Effect of Alkyl Chain Length on Mesomorphic Phase Transition Behaviour of Long-Chain Tetraphenylporphyrin Aluminium(III) complexes

Abstract

Hydroxo[5,10,15,20-tetrakis(4-n-dodecylphenyl)porphinato]aluminium(III) was found to exhibit D_hd mesophase,while the another square planar metalloporphyrins anologues show only lamellar type mesophases, and it was indicated the axial OH group could significantly contribute to formation of stacking clomns. In this work, it was shown that the phase transitions of the homologues (C₇ - C₁₀) strongly depend on the alkyl chain length. Especially, mesomorphism of the μ-oxo-dimer derived from the monomer Al(OH) complex is likely to drastically change with the alkyl length, the heptyl, octyl and nonyl derivatives showed different phase sequence from those of the decyl,dodecyl and hexadecyl ones.