A series of homologous symmetrical dimers N,N'-bis[(3-methoxy-4-alkoxybenzylidene)-1,4-phenylenediamine with different lengths of terminal alkyl groups of even parity ranging from butyl to octadecyl were prepared and characterized. Spectroscopic methods FT-IR, H-1 NMR, and C-13 NMR and mass spectrometry were carried out to determine the physical properties of the target compounds. The texture with respect to each compound within this series has been investigated along with their thermal stabilities. A diversity of phase-transition behavior was observed for the members of this series and explanation was given based on the possible molecular conformation. Almost all title compounds were nematogenic except the dimers containing butyl and hexyl chains as well as the longest octadecyl dimer in which the mesogenic properties were absent.