Alkyloxy-substituted CTTV derivatives that exhibit columnar mesophases

Abstract

The homologous series of 2,3,6,7,10,11,14,15-octaalkyloxytetrabenzo[a,d,g,j]cyclododecatetraenes (CTTV-n) containing n= 4–15 methylenic units in the alkyloxy substituents has been prepared both by alkylation of octhydroxytetrabenzocyclododecatetraenes (CTTV-OH), and by cyclotetramerization of the corresponding 3,4-(dialkyloxy)benzyl alcohols using excess CF₃CO₂H. CTTV-4 is crystalline. All other compounds display an enantiotropic columnar mesophase in addition to melting and crystallization transitions. The phase-transition temperatures of the CTTV-n compounds prepared by cyclotetramerization are lower than those synthesized by etherification of CTTV-OH. Melting and isotropization temperatures decrease in a continuous manner as n increases, without any odd–even alternation.