Abstract
Four homologous series of non-symmetric linear liquid crystalline trimers, the 4-[(4-{n-[4-(4-methoxy-phenylazo)phenoxy]alkyloxy}benzylidene)amino]benzoic acid 6-[4-(4-methoxyphenylazo)phenoxy]hexyl esters, 4-[(4-{n-[4-(4-cyanophenylazo)phenoxy]alkyloxy}benzylidene)amino]benzoic acid 6-[4-(4-methoxyphenylazo)phenoxy]hexyl esters, 4-[(4-{n-[4-(4-methoxyphenylazo)phenoxy]alkyloxy}benzylidene)amino]benzoic acid 6-[4-(4-cyanophenylazo)phenoxy]hexyl esters and 4-[(4-{n-[4-(4- cyanophenylazo)phenoxy]butoxy}benzylidene)amino]benzoic acid 6-[4-(4-cyanophenylazo)phenoxy]hexyl esters, have been synthesized and characterized. In each series one spacer was held constant while the length of the second was varied from 3 to 12 methylene units. All these trimers were nematogenic and exhibited pronounced odd-even effects in both their clearing temperatures and associated entropies. Only two of the trimers exhibited a smectic phase, and specifically those containing two differing terminal mesogenic groups and an undecyl spacer. This strongly suggests the driving force for smectic phase formation is a combination of molecular shape and a specific interaction between unlike mesogenic units. The smectic phase has been assigned as a triply-intercalated alternating smectic C phase, the first example of its kind.
Original language | English |
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Pages (from-to) | 673-682 |
Number of pages | 9 |
Journal | Liquid Crystals |
Volume | 32 |
Issue number | 6 |
DOIs | |
Publication status | Published - Jun 2005 |
Keywords
- smectic-C-phase
- mesophase properties
- oligomers
- polymers
- lengths
- dimers