Ionic hexagonal columnar metallomesogens derived from tetrabenzo[b,f,j,n][1,5,9,13] tetraazacyclohexadecine

A series of transition metal (Ni, Cu, Pd) complexes derived from macrocycli c tetrabenzo[b, f, j, n][1,5,9,13]tetraazacyclohexadecine (TAAB) was synthe sized and their mesomorphic properties studied by differential scanning cal orimetry, polarized optical microscopy and X-ray powder diffraction (XRD). These compounds have eight alkoxy side chains attached around the central m olecular core and form disc-like molecules. All the derivatives exhibited c olumnar mesophases over a wide range of temperature. The mesomorphic behavi our was found to be dependent on the incorporated metal and the carbon leng th of the alkoxy side chains. The clearing temperatures decreased in the or der M = Ni > Pd > Cu; this decrease was probably due to the size of the met al ions. Some derivatives with shorter side chains (n = 10, 12) were room t emperature liquid crystals. All compounds were found to exhibit hexagonal c olumnar (Col(h)) phases which were confirmed by powder XRD.