TG and DTA studies of [Cu-2(OOCCnH2n+1)(4)(nia)(2)] (nia = nicotinamide; n = 6-11) and [Cu-2(OOCCnH2n+1)(4)(Et(2)nia)(2)] (Et(2)nia = N,N-diethylnicotinamide; n = 6-11) are reported. The influence of the ligands in these complexes on the solid-to-liquid crystalline phase transition is established. Solid-to-solid, solid-to-liquid crystalline and liquid crystalline-to-isotropic liquid phase transitions are confirmed for the compounds with nia ligand [(Cu-2(OOCCnH2n+1)(4)(nia)(2)] (n = 10, 11) by variable temperature X-ray diffraction analysis and polarized optical microscopy. Only melting points are detected in all complexes with the Et(2)nia ligand.