Browsing by Author "Ong, Lay Khoon"

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Synthesis and mesomorphic properties of new Schiff base esters with different alkyl chains
(2009-07-01)
Ha, Sie Tiong
;
Ong, Lay Khoon
;
Ong, Siew Teng
;
Yeap, Guan Yeow
;
Wong, Joanna Pik Wan
A new series of Schiff base esters, 4-(dimethylamino)benzylidene-4'-alkanoyloxyanilines containing even number of carbons at the end group of the molecules (C(n-1)H(2n-1)COO, n = 6, 8, 10, 12, 14, 16, 18) were synthesized. The present compounds were monotropic liquid crystals. It was also found that the end groups of the molecules had effect on the mesomorphic properties. (C) 2009 Sie Tiong Ha. Published by Elsevier B.V. on behalf of Chinese Chemical Society. All rights reserved.
Synthesis and mesomorphic properties of Schiff base esters possessing terminal chloro substituent
(2010-06-01)
Ha, Sie Tiong
;
Ong, Lay Khoon
;
Lee, Siew Ling
;
Lin, Hong Cheu
;
Win, Yip Foo
A homologous series of Schiff base esters, 4-chlorobenzylidene-4'-n-alkanoyloxyanilines, containing even number of carbons at the end groups of the molecules (C(n-1)H(2n-1)COO-, n = 4, 6, 8, 10, 12, 14, 16) were synthesized. The mesomorphic properties were investigated by differential scanning calorimetry (DSC) and polarizing optical microscopy (POM). It was found that the end groups of the molecules had an effect on the mesomorphic properties. n-Butanoyloxy was found non-mesogenic, whilst n-hexanoyloxy exhibited monotropic smectic phase. The higher members in this homologous series were enantiotropic smectogens. (C) 2010 Sie Tiong Ha. Published by Elsevier B.V. on behalf of Chinese Chemical Society. All rights reserved.