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Banana‐Shaped Mesogens: Odd‐even Effect in Dimeric Twins
Author(s) -
Hsieh ChungChing,
Liu KwangTing,
Lai Chung K.
Publication year - 2006
Publication title -
journal of the chinese chemical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.329
H-Index - 45
eISSN - 2192-6549
pISSN - 0009-4536
DOI - 10.1002/jccs.200600185
Subject(s) - mesogen , chemistry , differential scanning calorimetry , crystallography , mesophase , liquid crystal , phase (matter) , carbon 13 nmr , stereochemistry , organic chemistry , liquid crystalline , physics , optics , thermodynamics
The synthesis, characterization, and mesomorphic properties of a series of homologue compounds 1 derived from salicylaldehydes are reported. These compounds were characterized by 1 H, 13 C‐NMR spectroscopy and elemental analysis. The phase behavior of these mesogenic compounds was characterized and studied by differential scanning calorimeter (DSC) and polarization optical microscope. All compounds 1 were found to be mesogenic, and the mesophases were dependent of the carbon length of the spacer group. The results indicated that all compounds with an even‐carbon spacer (m = 2, 4, 6, 8) exhibited smectic C phases; however, all other compounds with an odd‐spacer (m = 3, 5, 7) formed banana phases. The difference in phase behavior was attributed to the dependence of the molecular shape and/or geometry on the parity of the central spacer when considered in the all‐ trans ‐conformation. The formation of the mesophases was related to the optimized conformation of the compounds. The most stable optimized geometry was also simulated by the semi‐empirical Spartan ′04 version 1.0.0/AM1 method.