Jump to main content
Jump to site search

Issue 7, 2003
Previous Article Next Article

Substituent effects in columnar β-diketonate metallomesogens

Author affiliations

Abstract

A systematic study of the mesomorphic properties of two homologous series of copper(II) and palladium(II) complexes 1ab derived from unsymmetrical β-diketonate derivatives 2 containing a variety of functional substituents (X = H, CH3, C2H5, OCH3, Cl, Br, I, CN) on the phenyl ring is reported. These disc-like molecules all contain eight n-octyloxy chains, required for the formation of columnar phases appended to the central β-diketonate core. All complexes exhibited columnar phases studied by differential scanning calorimetry, polarized optical microscopy and powder X-ray diffraction. The mesomorphic results indicated that all compounds formed stable enantiotropic columnar mesophases, and the formation of columnar phases was strongly dependent on the electronic and/or the steric factors of the substituents. For compounds containing bulky substituents (i.e. X = Me, Et) a rectangular columnar phase (Colr) was observed, however, other compounds containing electron-withdrawing substituents (i.e. X = Cl, Br, I) exhibited a hexagonal columnar phase (Colh). Most of the palladium(II) complexes, except for X = CH3 and OCH3 derivatives, have lower clearing temperatures than those of the copper(II) analogues, and this is probably due to a weaker molecular interaction between the cores in the palladium(II) complexes. Lattice constants for these two types of compound obtained by powder X-ray diffraction were found to be insensitive to the metal center incorporated. These values were all relatively close in magnitude, which indicated that the two structures were quite similar. A satisfactory linear relationship with a correlation coefficient of 0.974 between the clearing temperatures and the Hammett σp constants of substituents was obtained only for the copper complexes.

Graphical abstract: Substituent effects in columnar β-diketonate metallomesogens

Back to tab navigation

Supplementary files

Publication details

The article was received on 12 Mar 2003, accepted on 29 Apr 2003 and first published on 16 May 2003


Article type: Paper
DOI: 10.1039/B302858E
Citation: J. Mater. Chem., 2003,13, 1588-1595

  •   Request permissions

    Substituent effects in columnar β-diketonate metallomesogens

    C. Chien, K. Liu and C. K. Lai, J. Mater. Chem., 2003, 13, 1588
    DOI: 10.1039/B302858E

Search articles by author

Spotlight

Advertisements