Synthesis and Mesomorphism of Octaalkyl-Substituted Phenanthrene-9, 10-dionedioximato Complexes with Nickel, Palladium and Platinum

Abstract

In this communication we describe the synthesis of 2,3,6,7-tetra-n-alkyl-substituted phenanthrene-9, 10-dionedioximes (with n = hexyl and decyl) and their complexation to the metals nickel, palladium and platinum to yield the corresponding complexes as amphi-and anti-isomers. The thermal behavior of these complexes was investigated by polarizing microscopy, differential scanning calorimetry and X-ray diffraction. The anti-complexes form discotic rectangular disordered columnar (D_rd) and discotic hexagonal disordered columnar (D_hd) mesophases, whereas the amphi-isomers do not exhibit mesomorphism. The amphi-complexes can be isomerized to anti-complexes either thermally or by treatment under acidic conditions.

Key Words:

• Transition metal complexes
• metallomesogens
• discotic columnar mesophases.