Two new series of columnar discotic liquid crystalline materials based on a tristriazolotriazine (TTT) core connected to three pendant hexyloxytriphenylene or pentafluoropentyloxytriphenylene groups via a flexible alkyl spacer are synthesised and investigated. It is found that the mesophase stability is very much dependent on the spacer length. For a short spacer length (propyl or butyl), Colh phases are found in which the disc-like moieties are randomly mixed in the columns. For one compound with a pentyl spacer and pentafluoropentyloxy tails on the triphenylene groups, a Colob phase is found in which the columns of triphenylenes and TTT moieties are separated. When the spacer is longer (hexyl), the liquid crystallinity is lost. The compounds with pentafluoropentyloxy tails on the triphenylene units have a higher thermal stability than those with hexyloxy tails.