SYNTHESIS AND MESOMORPHIC PROPERTIES OF DEUTERATED 4-N-PENTYLPHENYL-4'-N-ALKOXYTHIOBENZOATES (7)OVER-BAR-S5-D(26) AND (8)OVER-BAR-S5-D(28)

Specifically deuterated liquid crystals, 4-n-pentylphenyl-4'-n-aikoxyt hiobenzoates (($) over bar nS5) with n = 7(($) over bar 7S5-d(26)) and n = 8(($) over bar 8S5-d(28)) were synthesized by esterification of t he chain perdeuterated 4-n-heptyloxy and 4-n-octyloxybenzoyl chlorides with the chain perdeuterated 4-n-pentylbenzene-thiol. The mesomorphic properties of the deuterated ($) over bar 7S5-d(26) and ($) over bar 8S5-d(28) were determined by DSC. Phase transition temperatures as wel l as their enthalpy and entropy Values were almost always lower than t he respective values for the non-deuterated analogues.