The synthesis of mesomorphic Cu(II) and Ni(II) coordination compounds arising from a new series of tetradentate Schiff bases containing two salicylaldimine fragments connected by a very long spacer,-(CH(2))(12-), (H(2)L(n)): L(1) = p-(C(6)H(13)O)-C(6)H(4)COO, L(2) = p-(C(12)H(25)O)-C(6)H(4)COO, is described. The self-assembly and liquid-crystalline properties of these complexes have been investigated by variable temperature powder X-ray diffraction and the relationship between the global molecular shape and the mesogenic performances is discussed. The reported Cu(II) compounds are molecular materials which could be of interest for applications in the field of magnetic molecule-based devices.