dell'Istruzione, dell'Università e della Ricerca PRIN 2005 200503527 grant.

Notes

^a First line report transition temperatures measured on heating, second line report temperatures on cooling. K = solid, M = unidentified mesophase, Col_r = columnar rectangular mesophase, Col_h = columnar hexagonal mesophase, I = isotropic liquid.

^b Data taken from ref. [2].

^c Data taken from ref. [7].