Impact on the mesophase transition temperatures of 1,4-bis(naphthyl)-1,3-butadiyne of the attachment of terminal alkoxy chains

The synthesis of 1,4-bis(2-naphthyl)-1,3-butadiynes, containing terminal alkoxy chains, is reported. The mesomorphism of these compounds has been characterized by differential scanning calorimetry and polarizing optical microscopy. The introduction of terminal alkoxy chains, significantly lowers the melting temperature of the analogous core without terminal chains. The induction of a smectic phase occurred when two decyloxy chains were attached. The solid state structures and packing arrangements of the butyloxy derivative and the chainless core were determined by single crystal X-ray diffraction, and revealed greater layer interpenetration for the substituted material.