We have prepared two series of hexasubstituted triphenylene derivatives : hexaethers from CH3 to C13H27 and hexaesters from C3H7 to C13H27. Most of them exhibit a thermotropic mesophase with a large temperature range. We have found the existence of an additional transition within the mesophase domain of some hexaesters with long alkyl chains. The structure of this new type of liquid crystal is discussed with respect to ours results concerning miscibilities and heat of transition