| Autor: |
Prajapati, A. K., Pandya, H. M. |
| Předmět: |
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| Zdroj: |
Liquid Crystals; Apr2009, Vol. 36 Issue 4, p371-377, 7p, 1 Diagram, 4 Charts, 2 Graphs |
| Abstrakt: |
In this paper, we present the synthesis and characterisation of two new mesogenic homologous series, β-chloroethyl 4-(4'-n-alkoxyphenylazo) benzoates (I) and the β-chloroethyl [4-(4'-n-alkoxybenzoyloxy)phenylazo]-4”-benzoates (II), containing a terminal β-chloro ethyl chain. Series I was synthesised by alkylation of β-chloroethyl 4-(4'-hydroxy phenylazo) benzoate with an appropriate alkyl halide, whereas series II was synthesised by esterification of β-chloroethyl 4-(4'-hydroxyphenylazo) benzoate with an appropriate 4-n-alkoxybenzoic acid. The molecular structures of these new compounds of both the series were characterised by combination of element analysis and a standard spectroscopic method. The mesomorphic behaviour was studied mainly by use of a polarised microscope and, in some cases, differential scanning calorimeter as well. In series I, all nine members synthesised exhibited only an enantiotropic smectic A mesophase. In series II, all 12 homologues exhibited an enantiotropic nematic mesophase; a smectic A phase appeared in the n-octyloxy derivative as an enantiotropic phase and persisted through to the n-hexadecyloxy member. The mesomorphic properties of both series were compared with each other and also with the properties of other structurally related series to evaluate the effects of the β-chloroethyl tail on mesomorphism. [ABSTRACT FROM AUTHOR] |
| Databáze: |
Complementary Index |
| Externí odkaz: |
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